Atrazine Interim Reregistration Eligibility Decision (IRED) Q&A's - January 2003
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Q & A's
EPA is completing its interim reregistration eligibility decision (IRED) for the pesticide atrazine, a herbicide primarily used to control broadleaf and some grassy weeds for a variety of major and minor crops and nonagricultural uses. First registered in 1958, and used extensively throughout the country, atrazine is being reviewed as part of EPA’s program to ensure that older pesticides meet current health and environmental safety standards. As part of this effort, EPA has reviewed an extensive body of data and studies, conferred with independent scientific experts in a variety of disciplines, and encouraged public and stakeholder participation. The IRED document identifies the various conditions and risk mitigation measures necessary to ensure that approved uses of atrazine meet federal safety standards. EPA prepared this document after close consultation with our federal, state, and tribal regulatory partners. This Q&A document provides technical and general information about atrazine and its current regulatory status under pesticide and water laws.
On This Page
- What is atrazine and how is it used?
- Where is atrazine used most heavily?
- What are atrazine’s potential effects on human health?
- What action is EPA currently taking with atrazine?
- How did EPA come to this decision?
- How many community water systems are there, and how many are we concerned about?
- What are the new and innovative measures being implemented as part of the IRED?
- In which states are there watersheds where intensive monitoring going to begin now?
- Does this IRED address endangered species issues?
- Why is EPA taking this action now?
- What are the public health benefits we expect from this action related to drinking water?
- Are there other health benefits to be gained from this action?
- What are the environmental benefits we expect from this action?
- What about atrazine in rural well water - will monitoring assure that all home wells are O.K.?
- Recent studies and journals have raised new concerns regarding the potential effects of atrazine on frogs. Does the IRED address potential amphibian (frog) risk?
- What is atrazine and how is it used? Atrazine, which may be applied both before and after planting to control broadleaf and grassy weeds, was first registered for use as a herbicide on December 1, 1958. Atrazine is currently one of the most widely used agricultural pesticides in the United States, with estimated production of 76 to 85 million pounds annually. Approximately 76.5 million pounds of active ingredient are applied domestically per year. The main use sites for applying atrazine include the following:
- minor crops including: guava, hay, macadamia nuts, pasture, and winter wheat
- golf courses (turf)
- residential lawns
- Bermuda grass
- grasses grown for seed
- landscape maintenance
- ornamental trees
- Christmas trees
- recreational areas
- industrial areas
Atrazine is estimated to be the most heavily used herbicide in the United States. Its primary uses are on corn and sugarcane and on residential lawns in Florida and the Southeast. Currently, the heaviest atrazine uses per unit area occur in portions of Delaware, Iowa, Illinois, Indiana, Ohio, and Nebraska.
In EPA’s refined risk assessment, issued in May 2002, the Agency reviewed extensive data relating to the potential human health effects of atrazine exposure. EPA found, in consultation with an independent scientific advisory panel, that it is not likely to be carcinogenic to humans. However, there is concern that atrazine has been associated with causing imbalances in hormone levels in laboratory animals, possibly disrupting reproductive and developmental processes. EPA considered these effects, and the exposure levels that created such concerns, in determining what types of risk mitigation measures are necessary to meet Federal safety standards.
This is the latest step in a process to review atrazine and other older pesticides against current standards. The process includes updating available data on the pesticide being reviewed. To date, EPA has completed the following steps as part of the atrazine review.
- EPA released the Preliminary Human Health Risk Assessment for Atrazine in February 2001 and the Preliminary Environmental Fate and Effects Risk Assessment in September 2001. To ensure transparency and opportunities for public involvement, the public was invited to comment on these documents and these comments have been considered in atrazine’s revised risk assessments.
- In April 2002 the Agency completed the revised Human Health Risk Assessment and the Environmental Fate and Effects Risk Assessment. The revised assessment and supporting documents may be found at: http://www.epa.gov/oppsrrd1/reregistration/atrazine
There are approximately 50,000 community drinking water systems in the United States. Of these, 40,000 are served by ground water, and 10,000 are served by surface water.
Surface water is our focus in this action. For the 10,000 community water systems served by surface water, the Agency has identified 3,600 systems where atrazine is used and monitoring information is available.
- The current monitoring has identified 200 community water systems where detections have approached or exceeded the MCL for atrazine.
- Of the 200, eight of these community water systems have annual average readings that significantly exceed the MCL.
Human Health Measures
The IRED includes measures to address risks to workers, risks associated with residential uses, and risks from drinking water. EPA has put in place enforceable requirements, including:
- An intensive monitoring program for raw water – including weekly sampling during the pesticide use season and biweekly for the rest of the year – to ensure that the 200 most vulnerable watersheds are routinely monitored so atrazine levels do not reach levels of concern.
- For the eight highly vulnerable water systems, if atrazine is detected above the level of concern, use will be prohibited in the specific watershed area.
- For the remaining systems, there will be intense monitoring; then if there is another detection that exceeds the level of concern, site-specific mitigation plans will be put in place. Further, if atrazine is detected again above the level of concern, use of atrazine will be prohibited in that specific geographic area.
