Inefficacy of cooking methods on mercury reduction from shark.

Shark and other carnivorous fishes present high potential risk of excessive contamination by mercury. The distribution of mercury throughout the body of blue shark--Prionace glauca--was analysed, and the effects on mercury levels by frying and baking in a laboratory oven, and in a microwave oven, were measured. There was no significant statistical difference in mercury levels in the samples taken from regions near the head, or from central and tail parts, indicating homogeneous distribution of the metal in muscles throughout the body. Frying and baking did not affect original mercury levels present in blue shark. This study indicates that specific studies are needed to define the efficacy or inefficacy of the cooking methods on mercury reduction from fish, in order to clearly resolve divergent opinions in the literature.

[Evaluation of lead and cadmium levels in milk in environmental contamination in the Vale do Paraíba Region, southeastern Brazil]. / Avaliação dos níveis de chumbo e cádmio em leite em decorrência de contaminação ambiental na região do vale do Paraíba, Sudeste do Brasil.

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 established 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.

[Mercury content in bleaches sold in the southeastern region of Brazil]. / Determinação de mercúrio em águas sanitárias comercializadas em região do sudeste do Brasil.

In order to determine the mercury content present as a contaminant in samples of bleach used in water and food disinfection, a method for sample treatment using chloridric acid to eliminate the chlorine was proposed. The technique of cold vapour atomic absorption spectrophotometry, used to quantify the mercury, showed a recovery of 103%. Sixty nine samples of bleach were analysed and the values found for the median and 90th percentil were respectively, 15 and 67 micrograms/L. According to the values of residual mercury found and using the quantities of bleach recommended by the Brazilian Sanitary Authorities, the use of these disinfectants offers no risk to human health.