Blood Lead, Cadmium and Zinc Correlations in Elderly Rural Residents.

Abstract

Combined exposure to heavy metals could be expected among residents of two villages in Stara Zagora Municipality due to significant pollution sources in the region, confirmed by increased heavy metal concentrations in plant samples identified by previous studies. The risk is increased for retired villagers who consume food produced in their own farms. To determine blood levels of lead, cadmium and zinc and the correlation between them in high-risk elderly rural inhabitants in comparison with a control group. Lead, cadmium and zinc concentrations in whole venous blood were measured by atomic absorption spectrometry in exposed and in control groups adjusted by sex, age, smoking habit, lifestyle and duration of residence in the settlements. Blood values of lead and cadmium in the exposed group were significantly higher than these in the control group (p<0.001). A statistically significant positive correlation between lead and cadmium blood levels was estimated for the exposed group (ρ=0.39, p=0.023). Blood zinc levels correlated negatively with both lead (ρ=-0.41, p=0.015) and cadmium blood levels (ρ=-0.44, p=0.009). No correlations between the studied metals were found in the control group. The observed results could be explained by a long-term combined exposure to lead and cadmium in the studied elderly residents. The negative correlation of zinc blood levels versus lead and cadmium could be result of competition. Complete protein intake and supplementation with zinc, calcium and iron after control measurements are advisable for elderly rural inhabitants to reduce the health risk from heavy metal exposure.