Evaluation of dithiocarbamate and ethylenethiourea (ETU) residues in papaya, and their implication for public health

Ethylenethiourea (ETU) is a toxic substance formed during degradation and/or biotransformation of ethylene-bisdithiocarbamate (EBDC) fungicides, which are employed in foods. Presence of this substance may represent a risk to populations who consume fruits and other foods. The objectives of the present study were to validate the analytical methods for determining dithiocarbamates and ETU levels in papaya, and to determine the levels of both mancozeb and ETU residues in papaya Carica papaya L, and also to evaluate the association between the detected levels and the risk to the public health. The levels were determined by means of spectrophotometry, and high performance liquid chromatography was employed for determining ETU samples treated or non-treated with mancozeb were collected from three sites that are representative of papaya cultivation. The recovery studies showed a range from 70 to 110% for mancozeb, and from 80 to 110% for ETU with coefficients of variation ranging from 3.7 to 13.3% for ETU and from 4.8 to 13.2% for mancozeb, being all of them satisfactory. The method quantification limits was 0.5 mg/kg for mancozeb determination, and 0.01 mg/kg for ETU. All samples treated with mancozeb presented ETU residues ranging from 0.01 mg/kg to 0.32 mg/kg, and mancozeb levels ranged from 0.5 mg/kg to 2.1 mg/kg. The presence of ETU in papaya observed in the present study is a warning that is necessary to be acquainted with the occurrence of this substance in foods consumed by population.