Opinion ID: 390180
Heading Depth: 2
Heading Rank: 4

Heading: The Final Air Quality Standards for Lead

Text: 27 The Administrator promulgated the final air quality standards on October 5, 1978, prescribing national primary and secondary ambient air quality standards for lead of 1.5 ug Pb/m 3, averaged over a calendar quarter. 43 Fed.Reg. 46246, JA 2948. Although the final standards were the same as the proposed standards (with the exception of the change in the averaging period from 30 to 90 days), the Administrator arrived at the final standards through somewhat different analysis. The preamble to the final standards reveals that the comments on the proposed standards had led the Administrator to reconsider his analysis. In particular, he seemed to feel that legitimate questions had been raised concerning the health significance of the early stages of EP elevation and about the threshold blood lead level for this condition. 43 Fed.Reg. 46248, 46253, JA 2950, 2955. The Administrator's reexamination focused on two key questions: (1) What is the maximum safe individual blood lead level for children? and (2) what proportion of the target population should be kept below this blood lead level? Id. at 46249, 46252-46253, JA 2951, 2954-2955. Addressing the first issue required a review of the health effects of lead exposure discussed in the Criteria Document. The Administrator concluded that, although EP elevation beginning at blood lead levels of 15-20 ug Pb/dl is potentially adverse to the health of children, only when blood lead concentration reaches a level of 30 ug Pb/dl is this effect significant enough to be considered adverse to health. Id. at 46253, JA 2955. Accordingly, he selected 30 ug Pb/dl as the maximum safe individual blood lead level for children. Id. The Administrator based this choice on three mutually supporting grounds. First, it is at this blood lead level that the first adverse health effect of lead exposure impairment of heme synthesis begins to occur in children. Second, a maximum safe individual blood lead level of 30 ug Pb/dl would allow an adequate margin of safety in protecting children against more serious effects of lead exposure anemia, symptoms of which begin to appear in children at blood lead levels of 40 ug Pb/dl, and central nervous system deficits which start to occur in children at blood lead levels of 50 ug Pb/dl. Third, the Administrator reasoned that the maximum safe individual blood lead level should be no higher than the blood lead level used by the Center for Disease Control in screening children for lead poisoning 30 ug Pb/dl. Id. 28 Having determined the maximum safe individual blood lead level for the target population, the Administrator next focused on the question of what percentage of children between the ages of 1 and 5 years the standard should attempt to keep below this blood lead level. According to the 1970 census, there are approximately 20 million children under the age of 5 years in the United States, 12 million of them in urban areas and 5 million in inner cities where lead exposure may be especially high. The Administrator concluded that in order to provide an adequate margin of safety, and to protect special high risk sub-groups, the standards should aim at keeping 99.5% of the target population below the maximum safe individual blood lead level of 30 ug Pb/dl. 25 Id. at 46253, 46255, JA 2955, 2957. The next step in the analysis was to determine what target mean population blood lead level would ensure that 99.5% of the children below the age of 5 years would be kept below the maximum safe individual blood lead level of 30 ug Pb/dl. Using the lognormal statistical technique he had alluded to in the proposed standards, 26 he calculated that a target mean population blood lead level of 15 ug Pb/dl (the same number as in the proposed standards, but arrived at through different analysis), would accomplish this task. 27 Id. at 46253, 46254, JA 2955, 2956. Thereafter, the Administrator used the same estimate of the contribution from non-air sources, 12 ug Pb/dl, and the same air lead/blood lead ratio, 1:2, that he had used in calculating the proposed standards, 28 to compute the final ambient air quality standards for lead. The result was an ambient air quality standard of 1.5 ug Pb/m 3, the same as the proposed standard. Id. at 46254, JA 2956. The Administrator did, however, change the averaging period for the standards from one calendar month to one calendar quarter, id. at 46255, JA 2957, because he felt that this change would significantly improve the validity of the data to be used in monitoring the progress toward attainment of the standards without rendering the standards less protective. Id. 29 On December 8, 1978 LIA petitioned EPA for reconsideration and a stay of the lead standards. JA 2980-3000. The Administrator denied the petition on February 2, 1979. JA 3001-3007. These petitions for review of the lead standards regulations followed. Before examining the petitioners' challenges to the regulations, we consider the limits of our reviewing function.