March 5, 2008

EPA is currently in the process of reviewing the national ambient air quality standard (NAAQS) for lead. Over the last thirty years, improvements in the medical and scientific understanding of the health impacts of lead exposure have proven the current lead standard (set at 1.5 μg/m3 back in 1978) to be inadequate to protect public health.As part of the ongoing review, both EPA staff scientists and the Clean Air Scientific Advisory Committee (CASAC) have recommended that the lead standard be substantially lowered. EPA’s Final Staff Paper, issued last November, recommended significantly tightening the standard to within the range of 0.02 – 0.2 μg/m3.

Unfortunately, EPA Administrator Stephen Johnson appears poised to put politics before science in determining a new lead standard. In December, EPA issued an Advanced Notice of Proposed Rulemaking (ANPR), a new “policy assessment” document, in which it solicited comment on a wide range of policy options, including several that had already been dismissed on scientific grounds by both the CASAC and EPA staff. This includes the invitation for comment on de-listing lead as a criteria pollutant and revoking the lead standard altogether.

As EPA prepares to issue a formal proposed rule on the lead air standard in March, it is critical that members of the science and health community voice strong support for a much tighter lead standard. It is also important that our community makes clear that EPA’s changes to the NAAQS review process have undermined the scientific integrity of the process, as exemplified by the current review. (A strongly worded letter on this issue from CASAC to Administrator Johnson can be found here:$File/EPA-CASAC-08-008-unsigned.pdf).

Please consider adding your name to the letter below, which expresses support for a lead NAAQS set at 0.02 μg/m3 – the level recommended by the Children’s Health Protection Advisory Committee and the low end of the range recommended in the Staff Paper.

The letter also reflects CASAC’s recommendations for improving the new review process to restore the role of EPA staff and CASAC and preserve scientific integrity.

Please send your signature to Casey Weissman-Vermeulen at Physicians for Social Responsibility by emailing him at by March 14. Please include your title and institutional affiliation as you would like to see them listed (for identification purposes only, not for representation).

Thank you very much for your support of this effort.


The Honorable Stephen L. Johnson
U.S. Environmental Protection Agency
1200 Pennsylvania Ave., N.W.
Washington, D.C. 20460

Re: Proposed National Ambient Air Quality Standard (NAAQS) for Lead – [Docket ID #]

Dear Administrator Johnson:

We, the undersigned scientists, physicians and public health professionals, write to express our strong support for a more stringent ambient air quality standard for lead. Under the Clean Air Act, EPA is required to establish National Ambient Air Quality Standards (NAAQS) for criteria pollutants at a level that protects public health, including the health of sensitive populations, with an adequate margin of safety. As the scientific literature demonstrates, and as concluded by both EPA staff scientists and the Clean Air Scientific Advisory Committee (CASAC), the current lead NAAQS – set at a level of 1.5 micrograms per cubic meter (μg/m3) – fails to meet this requirement and must be significantly strengthened.

The scientific and medical understanding of the mechanisms by which lead exposure impacts human health has grown considerably since EPA first established a legal limit on lead in ambient air. When EPA promulgated the current lead NAAQS in 1978, the Centers for Disease Control (CDC) recognized a blood lead level of 30 micrograms per deciliter (μg/dL) as warranting individual intervention. CDC has since lowered the level of concern to10 μg/dL, but also formally recognizes that “no level of lead in a child’s blood can be specified as safe.” Having remained unchanged since 1978, EPA’s three-decade-old lead NAAQS fails to reflect this improved understanding of the health hazards associated with lead exposure.

Despite a steep decline in blood lead concentrations across the U.S. population over the last thirty years, environmental lead exposure continues to threaten public health. A wealth of new evidence now indicates a range of adverse health impacts at blood lead concentrations well below 10 μg/dL, a level which itself is three times lower than the 30 μg/dL “action level” upon which the current lead NAAQS is based. Children are particularly vulnerable to the toxic effects of lead, with evidence linking environmental exposures to lowered IQ levels, increased likelihood of Attention Deficit Hyperactivity Disorder and decreased school performance. In adults, lead exposure has been associated with increased risk of both cardiovascular mortality and renal disease, demonstrating that adverse effects extend well beyond childhood. After comprehensively reviewing the large body of research published since 1978, EPA’s own Staff Paper concluded that “studies appear to show adverse effects at mean concurrent blood [lead] levels as low as 2 μg/dL.”

