Biomarker of chronic cadmium exposure in a population residing in the vicinity of a zinc producing plant

Abstract

Measurements of cadmium (Cd) in air, soil and moss have shown elevated concentrations in residential areas close to a zinc smelter in Norway. This study aimed to evaluate whether men and women residing in the area with elevated Cd concentrations in air and soil had increased levels of Cd and microproteins in urine. An invitation to participate was mailed to 200 persons residing close to the zinc smelter and to 200 controls from an area more than 4 km away from the smelter. They were asked to complete a questionnaire, and to deliver a urine sample for analysis of cadmium (CdU), mercury (HgU), lead (PbU) and α1-microglobulin (ProteinHC). Two hundred and six participants (response rate 52%), between 19 and 88 years of age, were included. Results were analysed by multiple-adjusted linear and logistic regression. CdU was not significantly different between individuals in the two residence areas. Only ten individuals had CdU concentrations exceeding European Food Safety Authority (EFSA) critical value of 1 μg/g creatinine, whereas 35 persons (22% of the women vs. 11% of the men) had CdU concentrations higher than 0.66 μg/g creatinine, which EU suggested to be sufficiently protective for the general population. Smoking was the predominant contributing factor to values of elevated CdU. There was a tendency of higher CdU, although not statistically significant, amongst people regularly consuming fruit, berries and vegetables grown in their own garden near the smelter area. Home address in the polluted area was not a significant determinant. There was a positive correlation between CdU and ProteinHC in urine, but no significant difference was found for ProteinHC between residents from polluted area and controls. In spite of demonstrated industrial emissions of cadmium, the results do not indicate elevated cadmium exposure or kidney damage in the polluted area compared to the control area.