Determinants of blood lead levels in an adult population from a mining area in Brazil

During the last fifty years the Ribeira river valley, Brazil, had been under the influence of the full activity of a huge lead refinery and mining along the riverside. The plant completely stopped all kind of industrial activities at the end of 1995, and part of the worker population and their families still remain living nearby in small communities. The objective of the present study was to assess the determinants of blood lead levels (BLL) in these mining areas, where residual environmental contamination from the past industrial activity still remains. Blood samples of 350 adults aged 15 to 70, residing in areas around the mine and the refinery were collected. A questionnaire was given in order to gather information on food habits, current and former residential places, occupational activities, among other variables. Blood lead concentrations were analysed by graphite furnace atomic absorption spectrometry using Zeeman background correction. Logistic regression analysis was conducted to examine the independent contribution of selected variables in predicting BLL in those subjects. The following variables showed significant association with high BLL: residential area close to the lead refinery, former dwelling at the refinery village, male gender, smoking habits, and consume of fruits from home back yard.