Thyroid hormones and cytogenetic outcomes in backpack sprayers using ethylenebis(dithiocarbamate) (EBDC) fungicides in Mexico.

Abstract

Ethylenebis(dithiocarbamate) (EBDC) fungicides are used heavily in the United States. EBDCs (e.g., mancozeb, maneb) are metabolized to ethylene thiourea (ETU). The EPA classifies ETU as a carcinogen, based on thyroid and other cancers in rodents, and has restricted the use of EBDCs, while requiring workers to use protective equipment. There are no data on the potential carcinogenicity of EBDCs in humans, and there is only one study on human genotoxicity. ETU is known to cause decreases of thyroxine (T4) and increases in thyroid-stimulating hormone (TSH) in rodents. We have studied cytogenetic outcomes and serum thyroid hormone levels among 49 heavily exposed workers without protective equipment spraying EBDC on tomatoes in Mexico. We also studied 14 lightly exposed landowners and 31 nonexposed controls. Urinary ETU was used to compare exposure between groups. We found an increase in TSH (p = 0.05) among applicators compared to controls, but no decrease in thyroid hormone (T4). We found increases in sister chromatid exchange (p = 0.03) and in chromosome translocations (chromosome aberrations that persist through cell division) for applicators compared to controls (p = 0.05). However, the subset of reciprocal translocations showed a lesser increase (p = 0.24). Our data suggest that EBDCs affect the thyroid gland and the lymphocyte genome among heavily exposed workers. However, our data are limited to subclinical outcomes, are of borderline statistical significance, and should be interpreted with caution.ImagesFigure 1.

Time to first pregnancy among women working in agricultural production

“…Increasing evidence has originated from less developed countries, where exposures are often greater due to multiple growing seasons: a greater range of pesticide products applied, less adequate personal protective equipment use, and longer work hours (Matos et al 1988;Steenland et al 1997;Paz-y-Min˜o et al 2002). Some of the findings of concern are those suggesting adverse reproductive outcomes among agricultural workers (Nurminen 1995;Hanke and Jurewicz 2004).…”

Epidemiological Studies of Anticholinesterase Pesticide Poisoning in Mexico

“…34.2). In most cases, farmers are exposed to complex mixtures of pesticides, mostly OPs and CMs (Cortés-Genchi et al, 2008;Pérez-Herrera et al, 2008;Steenland et al, 1997). The most used mixtures are manzate/foley (CM/OP) and tamaron/lannate (OP/CM) (Cortés-Genchi et al, 2008).…”

“…The period of high frequency of pesticide use by sprayers in areas from the center of Mexico has been reported to be from June to November (Steenland et al, 1997); similarly, 92% of agricultural workers from the south of Mexico (Chiapas State) applied pesticides from April to August (Tinoco-Ojanguren and Halperin, 1998) and Pérez-Herrera (2008) reported an increase in pesticide use in the rainy season (JuneSeptember) in Yucatan State (southeast of the country). In addition, the highest percentage of poisoning episodes in Baja California (north of Mexico) has been observed from July to October, corresponding to the period of most intensive agricultural work (Valdez Salas et al, 2000), and acetylcholinesterase (AChE) activity in women living in agricultural communities in the north of Mexico (Chihuaha State) decreased during the months of greater use of pesticides (April -August) (Levario-Carrillo et al, 2004).…”

“…From Cortés-Genchi et al (2008), González-Arias et al (2010), Pérez-Herrera et al (2008),Steenland et al (1997) and Tinoco-Ojanguren and Halperin (…”

Étude d’ergoexpologie aux fongicides dithiocarbamates auprès de professionnels de trois secteurs agricoles

“…L'absorption serait comprise entre 1 et 10 % de la dose déposée sur les téguments. Par voie orale en 48 heures, 82 à 99 % de la dose est éliminée dans les urines et seulement 3 % dans les selles [8,12]. En raison de ces caractéristiques, la MSA a souhaité mené une étude d'exposition ou d'ergoexpologie pour objectifs de : contribuer à la connaissance de la cinétique d'excrétion de ces produits ; quantifier l'exposition par une mesure de l'excrétion urinaire du principal métabolite, l'éthylènethiourée (ETU) ; corréler les résultats aux pratiques observées pour appréhender l'impact des comportements [9][10][11].…”