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 in Vicia 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⁻¹ dry 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 in V. faba is increased.

LEAD EXPOSURE: POTTERY IMPACT IN TLAXCALA, MEXICO

Human beings and wild organisms are exposed daily to a broad range of environmental stressors. Among them are the persistent organic pollutants that can trigger adverse effects on these organisms due to their toxicity properties. There is evidence that metabolomics can be used to identify biomarkers of effect by altering the profiles of endogenous metabolites in biological fluids or tissues. This approach is relatively new and has been used in vitro studies mainly. Therefore, this review addresses those that have used metabolomics as a key tool to identify metabolites associated with environmental exposure to POPs in wildlife and human populations and that can be used as biomarkers of effect. The published results suggest that the metabolic pathways that produce energy, fatty acids, and amino acids are commonly affected by POPs. Furthermore, these pathways can be promoters of additional effects. In the future, metabolomics combined with other omics will improve understanding of the origin, development, and progression of the effects caused by environmental exposure.

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.

In Mexico, atrazine is one of the herbicides most widely authorized and used in different irrigation districts. Atrazine is a herbicide that contaminates aquatic systems. Previous studies have shown that atrazine causes damage to red blood cells and liver tissue in different aquatic species, including abnormalities in melanomacrophages. However, more information on amphibians is needed, since most of these studies have been done on fish. Furthermore, no study has determined the effect of atrazine on species native to Mexico. Therefore, in this study, we asked what the effects of atrazine are on the erythrocytes and melanomacrophages of the liver in the male frog (Lithobates spectabilis). In the present study, we analyzed (1) the cytotoxicity of atrazine using the micronucleus test, (2) the area of melanomacrophage centers and the presence of melanin, and (3) the characterization of liver damage using histological techniques. Our results show that atrazine is cytotoxic to erythrocytes, increases the area of and melanin presence in melanomacrophage centers, and causes liver damage in male L. spectabilis. Therefore, hepatotoxicity and cytotoxicity are indicators of environmental stress. We suggest monitoring Mexico’s aquatic systems and further analyzing atrazine effects and other pollutants on native species.