Avaliação de resíduos de etilenotiouréia (ETU) em frutas comercializadas na cidade de São Paulo

Abstract

Lemes, V.R.R. Evaluation of ethylene thiourea (ETU) in fruits traded in the city of Sao Paulo. Sao Paulo, 2007. [Doctoral thesis, Faculty of Public Health of the University of Sao Paulo]. Ethylene thiourea (ETU) is a toxic substance generated by the degradation and/or biotransformation of ethylenebisdithiocarbamates (EBDC) fungicides. Their residues may be found in plants and in the environment after EBDC’s use in agriculture or in animals and humans when exposed to such products. ETU is confirmedly able to induce tumors in rodents’ thyroids and in mouse’s liver, showing enough evidence of carcinogenicity in animals and inadequate evidence of carcinogenicity in humans. The aims of this study were validating an analytical method for determining ETU residues in the studied sources, verifying the presence of ETU residues in fruit samples (papaya, apple and strawberry) collected from different commercial centers in the city of Sao Paulo; evaluating the results and their contribution as a risk to the consumers’ health. Ninety fruit samples (30 samples of each fruit – papaya, apple and strawberry) were analyzed. The samples were purchased at different commercial centers in different regions of the city of Sao Paulo and over all seasons during December 2005 through December 2006. The validation parameters used were selectivity, linearity, accuracy and precision. Recovery studies were carried out with fortifications in 3 levels (1, 2 and 10 times the Limit of Quantification, LQ) in control samples. The determination of ETU residues was carried out by high performance liquid chromatography, ultra-violet absorption detector (HPLC/UV) and liquid chromatography coupled on tandem mass spectrophotometry (LC/MS/MS). Since all results obtained through HPLC/UV showed levels of ETU below the LQ (10.0 μg/kg), quantification were carried out through LC/MS/MS with quantification and detection limits of 1.0μg/kg and 0.5 μg/kg, respectively. The LC/MS/MS method proved adequate for analyzing quantities of ETU as low as 2.0 μg/kg in apple and strawberry and 10.0 μg/kg in papaya, with average recovery of 75 to 110 % and variation coefficients of 6 to 17 %. ETU residues were found in 10 (33%) apple samples with levels ranging from 1.0 to 3.7 μg/kg (ppb); in 20 (67%) of papaya samples with levels ranging from 1.0 to 5.3 μg/kg (ppb); and in 2 (7%) strawberry samples with levels ranging from 1.0 to 1.4 μg/kg (ppb). These values are below the limit established in European Community (50 μg/kg). The assessment of ETU intake, considering the consumption informed by IBGE (Instituto Brasileiro de Geografia e Estatistica, the Brazilian Institute for Geography and Statistics) and the highest level observed in total fruit samples in this research, represent 0.05 % and 0.20 % ADI (Acceptable Daily Intake, established by the Codex Alimentarius) for geral population and children, respectively. The assessment of EBDC intake, considering the consumption informed by IBGE (Instituto Brasileiro de Geografia e Estatistica, the Brazilian Institute for Geography and Statistics) and the highest level observed in food samples (apple, tomato, papaya, lettuce, strawberry, banana, orange, carrot), monitoring from 2001 through 2004 year in the PARA (Programa de Analise de Residuos de Agrotoxicos em Alimentos, Program Monitoring of Pesticide Residues in Food, Brazil), and that 100% of dithiocarbamate (CS2) residues from EBDC’s use, represent 7.2% and 28.9% ADI for geral population and children, respectively. ETU and EBDC data in other foods (including industrialized foods), water and environment samples, together with more refined food consumption data considering more sensitive population subgroups (as children and pregnants) are necessary to evaluate the risk in a more global and realistic way in favor of Public Health.