The Effect of Toxic Metal Exposure on Blood Pressure in Children: A Review of Pb, Hg, & Cd

Toxic metals are particularly potent nephrotoxicants and can have damaging effects even at low exposure levels. The epidemiologic literature that assesses the effect of mercury (Hg), lead (Pb), and cadmium (Cd) exposure and blood pressure changes in early life were reviewed. As developmental exposure is particularly toxic, this review focused on the effects of toxic metals in children. Studies have suggested that there is a correlation between toxic metal exposure and adverse cardiovascular outcomes such as hypertension (high blood pressure) and heart rate variability. These studies provide insight into the later life programming of adverse cardiorenal effects of metals. To examine the effects of Hg, Pb and Cd with respect to the development of high blood pressure/hypertension in children, a literature search to identify epidemiologic studies was conducted. PubMed and Web of Science search engines were used and the search was restricted to peer-reviewed human studies published in English. A total of 15 studies (5 each) for Hg, Pb, and Cd exposure were identified and summarized. Five studies were identified that examined the effects of Hg exposure on BP and other cardiovascular outcomes in children. Overall, only two studies reported a positive association between Hg exposure and childhood BP, and one of these studies was a clinical case study of a single child. Five studies were identified examining the effects of Pb exposure on BP in children. Three of the studies reported a significant association and two showed a correlation with cardiovascular outcomes. Five studies that assessed the effects of Cd exposure on BP in children were identified. None of the studies found a significant association, but one identified elevated BP in the participants and another showed a correlation with other cardiovascular outcomes. The association between toxic metal exposure and the development of elevated childhood BP has not been widely studied. As a result, a relatively low number of studies that examined this relationship were found. These findings suggest that Pb, Hg, and Cd may be associated with childhood BP, however additional research is needed. In particular, studies of early life Pb exposure demonstrate more consistent effects on childhood BP and deserve further study.