Urinary ethylenethiourea as biomarkers of exposure to ethylenebisdithiocarbamates in floriculture workers in Ecuador

Floriculture represents one of the major sources of income in Ecuador that is one of the greatest worldwide producers of ornamental flowers. Floriculture can be carried out both in open fields and in greenhouses with an extensive use of pesticides, among which, ethylenbisdithiocarbamate fungicides (EBDTCs). Aim of this study was to assess EBDTCs exposure in Ecuadorian floricultural workers by the determination of the urinary excretion of the major metabolite of these compounds, ethylenethiourea (ETU). Thirty-six floriculture workers and 34 unexposed healthy subjects (controls) from an Andean region entered the study. Workers were exposed to EBDTCs while applying plant protection products, and during re-entry activities or crop maintenance in one open field and two greenhouse farms. They provided morning pre-exposure (n=31) and afternoon post-exposure (n=24) urine spot samples. Controls provided one urine spot sample collected in the morning. In agricultural workers median ETU in pre- and after-exposure samples was 3.2 (<0.5-34.5) and 6.2 (1.5-26.5) µg/g creatinine. Although ETU increased after the workshift the difference was not significant. ETU was higher in workers then in controls (0.7, <0.5-7.1 µg/g creatinine, p < 0.01). When subjects were divided according to job titles, applicators showed the highest ETU (17.0, 1.5-34.5 µg/g creatinine) whereas growing, post-harvesting and maintenance workers showed similar levels (4.3, <0.5-26.5; 2.8, <0.5-11.1; 4.8, 3.2-6.5 µg/g creatinine, respectively). Higher ETU was observed in greenhouse compared to open field workers (p < 0.01). This study suggests that Ecuadorian floricultures are exposed to EBDTCs at levels approaching those observed in Italian vineyard workers. The lack of difference between ETU in pre- vs. post-exposure samples is attributable to previous day exposure, in fact the kinetic of excretion is such that in prior to next shift urine significant amount of ETU is still present.