Effects of low-level lead and arsenic exposure on copper smelter workers

An analysis of reported symptoms and their relationship with indicators of lead absorption--blood lead (Pb-B) and zinc protoporphyrin (ZPP)--and of arsenic absorption--urinary arsenic (As-U)--was undertaken among 680 active copper smelter workers. Lead and arsenic absorption in the copper smelter employees were characterized by the median values of 30.4 micrograms/dl for Pb-B, 41.5 micrograms/dl for ZPP, and 26 micrograms/L for As-U. Blood lead was 40 micrograms/dl or higher in 16.7% of cases, ZPP was 50 micrograms/dl or higher in 31.2%, and urinary arsenic was 50 micrograms/L or higher in 16.4% of currently active copper smelter workers. The number of reported symptoms (from a total of 14 symptoms) increased with ZPP levels; the relationship with Pb-B was less marked. Arsenic contributed relatively little. Mean Pb-B, ZPP, and As-U levels for subjects reporting each of the 14 symptoms were compared with those of subjects who did not report the symptoms. Mean Pb-B was found to differ significantly for one symptom, fatigue. Significant differences in mean ZPP levels were found for fatigue, sleep disturbances, weakness, paresthesia, and joint pain. Prevalence rates for these symptoms rose more markedly with increasing ZPP than with Pb-B levels. The results indicate a relationship between certain CNS and musculo-skeletal symptoms and increased lead absorption in this population. Adherence to exposure standards that preclude undue lead absorption and appropriate biological monitoring including ZPP levels, are necessary to prevent adverse, especially long-term, health effects.