Volume
15 Number 4 November 1999
IN THIS ISSUE:
YOUNG PEOPLE HELP EACH OTHER AGAINST IODINE DEFICIENCY
Iodine deficiency has its most devastating effects on the young, because they need iodine for proper mental and physical development. Mindful of the staggering loss of human potential from iodine deficiency, governments, international agencies, and other groups have accelerated their efforts during the past decade to correct it. Groups with a special concern for children, such as UNICEF and Kiwanis, have made IDD elimination a major focus.
Young people participate actively in the fight against IDD. Children in the Community Vacation Bible School in Fowler, Colorado, USA (upper left photo), having learned that many children in Africa are threatened by iodine deficiency, elected to contribute through ICCIDD to help. Children in Zimbabwe (lower photo) are the beneficiaries of these and other national and international efforts.
A tradition in the United States on Halloween (October 31) is for children in costume to go from door to door saying "Trick or Treat" and receiving candy or fruit. In a variation on this custom, two students of the Charlottesville High School Key Club (part of Kiwanis) Charlottesville, VA, USA, at a neighborhood door, (upper right photo) ask for money to help fight IDD; the donations are channeled through UNICEF.
THE IDD PROGRAM IN VENEZUELA
At the request of the Ministry of Health and Social Development, a group of experts met in Caracas, November 8-12, 1999 to evaluate the IDD program. The team was led by Dr. Eduardo Pretell, Regional Coordinator ICCIDD, and included Dr. Arnulfo Noguera, PAHO/WHO Consultant, Dr. Hans Vanhassel, of the Andean Subregional Program and UNICEF, and Ms. Ana Maria Higa and Ms. Ana Maria Vera, both program workers in the Ministry of Health of Peru. The group met the individuals responsible for the national program and visited different zones of the country to evaluate progress. They prepared a report and presented it to the Government in Caracas on November 12. The overall conclusion was that iodine deficiency is virtually eliminated in Venezuela and the prospects for its sustainability are very good if the program maintains its current momentum and reenforces some of its activities.
Organization - The country has had laws and technical standards since 1966, and these are periodically revised. The National Program for Control and Elimination of Iodine Deficiency (PRONACEDY) is located in the Technical Division of the National Institute of Nutrition. It provides supervision and support for all the states. The National Commission for Iodization and Fluoridation of Salt (CONYFLUSAL), an inter-institutional and multisectoral body, advises PRONACEDY. The government has provided human and financial resources for this effort, and it also receives support from international organizations, like PAHO, UNICEF, ICCIDD, and from private initiative.
The communication component is very important and has contributed to progress of the program. Sufficient material of high quality has been produced at both central and regional levels, particularly in the Andean region. The salt industry also contributes to the production and dissemination of information on iodized salt. The program has developed promotional activities and advocacy among political decision makers and has led the coordination among the inter-institutional, intersectoral, and private sector, giving special attention to the participation of the public.
Iodized salt - The estimated production of iodized salt covers the needs of the population, at 5 kg/person year. Fourteen production plants exist; of these, three large ones cover 75% of the annual output. Laboratories for internal quality control in the plants are being improved, with the support of PRONACEDY in cooperation with the University of the Andes of Merida and the Programa Subregional Andino de Micronutrientes. Salt monitoring shows that more than 90% of samples at the retail level have an iodine content equal to or greater than 15 mg/kg (ppm), sustained since 1997, and results at the national level are similar. At the household level 94% consume adequately iodized salt. These results conform to the recommendations of international organizations.
Impact - Urinary iodine concentration, the principal indicator of adequate consumption of iodized salt, has been examined annually since 1993, initially in Merida and subsequently in Trujillo in 1994 and Tachira in 1995, the three Andean states at risk for iodine deficiency. A national study took place in 1998. The regional results showed an increase in the median of 133 mcg/L in 1993-1996 to 187 mcg/L in 1999. During the same interval, the proportion of samples with a concentration less than 50 mcg/L decreased from 16.5% to 2.4%. In the last survey, all the medians were above 100 mcg/L, the minimal value for iodine sufficiency as defined by ICCIDD, WHO, and UNICEF. The results from sentinel sites in 1999 have been confirmed by those from the ThyroMobil project, conducted by ICCIDD in the same year. The 1998 national survey showed a median of 171 mcg/L, with 14.5% of samples less than 50 mcg/L and 7 of 137 communities (5%) with a median less than 100 mcg/L. Although goiter by palpation is a less valuable indicator, it has also diminished, from 63.5% in 1993-1995 to 30% in 1999. The evaluation of thyroid size by ultrasonography in the ThyroMobil project showed a value significantly lower and concluded that endemic goiter no longer persists in the Andean regions.
Monitoring and evaluation - The program systematically monitors iodine in salt and urine. Since 1996, the iodine content of salt is checked at the point of retail throughout the country, with emphasis on the three Andean states. In 1998, the program also evaluated salt qualitatively at the household level. Monitoring at the plant level is irregular, and a systematic information system does not exist. The National Institute of Nutrition and the National Institute of Hygiene Rafael Rangel analyze salt samples. The results are transmitted to the producers and the state health authorities within two or three months. Systematic monitoring of urinary iodines has been in place since 1993 in the three Andean states, and in the National Evaluation of 1998. All samples from the program are analyzed in the Chemistry Department of the Faculty of Sciences of the University of the Andes. The laboratories that analyze iodine in salt and urine use internationally recommended methods and apply systematic monitoring.
Sustainability - Many factors favor the program's sustainability, especially: (a) a clear political mandate reflected in legislation and the sustained maintenance of a national program with guaranteed funding by the government (80%), which assures an effective system of monitoring; (b) the commitment of the salt industry to produce and distribute adequately iodized salt that will satisfy the country's need; (c) a professionally competent and dedicated national team; and (d) sensitization of the public to demand iodized salt. However, since that iodine deficiency is a permanent natural phenomenon that could recur, a successful future will be assured only if these strengths continue.
Recommendations - The expert group recommended that political support for the program should be maintained and strengthened. The National Institute of Nutrition and the Division of Food and Hygiene should coordinate their activities in salt iodization control and should make sure that the information they obtain is used appropriately to monitor, evaluate, and make decisions in different parts of the program. The technical and administrative procedures for authorizing the use of noniodized salt in industry and iodized salt for food should be standardized, applied, and supervised. The program should develop a plan for education of health personnel and other sectors and institutions involved in relevant technology for prevention and control of IDD. The official sector and the salt industry should coordinate promotional activity on IDD prevention.
For iodized salt, a system of registering producers should be established and an estimate made of the daily salt intake by the consumer. To guarantee the reliability of results from these analyses, all personnel involved should be properly trained, and experts in quality control should be retained. The implementation and development of a quality control system are the responsibility of the salt producers and require agreement for assuming the involved cost. Monitoring of the salt should be national, systematic, and representative, and a plan for it needs to be developed and provided the necessary resources.
Monitoring of urinary iodine in the sentinel posts should be revised to agree with the recommendations of ICCIDD/WHO/UNICEF, taking into account the proper designation of the sentinel post. The program should pay attention to trends in the urinary iodine concentration and make necessary adjustments in the quantity of iodine added to the salt. The program should also seek the sustained participation of international reference laboratories for standardization of analytical methods for iodine in urine and salt.
For sustainability, the major challenge for the Venezuelan program is to maintain the current progress through a strong national program, regular monitoring, continued cooperation with salt producers and active participation by the public.
IODINE DEFICIENCY AND RELATED ISSUES: A PERSONAL HISTORICAL ACCOUNT
John B. Stanbury, M.D.
[Ed. note: This is one in a series of occasional articles by or about pioneers in IDD elimination. A recent Newsletter (15(2):22, 1999) summarized some of Dr. Stanbury's contributions to the study of IDD and to ICCIDD].
In 1948 Dr. J.H. Means, then Chairman of the Department of Medicine at the Massachusetts General Hospital, Boston, asked me to take responsibility for the Thyroid Unit beginning the following January. There were two aspects of the position: to manage the large flow of patients with thyroid diseases that flowed through the Clinic, and to conduct related research in the laboratory.
Not long afterwards, Dr. Means invited me to give a talk on the thyroid to a group of visiting physicians. I chose to describe the metabolic circuit of iodine, so that in preparing, I developed some knowledge of the various steps involved in production and fate of thyroid hormone. That summer a call from the Department of Pediatrics requested an opinion about a sixteen-year-old female with a huge goiter, growth retardation and profound mental deficiency B a cretin. Based on what I had learned about the various biochemical steps in the circuit of iodine through the gland, it seemed possible that organification of iodine, an oxidative step, might be at fault in this patient; I had in mind the famous Croonian lectures of Archibald Garrod in 1908 on the inborn errors of metabolism. It was possible to test this hypothesis by measuring the uptake of radioactive iodine in the gland and observing if it discharged rapidly after administering a competitive substance that would displace iodine not already fixed in organic form. Radioiodine accumulated extremely rapidly in the thyroid of this patient, and on administration of a small dose of the competing ion, thiocyanate, was equally rapidly discharged. Thus the disorder arose because the thyroid failed to perform its usual function of oxidizing iodide that allowed synthesis of thyroid hormone to proceed. Other members of her family were similarly affected, and this led to a long series of studies on other inherited disorders of the thyroid, and eventually to the compilation, with James Wyngaarden and Donald Fredrickson, of similar disorders in other systems in a monograph titled, "The Metabolic Basis of Inherited Disease." The book went through five editions over the next two decades. Later it was taken over by Dr. Charles Scriver of Montreal and his colleagues, and continues as a standard textbook.
