According to EPA, in recent years some scientists have speculated that certain chemicals might be disrupting the endocrine system of humans and wildlife.

On June 18, 2007, the U.S. Environmental Protection Agency (EPA) published a draft list of 73 chemicals selected for so-called "Tier 1" screening under the Endocrine Disruptor Screening Program (EDSP).  Although EPA states that the list should not be construed as a list of known or likely endocrine disruptors, those producers and users whose chemicals are listed are not happy. According to EPA, in recent years some scientists have speculated that certain chemicals might be disrupting the endocrine system of humans and wildlife, resulting in developmental and reproductive problems. Based on this and other evidence, Congress passed the Food Quality Protection Act (FQPA) in 1996, requiring that EPA initiate the EDSP to screen pesticide chemicals and environmental contaminants for their potential to affect endocrine systems.

Endocrine disruptor screening is currently proceeding on three fronts:  performing scientific and technical testing needed to validate the endocrine disruptor screens and tests; setting priorities for selecting chemicals for initial screening and testing; and developing the policies and procedures EPA will use to require testing.  The June 2007 notice announced the draft list of the initial 73 pesticide active ingredients and inerts to be considered for Tier I screening.

The Selection Approach
EPA produced the draft list using the approach described in its Sept. 27, 2005, Federal Register notice, and included chemicals that EPA, in its discretion, has decided should be tested first, based upon each chemical’s exposure potential.  Using the approach described in this notice, EPA analyzed data for exposure pathways for pesticide active ingredients and high production volume (HPV)/pesticide inert ingredients. The exposure pathways identified for pesticide active ingredients include food, drinking water, residential use and occupational exposure. The exposure pathways identified for HPV/pesticide inert chemicals include human biological monitoring, ecological biomonitoring, drinking water and indoor air.  Because there was a large number of chemicals on one or more of these candidate lists, EPA needed to establish priorities for selecting chemicals for initial screening.

EPA identified an initial list of 64 pesticide active ingredients and nine HPV/pesticide inert chemicals to undergo Tier 1 screening in the EDSP.  In choosing which pesticide active ingredients and HPV pesticide inert ingredients to include on the initial screening list, EPA gave priority to those that appeared most robustly in the exposure pathway databases.

The Tier I screening tests consist of a variety of endocrine test methods. These include an estrogen receptor binding assay, androgen receptor binding assay, steroidogenesis assay, aromatase assay, uterotrophic assay, Hershberger assay, pubertal assay and fish reproductive screening. EPA hopes to have these tests peer reviewed by the middle of 2008.

In its September 2005 Federal Register notice, EPA stated certain types of substances may be deferred from initial screening:  certain Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) List 4 pesticide inerts; most polymers with average molecular weights greater than 1,000 daltons; strong mineral acids and bases; and chemicals that are being used as “positive controls” to validate the screening assays. EPA examined the 73 chemicals identified for initial screening in light of applying these deferral criteria. None of the chemicals selected for initial screening is categorized as List 4 inerts, high molecular weight polymers or strong mineral acids or bases.

Next Steps
As noted in the Federal Register notice, any company subject to a testing requirement under Tier 1 may assert that the chemical is not an endocrine disruptor and that the Tier 1 EDSP screening procedure is unnecessary. EPA does not intend to permit chemicals on this list to bypass Tier 1 screening and move directly to Tier 2 testing without appropriate data to support such an action.

For chemical producers and users of these substances, it is important to ensure that the data supporting the nominations are correct. It is also important to remind EPA to conduct no Tier I test unless and until it has been peer reviewed and validated.  Otherwise, any forthcoming data will not be reliable.

Plainly, should any Tier I testing generate data that some could argue evidence endocrine disruption capability, the chemical substance will be associated with endocrine effects that will undermine the commercial vitality of the substance, and invite other adverse consequences. It is thus critically important for interested stakeholders to participate actively in this rulemaking initiative. Comments on the draft list are due on Sept. 17, 2007.

Lynn L. Bergeson is managing director of Bergeson & Campbell P.C., a Washington, D.C., law firm focusing on conventional and engineered nanoscale chemical, pesticide and other specialty chemical product approval and regulation, environmental health and safety law, chemical product litigation and associated business issues. She is president of The Acta Group LLC and The Acta Group EU Ltd., with offices in Washington, D.C., and Manchester, U.K. She can be reached at 202.557.3800.