Lead hazard among ironworkers. Dismantling lead-painted elevated subway line in New York City

Laboratory tests were conducted on 11 workers engaged in the continuation of the demolition project three months after the lead-poisoning incident; at this examination, 2 workers were found to have blood-lead levels exceeding 60 micrograms per 100 ml. (63 and 71 micrograms, respectively); the mean blood-lead concentration was 46 micrograms per 100 ml. (range 32 to 71); all 11 workers had hemoglobin levels above 14 Gm. per 100 ml. (mean of 15.4 Gm. per 100 ml. range 14.7 to 16.6). In addition, repair work on another elevated railway structure was initiated and the authors were therefore confronted with the opportunity of continuing a medical surveillance program. A one-year follow-up on this work crew indicates that undue lead exposure may be effectively prevented. This study is currently being prepared for publication. It is apparent from the present study that combined medical and industrial hygiene surveillance is essential for the safe management of such work. Provision of respiratory equipment should be followed by close industrial hygiene evaluation to identify and correct malfunctioning equipment. In the present study, the inadequacy of the respiratory equipment was discovered at the clinical examination of the workers, some of whom reported symptoms of respiratory distress as a result of negative pressure in the respirators. These conditions led to rapid build-up of toxic blood-lead levels and to other biochemical abnormalities indicative of adverse lead effects. Zinc protoporphyrin determinations were found to be highly practical and useful in registering such abnormalities. Careful biologic and environmental control of work operations that include burning of lead-painted metal surfaces is essential to prevent the occurrence of lead poisoning.