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Environmental Impacts
Introduction
The United States Environmental Protection Agency is reviewing atrazine for reregistration and tolerance reassessment under the Federal Insecticide, Fungicide and Rodenticide Act ("FIFRA") and the Federal Food, Drug and Cosmetic Act as amended by the Food Quality Protection Act of 1996 ("FQPA"). EPA developed an Environmental Risk Assessment for atrazine as part of this review. The Environmental Risk Assessment will ultimately form part of the basis of an Interim Registration Decision ("IRED"). The IRED will determine whether atrazine can continue to be used as a herbicide and under what conditions. Under a consent decree between EPA and the Natural Resources Defense Council ("NRDC"), an interim IRED will be issued in January 2003. A final IRED is required by October 31, 2003. This final IRED will include review of materials on amphibian effects submitted to EPA by February 28, 2003.
EPA's Environmental Risk Assessment identified two endpoints of concern: indirect effects and endocrine effects.
With regard to indirect effects, EPA stated:
"In areas of high atrazine use, there is widespread environmental exposure that (1) has resulted in direct acute effects on many terrestrial plant species at both maximum and typical use rates, (2) may have caused direct effects on aquatic non-vascular plants which in turn could have caused reductions in primary productivity, (3) may have caused reductions in populations of aquatic macrophytes, invertebrates and fish, (4) may have caused indirect effects on aquatic communities due to loss of species sensitive to atrazine and resulting in changes in structure and functional characteristics of the affected communities. Potential adverse effects on sensitive aquatic plants and other non-target aquatic organisms as well as their populations and communities, are likely to be greatest where atrazine concentrations in water equal or exceed approximately 10 to 20 µg/L on a recurrent basis or over a prolonged time period. Based on monitoring data, maximum concentrations at up to 35% of the sites exceeded the atrazine concentration (»10 µ/L) at which these adverse effects are found in simulated field studies. Up to 20% of the sites exceeded the atrazine concentration (»20 µ/L) at which adverse effects are found in simulated field studies as well as many of the 10th [per]centile values for acute and chronic effects from analyses of laboratory data populations."
Environmental Risk Assessment, p. 1
With regard to endocrine effects, EPA's Environmental Risk Assessment stated:
"In addition, atrazine has been reported to cause sub-lethal effects in aquatic organisms and amphibians. These include endocrine effects in frogs~0.1 µ/L and in largemouth bass at ~50 µ/L, as well as olfactory effects in salmon at ~0.5 µ/L."
Environmental Risk Assessment, p. 2
Like most of EPA's atrazine review, EPA's statements regarding indirect effects and endocrine effects are controversial.
EPA's assessment of atrazine's indirect effects are based on risk assessment method of questionable utility with regard to indirect effects. In fact, EPA states that it has no risk assessment method able to assess indirect effects.
EPA's statements about atrazine's endocrine effects on amphibians and fish are based on tests that have never been validated and that have never been demonstrated to be reliable and reproducible. These statements are the subject of one of the first Request for Correction petitions filed under the new Data Quality Act.
Indirect Effects
EPA's Environmental Risk Assessment states the agency's primary concern that atrazine may indirectly affect numerous organisms by intermittently killing aquatic vegetation upon which those organisms depend. In other words, EPA is concerned that atrazine at certain concentration levels harms the bottom of the food chain in some surface waters impacted by atrazine runoff. For example:
- "[T]he Agency identified the endpoints of greatest concern as indirect effects on aquatic communities due to loss of species sensitive to atrazine and resulting in changes in structure and functional characteristics of the affected communities, and reductions in populations of aquatic macrophytes, invertebrates and fish." Environmental Risk Assessment, p. 3.
- "[T]he Agency notes that the results of the agency's preliminary risk assessment shows that Levels of Concern (LOCs) are not exceeded for most of the direct acute and chronic effects on aquatic organisms." Environmental Risk Assessment, p. 12.
- EPA's Response to Comments on the draft Environmenal Risk Assessment contained similar statements: e.g.,
"[T]he Agency has concluded that the major effects from atrazine use are indirect effects on f ish and invertebrate populations...." Comment Response, p. 3.
"[T]he atrazine effects of concern are indirect effects on the aquatic community due to the loss of vegetative habitat." Comment Response, p. 3.
- EPA's Environmental Risk Assessment admits that there is uncertainty in its indirect effects assessment. For example at page 2, EPA points out that
"Recovery from the effects of atrazine and the development of resistence to the effects of atrazine in some vascular and non-vascular aquatic plants is reported and adds uncertainty to these findings. Further research is needed to quantify the impact that these effects would have on these risk conclusions."
