Long-delayed EPA Risk Assessment of Endocrine Disruptors Exhibits Flaws

In its ninth year of work on the issue, the U.S. Environmental Protection Agency (EPA) is about to begin the risk assessment process for an important but little-known group of chemicals called endocrine disruptors. However, scientists are concerned early indications of the assessment's construction will produce scientifically suspect results.

Risk assessments are an important early step in the regulatory process. Risk assessments often inform federal regulators of the certainty of a public hazard and serve as a factual basis for a regulatory response.

EPA's Endocrine Disruptor Screening Program (EDSP) is in the process of constructing a complex risk assessment to determine the effects of certain substances on the human endocrine system. As in the case of the EDSP, agencies often perform risk assessments to determine the hazard level of substances for which a great deal of data is not available and which have not yet been subjected to federal regulation.

Little is known of the exact effects of endocrine disruptors. An endocrine disruptor is any substance which alters the function of the endocrine system. The endocrine system regulates certain mood, growth and development functions including hormonal and thyroid functions. Scientists are still uncertain as to the types of substances which may be endocrine disruptors and the levels of exposure that may jeopardize public health. Scientists suspect endocrine disruptors to be commonly found in a number of consumer products including pesticides, cosmetics and finished plastics.

Concern over the impact of products on the human endocrine system caught the attention of Congress in 1996. That year, Congress passed the Food Quality Protection Act, which required EPA to screen the effects of pesticides on the human endocrine system. The law also instructs EPA to take action "as is necessary to ensure the protection of public health" if finding a substance to affect the endocrine system (21 USC 346a(p)).

Subsequently, in 1998, EPA established the EDSP. However, the agency is still in the process of finalizing its risk assessment. The agency has yet to study the effects of any pesticide on the human endocrine system.

The risk assessment will be a two-tier process. The first tier will use a variety of scientific experiments to determine whether substances interact with endocrine systems in any way. The second tier will attempt to determine exact effects at varying doses. EPA is still in the process of developing the experiments for use in the tier one stage.

Congress has indicated its growing impatience with EPA's lack of progress on implementing the requirements of the act. In a February House Appropriations subcommittee hearing, Rep. Jim Moran (D-VA) questioned EPA Administrator Stephen Johnson on the issue. Johnson's flippant response was, "We have been doing the research, but there's this pesky thing called science."

However, scientists are assailing this risk assessment as scientifically weak. A Dallas Morning News article summarizes the growing concern of the scientific community. For example, scientists are expressing concern EPA has not properly constructed the dose-response assessment, which compares dosage level to health effect. Unlike other contaminants, endocrine disruptors may cause different or more serious adverse effects at trace levels than at greater levels.

Scientists are also concerned about the influence of industry in construction of the risk assessment. Scientists worry EPA may allow chemical companies to choose the breed of rat on which they will test chemicals. Certain rats have exhibited high tolerances to the effects of endocrine disruptors.

Critics are also concerned with potential cuts to the budget of EPA's work on endocrine disruptors. President Bush's budget submission to Congress proposed a $1.6 million — or 22 percent — cut to EDSP. Democrats in both the House and Senate have indicated they would restore this and other proposed cuts to EPA's budget; however, those appropriations bills remain in committee.

On June 11, EPA released a draft list of 73 pesticides slated to undergo the first round of first tier testing. The public may comment on the list upon its publication in the Federal Register. EPA hopes to begin the risk assessment process for endocrine disruptors later this year.

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