A survey of air and population lead levels in selected American communities.

The concentration of lead in the ambient atmosphere was determined at 59 sampling sites in eight American communities during the period 1968-71. Nineteen sampling sites had existed in a similar survey in 1961-62. At 14 of these sites the lead-in-air value was found to be higher in the current study than in 1961-62. The observed annual mean atmospheric concentration of lead varied from 0.14 mug/m3 (Los Alamos) to 4.55 mug/m3 (Downtown Los Angeles). Higher lead values were associated with urbanization. The concentration of lead in the blood of specific well-defined populations was determined. Such populations lived in geographic proximity to specific air sampling sites. In the three metropolitan areas from which both urban and suburban population groups had been obtained, the mean blood lead levels were significantly higher in the former. In two of the three areas the blood lead level was higher in urban smokers and non-smokers than in the corresponding suburban populations, classified by smoking habits. At each location the concentration of lead in the blood of smokers was greater than that in the blood of non-smokers. The magnitude of the observed urban-suburban difference (for populations comparable in smoking habits) ranged from 0.9 mug/100 gms to 4.5 mug/100 gms. It is probable that these observations partially reflect lead absorption from ambient atmospheres differing in lead concentration. There was no significant concordance between the ranking by site of mean air lead levels and that of the mean blood lead levels prevalent in the related populations. The observation that urban levels of blood lead and higher than suburban levels, but that air concentrations of lead are not clearly reflected in blood lead levels on a general national basis, suggests that factors other than the atmospheric lead level are of relatively greater importance in determining the blood lead levels in population groups. No relationship was established between age of participant and the blood lead level. In husband-wife pairs, presumably exposed to similar diets and atmospheres, the males had significantly higher blood lead levels than did the females. This difference could not be attributed to smoking habits or to hematocrit levels. The possibility that the difference was due to dissimilar quantities of foods in the respective diets of men and women was not examined. Studies of dietary lead levels showed them to be generally lower than commonly reported in the literature, 100 mug/day being a closer approximation in the population studies than the widely quoted 300 mug/day.