Assessment of Cytogenetic Damage and Cholinesterases' Activity in Workers Occupationally Exposed to Pesticides in Zamora-Jacona, Michoacan, Mexico.

Pesticides have been considered as potential chemical mutagens; however, little is known about toxic and genotoxic effects during pesticide application in Zamora-Jacona, Michoacan State in Mexico. This study sought to determine DNA damage and cholinesterase activities inhibitions in 54 agricultural workers exposed to complex mixtures of pesticides vs. control group (26 individuals) using Comet assay in peripheral whole blood, micronucleus (MN) test in oral mucosa cells, Cytokinesis-blocked MN assay in lymphocytes (L-CBMNcyt) and measuring AChE and BChE activities in whole blood and plasma samples, respectively. Exposed subjects demonstrated significantly elevated levels of primary (Comet assay: tail intensity, tail length, tail moment, Olive tail moment) and permanent DNA damage (MN assay: in blood/buccal cells; frequencies of nuclear buds, binucleated cells, cells with condensed chromatin, karyorrhexis, pyknosis, and karyolysis). However, inhibition of cholinesterase activities (AChE and BChE) was not observed in the workers. Confounding factors including sex, age, BMI, working exposure period, protection level, smoking habit (cigarettes per day units), alcohol consumption (weekly), medication, were considered in the analysis. These combined techniques demonstrated usefulness in the health hazards risks pesticide exposure assessment and suggested the need for periodic monitoring together with the education and the training of occupational workers for the safe application of potentially harmful pesticides.

Methyl parathion causes genetic damage in sperm and disrupts the permeability of the blood-testis barrier by an oxidant mechanism in mice.

Methyl parathion (Me-Pa) is an extremely toxic organophosphorus pesticide still used in developing countries. It has been associated with decreased sperm function and fertility and with oxidative and DNA damage. The blood-testis barrier (BTB) is a structure formed by tight junction (TJ) proteins in Sertoli cells and has a critical role in spermatogenesis. We assessed the effect of repeated doses of Me-Pa (3-12 mg/kg/day for 5 days, i.p.) on sperm quality, lipid oxidation, DNA integrity, and BTB permeability in adult male mice and explored oxidation as a mechanism of toxicity. Me-Pa caused dose-dependent effects on sperm quality, lipoperoxidation, and DNA integrity. Testis histology results showed the disruption of spermatogenesis progression and atrophy of seminiferous tubules. The pesticide opened the BTB, as evidenced by the presence of a biotin tracer in the adluminal compartment of the seminiferous tubules. This effect was not observed after 45 days of exposure when a spermatogenic cycle had completed. The coadministration of the antioxidant α-tocopherol (50 mg/kg/day for 5 days, oral) prevented the effects of Me-Pa on sperm quality, DNA and the BTB, indicating the importance of oxidative stress in the damage generated by Me-Pa. As evidenced by immunochemistry, no changes were found in the localization of the TJ proteins of the BTB, although oxidation (carbonylation) of total proteins in testis homogenates was detected. Our results show that Me-Pa disturbs the BTB and that oxidation is involved in the observed toxic effects on sperm cells.

Alterations in oocytes and early zygotes following oral exposure to di(2-ethylhexyl) phthalate in young adult female mice.

Because di(2-ethylhexyl) phthalate (DEHP) toxicity on ovarian function is incomplete, effects of DEHP oocyte fertilization and the resulting zygotes were investigated. Further, an analysis characterizing the stage of zygote arrest was performed. Female CD1 mice were dosed orally with DEHP (0, 20, 200 and 2000 µg/kg/day) for 30 days. Following an in vivo mating post-dosing, DEHP-treated females exhibited fewer oocytes/zygotes, fewer oocytes displaying the polar body extrusion, fewer 1-cell zygotes having 2-pronuclei, more unfertilized oocytes, and decreased number of zygotes at every stage of development. DEHP induced blastomere fragmentation in zygotes. DNA replication in zygotes directly assessed by the 5-Ethynyl-2'-deoxyuridine (5-EdU) incorporation assay and indirectly by dosing mice with 5-fluorouracil (5-FU) suggested that DEHP inhibits DNA replication. Our data suggest that DEHP at doses found in 'every-day' (200 µg/Kg/day) or occupational (2000 µg/Kg/day) environments induces zygote fragmentation and arrests its development from the 2-cell stage potentially impairing DNA replication.