It is interesting to reflect on that initial study. It was performed in one of the basement rooms of the ancient Bulfinch Building that housed the laboratory of the Thyroid Unit. Accumulation of radioiodine was followed with a hand-held geiger-muller detector and a hand-operated scaler. Thyroid scanning had not yet been invented, nor had a geometrically designed and calibrated apparatus been devised for exact measurements of uptake.
That early encounter with nodular goiter in a cretin was followed within a few months by a visit from Dr. Hector Perinetti, a surgeon from Mendoza in western Argentina. Much of his practice was the removal of disfiguring nodular goiters that were found in high prevalence in the Andean and sub-Andean region. He described the problem with dramatic photographs of his patients prior to surgery. My immediate reaction was that the phenomenon of endemic goiter needed study, with the then-new methods for measuring the blood concentration of thyroid hormone, the iodine in the urine, and the metabolism of iodine using the radioactive isotope. A plan of study was devised, funding raised by Dr. Means, and the research began in late June of 1951. I was joined by Dr. Douglas Riggs of the Department of Pharmacology at Harvard Medical School, his technician Ms. Eleanor Brown, Dr. Gordon Brownell, who had recently joined the Thyroid Unit from the Department of Physics at M.I.T., and Argentine colleagues, including Dr. Perinetti, Jack Itoiz and E. del Castillo. On our way to Mendoza we stopped to give talks in Lima under the sponsorship of Dr. Alberto Hurtado, a graduate of the Harvard Medical School and a leading authority on high altitude physiology. We also stopped for talks in Santiago before traveling across the Andes by cog railway to Mendoza. All our equipment was flown by the Argentine Air Force to Mendoza, where it was housed in a large suite of rooms in the Hospital das Clinicas of the University of Cuyo. The only piece of apparatus, including scalers, fragile stills and other glassware, that was damaged in transport was a thermometer.
At the hospital we set up and calibrated our radioiodine uptake device with a cadaver into whose neck we sewed a standard source in order to have a factor for back-scatter. After this, Dr. Perinetti provided us with as many thyroid patients as we could handle. There were almost daily visits from interested physicians from around the country. This activity was the first of its kind and the first to use radioiodine in the country. It was given huge coverage by the Argentine press, especially the regional newspaper, Los Andes, which carried an article almost every day highlighting the contribution of President Juan Peron in bringing this study about. Had we balked at all this publicity, our project would have been terminated. Among other diverting events was the frequent arrival of a group of photographers who illuminated their subjects with trays of flash powder that filled the room with smoke and dust. Meanwhile, Riggs set up his stills for measuring iodine in urine by the old distillation method. He had trouble for the first few weeks because one of his reagents was contaminated with iodine, which had never happened to him before. As he worked his stills, his hands became blue from the cold Argentine winter.
The hospital itself was an imposing structure. Once when walking along a corridor we looked in a door to see three adolescent boys standing around a bucket into which they were spitting blood. They had just had tonsillectomies. Once each week we indulged ourselves with a visit to an excellent local restaurant.
The publicity and attention we received and the noisy backing from the political regime were an annoyance, but served the purpose of gaining an astonishing measure of support from our subjects and their compliance with our need for forty eight hour or more collections of urine. To carry a bottle around town became a symbol generating respect from one=s fellow citizens.
Our first subject was a young Argentine woman with a nodular goiter. It was satisfying to see the monitoring lights on the scaler flash rapidly, just as in a patient with thyrotoxicosis back home. We were asked incidentally to treat a patient with thyrotoxicosis. She had two previous thyroidectomies and had recurrent disease. I recently heard that now, more than forty years later, she is still quite healthy.
Our hosts treated us extremely well. Our first luncheon was at the hotel where we were housed. As was the local custom, lunch was huge. We rebelled after this and had a light lunch served at the hospital, else we never could have completed our work. On two occasions I had to travel the six hundred miles to Buenos Aires to make a presentation to President Peron. At the end of our work we were flown in one of his planes to Bareloche in the southern Andes for a holiday in that magnificent part of the world, with crystal lakes surrounded by jagged snow-capped mountains. There we had lunch one day with the infamous Dr. Richter, who confided that he had a new method for producing fusion energy, the details of which he would not disclose. He subsequently disappeared and has not been heard of since. On the flight to Buenos Aires for our departure home the door of the plane came off. We returned to Boston with a thousand urine samples and some amusing episodes going through customs en route. We spent months consolidating measurements, data analysis, and preparation of a monograph that was published by the Harvard University Press (Endemic Goiter. The Adaptation of Man to Iodine Deficiency, 1954).
In 1952 the World Health Organization called a meeting on endemic goiter that took place in London. Among the attendees were a number of persons who had made contributions to the study of endemic goiter, or were destined to do so, including N. Scrimshaw, V. Ramalingaswami, S. Taylor, A. Querido, J. Roche and O. Kimball (who with David Marine did the first study on prevention of endemic goiter with iodine).
A sabbatical period in 1955 with Professor Andries Querido of the University of Leiden, who had earlier been a Rockefeller fellow in The Thyroid Unit, proved to be particularly felicitous. We had the good fortune to describe and characterize still another inborn error of thyroid metabolism in a patient with nodular goiter, this instance being the result of a missing thyroid deiodinase.
In the late 1950's an advisory committee of the Pan American Health Organization (PAHO) chose a number of important health problems in Latin America that needed attention. One of these was endemic goiter. Shortly thereafter I received a call from Dr. Martins da Silva of PAHO asking my advice about approaching this problem. My reply was that I needed to make a quick survey of the region. Within two weeks I set off on a visit to many countries from Mexico south to ascertain the dimensions of the problem and to identify persons who might contribute to an attack from both the laboratory and the public health points of view. From this developed a group of investigators who over the years have conducted studies and surveys, published, and met on occasion, including Fierro-Benitez, Cortazar, Pretell, Medeiros-Neto, Lobo, Gandra, and M. Roche. These meetings occurred in Caracas, Cuenavaca, and Pueblo in Mexico, and at the Kroc Foundation in California. Several publications emerged from these conferences.
An important contact was Professor Rodrigo Fierro-Benitez of the Central University of Ecuador. Over the years Dr. Fierro-Benitez has made many studies of the regional thyroid scene. One of the most important was a controlled trial of iodinated oil that proved its effectiveness as a prophylactic agent. Another was the dawning of the recognition that in addition to the locally prevalent cretinism, mental deficiency of varying degrees existed in many persons who were considered normal in that agrarian environment but were distinctly retarded when formally tested for cognitive and neuromuscular function. The regional problem attracted a number of investigators from the United States, including Drs. Raymond Adams, Phillip Dodge, Lawrence Green, Robert DeLong and Frederick Trowbridge. Their findings have been confirmed in many other regions around the world. Dr Fierro's studies and programs led to an exemplary national prophylactic program with iodized salt.
The possibility of an organized international attack on endemic goiter and its varied complications arose through a chance encounter between Dr. Basil Hetzel and Mr. David Haxton of UNICEF at a meeting in southeast Asia in 1984. They wanted to explore what might be done about iodine deficiency and its consequences in Southeast Asia and elsewhere. UNICEF support was offered. This eventuated the following year in the formation in New Delhi of the International Council for the Control of the Iodine Deficiency Disorders (ICCIDD), with Dr. Hetzel as the Executive Director and myself as Chairman. This organization has worked tirelessly through the intervening years to promote research and to educate officials and the public world-wide about the consequences of iodine deficiency and the necessity for supply and consumption of properly iodized salt.
One interesting puzzle that emerged was that the clinical description of the cretins in Ecuador differed in certain important respects from the cretins observed by Dumont, Ermans, and their colleagues in Congo, especially on Idjwi Island in Lake Kivu between Congo and Rwanda, but also in the Uele region. Because these differences were unresolved, I joined the Belgian team in Congo to study the puzzling differences. It has only recently been resolved when Drs. Dumont, Ermans and their colleagues showed that the unique features of the typical myxedematous cretin of central Africa arise from a combination of iodine deficiency, cassava excess (a component of which is metabolized to thiocyanate, an iodide competitor), and selenium deficiency (selenium being part of an enzyme that destroys excess peroxide in the thyroid and of another that deiodinates thyroxine to the active hormone, triiodothyronine).
Another unanticipated development was the finding by a student from the Harvard Medical School, under my sponsorship but not my direction, during a three month period in a Zimbabwe hospital, that the number of patients presenting with thyrotoxicosis had risen sharply since the introduction of iodized salt for prevention of endemic goiter. While iodine-induced thyrotoxicosis was known as an occasional phenomenon elsewhere, fatalities had not previously been reported. This observation stimulated an ICCIDD-sponsored meeting on iodine-induced hyperthyroidism in Boston, and has generated considerable interest and caution to ensure that prophylactic programs are carefully monitored for the proper concentration of iodine in salt.
The list of supportive colleagues through the years is far too lengthy for this short account, but they have done the work and have established clinics, laboratories and programs in their own countries. It has been a collaborative enterprise. Their efforts have helped make it possible to come close to the ICCIDD-UNICEF-WHO goal of worldwide elimination of the iodine deficiency disorders by the end of the first year of the new millennium.
PROGRESS AGAINST IDD IN POLAND
The 3rd Conference of the Polish Council for Control of IDD, entitled Iodine Prophylaxis and the Program of Iodine Deficiency Elimination in Poland took place in Krakow in May 1998. The proceedings have now been published in the Polish Journal of Endocrinology, 49:(suppl 1), 1998, Dr. Z. Szybinski, guest editor. This article summarizes some of the presentations.