Recent research also indicates that the direct and indirect contribution of airborne lead to blood lead levels is higher than previously estimated. When the current 1.5 μg/m3 standard was set, EPA relied on an air lead to blood lead ratio of 1:2. As explained in the Staff Paper, “the current evidence indicates a notably greater ratio, with regard to increase in blood [lead], than the 1978 1:2 relationship e.g., on the order of 1:3 to 1:10.” In its review of the Agency’s first draft Staff Paper, CASAC identified air lead to blood lead ratios of 1:5 as used by the World Health Organization and 1:10 as derived from empirical analysis of relative changes in air lead and blood lead between 1976 and when the phase-out of lead in gasoline was completed.

In light of this compelling body of evidence, the Staff Paper states that “the overall body of evidence clearly calls into question the adequacy of the current standard.” CASAC similarly affirms that the current lead NAAQS “are totally inadequate for assuring the necessary decreases of lead exposures in sensitive U.S. populations” and concludes that “the NAAQS for Lead must be decreased to fully-protect both the health of children and adult populations.” EPA’s Staff Paper recommends a revised lead NAAQS within the range of 0.02 and 0.2 μg/m3, while also noting that a standard of 0.02-0.05 μg/m3 would provide somewhat greater public health protection by limiting IQ loss at the population level to less than the 1-2 point range identified by CASAC as highly significant from a public health perspective. EPA’s own analysis shows that even at the lower end of the range recommended in the Staff Paper, selecting a lead NAAQS of 0.02 μg/m3 rather than 0.05 μg/m3 would achieve a significantly greater reduction in the number of children with IQ losses of 7 points or more. Given the extensive research demonstrating the impact of lead exposure-related cognitive impairment on earning potential, this reduction in the number of highly exposed children would be expected to yield significant social and economic benefits in addition to improved public health. Therefore, we strongly recommend that EPA strengthen the lead NAAQS to 0.02 μg/m3 or below.

Additionally, we urge EPA to establish an averaging time no longer than one month for the lead NAAQS, as recommended by CASAC, the Children’s Health Protection Advisory Committee (CHPAC) and EPA staff. A monthly, rather than quarterly, averaging time is needed to more adequately protect the health of children, for whom blood lead levels have been shown to respond to monthly variations in lead emissions. An averaging time of one month also would better guard against short-term exposures during pregnancy and early life that evidence suggests may be critical to future development. In addition, establishing a monthly averaging time would better protect against short, sporadic emissions bursts and would ensure that lead NAAQS attainment status reflects potentially significant localized soil and dust lead loading from very short-term emissions. We further recommend that the maximum monthly mean be calculated over a period no longer than a calendar year. Applying the monthly averaging time over a period longer than one year would unjustifiably delay any designations of areas as non-attainment and would allow sporadic emitters to continue to blanket communities with lead without violating the NAAQS.

EPA must also move quickly to repair and improve the nation’s monitoring network for airborne lead. Across the country, the number of monitoring stations has decreased from more than 900 in 1981 to less than 200 active sites today. Moreover, as stated in the ANPR, “many of the largest Pb emitting sources in the country do not have nearby monitors, and there is substantial uncertainty about ambient air [lead] levels resulting from historic [lead] deposits near roadways.” The result, as the Agency’s own analysis indicates, has been an underestimation of the extent of occurrences of relatively higher ambient air lead concentrations. The uncertainty associated with the lack of adequate monitoring and the attendant possibility of considerably higher lead exposures and impacts than estimated underscores the need for a significantly stronger lead NAAQS.

As representatives of the science, medical and public health communities, we also seek to express our serious concerns regarding the scientific integrity of the new NAAQS review process. Our concerns echo those expressed by the seven members of CASAC and focus chiefly on the replacement of the Staff Paper with the Advanced Notice of Proposed Rulemaking (ANPR). The current “hybrid” lead NAAQS review has resulted in the production of both a Staff Paper and ANPR, thereby providing an important opportunity to compare the old and new processes. While the final Staff Paper in the current review offers a set of focused, concrete policy recommendations based upon thorough scientific analysis, CASAC found that the “ANPR for the Lead NAAQS did not contain any such ‘policy assessment’ of scientific and technical information,” and therefore was “both unsuitable and inadequate as a basis for rulemaking.”

To correct these problems, EPA should not rely on the ANPR as a replacement to the Staff Paper in future air quality rulemakings. As recommended by CASAC, the Agency should instead employ the ANPR to initiate a rulemaking process, while also issuing a distinct policy assessment document that explains the range of specific policy options under consideration for setting the standard, accompanied by supporting scientific data and rigorous analysis.

In conclusion, we strongly recommend that EPA strengthen the lead NAAQS to 0.02 μg/m3 in order to adequately protect children and other sensitive populations from the toxic effects of lead. We also ask EPA to preserve the scientific integrity of the NAAQS review process by following the recommendations outlined above.

Thank you for considering our views.