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Tuesday, December 18, 2007

EPA Begins Rulemaking on Air Pollution Standard for Lead

Yesterday, EPA published an Advanced Notice of Proposed Rulemaking for its planned revision to the National Ambient Air Quality Standard (NAAQS) for lead. Lead is one of six pollutants regulated by the NAAQS program under the Clean Air Act.

An Advanced Notice of Proposed Rulemaking (ANPRM) is a relatively minor step in the rulemaking process. Nonetheless, the ANPRM for the lead standard has been controversial because of the range of policy options EPA is considering.

According to the ANPRM, EPA may tighten the standard to a level as low as 0.02 μg/m³ from the current level of 1.5 μg/m³. EPA is also considering maintaining the current standard, or eliminating the regulation for lead air quality altogether — an option EPA's own advisors say has no scientific basis.

EPA will take comments through Jan. 16 on any and all of its surprisingly broad range of policy options.

EPA's revision to the lead standard has been the subject of varying scientific interpretations.

Environmental scientists on EPA's staff are recommending a markedly tighter air quality standard for lead. In its Nov. 1 final Staff Paper, EPA's Office of Air Quality Planning and Standards found, "The overall body of evidence on lead health effects: Clearly calls into question the adequacy of the current standard; and provides strong support for consideration of a lead standard that would provide greater health protection for sensitive groups, especially for children." The staff paper recommends a range of levels from 0.2 μg/m³ to as low as 0.02 μg/m³.

Administrator Stephen Johnson will use the staff recommendations — along with the input of EPA advisory committees, public comment, and his own examination of the scientific evidence — when deciding on the standard.

However, statistics from the Centers for Disease Control and Prevention (CDC) — a federal body housed within the Department of Health and Human Services — are confounding the EPA staff recommendations. CDC establishes a "level of concern" for lead and other toxins. The current level of concern for lead is 10 μg/dL (micrograms per deciliter), a measure of lead concentration in the human bloodstream. Although CDC recognizes "recent studies suggest that adverse health effects exist in children at blood lead levels less than 10 μg/dL," the agency has not lowered the level of concern because it believes adequate evidence does not exist to properly identify a lower level partially because current laboratory testing technologies can not accurately measure below that level. CDC also claims there is no threshold of safety for lead therefore selecting a new lower level of concern would be "arbitrary."

If EPA abides by CDC's current endorsement of a 10 μg/dL level of concern, there would be no need to tighten the air pollution standard to achieve that health outcome, experts say. However, if EPA were to endorse a lower blood lead level as protective of public health, it would be obligated to tighten the air quality standard in order to effect the lower concentration.

Policy analysts inside EPA's Office of Policy, Economics & Innovation (OPEI) are using CDC's numbers to chart a course in which the agency could weaken the standard. According to Inside EPA (subscription), OPEI is pushing EPA to endorse the CDC's blood lead level of concern of 10 μg/dL. If officials within OPEI are successful, EPA will likely propose a revision to the standard that is weaker than the current one.

A recent scientific study gives further credence to the EPA staff argument that the current standard is not sufficiently protective of public health. A study published in the journal Environmental Health Perspectives found children with blood lead levels between 5 μg/dL and 9.9 μg/dL scored lower on IQ tests than children with blood lead levels less than 5 μg/dL.

The study examined children between the ages of six months and six years. The authors concluded, "Children's intellectual functioning at 6 years of age is impaired by blood lead concentrations well below 10 μg/dL, the CDC definition of an elevated blood lead level."

Under the Clean Air Act, EPA must revise all NAAQS every five years. EPA set the current standard in 1978. EPA has not reviewed the national standard for lead since 1990. During the 1990 review, EPA decided a revision of the standard was unnecessary.

EPA began its current review of the NAAQS for lead after a federal court mandated the agency undertake the rulemaking. In September 2005, as a result of a lawsuit brought by the Missouri Coalition for the Environment, the U.S. District Court for the Eastern District of Missouri ordered EPA to begin a review of the lead standard and set out a timetable for the review.

EPA has indicated it will propose a new standard for lead in March 2008 and make its final decision by September of that year.