Z. Szybinski, et al reviewed Results of the programs on iodine deficiency in Poland, and monitoring systems of mandatory model of iodine prophylaxis (pages 9-19). Poland began iodine prophylaxis in 1935 at 5 mg KI/kg salt, with interruptions between 1940-1945 and 1980-1986. After 1986, consumption became voluntary, at 20 mg KI/kg salt. Studies from 1992-1995 concluded that iodine deficiency was mild in the seaside areas and moderate in the rest of the country. In January 1997, the Ministry of Health mandated iodization of household salt at 30 " 10 mg KI/kg salt. Iodized salt production increased from 4,000 tons in 1991 to 75,000 tons in 1998. The reference value of thyroidal radioactive iodine uptake decreased from 46% in 1986 to 28% in 1998. The urinary iodine concentration, expressed as the fraction of samples > 100 mcg/L, increased in Krakow from 18.8% in 1992 to 48.5% in 1998. A significant increase in the incidence of thyroid cancer was noted beginning in 1990 and has continued, characterized by an increase in the papillary form and a decrease in the follicular. The authors speculate that the radiation dose to the thyroid after the Chernobyl accident might be a contributing factor. The Program plans monitoring, to include goiter prevalence, urinary iodine concentration, analysis of standardized neonatal TSH, and organization of regional standardized registries of thyroid cancer incidence.
S. Bobek, et al discussed Supplementation pattern of cow fodder with iodine (pages 35-44). The Polish Council for Control of Iodine Deficiency Disorders (PCCIDD) had recommended iodization of fodder to enhance iodine levels in animal products. Previous work had shown that eggs and milk are easily enriched with iodine. Feeding hens 153 mcg iodine/day/hen increased the iodine content of eggs almost two-fold (from 18.3 to 32.4 mcg iodine/egg). A tenfold iodine consumption (1530 mcg iodine/day/hen) further increased the iodine content of eggs to 187 mcg iodine/egg. Similarly, when 1.2 or 4 mg iodine/kg as KI was fed to cows, the iodine content in milk increased from 205 to 757 mcg/ml, while the iodine content in meat did not change with 2 mg iodine/kg and only slightly even when supplemented with 4 mg/kg iodine. The average iodine content of milk in south Poland remained fairly constant from 1960 to 1997, about 22 mcg iodine/L. The average milk intake in Poland is 200 ml/person/day.
These authors proposed increasing the iodine in milk so that it comprises about one-fifth of the daily requirement, or about 30-60 mcg iodine per 200 ml of milk. They investigated how much supplementary iodine needs to be added to salt licks or fodder to achieve 150-300 mcg iodine/L milk, and the availability of organic ethylenediamine dihydroiodide (EDDI) versus inorganic (KI) forms of iodine. They also studied whether selenium could improve transfer of iodine to milk, an issue raised in work elsewhere. In a first experiment, different amounts and forms of KI and selenium were incorporated into salt licks. Milk iodine reached levels of 150 or 300 mcg iodine/L after cows consumed 58 or 128 mg iodine/day in the form of EDDI, or 121 or 300 mg iodine/day in the form of KI, respectively. However, transfer of iodine from the salt lick to milk was quite inefficient for both EDDI and KI, considerably less than the 10% noted by other authors in similar experiments. Furthermore, EDDI transiently decreased milk yield. The presence of selenium in the salt licks did not change the iodine level in milk.
A second group of experiments added EDDI or KI in wafer capsules to concentrated food, to give 30, 60, or 100 mcg iodine/day/cow and measured iodine and selenium contents of the milk. These additions increased the milk's iodine concentration. Consumption of 7 or 22 mg iodine/day in the form of EDDI, and 10 or 25 mg iodine/day as KI, resulted in levels of 150 or 300 mcg iodine/L of milk, respectively. These daily doses are similar to those proposed by the US National Research Council, 12 mg iodine/day/cow. The fraction of iodine appearing in the milk was about 27% for both EDDI and KI. While EDDI provides a greater increase in milk iodine than KI, it also transiently suppresses milk yield and is not as well ingested. The authors recommend KI, particularly if it can be stabilized.
A paper entitled Primary prevention of iodine deficiency in bottle-fed infants (pages 45-53) by L. Szponar, et al. began with a review of different recommendations for minimum daily iodine intake for infants. Previous American recommendations (RDA) were 35-40 mcg/day for 0-5 months, 50 mcg/day for 5-12 months, and 70 for 1-3 years. ICCIDD in 1992 proposed 90 mcg/day for age 0-3 years, while Polish recommendations from 1995 were 40 mcg/day for age 0-6 months and 50 mcg/day for 6-12 months. Poland's mandatory salt iodization at 30 " 10 mg KI/kg is adequate for most of the population, but too low for young infants and for lactating or pregnant women, particularly because increased salt intake during pregnancy is generally discouraged. Various iodine supplements during pregnancy and lactation are recommended, most containing about 100 mcg iodine/capsule. The only effective way to give iodine to breastfed babies is through supplementation of the mother's diet. In Poland, 83% of infants are breastfed at one month, decreasing to 45% at five months; parallel figures for infants fed entirely with mother's milk are 43% and 3%, respectively. The authors examined a number of different infant milks available in Poland. Guidelines from the European Union recommend that formulas contain at least 3.5 mcg iodine/100 ml. ICCIDD has recommended 10 mg iodine/100 ml for term babies, and 20 mg/100 ml in formulas for premature infants. This paper gives detailed data on various brand preparations that are permitted in Poland. Starting formulas range from 7 to 12 mcg iodine/100 ml, as do follow-up formulas. The authors propose raising the required levels to conform to the ICCIDD recommendation and making them more uniform.
E. Bar-Andziak and J. Nauman reviewed the general problem of hyperthyroidism associated with iodine supplementation and include some data from Poland (Possible risk of iodine induced hyperthyroidism (IIH) as a consequence of obligatory iodine prophylaxis in Poland, pages 55-62). Project Chernobyl I in 1987-1990, covering 34,000 subjects, and investigation of 16,000 schoolchildren from 1992 and 1993, both showed that Poland continues to have iodine deficiency. Eighty percent of the schoolchildren had urinary iodines below 100 mcg/L, the average being about 73 mcg/L. In some regions of central Poland the mean urinary iodine concentration was about 56 mcg/L. The goiter prevalence was 21% in schoolchildren and adolescents and 17% in adults (27% in women, 8% in men). The mean TSH was 1.3 mIU/L and 1.5 in children. 0.28% of adults had hyperthyroidism, leading to the prediction that about 3% of adults and 1.3% of children with nodular goiter will develop hyperthyroidism. With mandatory iodization of salt at 30 mg KI ppm (22 mg I/kg salt) and a daily salt consumption of 4-14 g/day, mean daily iodine consumption will reach 73 to 144 mcg. A further study, Chernobyl II, is now in progress to extend observations since completion of Chernobyl I. Preliminary data on a small number of patients from an endocrine clinic in Warsaw in late 1997 and 1998 showed a mean urinary iodine concentration of about 150 mcg/L.
M. Oltarzewski, et al reported Preliminary evaluation of changes in blood spot TSH levels based on the neonatal screening program in Poland (pages 63-71). Poland has had standardized neonatal screening for hypothyroidism for four years, registered in a central database. From 1994 to 1997, the fraction of TSH samples above 5 mU/L decreased from 12.7% to 6.3%, and those above 20 mU/L decreased from 1.94 to 0.16%. The areas with higher neonatal TSH's did not correlate geographically with the known distribution of goiter prevalence and urinary iodine concentration, but a high correlation was found between neonatal TSH elevation and the use of iodine-containing antiseptics before and during delivery. In clinics using iodine, the fraction of TSH levels over 5 mU/L was three times higher (9%) than in those not using iodine (3.2%). The authors conclude that some increased TSH levels are from the use of antiseptic iodine and this must be remembered in using the neonatal TSH in screening for iodine deficiency.
Neonatal screening program for congenital hypothyroidism as a monitoring system of iodine deficiency in newborns and their mothers in the Lodz Macroregion was reported by B. Pniewska-Siark, et al. (pages 77-83). Between 1993 and 1997 they compared four subregions by fraction of newborns with neonatal TSH above 5 mU/L, median urinary iodine in randomly selected children, median urinary iodines of their mothers, and mean concentrations of TSH and of T4 in the children's serum. A strong negative correlation existed between the number of newborns with increased TSH and the urinary iodine excretion in both mothers and children. The areas with highest neonatal TSH also had higher serum TSH's in children of the region, although still well within the normal range. The paper offers detailed examples of these relationships.
In a study Regional differences in goiter incidence and urinary iodine concentrations among schoolchildren (ibid, page 93-99), Szybinski and colleagues summarized data from the national survey and the ThyroMobil study. In the seaside area (Hel Peninsula) the goiter prevalence was 3.4% and the urinary iodine, 161 mcg/L. In six goitrous areas studied by the ThyroMobil, the incidence of goiter reached 57% in Karpacz in the Sudeten area, with urinary iodine concentration of 32 mcg/L. Other sites gave a goiter prevalence range of 18% to 49% and urinary iodines from 45 to 65 mcg/L. Several environmental factors were suggested, including a relatively increased iodine concentration in the Vistula River (possibly from coal mines), and a possible relation to sulfur mining areas, selenium deficiency, increased calcium in water, and genetic factors. These deserve further exploration. The conference gave detailed descriptions of studies on goiter and urinary iodine in several other areas as well.
Iodine nutrition during pregnancy was also addressed. Szybinski and colleagues evaluated 156 pregnant women by ultrasound and urinary iodines (Influence of iodine supplementation on the incidence of goiter and ioduria in pregnant women with iodine deficiency, pages 151-161). In those with urinary iodine concentrations lower than 150 mcg/L (average 60.3) the frequency of goiter increased from 31% at the beginning of pregnancy to 49% at the end (the upper limit of thyroid volume for women was taken at 18 ml). One group of women received 150 mcg iodine as KI daily; their urinary iodine increased from 65 to 95 mcg/L, and the increase in their thyroid volume was less than that of the untreated group. Serum thyroglobulin values did not change. Babies from the treated group had a higher Apgar score at one minute compared to the untreated group (9.75 versus 9.08, respectively).
