Biological monitoring of workers exposed to inorganic lead in Singapore.

Medical surveillance of workers exposed to a lead hazard is a common practice in many countries. In Singapore, legislation on periodic medical examinations for lead exposed workers in factories was introduced in 1985. This paper discusses the results of the laboratory tests in workers exposed to inorganic lead in 1987. The WHO recommended that the health-based limit for lead absorption be 40 micrograms/dL for adult male workers. Taking this level, we could divide the factories into a "higher risk" category and a "lower risk" one, the latter not having a single result of blood lead of 40 micrograms/dL or above. The former category included factories manufacturing PVC and lead storage batteries, with the highest level of 79.6 micrograms/dL found in PVC manufacture. Of the 3 main races in Singapore, the Chinese have the lowest blood lead levels after adjusting for the type of industry, age and duration of exposure to lead. Age was correlated with the duration of lead exposure. The higher blood lead levels in Malays and Indians may have been contributed to by eating habits (eating with hands). The higher prevalence of smoking among Malays may also be contributory. The results in this study, while reassuring that no worker was found with blood lead above 80 micrograms/dL, also indicated that workers in some factories were still exposed to a health risk.