Assessment of peripheral nerve function in an Ecuadorian rural population exposed to pesticides.

To explore the peripheral nervous system effects of regular agricultural pesticide use, a cross-sectional survey was conducted in highland Ecuador. Participants were 144 occupationally exposed farm members, 30 female farm members with little direct exposure, and 72 unexposed local town residents, frequency matched to the exposed people on age, sex, and education. Organophosphorus and carbamate insecticides and dithiocarbamate fungicides accounted for the majority of pesticide applications, with leaking backpack sprayers, minimal use of personal protective equipment, and frequent dermal contact being the norm. In polytomous logistic regression analyses, applicators had significantly greater odds for more current peripheral nerve symptoms (odds ratio OR = 3.1), signs of poor coordination (OR = 4.3), abnormal deep tendon reflexes (OR = 2.9), and reduced power (OR = 2.1) compared to controls. Mean toe vibration threshold scores, on a logarithmic scale, were significantly higher among applicators (beta = 0.035) and those reporting previous pesticide poisonings (beta = 0.074). Such indicators of peripheral nervous system effects may be due to a variety of factors, including high pesticide exposure conditions.

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

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.

Ethylenebisdithiocarbamates and ethylenethiourea: possible human health hazards.

Humans are exposed to ethylenebisdithiocarbamates (EBDCs) from environmental sources. Exposure to EBDCs is chronic for workers in a variety of industries, where EBDCs are used for their properties as slimicides, vulcanization accelerators, antioxidants, and scavengers in waste-water treatment. EBDCs, and particularly the EBDC metabolite ethylenethiourea, have clearly defined, important toxic effects in various animal species, and there is reason to suspect they are carcinogenic in humans. In the absence of definitive information regarding human risk, further studies need to be done. In the interim, regular surveillance of workers with high levels of exposure to EBDCs, with specific attention to markers of thyroid and hepatic pathology, should be considered.

[Evaluation of urinary excretion of ethylenethiourea in subjects occupationally and non-occupationally exposed to ethylenebis(dithiocarbamates)]. / Valutazione dell'escrezione urinaria di etilentiourea in soggetti professionalmente e non professionalmente esposti ad etilenbisditiocarbammati.

Ethylenebisdithiorcabamate (EBDC) fungicides are broken down metabolically and in the environment to ethylenethiourea (ETU), a suspected carcinogen. Urinary ETU was assayed in control groups and subjects occupationaly exposed to EBDC and was found to be an excellent indicator of exposure both to ETU and EBDC. Correct use of protective clothing greatly reduced exposure and urinary excretion of ETU. ETU was excreted, albeit in low concentrations, in a high percentage (91% and 30%) of subjects in both control groups, demonstrating its utility as an indicator of widespread EBDC contamination.