In a similar study, Sobieszczanska-Jablonska, et al. (Effects of iodine prophylaxis and of levothyroxine treatment on clinical and biochemical indicators of excessive thyroid stimulation in pregnant women and newborns, pages 171-182) separated 60 pregnant women into three groups, one receiving only iodized salt, the next with an added 200 mcg iodide as KI daily, and the third treated with 200 mcg iodide plus 100 mcg levothyroxine. Thyroid volume increased by 30% in the untreated group, remained the same in the KI group and decreased in the KI plus T4 group. The incidence of positive titers of anti-TPO in the third trimester increased significantly in the group treated with KI plus T4. The serum thyroglobulin concentration in the maternal serum and umbilical blood was higher in the untreated group than in the treated.
This conference of the Council ended with Recommendations. It endorsed household salt iodization, but proposed that other food categories and products should not be supplemented with iodine by the food industry. Iodine prophylaxis in farm animals may start after further study, no earlier than the year 2000. The National Program of Elimination of Iodine Deficiency in Poland, in cooperation with the National Food and Nutrition Institute, should include monitoring as follows: (1) goiter prevalence and determination of iodine in urine of pregnant women, children, and adults; (2) the frequency of neonatal TSH in the 5-20 mU/ml range; (3) standardized registries for thyroid cancer and iodine-induced hyperthyroidism; (4) quality control of technology for household salt iodization; (5) surveys on household salt consumption; and (6) standardization of iodine supplementation in formulas for bottle-fed newborns. These recommendations were presented to the Ministry of Health and Social Welfare.
The Council made additional recommendations to deal with iodine-induced hyperthyroidism. These included reduction of the daily dose of iodine in treatment of euthyroid goiter by 30-50%, supplementation for pregnant and breast feeding women with 150-200 mcg iodine daily, use of rapid urinary iodine test kit to test daily iodine intake in clinical situations, avoidance of treatment with iodine in subjects at risk for iodine-induced hyperthyroidism, and approaching iodine-induced hyperthyroidism, when it occurs, by eliminating most sources of iodine and providing effective treatment of the hyperthyroidism.
Drs. Szybinski and Lewinski outlined a National Program for IDD Elimination for the Years 1999-2003. The main goals are: elimination of IDD and endemic goiter in pregnant women, neonates, and children; diminishing and monitoring the consequences of iodine deficiency in the elderly; developing an effective program of continuous monitoring of iodine prophylaxis; and implementing iodine prophylaxis in farm animals. The following are specific projects for this period: (1) determine the incidence of goiter and urinary iodines in target groups; to include 5,000 children, age 6-13 years old in 30% of the schools studied in the 1992 survey; follow-up studies in the same centers previously used for pregnant women, studying from 240-400 altogether, by the protocol described above; continuation of the second phase of the Chernobyl study; (2) continue monitoring of neonatal TSH in relation to iodine nutrition; (3) continue evaluation of the thyroid cancer incidence rate, based on a standard registry; (4) evaluate iodine-induced hyperthyroidism by establishing a registry with basic information about patients with newly diagnosed hyperthyroidism; (5) impose quality control of iodized salt and its storage, and standardize formulas for bottle-fed infants; (6) analyze the daily intake of household salt in Poland, particularly an apparent decrease in salt intake; (7) introduce iodine prophylaxis in animals by supplementation in animal fodder, but not to be initiated until the studies on humans have been completed. The National Program includes the cooperating centers that have already worked together on projects that deal with iodine deficiency in Poland. The main coordinating centers will be at Krakow and Lodz, in collaboration with the National Institute of Food and Nutrition in Warsaw. Financial support is being provided by the Ministry of Health and Social Welfare. International cooperation with ICCIDD, UNICEF, and WHO will continue.
ENVIRONMENTAL CONTROLS IN IDD - WHAT DO WE REALLY KNOW?
by C. C. Johnson, F. M. Fordyce, and A.G. Stewart, British Geological Survey, Keyworth, Nottingham and Edinburgh, and Department of Public Health, Wirral Health Authority, St. Catherine's Hospital, Birkenhead, UK.
Search any library or the internet for information on iodine deficiency disorders (IDD) and you will find volumes of information on symptoms, assessment and treatment but very little on its primary cause - a lack of readily available iodine in the environment. A recent search of the World Wide Web revealed numerous links and discussions concerning IDD, all medically related, but not a single reference to the behaviour and distribution of iodine in the environment. The medical community is well organized when it comes to tackling the problem of IDD, as exemplified by the activities and information dissemination of the ICCIDD. Unfortunately, amongst earth scientists who have an interest in the geochemistry of iodine there is not such a good forum for discussion and dissemination. Not since the Chilean Iodine Educational Bureau's works of the 1950's has there been any concerted effort in the scientific community to widely disseminate information on iodine.
In recent years data on the distribution of iodine at the earth's surface has been approached from four different and largely independent perspectives.
Firstly, workers in the field of iodine deficiency disorders, dominated by researchers with a medical background, have done case studies in which a variety of materials from the environment have been analyzed and results published. Much of the data on iodine geochemistry from the early years of the last century owes their origin to this type of research.
In the 1970's and 1980's there was interest in the geochemistry of iodine from scientists involved in mineral exploration. Iodine in brine solutions is associated with some of the ore forming processes and so it can be found within zones of mineralization in the earth's crust. As iodine is a mobile element it will migrate a long distance from its source so it can be used as an indicator element ("pathfinder" element) for the location of deeply buried mineral deposits. Much of this work was done in the USSR and yielded a lot of information concerning iodine's behaviour in rocks and soils.
More recently, the majority of research into the behaviour of iodine in the environment has been connected to the nuclear industry and the threat posed by radionuclides of iodine in the environment. In the aftermath of nuclear accidents I-131 readily finds its way through the food chain to humans where it is preferentially concentrated in the thyroid and may lead to thyroid cancer. I-131 has a half-life of only 8 days but I-129, which is less radioactive, remains for a much longer time with a half-life of 16 million years. Research in this field, principally connected with the safe disposal of radioactive waste, has led to a much better understanding of the migration of iodine in the environment. Particularly, fixation of iodine by different components of a soil along with volatilization to the atmosphere from the soil-plant interface are both far more significant in the geochemical cycle of iodine than previously recognized (1, 2).
Finally, there has also been a small but significant interest in the oceanic and atmospheric distribution of iodine. An increasing understanding by marine scientists of how and where iodine is concentrated by algae in hot spots in the middle of the oceans and near the coast has improved our understanding of how iodine is transferred from the ocean to the atmosphere (3). This has supplemented analyses of air masses showing sources and transport of mainly particulate iodine.
Despite these interests, the flow of data on iodine's behaviour in the environment has often been limited because of the analytical methods used for the determination of iodine in environmental materials. Iodine is not an element that is routinely determined in most geochemical or environmental surveys as its generally low levels require separate methods from the majority of elements routinely determined. Techniques for the determination of iodine have improved over the past few decades and this had led to much more information regarding levels of iodine in the environment becoming available. Early researchers tended to publish data only for materials in which iodine could be measured, giving rise to mean values for rocks and soils much higher than those generally recorded today.
There are some perpetuated myths concerning
iodine in the environment, such as those connected with glaciated soils and
the relationship between iodine levels in the environment and distance from
the sea. Communities in remote highland
regions are said to be most at risk from IDD. Is this risk just because of
remoteness? Are highland areas really iodine-deficient and just what is meant
by an iodine-deficient environment? The British Geological Survey, funded
by the UK Department for International Development, has just commenced a three
year project looking at the environmental controls of IDD. The project hopes
to address some of these questions and make resources concerning iodine's
behaviour in the environment more available to any researchers with an interest
in IDD. Information will be disseminated from the project's web site at http://www.bgs.ac.uk/dfid-kar-geoscience/idd
. Hopefully, this site will be recognized as
useful by many interested in IDD, not just geochemists, and links made from
other iodine and IDD sites.
A better
understanding of the distribution and behaviour of iodine in the environment
creates another tool to tackle the worldwide risks of IDD. Environmental intervention
schemes could be developed that make more efficient use of the iodine that
is already there in the environment but not currently available to the food-chain.
Certain environmental conditions are known to fix iodine in the soil and hence
restrict its bio-availability. Some research has demonstrated how certain
land management activities (e.g. drainage improvements) have led to problems
of IDD amongst livestock (4). In schemes where iodine is added to the environment
by irrigation water or by fertilizers, our knowledge of the geochemistry of
iodine will help to ensure that the precious iodine is not lost by volatilization
to the atmosphere or taken out of the food-chain by being too strongly fixed
in the soil. Every soil will have a certain potential to fix or release iodine
and we need to develop better understanding and methods to determine just
what this is.
We do know
a lot about more about the behaviour of iodine in the environment than we
did ten years ago. The different lines of research need to be brought together
to present a more comprehensive account of iodine geochemistry that is made
more readily available to workers in the field of IDD. It is hoped that our
current project will achieve this aim.
(Published by permission of the Director
of the British Geological Survey (NERC).)
REFERENCES
1. Muramatsu Yand Yoshida S 1995 Volatilization
of methyl iodide from the soil-plant system. Atmospheric Environment 29(1),
21-25.
2. Schmidtz K and Aumann DC 1995 A study on the
association of two iodine isotopes, of natural I-127 and of the fission product
I-129, with soil components using a sequential extraction procedure. Journal
of Radioanalytical and Nuclear Chemistry, Articles, 198(1), 229-236.
