Chlorpyrifos

Chlorpyrifos is an organophosphate insecticide, acaricide and miticide used to control foliage and soil-borne insect pests on a variety of food and feed crops.

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Basic Information

Chlorpyrifos has been used as a pesticide since 1965.

Uses for chlorpyrifos include agricultural and non-agricultural:

  • The largest agricultural market for chlorpyrifos in terms of total pounds of active ingredient is corn.
  • It is also used on soybeans, fruit and nut trees, Brussels sprouts, cranberries, broccoli, and cauliflower, as well as other row crops. 
  • Non-agricultural uses include golf courses, turf, green houses, and on non-structural wood treatments such as utility poles and fence posts.

Products are sold as liquids, granulars, and flowable concentrates and may be applied by either ground or aerial equipment.

Using Chlorpyrifos Products Safely

Chlorpyrifos can cause cholinesterase inhibition in humans at high enough doses; that is, it can overstimulate the nervous system causing nausea, dizziness, confusion, and at very high exposures (e.g., accidents or major spills), respiratory paralysis and death.

Occupational exposure to chlorpyrifos is of concern to the Agency. EPA recognizes that there are concerns for some workers who mix, load and apply chlorpyrifos to agricultural and other non-residential sites. Generally, these risks can be mitigated by a combination of additional personal protective equipment and engineering controls, and by reductions in application rates.

Chlorpyrifos products can be safely used by following label directions. 

Personal Protection Equipment (PPE) for agricultural workers should consist of:

  • Double layers. 
  • Chemical-resistant gloves.
  • Chemical-resistant shoes plus socks;
  • Chemical-resistant headgear for overhead exposure.
  • Chemical-resistant apron when cleaning and mixing or loading.
  • A dust/mist respirator are required for the following scenarios:
    • Mixing/loading liquids for groundboom and airblast application.
    • Loading granulars for ground application, tractor drawn granular spreader, and low pressure handwand.

Engineering controls are required for the following scenarios:

  • Mixing wettable powder for ground boom application (water soluble packaging).
  • Mixing wettable powder for air blast application (water soluble packaging). 
  • Aerial application of sprays (enclosed cockpit).

EPA Actions

Recognizing the health and environmental risks from chlorpyrifos exposure, the following restrictions have been placed on pesticide products containing chlorpyrifos:

  • In June 2000, the Agency eliminated all homeowner uses, except ant and roach baits in child resistant packaging. In addition, termiticide uses were phased out.
  • In 2000, EPA required that all uses of chlorpyrifos products in the U.S. be discontinued on tomatoes. The use on apples was restricted to pre-bloom and dormant application. The grape tolerance was lowered to reflect the labeled dormant application.
  • In 2002, EPA restricted the use of chlorpyrifos on citrus and tree nuts as well other crops.
  •  In 2012, EPA further limited the use of chlorpyrifos by significantly lowering pesticide application rates and creating “no-spray” buffer zones around public spaces, including recreational areas and homes.

Chlorpyrifos is currently undergoing registration review, a program that re-evaluates all pesticides on a 15-year cycle. In 2009, registration review of chlorpyrifos was initiated by the publication of the Preliminary Work Plan. All documents related to the registration review can be located in docket number EPA-HQ-OPP-2008-0850 located at www.regulations.gov

Additional Information