Concentrations of lead and mercury in multimedia samples from homes near the former Clark Air Base, Philippines

We measured lead and mercury in samples collected from 31 homes in communities near the former Clark Air Base, Philippines during May and October 2002. Sample media included water used for drinking and cooking, house dust and entryway soil. Composite samples of 15 food items purchased at local markets were also collected. Samples were analyzed for total lead (Pb) and total mercury (Hg) to evaluate the relative importance of each media to residential exposure concentrations in the community adjacent to Clark (Community A) versus a control community 5 km away (Community B). In general, we measured low (e.g. background) to undetectable levels of the target analytes in all media sampled with two important exceptions. First, the Hg concentrations we measured in canned mackerel composites, which were within the range reported for mackerel from other locations worldwide, may pose a risk to pregnant women who are frequent consumers (e.g. one or more cans per day). Second, we measured Pb above the USEPA residential screening concentration (400 Ag/g) in dust and soil from two homes, illustrating the need for periodic residential lead monitoring in these and other communities in the Philippines. We found no significant difference between Communities A and B with respect to Pb and Hg concentrations in water or food, although we were not able to detect very low levels of Pb in most of the foods we sampled because of trace Pb contamination added during sample homogenization. Although the Pb levels we measured in dust and soil from Community A homes were higher on average than Community B homes, the levels in both communities were low (e.g. background) thus we did not investigate the difference further. To our knowledge, these are the first reported measurements of Pb in house dust in the Philippines. The concentrations of Pb we measured in house dust were significantly higher than those in entryway soil from both communities, adding empirical support to the assertion that yard soil should not be considered a proxy for house dust in exposure studies in the Philippines or elsewhere.