3. Moore RM, Groszko W 1999 Methyl iodide distribution
in the ocean and fluxes to the atmosphere. Journal of Geophysical Research
- Oceans 104 [C5], 11163-11171.
4. Lidiard HM 1995 Iodine in the reclaimed upland
soils of a farm in the Exmoor National Park, Devon, UK and its impact on livestock
health. Applied Geochemistry 10, 85-95.
THE SWISS LEGISLATION
ON IODIZED SALT. Hans Bürgi, M.D., Solothurn, Switzerland
Switzerland
introduced salt iodized at 3.75 ppm in 1922.
The iodine content was raised to 7.5 ppm in 1962, to 15 ppm in 1980,
and finally to 20-30 ppm in 1999. About
95% of kitchen salt and 70% of salt for industrial food production is iodized,
even though iodized salt use has always been voluntary and manufacturers and
retailers must offer both non-iodized and iodized salt. It is astonishing that this success was initially
achieved based only on a federal decree, the Ordinance on Foodstuffs of 1936
(amended several times until 1984). This
ordinance simply stated that the cantons (which by constitution are the holders
of the salt monopoly) may allow and regulate the sales of iodized salt.
In 1974 a legislative process was initiated that led to the passage
by Parliament of the new Federal Law on Foodstuffs in 1992.
After ordinances regulating details had been decreed, this law was
finally enacted in 1995, 21 years after the start of the legislative process!
The idea
behind the Swiss regulatory system is the following:
! A federal
law (pertaining on foodstuffs in
general):
! States
the basic principle that certain additives
to foodstuffs are
allowed.
! Regulates
penalties in case of infringement.
! Decentralizes
quality control by delegating it
to the cantons (Switzerland is politically organized into 26 cantons, that
have wide competencies, comparable to the 50 states of the United States).
The control concerns only salt quality, but no checking of epidemiological
data, such as thyroid volume, goiter prevalence or urinary iodine excretion.
Interested university departments have so far performed such epidemiological
controls in a more or less haphazard manner and without mandate by the government.
! Two federal
ordinances (decrees) regulate details,
such as the exact substances that may be added, the admissible concentrations,
the labelling and permissible health claims. The separate regulation of details in ordinances
(which can be decreed by the government) allows quick adaptations to new scientific
evidence, without passing through a lengthy parliamentary process.
The relevant
law and ordinances are:
1.
Federal Law on Foodstuffs and
Substances of Daily Use (October 9, 1992; RS 817.0).
Article 10
states (among other points):
The Federal Government, based on toxicologic or epidemiologic
evidence, fixes:
1. additives that are admissible in different
foodstuffs, as
well
as their maximal quantities.
2. maximum concentrations for foreign substances
and
components.
Article 40
states (among other things):
The cantons execute this
law, as far as not appertaining to the Federal Government, and they take care
of food control in the interior of the country. They appoint a cantonal chemist. The cantons operate specialized laboratories
for the analysis of samples. Cantons
may cooperate with each other and operate common laboratories. They may also delegate the analysis of samples
to private laboratories. Persons entrusted
with the controls must fulfil the qualifications set by the Federal Government.
2.
Ordinance on Foodstuff (March
1, 1995; 817.02)
Article 6
states (among other points):
For the conservation or
the improvement of the nutritional value as well as for reasons of public
health, essential or physiologically useful substances, such as vitamins or
minerals may be added to foodstuffs. The Federal Department of the Interior regulates by separate ordinance:
1. labelling
2. admissible maximal quantities
3. admissible health claims
Article 48
regulates penalties for transgressions of the law; among other things it says:
With prison terms or fines
of up to Sfr 20,000 (approximately US $13,000) is penalized whoever:
! evades or impedes controls of foodstuffs or additives
! produces, treats, stores, transports or distributes foodstuffs
in
such a way that
they do not conform to the present law
! makes false or deceiving claims about foodstuffs
! omits
3.
Ordinance on Nutritional Value
(June 26, 1995, with latest amendment January 30, 1998; 817.021.55).
Article 10
states:
Fluorides, iodides, or
iodates may be added to salt used for nutrition, and fluorides may be added
to drinking water, as long as this is indicated for reasons of public health.
Salt used for nutrition must contain per kilogram 20 to 30 mg of iodide
or iodate, calculated as iodine, or 250 mg of fluoride, calculated as fluorine.
Drinking water may maximally contain per liter 1 mg of fluoride, calculated
as fluorine. The following claims
are allowed with salt used for nutrition: (a) "sufficient iodine intake prevents goiter" for iodized
salt, and (b) "fluoride reduces dental caries" for fluoridated salt.
Article 11
states (among other things):
Iodized and fluoridated
salt for nutrition must be labelled as such.
Since its
enactment in 1995, the system has already proved its value. In 1998, after decreasing urinary iodine values
had been reported, the iodine content of salt could be raised without delay,
by changing article 10 of the Ordinance of Nutritional value by decree.
References:
1. Das neue Lebensmittelrecht (the new food law).
Bull Bundesamt für Gesundheitswesen, 1995, Suppl. to No. 29.
2. The Swiss law and ordinances cited above are
available in full text in either French, German or Italian on the Swiss government
web sites:
German: http://www.admin.ch/ch/d/sr/c817_0.html
http://www.admin.ch/ch/d/sr/c817_02.html
http://www.admin.ch/ch/d/sr/c817_021_55.html
French: http://www.admin.ch/ch/f/rs/c817_0.html
http://www.admin.ch/ch/f/rs/c817_02.html
http://www.admin.ch/ch/f/rs/c817_021_55.html
Italian: http://www.admin.ch/ch/i/rs/c817_0.html
http://www.admin.ch/ch/i/rs/c817_02.html
http://www.admin.ch/ch/i/rs/c817_021_55.html
SALT PRODUCERS'
MEETING FOR CENTRAL AND EASTERN EUROPE, COMMONWEALTH OF INDEPENDENT STATES
AND THE BALTIC STATES, held at Kiev,
Ukraine, September 29-October 1, 1999. This
was the first of a series of meetings with the productive salt sector organized
in preparation for the Salt 2000 symposium in the Hague, May 2000, where the
global achievements in universal salt iodization (USI) will be celebrated. The concept and process for accelerated activities
in support of IDD elimination through USI under the Salt 2000 banner have
been mentioned previously and are available on the PAMM web site (http://www.sph.emory.edu/PAMM).
Dr. F. van der Haar has provided the following summary.
With the
UNICEF Regional Office in Geneva leading, the meeting in Kiev was organized
with WHO, MI, Kiwanis WSP, ICCIDD, ESPA, VDS, PSI, Salt 2000 and PAMM as partners.
The overall aim was to consider the results and strategies for promoting
USI in the region, and to address barriers and opportunities for its implementation,
particularly from the viewpoint of salt producers.
Participants, 120 in total, were from 24 countries in the region, mainly
from the salt production and import/export trade sector, and from Food Inspection
Institutes and Food Standards Bureaus. Members of the organizing and supportive organizations made presentations
and organized the discussions, leading to a resolution.
In June 1999,
a preparatory consultation was held with the CEO's of key salt industries
of the region to design an agenda in response to the needs of the iodized
salt productive sector. Also, experts
from the region and UNICEF, with ICCIDD Subregional Coordinator Dr. Gregory
Gerasimov supervising, conducted market-based salt situation assessments,
covering the wide range of activities ongoing in production, trade, retail,
and consumption of iodized salt. The
methodology for this is posted on the PAMM web site.
The opening
ceremony of the meeting was chaired by Ms. Valentyna Dovzhenko, Chairwoman
of the State Committee for Family and Youth Affairs of Ukraine. Speeches were delivered by Dr. Bruno de Benoist,
Focal Point for Micronutrients of WHO and Dr. Francois Delange, Executive
Director of ICCIDD. In his opening
address, Mr. John J. Donohue, Regional Director, UNICEF Regional Office for
CEE/CIS/Baltics, welcomed and challenged the participants and put the meeting
in perspective.
The progress
made toward IDD elimination through USI in the region was presented by Dr.
Gerasimov from the data obtained. Overall,
coverage with iodized salt is lagging in this region. Within the region, however, the track record
is highly variable: at the lower end,
coverage is below 10% in markets of Russia and Ukraine, and at the high end,
up to 70% in households of Bulgaria and Turkmenistan. In his response, Mr. Vadim Ermakov, Director of the Ukraine Salt
Producers Association Ukrsol stressed the major political, economic and administrative
factors that continue to be formidable challenges to the salt sector.
In a session
on modern salt technologies, presentations covered modern salt iodization
technology (Mr. Lorenzo Locatelli-Rossi, UNICEF consultant) and specific examples
of state-of-the-art packaging technologies (Dr. Justus de Jong, Akzo Nobel),
with brief responses by salt producers from Turkmenistan, Russia, and Uzbekistan.
A panel of exporters, importers, and salt traders discussed issues
in dealing, importing, exporting, and trading iodized salt.
Legal aspects were covered in a session on "Inspection, Harmonization,
and Enforcement of Standards." Mr.
Locatelli-Rossi spoke on standards for iodized salt, Mr. Eddie McLoughney
(UNICEF Representative in Macedonia) on monitoring and enforcement of standards,
and Mr. Franz Goetzfried (Director, Verein Deutsche Salzindustrie VDS) on
why iodized salt regulations work in some countries of western Europe. Responses were by the chief sanitary doctors
from Ukraine and Armenia.
Upon request
of salt producers in a preparatory consultation, a special session was dedicated
to the "Structure, Function and Activities of a Salt Producers' Association."