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"Plant recovery and resistence are two complicating issues which add uncertainty to any risk assessment on atrazine, and there is insufficient information to do more than report that both occur."
EPA also acknowledged that there are substantial uncertainties regarding the field and laboratory standards used to support the Environmental Risk Assessment's conclusion of indirect effects: e.g., lack of reproducibility and lack of transparency. Environmental Risk Assessment, pp. 63-64.
Before EPA prepared and published its ecological risk assessment, the primary atrazine registrant, Syngenta, submitted a refined probabilistic risk assessment for atrazine's ecological effects and fate entitled Aquatic Ecological Risk Assessment of Atrazine-A Tiered Probabilistic Approach. This probabilistic assessment was prepared by a panel of highly regarded, independent scientists. It concluded that
"The integration of an unusually comprehensive data set including laboratory bioassays, field microcosm studies, simulation modeling, and environmental monitoring revealed that atrazine does not pose an ecologically significant risk to most aquatic environments in North America. Although direct toxic effects on aquatic animals are very unlikely to occur, some inhibitory effects on algae, phytoplankton or macrophyte production may occur in certain habitats vulnerable to agricultural runnoff. These effects are likely to be transient and recovery would be rapid..."
EPA explained that
"A probabilistic risk assessment is a general term for a risk assessment that uses probability distributions to characterize variability and/or uncertainty in risk estimates. In these risk assessments, one or more (random) variables in the risk equation are defined mathematically by probability distributions. Similarly, the output of a probabilistic risk assessment is a range or distribution of risks experienced by the various members of the exposed population of non-target organisms of concern."
Environmental Risk Assessment, p. 6
Virtually everyone agrees that probabilistic risk assessments are the appropriate risk assessment method for pesticide registration reviews. For example, EPA's Office of Pesticide Programs explains on its website:
"In May 1996 the Environmental Fate and Effects Division (EFED) of the Office of Pesticide programs (OPP) presented two pesticide risk assessment case studies to EPA's Scientific Advisory Panel (SAP) and asked them to address the agency's current pesticide risk assessment methodology. The SAP commented that while the current process is believed to be cautious and protective in terms of adverse environmental effects, it best serves as a screen because it provides little information on the likelihood of damage. The SAP recommended that the pesticide risk assessment process be expanded to include probabilistic assessments of risk and to identify the uncertainties associated with the assessment."
Nevertheless, EPA did not use or rely on Syngenta's probabilistic risk assessment, or on any other probabilistic risk assessment method. Instead, EPA only used and relied on a preliminary, lower tier (Tier I/Tier II) risk analysis of atrazine's ecological effects and fate. EPA stated that it rejected Syngenta's probabilistic risk assessment because it had "problems in the areas of transparency concerning the information used and the calculations performed, lack of sensitivity analyses, inconsistencies in the Tiered process, and the lack of model availability and documentation." Environmental Risk Assessment, p. 10. EPA also stated that it did not have data sufficient to perform a probabilistic risk assessment of atrazine's indirect effects:
"The endpoints of major concern were indirect adverse effects on aquatic communities due to loss of species sensitive to atrazine and resulting changes in structure and functional characteristics of the affected communities, and reductions in populations of aquatic macrophytes, invertebrates and fish. These adverse effects are shown in mesocosm and microcosm studies. A fully probabilistic risk assessment cannot be conducted for the community-level and population-level effects because the available microcosm and mesocosm studies showing effects on aquatic populations and communities only establish thresholds of adverse effects. They do not provide measures of severity of impacts with increasing exposure levels (dose-response relationships) which are needed for conducting a probabilistic risk assessment. In addition, the Agency notes that the results of the Agency's preliminary risk assessment shows that Levels of Concern (LOCs) are not exceeded for most of the direct acute and chronic effects on aquatic organisms. This would indicate that a probabilistic risk assessment for these endpoints is not needed at this time."
Environmental Risk Assessment, p. 12
Instead of a probabilistic risk assessment, EPA used the quotient method to assess atrazine's environmental risks. Use of this method to assess atrazine's indirect effects is problematic because EPA has stated "[t]he quotient method cannot evaluate secondary effects." 61 FR 47552, 47594 (Sept. 9, 1996). EPA defines the term "secondary effects" as "an effect where the stressor acts on supporting components of the ecosystem, which in turn have an effect on the ecological component of interest (synonymous with indirect effects...)." Id. at 47615.