- In addition, for all others watersheds where atrazine is used, the Safe Drinking Water Act requires routine monitoring of finished drinking water for atrazine. For these systems, if atrazine is detected at levels approaching the MCL, then additional monitoring and regulatory oversight will be triggered.
- In these cases, it would be considered a highly vulnerable watershed category for regulatory purposes.
- If atrazine levels exceed safety standards in raw water, atrazine will be prohibited in geographic areas or watersheds.
- If the MCL is violated, the pesticide manufacturer is required to take steps necessary to assist the community water supply to come into compliance with the MCL.
- In addition, the manufacturers will conduct an education program with farmers to ensure that atrazine is used according to more restrictive management practices. These practices have been shown to reduce atrazine contamination to safe levels for ground and surface water.
In addition, to confirm that rural drinking water wells are not expected to have atrazine levels that exceed the Agency's level of concern, the Agency will require that the registrant(s) conduct a rural well monitoring study in atrazine use areas.
EPA also is requiring changes to better protect workers and people who may be exposed to atrazine used in residential settings.
Ecological MeasuresTo mitigate risks to the environment from atrazine residues, the Agency is establishing a tiered ecological assessment process that will identify waterbodies affected by atrazine and determine which of these waterbodies are candidates for atrazine monitoring and/or mitigation. Waterbodies that may be identified for mitigation are waters officially listed by a state as impaired and/or waters with measured exceedences of the Agency's level of concern. Monitoring programs to determine if mitigation is required may be based on such factors as frequency, duration, and level of atrazine concentrations; atrazine use in the watershed; and environmental vulnerability. The plan will be completed in spring 2003.
EPA has long considered its review of atrazine to be a high priority in the reregistration and tolerance reassessment program, and has been working to complete the scientific analysis and public consultation necessary to release a well-grounded decision as quickly as possible. In addition, EPA agreed in a Consent Decree with a number of public interest groups to complete this portion of the atrazine review by January 31, 2003.
- EPA has Completed an Extensive Review: This IRED is a product of years of scientific analysis of both ecological and health risks. We have also ensured that the process incorporated appropriate opportunities for expert and stakeholder consultation and to allow for the use of sound scientific analysis.
- FIFRA Requires Reregistration Review of Older Pesticides: EPA’s review of atrazine as part of the Agency’s comprehensive effort to ensure that older pesticides meet current Federal health and safety standards. As part of that effort, we are considering a wide range of scientific data and public input to ensure that any final risk management decision is grounded in sound science and informed by all perspectives.
- Completing the IRED Fulfills an Obligation in the NRDC Consent Decree: This deadline is imposed by a Consent Decree that resolved lawsuits brought against the Environmental Protection Agency by the Natural Resources Defense Council (NRDC), the United Farmworkers of America, the AFL-CIO, and other farmworker/environmental groups with respect to pesticide tolerance reassessment and pesticide reregistration.
- We are announcing a new, watershed based action that will better protect people from potential risks associated with the use of atrazine -- one of the most widely used herbicides in the United States.
- By providing for an early alert system, these actions will better protect all water supply systems in areas where atrazine contamination can be a problem.
- This new approach will substantially increase the monitoring for vulnerable water supply systems–so when we detect atrazine at levels of concern–use of the pesticide will be prohibited in that specific geographical area.
- The Agency’s existing MCL remains protective and in place. If the MCL is violated, the pesticide manufacturer will take steps necessary to assist the community water system to become compliant with the MCL for atrazine.
By implementing an intensive monitoring program when certain levels of atrazine are detected in water supplies, and by prohibiting atrazine uses in watersheds that result in exceedences, EPA will be able to ensure that exposures to atrazine in drinking water do not reach levels that pose a risk to public health. The study of rural wells will similarly provide a level of assurance that unacceptable exposure to atrazine is not occurring by this means.
Other measures included in the IRED, such as changes to the way atrazine is handled and its use in residential settings, including reducing application rates, changing the application method to spot treatments, and requiring that grass be watered after application. Label changes for residential use, which take effect in 2004, will reduce potential exposure and risk to workers and people in residential situations.
EPA is in the process of evaluating data relating to potential effects of atrazine on amphibians from researchers representing eight universities. EPA is considering a number of additional new studies on potential amphibian risk. Where possible, raw data from these studies are being analyzed and study methods are being documented in order to perform our own, independent quality review of the studies. Additional information is expected to be submitted in the coming months, and the Consent Decree obligates EPA to review data relevant to these issues that is submitted before February 28, 2003 for an amendment to the IRED to be issued no later than January 31, 2003. OPP is planning to summarize all these studies in preparation for a FIFRA Science Advisory Panel (SAP) meeting where the potential effects of atrazine on amphibians will be discussed, and EPA will seek SAP guidance on the Agency’s assessment of these data and on other scientific issues concerning atrazine. The Agency’s amended IRED will incorporate the results of the SAP consultation on these issues.