In the unavoidable absence of Mr. Bernard Moinier, Secretary General
of the European Salt Producers Association ESPA, Mr. Franz Goetzfried of VDS
presented. Responses were by Ms. Corina Nicolau of the
Romanian National Salt Society SALROM, and Mr. Alexandr Nikolaev, Director
of Sentrosol, Moscow. In a session
on "Promotion of Iodized Salt", commercial marketing was introduced
by Mr. Paul Inge Paulsen, Chairman PR Committee of Kiwanis International's
World Service Project. He was followed
by Dr. de Jong with a case study of successful marketing, based on experiences
in Belgium and the Netherlands. Social
marketing expertise was presented by Ms. Sharon Slater, Program Manager of
Population Services International. The
session concluded with experiences in promotion shared by salt producers and
traders from the region.
A series
of break-out discussion groups considered technical and political issues. The outcomes were coordinated into a draft
resolution and discussed in a plenary session chaired by Dr. Gianni Murzi,
UNICEF Area Representative in Russia, Ukraine, and Belarus. Mr. John Donohue, Regional Director UNICEF
led the final plenary session in which a number of follow-up actions were
proposed, followed by commitments to action by the participants on basis of
the resolution.
The participants
recognized that an appropriate diet with sufficient iodine is the right of
all children and families, that IDD in the majority of countries of the region
still is of major concern, and that sustained access to iodized salt is the
key to sustaining the elimination of iodine deficiency. They reiterated the need for public, civic,
and private sector collaboration. The
resolution binds the productive salt sector to help pursue USI within the
next 12 months, to collaborate with public and civic partners in promotion
of USI and creation of consumer demand, to produce iodized salt according
to appropriate standards, and to contribute to continued consensus on USI
policies and regulations. It was agreed
that progress in achieving these pledges will be publicly reported upon within
one year.
In follow-up,
UNICEF representations in countries have initiated a coordinated effort to
intensify advocacy for IDD elimination through USI with politicians and scientific
groups, to recognize particularly and support the productive salt sector in
USI, and to create popular demand by ensuring that mass catering institutions
only use iodized salt. Results from
the meeting and follow-up actions by the participants and UNICEF will be presented
at the Salt 2000 symposium in the session entitled "Sustaining the Success."
XINJIANG AND TYVA:
TWO AGRICULTURAL APPROACHES TO IODINE SUPPLEMENTATION, AND THE FLUX OF IODINE
THROUGH THE ENVIRONMENT, by G. Robert
DeLong, M.D., Duke University Medical School, Durham, NC, USA.
Most developing
nations importantly affected by iodine deficiency are rural. This fact compounds the difficulties of distribution
of iodine, whether by salt or by capsules or other means, since "rural"
inevitably equates with remote, scattered, difficult to communicate with,
hard to reach, and usually poor. One might suggest this is the remaining challenge to control of
iodine deficiency.
A rural iodine-deficient
population suggests an agricultural approach to iodine distribution.
We have undertaken such an approach in Xinjiang, western China, with
apparent success, by dripping potassium iodate into irrigation water, from
which it progresses through soil, grain and vegetable crops, and animals to
the human population. Added iodine in the soil is still present for
at least six years. In Xinjiang, a
dense population (about one person per mu (16 mu per hectare)) has simplified
the iodine application. In Tyva (Siberia), the situation is different. Its iodine deficiency is as severe as Xinjiang's,
but the country is mostly pastoral, with large herds of sheep and of cattle,
particularly in the western portion of the country that also has the most
severe iodine deficiency. People eat
mostly meat, some at every meal, and dairy products; together they constitute
about 60-70% of the diet. Vegetables
and grain are grown locally in limited plots, usually irrigated.
Animals do
not receive iodine supplementation except minimally and sporadically. The possibility of supplementing iodine to
animals immediately suggests itself. It
would be expected to have two beneficial effects: (1) improving animal production by improving reproduction and growth,
thus affording an immediate economic benefit, as was seen in Xinjiang; and
(2) increasing iodine intake by the human population who eat the animal products.
If 90% of iodine intake is in food, and 60% of food is animal products
(meat, milk and milk products, and eggs), then a four-fold increase in iodine
content in animal products (easily obtainable in Xinjiang) could produce a
2.6 fold increase in total iodine intake in humans.
This calculation omits the further benefit that more animal production
also increases the availability of animal products as well as increasing purchasing
power if such products are sold.
The population
density in Tyva is much less than that in Xinjiang. In Chaa-Xol, Tyva, 10,000 people live on 18,000
hectares (local estimates say 30% is cultivated, the rest is grazing land),
thus there is 1.8 hectare per person or about 3% the population density of
Xinjiang. Iodinating this broad expanse
of land is unrealistic. However, the
animal population can be targeted quite efficiently using iodized salt licks.
On a recent visit, we met with the Chairman of the Republic's Committee
on Agriculture, who is also the Chief Veterinarian.
She told us that all herd animals receive rock salt that comes from
one source in the country and it is not supplemented with iodine. Two thousand tons of this rock salt are produced and apparently
consumed. The herds consist of 800,000
sheep and goats, and 160,000 large cattle.
"Endemic ataxia," attributed to iodine deficiency, is known,
and "white-muscle disease" attributed to selenium deficiency, has
also been confirmed. Iodine drops
are added to water for young animals, but apparently not very consistently
or adequately. Rock salt costs 2 rubles
(= about 8 cents US) per kilogram. No
data are available on the iodine content of rock salt.
If we divide
the total production of rock salt by the number of animals, each animal consumes
an estimated 2 kgs of salt per year, or 5.5 g/day. This figure is reasonable because 83% of these
are sheep or goats, thus smaller than humans. If rock salt were iodized to a level of 50 mgs/kg, the average iodine
intake per animal from this source would be 275 mcg/day. Iodinating 2000 tons of rock salt to 50 mg/kg
would require 100 kg of iodate, costing about $1600 US, obviously an extremely
modest amount. Milling the rock salt
to a coarse granular consistency would probably be necessary in order for
it to mix effectively with KIO3 crystals. It must then be formed into convenient blocks
of perhaps 20 kilograms (about 44 pounds) for use in the field. A simple form mold and modest wetting might
be sufficient to make such blocks. Optimally,
this processing would be done centrally at the rock salt source.
In the beginning, if we were to introduce a demonstration project in
Chaa-Xol, the grinding, mixing, and block formation could be done locally
by manual means.
We are considering
the advisability of a local demonstration project. This was recommended by the Chairman of the
Agricultural Committee. The Chaa-Xol
community has conditions and resource people that make it an excellent choice
to begin. Supplementation of selenium
should also be considered, guided by local soil analyses.
Such calculations
suggest further that we would do well to consider the iodine flux in the environment
of iodine-deficient populations. By this is meant the flow of iodine from soil to plants, to animals,
to humans, and then to the environment again. Providing iodine directly to humans is generally
most efficient, as with iodized salt. However this solution does not provide iodine supplementation for
animals, unless a specific program is added.
The need for iodization of animals is clearly established by our results
from Xinjiang, at least in circumstances where iodine deficiency is severe.
If iodization of grazing animals were successful in Tyva, similar methods
might be useful in Mongolia and Inner Mongolia, and perhaps in Tibet.
Tyva clearly
has severe iodine deficiency disorder, based on the highest incidence of infant
mortality in the Russian Federation. Infant
mortality can be decreased by 50% in some areas of severe iodine deficiency
by adequate iodine supplementation, so prompt action is urgent. We offer the following recommendations for
Tyva, based on available data and observations during our brief visit:
1. Mandate by force of law, regulation or legislation,
that all salt for human and animal use in the country be iodized up to a minimum
of 40 ppm at the retail site.
2. The President should form a special agency
with an urgent priority to deal with IDD, add resources to that agency from
other spheres of activity, and provide adequate resources of money, manpower,
and transportation to the agency to assure its effective operation. In his discussion with us, he indicated his
intention to do all this. This agency
would be responsible for providing iodized salt, in conjunction with the salt
industry, for monitoring of salt iodization at salt plants and at outlets,
and for coordinating efforts with the research and medical spheres of activity.
3. Adequate iodization of all agricultural grazing
animals should be a goal. This might
begin with a demonstration project in one region such as Chaa-Xol, with the
intention to extend it country-wide on a continuing basis if results are positive.
4. Iodization of cultivated irrigated fields producing
grain and/or vegetables for human consumption should be considered, especially
those irrigated by open-ditch irrigation. Iodization of fields irrigated via artesian-wells and spraying would
require further consideration.
CLINICAL OBSERVATIONS:
IODINE DEFICIENCY'S IMPACT ON HUMAN DEVELOPMENT IN SIBERIA,
by G. Robert DeLong, M.D., Duke University Medical School, Durham, NC, USA.
[Ed. note: Dr. Delong is a pediatric neurologist with a longstanding interest
in the clinical features of cretinism and other manifestations of iodine deficiency.
This article describes the profound effects of iodine deficiency in
Tyva]
Chaa-Xol
district has 10,000 people on 18,000 hectares, with 18,000 head of cattle. The village of Chaa-Xol itself has 5,000 people;
the rest live in three outlying towns. About
20 miles east is a town of about 25,000 where one-half of the newborns had
congenital hypothyroidism on newborn screening. Chaa-Xol village has a hospital of 70 beds
with minimal facilities. The people
of this district were moved there about 15 years ago following the building
of the Sayan Hydro-electric Power Station, which flooded their old homes. A marked increase in goiters, and in illness
in general, is said to have occurred since this move and may represent migration
into a more iodine-deficient environment. We have no data on the old environment; certainly the present one
is severely iodine-deficient.
In the village
I examined the following cases:
1. Male, 3 y 4 mos old, diagnosed at 1 yr 8 mos
as severely hypothyroid, TSH 801; could not walk or sit at age 2; began walking
at age 2.1. Now: hearing decreased, no understandable language,
open fontanelle. Classical cretinism
with increased adductor, knee reflexes; no strabismus.