EPA has described the quotient risk assessment method as follows:
"The standard method used in the EPA Office of Pesticide Programs (OPP) to characterize ecological risk is the ratio or quotient method. "Typically, the ratio (or quotient) is expressed as an exposure concentration divided by an effects concentration: (U.S. EPA, Part A, Section 5.1.3). A risk quotient (RQ) is the ratio of the estimated environmental concentration of a chemical to a toxicity test effect level for a given species. It is calculated by dividing an appropriate exposure estimate (e.g., EEC or estimated environmental concentration) by an appropriate toxicity test effect level (e.g. LC50). Thus, the RQ is an index (an indicator or measure of a condition) of the potential adverse effects. As an index, the risk quotient needs some reference point or bearing to have meaning. Thus, the Agency has established Levels of Concern (LOCs) in order to identify when the potential adverse effects are of concern to the Agency (See Appendix XVI, Table 1). LOCs are criteria used to indicate potential risk to nontarget organisms and the need to consider regulatory action. When an LOC is exceeded, it means that a pesticide, when used as directed, has the potential to cause adverse effects on nontarget organisms."
Environmental Risk Assessment, p. 5
The referenced Appendix Table contains the LOCs that EPA has established for all pesticide Environmental Risk Assessment. These LOCs do not vary from pesticide to pesticide.
EPA's refined risk assessment for atrazine's environmental effects consisted primarily of computer modeling of atrazine concentrations in various surface waters based on the available monitoring data. The model results were then compared to the LOCs. Environmental Risk Assessment, pp. 4-5, 7-8, 16.
Use of the quotient method for pesticide risk assessments has been questioned on peer review. For example, EPA's Office of Pesticide Programs explained on its website that the SAP concluded that the quotient method lacks utility:
"The [SAP] panel suggested that the current test methodologies and specific endpoints used by OPP in its model assessments were designed to support the relative simplistic process of hazard assessment, not risk assessment. The Panel indicated that the current approach has a number of limitations, and its utility in risk assessments is of questionable value. They also pointed out that gaps in the current methodologies must be filled to accomplish effective and comprehensive risk assessments. As a result, they strongly urged OPP EFED to conduct probabilistic assessments (risk assessments) to evaluate the ecological impacts from pesticides."
The SAP has also emphasized its concern "with the notion that the frequency of LOC exceedances is a useful measure." The SAP concluded that the LOC-exceedance standard is "essentially an arbitrarily selected threshold." FIFRA Scientific Advisory Panel, Final Report on a Set of Scientific Issues Being Considered by the Environmental Protection Agency Regarding Methodology for Conducting Comparative Ecological Risk Assessments," p. 9 (SAP Report No. 99-01A, Jan. 22, 1999).
In addition, EPA's Ecological Committee on FIFRA Risk Assessment Methods ("ECOFRAM") published in 1999 an Aquatic Report which on page 3 summarized the SAP's conclusions in part as follows (emphasis added):
"The panel suggested that the current test methodologies and specific endpoints used by OPP in its model assessments were designed to support the relative simplistic process of hazard assessment, not risk assessment. The Panel indicated that the current approach has a number of limitations, and its utility in risk assessments is of questionable value. They also pointed out that gaps in the current methodologies must be filled to accomplish effective and comprehensive risk assessments. As a result, they strongly urged OPP EFED to conduct probabilistic assessments (risk assessments) to evaluate the ecological impacts from pesticides."
In sum, EPA concluded that indirect effects were the primary concern for atrazine. Yet EPA used a risk assessment method to assess indirect effects that cannot assess indirect effects. In fact according to EPA , the Agency has no risk assessment method able to assess indirect effects:
- "EFED contends that there is 'inadequate data' on indirect effects to assess risk...." Comment Response, p. 3.
- "Currently, there is no methodology...which can model and statistically analyze indirect effects." Comment Response, p.3.
EPA acknowledged this flaw in its pesticide risk assessment process ten years ago:
- "Although the Agency believes that long-term, indirect effects of pesticide use on aquatic ecosystems may be important, the Agency does not have a testing scheme in place to accurately measure such effects within the time specified for Reregistration. Decisions on the Ecological, Fate, and Effects Task Force, Linda J. Fisher, EPA Assistant Administrator, Attachment: Program Guidance on Ecological Risk Management, p. 1 (Oct. 29, 1992)."
CRE's Position on Atrazine's Indirect Effects
CRE does not believe that EPA should or could reach any reliable conclusions regarding atrazine's indirect effects until and unless EPA has data and a risk assessment method able to assess such effects. CRE believes that EPA should develop a probabilistic method able to assess all risks from atrazine and all other pesticides.
