Toxic effects of lead impurities found in aluminum factories.

A study of workers exposed to low levels of lead as impurities in aluminum (as low as 0.07%) shows a statistically significant difference in blood and urine lead levels as compared with a control group. In addition, alterations in precursors of heme were demonstrated as reflected in elevated levels of urinary delta-aminolevulinic acid and erythrocyte protoporphyrin IX. This study has implications for workers who are exposed to metals with low concentrations of lead (less than 1%) since this exposure tends to go unnoticed both by the workers, even when symptoms are present, and by physicians who ignore or discard signs of lead intoxication because they relate the occupational exposure of the workers to other metals, not directly to lead.