2. 11 yo female: short stature, poor memory.
TSH 480 (1997), bone age 3 years. Treated irregularly, diagnosis Acongenital hypothyroidism@. Cretin
3. Male aged 4 y 8 mos, diagnosed 1996 as hypothyroid.
Poor speech, does not understand language.
Hearing satisfactory (?), mentally delayed.
Mother has history of severe hypothyroidism. Cretin.
4. Female, 7 y, visible goiter.
4a. Male, 17 y, (brother of above) walked first
at 3 y, first speech at 6 y. Sustained electric trauma, coma 6 days. Now moderately hyperreflexic, mute. Cretin.
5. Female adult, clinical hypothyroidism, pulse
60.
6. Adult female, hypothyroid, nodular goiter,
Rx thyroxine
7. Adult female, hypothyroid, nodular goiter,
Rx Anti-strumine (iodine)
8. Adult young female, hypothyroid, goiter
9. 11 yo male: hypothyroid, TSH 367. Poor memory, poor hearing. Cretin.
10. 27 yo male: congenital deaf-mute; family history
of same; normal intelligence.
11. Adult young female: hypothyroid, goiter
12. 12 yo female: goiter 4th degree; Rx thyroxine
13. 17 yo female: 27 weeks pregnant. Rx with I occasionally; uses iodized salt at
home; exam normal.
14. 7 yo female: 5th of 5 sibs, others normal;
low birth weight (about 2.5 kg); poor growth, retarded bone age, goiter.
Bright. Head circumference
47 cm (-3 SD). Increased knee jerks. Iodine-deficient sub-cretin
15. Adult female: hypothyroid, goiter
16. 18 yo pregnant female (26 weeks): goiter.
Recommend immediate treatment; iodized oil capsules unavailable.
Given iodized salt 23 ppm iodine.
17. 15 yo female: hypothyroid, goiter
18. 11 yo female: goiter 3rd degree diagnosed one
year ago; Rx with lipiodol capsule: now
no goiter. (Points up inadequacy of
usual treatment here, including iodized salt; good response seen only after
lipiodol).
19. Family with congenital hypothyroidism: Mother: nodular goiter
5 yo daughter:
diagnosed at 2 y 8 mos; clinically hypothyroid. Speech minimal; hears (? how well). Walks poorly. T3, T4 zero. Cretin, primarily
post-natal.
3 year old
son: diagnosed at 10 months; severe hypothyroidism. T3 0.6, T4 zero, TSH 303. Treated
with thyroxine 200 mcg. with no improvement. Adductor, knee reflexes increased, balance
poor. Cretin, pre- and post-natal.
This family
may represent an inherited metabolic disorder, perhaps with athyreosis, exacerbated
by iodine deficiency especially in the younger child, who apparently suffered
more intrauterine damage.
20. 16 yo male, mentally retarded, mute. Web neck, shield chest, typical face: Noonan=s syndrome.
21. 13 yo female: goiter, symptoms not established.
22. 10 yo female: goiter, Rx thyroxine (wrong treatment,
as often here; not given iodine).
Khizil City
is a 22 hour drive over level plains of cultivated and grazing land.
There I examined cases at the Institute of Endocrinology as follows:
1. 4 year old male: at 12 years not walking. TSH 40, T4 normal on neonatal screening.
At 12 years spoke 4 -5 words.
Rx thyroxine, walking started after treatment. Still falls. Speaks well.
Bone age normal. Normal hgt, wgt. Normal reflex examination. Case
unclear to me: attributed to clinical hypothyroidism, improvement after treatment;
perhaps so.
2. 8 year old male from a first pregnancy, birth
weight 5 lbs., anemic, jaundiced 1 month. At age 2 yrs, couldn't walk, myxedematous, constipated, stopped
talking and stopped hearing. Diagnosis: congenital hypothyroidism. After treatment, lost swelling, became active;
still deaf/mute. TSH 468 at 2 years,
0.3 in 1999. T3 and T4 normal in 1999. Seems
intelligent, learning sign language. Dx.: congenital hypothyroidism, cretin; but some questions re: neonatal
diagnosis: could be kernicterus secondary
to anemia and jaundice (but up gaze good, no choreoathetosis).
3. 5 year old male: Examined at 2 y 9 mos, no
speech, normal height and weight. During
first year considered to have birth trauma, walked at 1 y 3 mos.
At 2 y 9 mos, TSH 557; had low T4, normal T3; treated with thyroxine
without improvement. In sum, has normal growth despite severe hypothyroidism,
but deaf and severe mental retardation, nearly unresponsive, apathetic.
Is this a peculiar syndrome of failure to form T4 but normal T3, and
normal somatic growth (? secondary to normal T3) but very poor hearing/mental
function (? secondary to deficient T4)? Severe cretinism.
4. Male, 3 y 5 mos, adopted from orphanage. TSH 16, T4 and T3 normal. Has rachitic rosary, malnourished. Bright, alert, inquisitive. Normal potential.
5. Female, 3 y 10 mos, embryopathic face (ptosis, flat nasal bridge,
small nose, prominent epicanthal folds, frontal bossing), renal and genital
defects, heart murmur. Speaks well, hears well, walks normally. TSH, T4, T3 normal. Probable chromosomal defect, but could it be
myxedematous cretinism? Growth parameters
not available, anterior fontanelle was not open (see below).
6. 13 yo
male. Congenital hypothyroidism, diagnosed
at birth. Now tight hips and thighs,
increased knee and adductor reflexes, slow facial movements and smile.
T3 9.8, T4 16.4 (low). Walks with slightly flexed gait, shuffling;
motor rigidity; spasticity with increased reflexes and ankle clonus, but proximal
greater than distal; arms held semi-flexed over trunk. Speech minimal, dysarthric; mentally retarded
but personable. Classical neurological
cretin, moderate.
7. Male, 2 y 10 mos. Neonatal TSH high, repeated at one year TSH, T3, T4 all normal.
At 2 y 8 mos, delayed, poor walking, lower extremity weakness (?),
poor teeth development, hears but no speech, understands.
Reflex examination normal. Walks,
somewhat toddling. Has mild but definite features of embryopathic
face as above: flat nasal bridge, epicanthal folds, bossing. Dx as transient congenital hypothyroidism,
but definite delay. Mild cretinism. I was told of 280 cases with positive neonatal
screen, later normal testing, who at ages 6 to 9 years have mental and physical
developmental retardation. This group
needs further description.
8. 20 year old female: large goiter, present since
age 15. Clinical diagnosis autoimmune
thyroiditis. Wants to become pregnant.
9. Older adult female: goiter
10. Female
4 years old, born jaundiced with big tongue, congenital hypothyroidism, treated
since birth. (Mother has goiter, denies
symptoms during pregnancy but wasn't tested).
Now growth delayed, retarded, speech just beginning, walked at 2 1/2
years. Height small, anterior fontanelle
closed, hears; hypertelorism, epicanthal folds, flat nasal bridge, frontal
bossing -- similar to above. Cretinism,
intrauterine damage, ? myxedematous. (The embryopathic facies suggest myxedematous
cretinism. Selenium deficiency is
known here; animals have Awhite muscle disease@. The facial distortion
must occur much earlier than the 7th month, and must relate to T3 deficiency,
in contrast to motor symptoms, related to T4 in brain, after 6th month.
Does T3 relate to serotonin, which has an important role in shaping
the face?)
11. Older adult female: operated for Grave=s disease one year ago, histology showed cancer. ? misdiagnosis?
Cases seen in the Central Hospital, Abakan, capital of Khakasian
Republic:
1. Female, 2 y 3 mos, diagnosed as hypothyroid
at 1 y 9 mos, short stature; no increased height growth after treatment. Stands holding on at 2 y 3 mos. No speech.
Head circumference 50 cm (90th percentile). No indication of hydrocephalus.
Diagnosed as congenital hypothyroidism; more data not available. Cretinism, mild
2. Older adult female: treated for hypothyroidism
with thyroxine, TSH increased recently.
3. 9 year old female: diagnosed hypothyroid at
5 months, treated briefly. At age
2 years, looked hypothyroid, treated inadequately. At 3 years slowed developmentally, now about 5 years developmental
level. Short stature, hypertelorism.
Congenital hypothyroidism, now mild cretinism with embryopathic face.
4. 17 year old female: nodular goiter, resected,
with resulting aphonia, now improved. Reappearance
of goiter.
5. Male 5 year 1 month: Mother had autoimmune thyroiditis during pregnancy.
Congenital hypothyroidism diagnosed.
Now strabismus, hypertelorism, developmental delay.
Height 111 cm (50th percentile). Cretin
with facial embryopathy and neurological features.
6. 15 yo female: goiter 3rd degree, nodules.
Rx thyroxine
7. 13 yo male, 3rd degree goiter; very tall.
No symptoms
8. 16 year old male: Neurofibromatosis I. Diagnosed
with hypothyroidism at age 7 years; TSH high. Rx thyroxine; mother insists neurofibromatous
lesions grew rapidly after initiation of thyroid treatment.
(Interesting observation.)
9. 13 yo female: goiter, ? hypothyroidism. Rx anti-strumine (iodine).
10. Young adult female: goiter, visible, diffuse;
treated with thyroxine. No symptoms.
(Iodine treatment has been inadequate here, thus perhaps the frequent
resort to thyroxine.)
