Temporal variability of blood lead, mercury, and cadmium levels in elderly panel study (2008-2014)

•Pb, Hg, and Cd are hazardous heavy metals, especially in elderly populations.•We repeatedly determined blood Pb, Hg, and Cd levels in Korean elderly.•Intra-class correlation for Pb, Hg, and Cd was 0.81, 0.71, and 0.83, respectively.•Korean elderly were consistently exposed to environmental heavy metals.

BackgroundBiological measurements have been employed as useful biomarkers for exposure. Because of its property of reflecting toxicokinetic differences, however, within-subject variability leads to biased results in epidemiologic studies.MethodWe examined the variability of lead (Pb), mercury (Hg), and cadmium (Cd) levels in blood samples from 1429 participants among 1677 elderly individuals aged over 60 years who lived in an urban area from August 2008 to April 2015.ResultsThe geometric means of blood Pb, Hg, Cd were 1.92 μg/dL, 2.48 μg/L, and 1.33 μg/L, and the intra-class correlations (ICCs) were 0.81, 0.71, and 0.83, respectively. The mean values of Pb and Hg levels in this study were lower than the results from single spot samples in other national biomonitoring surveys in Korea, with the exception of Cd was higher than those in other studies. Moreover, the predicted exceedances over the guidance levels for Pb, Hg, and Cd were 1.9%, 4.2%, and 0.3%, respectively.ConclusionKorean elderly were exposed to high levels of Pb, Hg and Cd. Especially, those who had high levels of Cd were continuously exposed to Cd during study period with the 6 collection intervals. Therefore, factors affecting environmental Cd exposure should be further studied in the future.