Effects of exposure to malathion on blood glucose concentration: a meta-analysis.

Exposure to malathion (an organophosphate pesticide widely used around the world) has been associated with alterations in blood glucose concentration in animal models. However, the results are inconsistent. The aim of this meta-analysis was to evaluate whether malathion exposure can disturb the concentrations of blood glucose in exposed rats. We performed a literature search of online databases including PubMed, EBSCO, and Google Scholar and reviewed original articles that analyzed the relation between malathion exposure and glucose levels in animal models. The selection of articles was based on inclusion and exclusion criteria. The database search identified thirty-five possible articles, but only eight fulfilled our inclusion criteria, and these studies were included in the meta-analysis. The effect of malathion on blood glucose concentration showed a non-monotonic dose-response curve. In addition, pooled analysis showed that blood glucose concentrations were 3.3-fold higher in exposed rats than in the control group (95% CI, 2-5; Z = 3.9; p < 0.0001) in a random-effect model. This result suggested that alteration of glucose homeostasis is a possible mechanism of toxicity associated with exposure to malathion.

Methamidophos alters sperm function and DNA at different stages of spermatogenesis in mice.

Methamidophos (MET) is a highly toxic organophosphate (OP) pesticide that is widely used in developing countries. MET has male reproductive effects, including decreased fertility. We evaluated MET effects on sperm quality, fertilization and DNA integrity, exploring the sensitivity of different stages of spermatogenesis. Adult male mice received MET (3.75 or 5mg/kg-bw/ip/day/4 days) and were euthanized 1, 28 or 45 days post-treatment (dpt) to evaluate MET's effects on epididymal maturation, meiosis or mitosis, respectively. Spermatozoa were obtained from the cauda epididymis-vas deferens and were evaluated for sperm quality, acrosome reaction (AR; Coomassie staining), mitochondrial membrane potential (by JC-1), DNA damage (comet assay), oxidative damage (malondialdehyde (MDA) production), in vitro fertilization and protein phosphorylation (immunodetection), and erythrocyte acetylcholinesterase (AChE) activity. At 1-dpt, MET inhibited AChE (43-57%) and increased abnormal cells (6%). While at 28- and 45-dpt, sperm motility and viability were significantly reduced with an increasing MET dose, and abnormal morphology increased at 5mg/kg/day/4 days. MDA and mitochondrial activity were not affected at any dose or time. DNA damage (OTM and %DNA) was observed at 5mg/kg/day/4 days in a time-dependent manner, whereas both parameters were altered in cells from mice exposed to 3.75 mg/kg/day/4 days only at 28-dpt. Depending on the time of collection, initial-, spontaneous- and induced-AR were altered at 5mg/kg/day/4 days, and the fertilization capacity also decreased. Sperm phosphorylation (at serine and tyrosine residues) was observed at all time points. Data suggest that meiosis and mitosis are the more sensitive stages of spermatogenesis for MET reproductive toxicity compared to epididymal maturation.

Comparative effect of technical and commercial formulations of methamidophos on sperm quality and DNA integrity in mice.

Methamidophos (MET), widely used in developing countries, is a highly neurotoxic organophosphate pesticide that has been associated with male reproductive alterations. Commercial formulations of pesticides used by agricultural workers and urban sprayers are responsible for thousands of intoxications in developing countries and may not have the same effects as active pure ingredients. Therefore, we compared effects of MET technical (METt) and commercial (METc) grades on sperm quality and DNA integrity. Male mice were injected (intraperitoneal, i.p.) with METt or METc (3.75, 5, and 7 mg/kg bw/day/4 days) and sacrificed 24 h post-treatment. Sperm cells collected from epididymis-vas deferens were evaluated for quality parameters, DNA damage by the comet assay, and lipoperoxidation by malondialdehyde (MDA) production. Erythrocyte acetylcholinesterase (AChE) activity was evaluated by acetylthiocholine inhibition as an index of overall toxicity. A dose-dependent AChE inhibition was observed with both formulations. Sperm quality was decreased after treatment with both MET compounds, but the commercial formulation showed stronger effects; a similar profile was observed with the DNA damage, being METc more genotoxic. None MET formulation increased MDA, suggesting no peroxidative damage involved. In summary, the commercial formulation of MET was more reprotoxic and genotoxic than the active pure ingredient, highlighting that commercial formulations must be considered for more appropriate risk assessment of pesticide exposures.