Evaluation of lead and cadmium levels in milk due to environmental contamination in the Paraiba Valley region of Southeastern Brazil

Abstract

INTRODUCTION: A factory producing lead ingots, located in Caçapava, caused lead and cadmium contamination of the environment, in the Paraiba Valley region of Southeastern, Brazil, through the discharge of industrial waste and the recycling of batteries. The factory, set in a rural, dairy cattle breeding area, worried sanitary authorities who envisaged the possibility of these metals' having entered the food chain. For the purpose of assessing the levels of contamination of the milk produced in the region, due to the cattle's possible consumption of contaminated grass and water, the amounts of cadmium and lead present in the milk were verified. MATERIAL AND METHOD: Major producers, covering an area of up to 20 km from the contaminated source, authorized collection of 218 samples of both pasteurized and non-pasteurized milk, which were analysed. Lead and cadmium levels were determined by flame atomic absorption spectrophotometry, the lead being pre-concentrated by complexation with APDC (ammonium 1-pyrrolidinecarbodithioate) and further extraction with isobutyl methylketone. RESULTS AND CONCLUSIONS: Of the total number of samples, 43 presented lead levels over the maximum limit of 0.05 mg/kg estabilished by Brazilian legislation. The median value found for lead was 0.04 mg/L. The variance analysis, with 95% confidence level, found no significant difference among the types of milk studied with regard to lead levels. As for cadmium, all samples showed levels below the 0.02 mg/L quantification limit of the method. In spite of the environmental contamination, the levels of cadmium found in the milk were below the 1.0 mg/kg limit established by Brazilian legislation.