Search

The application of herbicides is one of the leading causes of the decline of amphibians in the world. Atrazine is widely used to control herbaceous weeds in crops. In Mexico, it is not regulated and widely applied. More information regarding the effects of atrazine in aquatic systems and on amphibians in this country is therefore needed. Amphibians have a smooth skin coated with excretions that protect them from harmful environmental influences, yet still facilitates the exchange of gases, ions, and thermoregulation, but is especially susceptible to absorbing toxic substances, including atrazine. A few studies have revealed that atrazine modifies the thickness of the epithelial layer in fish, but there are few studies to that effect in frogs. No studies have investigated whether atrazine exposure affects mucopolysaccharides or glucans, which are essential for hydrating the skin. We hypothesized and found confirmed that the herbicide atrazine reduces the thickness of the dorsal epithelium and promotes a greater presence of mucopolysaccharides in the dorsal epithelium and glands in Lithobates spectabilis. Our findings suggest that this frog is likely more vulnerable to dehydration, ultraviolet radiation, and will suffer impaired wound healing when exposed to atrazine. [ABSTRACT FROM AUTHOR]

This study assesses the potential risk of Texcalac River and riparian area. The p,p′ DDT and ∑DDTs levels in agricultural soils (3.9-208.0 µg/kg) and in surface sediments (0.6-137 µg/kg) surpassing the guidelines for protection of aquatic life (75% > TEC). The ∑PCBs concentration oscillated from 135 to 93941 µg/kg; the half of sediments exceeded the international guidelines (PEL, PEC), as well as two soils (SQGE = 500 µg/kg). The TEQ concentration of four PCB-DL varied between 0.1 and 24.9 µg TEQ/kg, chiefly affected by PCB 169. Five sediments were lethal for E. foetida, two resulted to be cytotoxic and the 58% produced genotoxicity higher than negative control (A = 0.28 ± 0.05; DICA = 72.5 ± 16.9 au). Likewise, 31.6% of samples increased the micronuclei frequency in V. faba in comparison with negative control. The analytical data and the bioassays results suggest a significant and immediate risk to exposed biota of this region, highlighting a specific area in Texcalac River and other one in Sambrano Ravine. It is necessity assess the dispersion of pollutants and perform biomonitoring studies that display the exposure levels in biota with the goal to characterise the ecotoxicological risk. [ABSTRACT FROM AUTHOR]

The aim of this study was to assess the levels of some persistent organic pollutants in the surface sediments from the Zahuapan and Atoyac rivers (Tlaxcala, Mexico), as well as to determine the genotoxic potential, by the micronucleus test inVicia faba, of the sediments and agricultural soils irrigated with water from these rivers. This document is the first study on the presence of POPs in surface sediments of the above-mentioned rivers; among the compounds analyzed are the HCH isomers, DDT and its metabolite DDE, HCB, mirex, aldrin, and 41 PCB congeners. The concentrations of HCB, ΣDDTs, ΣHCHs, and ΣPCBs ranged from 138–510, 45–450, 3–27, and 59–1876 μg kg−1dry weight, respectively. The highest levels of HCB, HCH isomers, and PCB congeners were found in the Atoyac River, and these compounds have the potential for causing an environmental impact. On the other hand, biological testing shows that both sediments and agricultural soils possess a genotoxic potential, given that the micronuclei frequency inV. fabais increased. [ABSTRACT FROM AUTHOR]

Exposure to pesticides such as paraquat and 2,4-dichlorophenoxyacetic acid (2,4-D) has been linked to harmful health effects, including alterations in male reproduction. Both herbicides are widely used in developing countries and have been associated with reproductive alterations, such as disruption of spermatogenesis and steroidogenesis. The thyroid axis and Ca 2+ -permeable ion channels play a key role in these processes, and their disruption can lead to reproductive issues and even infertility. This study evaluated the short-term effects of exposure to commercial herbicides based on paraquat and 2,4-D on gene expression in rat testes. At the molecular level, exposure to paraquat increased the expression of the thyroid hormone transporters monocarboxylate transporter 8 ( Mct8 ) and organic anion-transporting polypeptide 1C1 ( Oatp1c1 ) and the thyroid receptor alpha ( TRα ), suggesting a possible endocrine disruption. However, it did not alter the expression of the sperm-associated cation channels ( CatSper1-2 ) or vanilloid receptor-related osmotically activated channel ( Trpv4 ) related to sperm motility. In contrast, exposure to 2,4-D reduced the expression of the Mct10 transporter, Dio2 deiodinase, and CatSper1 , which could affect both the availability of T3 in testicular cells and sperm quality, consistent with previous studies. However, 2,4-D did not affect the expression of CatSper2 or Trpv4 . Deregulation of gene expression could explain the alterations in male reproductive processes reported by exposure to paraquat and 2,4-D. These thyroid hormone-related genes can serve as molecular biomarkers to assess endocrine disruption due to exposure to these herbicides, aiding in evaluating the health risks of pesticides.