Orientador: Prof. Dr. Miguel Machinski Junior

Data da Defesa: 24/04/2013



 Mycotoxins are secondary metabolites produced by a variety of fungi, including aflatoxins produced of Aspergillus flavus, A. parasiticus and A. nomius and are present in many important agricultural products, such as cereals. Aflatoxin B1 is the most studied because it is the most frequent and is a potent hepatocarcinogenic. In mammals, aflatoxin B1 is biotransformed in aflatoxin M1, hydroxylated product, eliminated in urine and secreted in milk. The introduction of aflatoxin M1 in diet has occurred mainly by ingestion of bovine milk. Due to its effects, the International Agency for Research on Cancer - IARC in 2002 included aflatoxin M1 in group 1, carcinogenic to humans. Brazil produced 32.091 billion liters of milk in 2011, 67.9% of which were purchased by the dairy industry. The state of Paraná occupied the third place in the national production with 11.9%. According to the Brazilian Association of Long Life Milk, UHT milk consumption has increased in 2011 by 6.7% from 5.45 million liters to 5.81 million liters, exceeding the segment milk powder and pasteurized.  Exposure to mycotoxins occurs by ingestion of contaminated food, so there is a risk the health of human and animal population. The risk assessment is to analyze human exposure to toxicant quantified in food in one place. Therefore, there is need for reliable analytical methods for determining toxicantes in foods, ie for quantification of aflatoxin M1 in milk requires the determination of trace levels of this toxin (ng or pg). Given the importance of consumer and UHT bovine milk to feed the population, the objectives of this study were to optimize and validate an analytical method for the determination of aflatoxin M1 in cow milk by high performance liquid chromatography with fluorescence detection system, estimate the population exposure to aflatoxin M1 in milk marketed in Maringá, Paraná, Brazil and investigate the occurrence of toxin in different seasons. The intralaboratory validation was performed according to Directive 2002/657/EC of 12 August 2002 of the European Community and the Manual of Analytical Quality Assurance of the Ministry of Agriculture, Livestock and Supply (MAPA) of Brazil. The method proved to be selective, showed an average recovery of 89.9% and a reproducibility of 5.6%, the values of detection and quantification limits were 0.0000156 g/kg and 0.0000519 g/kg and the values for the decision limit (CCα) and detection capability (CCβ) were 0.56 g/kg, 0.62 g/kg, respectively. A validated analytical method is efficient for determination of aflatoxin M1 in milk and bovine met the criteria established by the rules.  To evaluate the estimate population exposure to aflatoxin M1, we collected 152 samples of bovine milk UHT of four brands in three different supermarkets from Maringá, Paraná, Brazil. Of the 152 samples, 133 (87.5%) was contaminated with an average value of aflatoxin M1 19.6 ng/L. The samples that showed higher levels of contamination belonged seasons winter and autumn showed a mean concentration of 121 and 72.8 ng / mL, respectively. In our study, the autumn season, which was significantly higher than the averages of the other seasons (p <0.05) showed a mean contamination level of 30.4 ng/L, therefore had the highest level of probable daily intake (PDI), 0.07 ng/kg of body weight. In this study, the PDI estimated for aflatoxin M1 in the population were below the PDI proposed by Kuiper-Goodman (1991). However, the high occurrence of this mycotoxin in milk (87.5%) found in the samples demonstrates the necessity of monitoring of food to reduce the risk of hepatocellular carcinoma in the Brazilian population.
Key words: Aflatoxin M1, high performance liquid chromatography, UHT milk, mycotoxins.

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