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Atrazine Background
Resources
- Questions On Pesticides?
National Pesticide Information Center (NPIC) 1-800-858-7378
Use Profile
- Atrazine is a triazine herbicide registered for the control of broadleaf weeds and some grassy weeds.
- Atrazine controls weeds by inhibiting photosynthesis.
Uses include:
| corn (field and sweet) | summer fallow |
| sorghum | forestry or woodlands |
| sugarcane | conifers |
| wheat (application to wheat stubble on fallow land following harvest) | woody ornamentals |
| guava | Christmas trees |
| macadamia nuts | sod |
| hay | residential and recreational turf (parks, golf courses) |
| pasture |
- Atrazine is estimated to be the most heavily used herbicide in the U.S. Its top agricultural use areas in terms of use per acre include the midwest, particularly Iowa, Illinois, Indiana, Ohio, and Nebraska, and Delaware .
- Atrazine's use on lawns is mainly in Florida and the Southeast.
- Estimated 76.4 million pounds are applied annually.
- Usage on corn accounts for approximately 86% of total U.S. domestic usage (in pounds), followed by sorghum at 10% and sugarcane at 3% (all other uses take up the remaining 1%).
- Approximately 75% of the field corn acreage grown in the U.S. is treated with atrazine.
- Atrazine formulations include emulsifiable concentrate, flowable concentrate, water dispersable granular (dry flowable), soluble concentrate, wettable powder, granular, and as a ready-to-use formulation
- Application methods include groundboom sprayer, aircraft, tractor-drawn spreader, rights-of-way sprayer, hand-held sprayers, backpack sprayer, lawn handgun, pushtype spreader, and bellygrinder.
- Atrazine is the most commonly detected pesticide in surface water. Atrazine's frequent detection in streams, rivers, groundwater, and reservoirs is related directly to both its volume of usage, and its tendency to persist in soils and move with water.
Human Health Risk Information
- Atrazine has low acute toxicity.
- Based on all the available test data, the Agency's evaluation, and scientific peer review, atrazine is not likely to be a human carcinogen.
- Our analysis has determined that atrazine does not pose any risk from food.
- Our concern for atrazine reflects potential hormonal effects observed in laboratory animals associated with shorter term exposure.
- Atrazine and three of its metabolites are found in water. These three metabolites are chlorinated atrazine compounds, desethylated atrazine (DEA), desisopropyl atrazine (DIA), and diaminochlorotriazine (DACT - the terminal degradate).
History of regulating atrazine
- Atrazine first registered in 1958
- Groundwater mitigation (1990)
- Surface water mitigation (1992)
- Special Review initiated under FIFRA (1994)
- Additional surface water mitigation (1996)
- Revised cancer characterization (2000)
- NRDC consent decree (2000 & 2001)
- Preliminary risk assessments (2001)
- Revised risk assessments (2002)
- Interim Reregistration Eligibility Decision (2003)
- Amended IRED with consideration of ecological issues, including amphibians (scheduled for October 31, 2003)
Atrazine is also regulated under water statutes
- Maximum Contaminant Level (MCL) of 3.0 ppb was established in 1991 (Safe Drinking Water Act)
- MCL will be reevaluated as part of EPA's National Primary Drinking Water Standards 6-year review of regulated contaminants
- Draft water quality criteria for aquatic life were published for comment in 2002 (Clean Water Act)