A follow-up study in a lead smelter community following the introduction of an effective pollution control system.

A follow-up study using biological and environmental monitoring was performed in a lead smelter community to assess the health risk of inhabitants and to establish how long it takes after the introduction of an effective emission control system to declare a lead-contaminated area safe for normal living. In specific population groups (mothers and children) biological indicators of lead exposure and lead effect on hemoglobin synthesis were determined 2 years before and 11 consecutive years after the installation of bag filters. At the same time lead was monitored in the airborne and deposited particulates, in household dust and in soil. The results clearly show that the process of normalization is rather slow. The difference in blood lead and erythrocyte delta-aminolevulinic acid dehydratase between the exposed and control groups, even 12 years after bag filters installation, was still remarkable. It appears that soil, contaminated with lead from past exposure, is a major source of increased lead absorption in a population for many years.