Endocrine Effects
EPA's Environmental Risk Assessment, at pages 90-95, includes a section entitled "Reported Sub-Lethal Effects," which includes a subsection entitled "Endocrine Effects." This sub-section of the risk assessment first describes, without criticism, atrazine tests performed by Dr. Tyrone Hayes on frogs. According to these tests, atrazine at very low concentrations caused "gonadal abnormalities including multiple testes and/or ovarian tissues within testes (hemaphroditism)...."
Environmental Risk Assessment, p. 90
To account for these endocrine effects, Dr. Hayes,
"...hypothesized that atrazine induces aromatase and promotes the conversion of testosterone to estrogen. This disruption in steroidgenesis via induction of aromatase is hypothesized as a likely explanation for the 10-fold decrease in plasma testosterone, demasculization of the male larynx and the production of hermaphrodites."
Environmental Risk Assessment , p. 90
After discussing the Hayes frog tests, EPA concluded that:
"Atrazine effects on tadpoles are a concern because atrazine use coincides with spring rains and the breeding season for amphibians. While these gonadal abnormalities and laryngeal alterations raise concerns about adverse effects on amphibian reproduction, there is no conclusive evidence that these changes have an adverse effect on amphibian reproduction. Additional testing with atrazine-treated tadpoles and adult frogs should be conducted to determine what, if any, effects occur on reproduction."
Environmental Risk Assessment, pp. 91-92
Thus, EPA's Environmental Risk Assessment accepts the endocrine effects allegedly shown by the Hayes Frog Tests as accurate and reliable. According to EPA, the only remaining question is whether those endocrine effects affect frogs' ability to reproduce.
The Hayes Frog Test Studies have received considerable publicity. They form part of the basis for NRDC's Petition to EPA to ban atrazine.
The Endocrine-Effects subsection of the Environmental Risk Assessment also discusses tests on the effects of atrazine on estradiol, 11-ketotestosterone, testosterone, and vitellogenin in largemouth bass. EPA's Environmental Risk Assessment concluded:
"Although high variability confounds this study's ability to resolve the effects of atrazine on plasma steroids and vitellogenesis, the study has demonstrated that technical grade atrazine affects plasma 11-ketotestosterone in males and that the formulated product affects plasma estradiol in females. The non-guideline study is classified as supplemental and provides useful information on the potential effects of atrazine on endocrine-mediated pathways."
Environmental Risk Assessment, p. 93
These statements regarding atrazine's endocrine effects are based on tests that have never been properly validated, and that have never been demonstrated to be reliable and reproducible. EPA acknowledged this lack of validated tests in its response to comments on the Environmental Risk Assessment:
"The Endocrine Disruptor Screening program has proposed a number of test protocols for identifying endocrine effects in wildlife species. Some of these protocols are currently in round-robin testing. As of this date, none of them have been approved for regulatory testing."
Comment Response, p. 22
Dr. Hayes' tests have been criticized by a panel of scientists working on the atrazine endocrine effects issue. Other laboratories have been unable to reproduce the results of Dr. Hayes' frog tests as explained in an article to be published in Environmental Toxicology and Chemistry in February 2003.
There are reports that Dr. Hayes is teaming with the United States Geological Survey on a nationwide frog survey to begin in early 2003.
CRE's Position on Endocrine Effects
EPA and most other federal agencies have established a Government-wide Data Quality Standard that requires proper validation of tests before the test results can be considered reliable:
"Before a new or revised test method is used to generate information to support regulatory decisions, it must be...validated to determine its reliability and relevance for its proposed use..."
Evaluation of the Validation Status of Toxicological Methods: General Guidelines for Submissions to ICCVAM, Prepared by Interagency Coordinating Committee on the Validation of Alternative Methods , et. al., p. v., October 1999. ("Validation Guidelines").
There are no properly validated tests for the endocrine effects discussed in EPA's Environmental Risk Assessment for atrazine. Consequently, EPA's statements regarding atrazine's endocrine effects on fish and amphibians do not meet this Government-wide Data Quality Standard. For this and other reasons, CRE and and several agricultural groups have filed a Request or Correction under the new Data Quality Act and EPA's Data Quality Act Guidelines. This Petition requests EPA to correct the Environmental Risk Assessment to state that EPA cannot reach any conclusions regarding atrazine's endocrine effects on fish and amphibians until and unless there are properly validated tests for those effects.
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