Mercury and Blood Pressure Levels in Inhabitants from a Highly Industrialized Region in Northern Portugal

Abstract

Objective: Estarreja is a highly industrialized municipality in NW Portugal, well known for its historical mercury contamination. Mercury exposure is a serious risk to human health (cf. Minamata Disease), and due to its widespread occurrence and persistency, it is recognized as a priority substance. Amongst the myriad deleterious effects of mercury on human health, hypertension has only recently gained attention. The aim of this work was to evaluate the levels of mercury in matched dust and hair samples from inhabitants of Estarreja; and to study possible associations between hypertension and mercury. Methods: House dust and hair samples from the residents of Estarreja were collected, together with systolic (SBP) and diastolic (DBP) blood pressure measurements. Mercury levels were analyzed by CV-AAS. Results: Levels of mercury in dust (93–9100 ng/g) were, on average, higher than those in hair (624–4535 ng/g). No statistically significant association between dust and hair could be established (Spearman Rank Order Correlation, p=0.199), reinforcing that dust is not the major exposure pathway to this toxicant. Twentyeight per cent of the participants were hypertensive. No statistically significant differences in mercury levels between the hypertensive and normal group were found (One-tailed P-value=0.444). No significant associations between SBP (p=0.826) or DBP (p=0.695) and hair mercury levels were obtained. Conclusions: Overall, 72% exhibited levels higher than the acceptable dose set by the USEPA (1000 ng/g), and 44% of individuals exhibited hair mercury levels higher than the WHO acceptable dose (2000 ng/g).