Assessment by hair analysis of mercury exposure among mining impacted communities of Mindanao and Palawan, the Philippines

Human mercury (Hg) exposure in two contrasting areas of mining and mineral processing activity on the Philippine islands of Mindanao and Palawan was e valuated using hair analysis. On Mindanao, samples were collected from resi dents of Apokon, a major regional centre for gold beneficiation. On Palawan , a former cinnabar mine and mine-waste disposal site in Honda Bay formed t he focus of investigation. Relatively high hair Hg burdens (up to 13 mg Hg kg(-1) at Apokon and 18.5 mg Hg kg(-1) in Honda Bay) were observed in both populations, with occupational factors apparently constituting a first-orde r exposure control. At Apokon, hair burdens in excess 2 mg Hg kg(-1) were r ecorded in 90% of Au processing plant workers, compared with 21% of other s ectors of the population. In Honda Bay, ex-mineworkers, although possibly s ubject to occupational Hg exposure in the past, now display no evidence of this influence. Fishermen, however, systematically yielded hair Hg concentr ations a factor of 2.5 higher than those of the remaining population. Appro ximately 7% of the Apokon and Honda Bay residents sampled presented hair Hg concentrations equal to or in excess of the World Health Organisation (WHO ) reference dose. There is little evidence to indicate that residential fac tors significantly influence Hg exposure in either area. Hazard mitigation strategies involving the isolation of resident populations from perceived c ontaminant sources such as ore processing plant and sites of mine-waste dis posal are, therefore, unlikely to prove beneficial.