Correlation between blood ethylenethiourea and thyroid gland disorders among banana plantation workers in the Philippines.

Abstract

Ethylenebisdithiocarbamates (EBDCs) are metabolized into ethylenethiourea (ETU), a possible human carcinogen and an antithyroid compound. In this study our goal was to correlate ETU levels with the incidence of thyroid gland disorders among banana plantation workers exposed to EBDC. We randomly selected 57 directly exposed workers and 31 indirectly exposed workers from four banana plantations and 43 workers from an organic farm; all subjects underwent complete medical examinations and laboratory tests. Results showed a higher mean thyroid-stimulating hormone measurement among exposed workers compared with the control group, although the levels were well within normal range. Nine of the exposed farmers had abnormal thyroid ultrasound findings, consisting mostly of solitary nodules, compared with three among the control group. Analysis of variance showed significantly different blood ETU levels among the directly exposed, indirectly exposed, and control groups (p < 0.001), but ETU levels in urine were not significantly different (p = 0.10). Environmental ETU levels were below the U.S. Environmental Protection Agency remediation levels. Among farmers with solitary thyroid nodules, we found a very good direct correlation between the size of the nodule and blood ETU level. In this study we showed that blood ETU is a more reliable biomarker for EBDC exposure than urinary ETU; therefore, the determination of blood ETU should be part of medical surveillance efforts among workers exposed to EBDC to detect occurrences of thyroid gland disorders.

Biomonitoring of Contemporary Pesticides: Ethylenethiourea in Occupational Settings

“…There was no significant difference in T 4 concentrations between these two groups. Studies conducted with banana plantation workers in the Philippines did not find any difference in TSH and T 4 levels between workers and the control group (Panganiban et al, 2004). However, nutritional iodine intake as assessed by urinary iodine concentration was higher in the workers than in the control group.…”

“…These studies are outlined in Table II. The assessment of the workers' exposure, based on ETU concentrations in urine, has been done in Mexico in tomato growing areas (Steenland et al, 1997), in areas of floriculture in Ecuador (Colosio et al, 2003), in banana plantations in the Philippines (Panganiban et al, 2004), vineyards in Italy Corsini et al, 2005;Colosio et al, 2007;Fustinoni et al, 2008), in grains, tobacco, vegetable and cut flower areas in Thailand (Panuwet et al, 2007), potato farms in Finland, , in the flower bulb growing industry in the Netherlands and in vegetable growing areas in Bulgaria . These studies have shown that the concentration of ETU in urine of exposed workers reflects the type of activity on the farm, the use of personal protective equipment such as gloves, respirators, plastic suits and boots, and the level of mechanization and training.…”

“…Thyroid disorders are a major area of interest based on experimental animal studies demonstrating ETU-induced thyroid gland enlargement as a consequence of impaired thyroid hormone synthesis and on an occupational health study demonstrating mild but statistically significant lower T 4 concentrations in workers with higher exposure to powdered ETU than those with lower exposure (Smith 1984). Two cross-sectional studies, with reference groups to control for exposure to EBDCs, have been conducted to investigate the incidence of thyroid gland disorders in agricultural settings (Panganiban et al, 2004;Steenland et a., 1997;Smith 1984). Measures of thyroid hormone levels were carried out among 49 heavily exposed workers without protective equipment spraying EBDCs on tomatoes in Mexico (Steenland et al, 1997).…”

Reproduction impact of mancozeb on rainbow trout (Oncorhynchus mykiss W.) and accumulation of its carcinogen metabolite, ethylene thiourea in fish products

“…Because of their chelating properties, the dithiocarbamates (DTCs) modify cellular metabolism by their direct interactions with different molecules such as signaling proteins, peptides and enzymes, and influence the oxido-reductive metabolism of the cells (Vohr, 2012). Carcinogenicity of DTCs, including mancozeb, is due to their metabolite -2-imidazolidene thion (ethylene thiourea, ETU), which causes thyroid and pituitary tumors (Houeto et al, 1995;Panganiban et al, 2004;Axelstad et al, 2011).…”

Indicators of mancozeb exposure in relation to thyroid cancer and neural tube defects in farmers’ families

“…ETU was earlier classified by the International Agency for Research on Cancer as possibly carcinogenic to humans (group 2B), but, in 2001, it was reclassified into group 3 (not classifiable as to its carcinogenicity in humans) (11). This reclassification has been disputed (12), and published studies indicate that occupational exposure to ETU resulting from mancozeb use may perturb thyroid homeostasis (3,(13)(14)(15).…”