Lead levels in long-tailed macaque (Macaca fascicularis) hair from Singapore

Nonhuman primates are potentially good sentinels of environmental toxicants because they share a similar physiology and life history with humans. In this report we present the results of an analysis of lead concentrations in hair from long-tailed macaques in Singapore. We hypothesized that because Singapore is highly urbanized, its macaque population may be exposed to higher levels of lead. The results of our study indicated that Singapore's macaque population has not been exposed to high levels of environmental lead. Compared with previous studies of lead levels in human and nonhuman primate hair, the results of our analysis indicate a low level of exposure of monkeys to environmental lead (n = 27, arithmetic mean = 2.51 ppm, max = 6.45, min = 0.21 ppm). Hair lead concentrations varied both within social groups and by geographic location, with the highest concentrations observed in monkeys residing within an area containing a small-arms firing range and a manufacturing facility. Although lead exposure in this area seems to be low, additional monitoring and possible remediation may be warranted. Our study is among the first to illustrate how primates can serve as potential sentinels of environmental toxicants such as lead. Future research examining the efficacy of primates as sentinels of lead exposure should include monitoring of environmental lead levels, and comparison of hair lead levels with levels measured in blood samples.