Conclusion
BOOK REVIEW
The Economics of Iodine, 7th Edition, May 1998, published by Roskill Information Services, Ltd., 2 Clapham Road, London SW9 0JA, England; fax 44 171 793 0008; e-mail info@roskill.co.uk
The book is full of interesting facts. The iodine market was in over-supply in 1990, and prices fell to a low of about US $9.00/kg by 1993, but rose again to around US $20.00/kg by 1998. World consumption is about 18,000 metric tons. Over 80% is used in North America, Western Europe and Japan. Major applications include photography, nylon manufacture, catalysis (e.g., in synthetic rubber), X-ray contrast media, disinfectants, and supplements in humans and animals. The world's largest producer is SQM in Chile, with a capacity of 8,000 tons. Several other Chilean companies bring the country's total to about 15,000 tons, slightly over half of the world's production. Three major companies in Japan provide an additional 9,000 tons. Other iodine reserves are in Azerbaijan, China, Indonesia, Turkmenistan, the USA, and Russia. Many other countries have companies manufacturing various iodine derivatives from imported iodine.
The book
details the many uses of iodine, including for iodized salt. It quotes ICCIDD and UNICEF on country data
and iodized salt usage for the correction of iodine deficiency. It calculates that at 1998 prices (US $12-16/kg
for iodine), the iodization of one ton of salt at 40 ppm increases the cost
by US $1.00. Thus, addition of iodine
represents between 7 and 15% of the cost of bulk salt. The world's consumption of salt in 1996 was
estimated at 44 million tons. The
total amount of iodine for salt iodization is less than 1,000 tons per year,
but is increasing. Animal feeds also
include iodine, in the forms of potassium iodide, calcium iodate, ethylenediamide
dihydriodate and ethylenediamine dihydriodide.
Recommended levels have been 120 mcg/kg of dry matter for calves and
0.0076% iodine in iodized salt licks for pregnant cows. In the United Kingdom, the maximal level permitted
in whole feeding stuff is 40 mg/kg. Other
applications of iodine that may impact on humans are antiseptics and disinfectants,
water purification, pharmaceuticals, X-ray contrast media, and protection
from radioactive iodine fallout. Increased use of iodine in disinfectants and animal feeds, as well
as for correction of iodine deficiency, is anticipated.
The book is clearly written and has a wealth of detail. The information about IDD is now a bit out of date, but much valuable information about the production, utilization, and marketing of iodine remains. This is a valuable reference work that will interest agencies and governments involved in obtaining iodine for human use.
In Brief.....
CROATIA - A meeting entitled "Iodine Deficiency and Goiter in
Croatia: Epidemiology and Iodine Prophylaxis"
took place October 21, organized by Professor Z. Kusic, sponsored by the Ministry
of Health and the Academy of Sciences and Arts of Croatia, attended by representatives
of the Ministry, the Academy, the salt sector, the Institute of Public Health,
and the health sector including the National Screening Committee.
All aspects of the national program were reviewed, from the iodized
salt production to the monitoring by neonatal TSH on a national basis. It was concluded that the program had resulted
in major achievements and almost complete national correction of iodine deficiency.
The 1996 legislation increased the concentration of iodine in salt
from 10-25 ppm in a program of mandatory universal salt iodization.
Critical issues are the level of iodization of imported salt, IDD control
in immigrant populations, and the iodine status during the perinatal period
to explain the persistence of slightly elevated neonatal TSH. Dr. Delange attended the meeting and with Dr.
Kusic met Mr. I. Kostovic, Chief of Staff of the President of the Republic,
at the President's residence. The
achievements and perspectives of the IDD program were reported and discussed.
Drs. Kusic and Delange were interviewed for the TV news in Croatia.
RUSSIA - The Prime Minister, V. Putin, signed the Decree of the
Government of the Russian Federation 1119, October 5, on measures for prophylaxis
of IDD, that had been drafted by the Ministry of Health more than a year ago.
It includes amendments to the working plan to assign responsibility
and a time line for organization of monitoring of both iodized salt and iodine
in people. Governmental agencies should purchase iodized salt for their personnel.
Iodized cooking salt should be added to a list of products that should
not be used after expiration of shelf life.
The Ministry of Health, the ministry for affairs in TV and radio broadcasting
and the media should develop TV and radio programs and publications on IDD
prophylaxis. Groups with executive power should work to
implement programs for IDD prophylaxis, to increase demand for iodized salt,
and to start communication campaign in the media.
MALI - Dr. A. K. Traore sends an update. Coordination for the National Program for IDD
Control was set up in 1996 as part of the Department of Family and Community
Health. The Nutrition Department will
work with the scientific and technical community on applied research and training.
The group's next meeting is planned for December 1999, and will discuss
national evaluation of the IDD prevalence.
Iodized salt is the major vehicle for IDD control.
Iodized oil and iodized water are occasional strategies. Problems with iodized salt have included a low level of information
about legislation, the price of iodized salt, the availability of noniodized
salt, and high taxes on iodized salt. A workshop organized with the help of UNICEF is addressing these
issues. Epidemiologic data from as
far back as 1948 have been reviewed. A
study this year supported by WHO reviewed micronutrient deficiencies in the
district of Bamako. Others are assessing
IDD prevalence in the first region of Mali and in schoolchildren in the peri-urban
area of Bamako. A study on the utilization
of Brassiodol in Mali is planned for 2000.
FOOD AND NUTRITION ACTION PLAN, WHO/EURO
- Held on Malta, November 8-10. The
objectives were to develop a food and nutrition action plan for the region,
to ensure support of WHO member states for it, and to consider how national
food and nutrition coordination mechanisms could be organized in each country.
Attendees included representatives from Ministries of Health of 32
European countries and temporary advisers and/or representatives of UNICEF,
FAO and ICCIDD. Dr. Delange represented
ICCIDD and presented a paper entitled "Action plan for the sustainable
elimination of IDD in Europe." In
addition to contributing to the formation of the action plan, the meeting
provided an opportunity for ICCIDD to meet with colleagues in WHO/EURO, UNICEF
and Ministries of Health from countries in the region. A WHO/UNICEF/ICCIDD subregional meeting on
IDD in the Baltic countries is contemplated, at the request of representatives
of the countries.
THYROMOBIL PROJECT IN WEST AFRICA - Field surveys in this collaborative project between ICCIDD
and le Centre Regional de Recherche en Alimentation et Nutrition (CRAN), based
in Lomo, Togo, are now underway. The
overall objective is to provide accurate, up-to-date information on current
iodine status in Togo, Benin, Burkina Faso, Mali and Niger. Goiter rates show these countries to have areas
of moderate to severe IDD. IDD control
programs are in various stages, with high availability of iodized salt in
Benin, moderate availability in Togo, and low availability (< 50% of households)
in the remainder. There have been
very few in-depth studies of IDD utilizing modern methods (thyroid ultrasound,
urine iodine excretion). It is hoped
that the project will serve to galvanize action on IDD control in areas where
progress to date has been relatively slow. The survey protocol is based on that of similar
projects which have been successfully carried out by ICCIDD in Europe (Delange),
South America (Pretell), and Indonesia (Djokomoeljanto). Thyroid ultrasonography and collection of urine
and salt samples is being carried out in 8-10 primary schools in each of the
five countries. The research team,
led by Dr. Ntambwe, ICCIDD Subregional Coordinator for Francophone West Africa,
has already completed surveys in Togo and Burkina Faso, and is currently in
Mali. The project was made possible
by the donation of the ThyroMobil van, previously used for studies on IDD
in Europe, by Merck Pharmaceuticals. Financial
support for the project has been received from WHO and UNICEF.
IODINE LEVELS IN AUSTRALIA - A limited survey in a Sydney hospital (Med J Austral 171:467-470,
1999) found median urinary iodine excretions of 104 mcg/L in 81 pregnant women,
79 mcg/L in 26 postpartum women, 65 mcg/L in 135 patients in a diabetes clinic,
and 64 mcg/L in 19 volunteers. Values below 50 mcg/L were found in 20% of the pregnant women, 19%
of the postpartum, 34% of the diabetics, and 26% of the volunteers. The authors conclude that iodine deficiency
may have returned to Australia, and recommend further studies. In an accompanying editorial (ibid, p 455-456),
Dr. Cres Eastman, ICCIDD Senior Advisor, recommends a national survey to determine
the status of iodine nutrition, education of the population and health care
providers about the effects of iodine deficiency, and legislation for universal
salt iodization for human and animal consumption.
LATIN AMERICA - The ThyroMobil has visited 11 countries. This ICCIDD project has been carried out by
Dr. Pretell, Regional Coordinator for the Americas, with financial and logistical
support by Merck KGaA, Darmstadt, and its representatives in the countries.
The van will go next to Panama, and then to Brazil in early 2000.
Preliminary data are available on urinary iodine and iodized salt samples
for 10 countries. Details will be
presented in the IDD Newsletter and reported more formally later.
The results have been sent to the governments and shared with PAHO,
and UNICEF. The sentinel sites, not selected at random, varied from a minimum
of 5 (Honduras) to a maximum of 23 (Mexico and Peru). Totals of samples for the 11 countries: sentinel sites, 129; thyroid volume measurements, 13,289; urinary
iodine samples, 6,450; salt samples, 1,369.
The median urinary iodine concentration was from 100 to 200 mcg/L in
Bolivia, Mexico, El Salvador, Argentina, and Peru; from 200 to 300 in Honduras
and Venezuela; above 400 in Ecuador (420) and Chile (540); and below 100 in
Guatemala (72). Countries with at
least 90% of the salt samples containing more than 15 ppm iodine: Argentina, Chile, Bolivia, Peru, Ecuador, and
Venezuela; figures for the remaining countries were Mexico, 74.3%; Guatemala,
33.3%; El Salvador, 60%; and Honduras, 74%. The percent of samples containing more than
50 ppm were high in Chile (77%) and Ecuador (94%). Most thyroid volumes in all countries are below the upper limit
of the European standards.