An internal panel of EPA toxicologists has concluded that EPA currently overestimates the cancer risk posed by most widely used herbicide in the country, according to agency sources who say the finding will likely spur EPA to reassess the way it regulates atrazine.
The panel's recommendations, according to EPA sources, could push the agency to relax its current drinking water and water quality limits for atrazine, as well as its controversial proposal requiring states to develop "state management plans" (SMP) to control runoff from pesticides and herbicides.
For the past several years, environmental groups have pressed EPA to tighten its regulation of atrazine, claiming that runoff from the pesticide is a major source of drinking water contamination. In addition, atrazine is one of five pesticides for which states would have to submit runoff control plans under the agency's proposed SMP regulation.
EPA is currently reviewing its residue limits for atrazine under the Food Quality Protection Act's registration requirements, and agency staff expect to decide whether to re-register the compound by 1999 or 2000. Under this review process, the Office of Pesticide Program's peer review panel has examined a proposal from Novartis the herbicide's manufacturer, that claims that atrazine poses no cancer risk at low levels. The panel recently agreed with Novartis, concurring that atrazine "is more suitable for a non-linear risk assessment model," according to one EPA official. Hence, this source says the panel believes it would be appropriate to regulate the herbicide under the assumption that it poses no cancer risk at a low level of exposure.
One EPA source explains that this finding could prompt the agency to relax its atrazine regulations. "Traditionally, chemicals that are found to have a threshold at which there is no effect tend to be regulated with less scrutiny," says one EPA source. At the same time, another agency source thinks it is far too early to assume that this recommendation will translate into regulatory relief. This source says that atrazine is currently regulated in a vacuum and thus it is not considered in conjunction with other triazine compounds. This source thinks the new food safety law will require the agency to establish risk levels for atrazine by evaluating it in combination with other triazine chemicals. This source believes that this kind of evaluation could raise new concerns about the chemical.
In the interim, the panel's finding should have dramatic impacts on other regulations and particularly the SMP program. "We have started to analyze what this would mean for the SMP rule," one EPA source says. This source says the panel's findings would not impact the controversial structure of the rule which requires states to seek EPA approval for runoff management plans, but may alter the current decision to include atrazine and other triazines on the list of pesticides which would require such a plan. Other EPA sources say the new risk data will likely factor into upcoming decisions to revisit the drinking water standard for atrazine as well.
The panel's recommendations are still being reviewed by upper level management, according to one EPA official. Eventually, the recommendations from the panel will be forwarded to the pesticide program's science advisory panel (SAP), a group of independent scientists which review science policy for the program. An EPA source says the SAP initially intended to review the recommendations in March of 1998, but this meeting was canceled and has not been rescheduled.
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