The metropolitan area of the Toluca Valley (MATV) extends over an area of 1208.55 km2 and has 1,361,500 inhabitants making it the fifth highest populated area in the country and the second highest in the state. The MATV has several environmental problems, with regards to the air quality. Particles PM10 and PM2.5 are considered to be the main pollutant due to these particles frequently exceeding the limit laid down in the standards of the air quality in the country. For this reason, samples of the mosses Fabriona ciliaris and Leskea angustata were collected at different sites in MATV, Mexico in order to establish the atmospheric deposition of heavy metals by means of the analysis of the mosses tissues. Results show the average metal concentrations in the mosses in the order of: Zn > Pb > Cr > Cd. The concentration capacities of heavy metals were higher in Fabriona ciliaris than Leskea angustata. Enrichment factors for Cr, Zn, Pb and Cd were obtained using the soils from the same sampling area. Enrichment factors results show that Cr is conservative in both sampling seasons with a terrigenous origin; Zn is moderately enriched in both sampling seasons and mainly associated to pedological-soil or substrate contribution and anthropogenic activities and Cd is highly enriched in the rainy season and Pb is highly enriched in both sampling seasons, with a predominantly anthropogenic origin. This study provides information to be considered in the strategies for similar environmental problems in the world.

Endosulfan is an organochloride and persistent pesticide that has caused concern because of its impact in the environment and its toxicity to and bioaccumulation in living organisms. In this study, we isolated an endosulfan-degrading fungus from the activated sludge from an industrial wastewater treatment plant. Through repetitive enrichment and successive subculture in media containing endosulfan as the sole carbon source, a fungus designated CHE 23 was isolated. Based on a phylogenetic analysis, strain CHE 23 was assigned to the genus Penicillium sp. In a mineral salt medium with 50 mg/l endosulfan as the sole source carbon, CHE 23 removed the added endosulfan in a period of six days. To verify the decrease in endosulfan toxicity due to the activity of the fungus, we performed genotoxicity tests trough the single cell gel electrophoresis assay or comet assay, with Eisenia fetida as the bioindicator species. This organism was exposed to the supernatants of the culture of the fungus and endosulfan. Our results indicated that the genotoxicity of endosulfan was completely reduced due the activity of this fungus. These results suggest that the Penicillium sp. CHE 23 strain can be used to degrade endosulfan residues and/or for water and soil bioremediation processes without causing toxicity problems, which are probably due to the generation of no-toxic metabolites during biodegradation.

Phthalates are widely used as plasticizers, additives, or solvents. Its extensive use has generated environmental and food contamination, which implies continuous population exposure. The aim of this work was to determine the probability of health risk of Mexican children exposed to phthalates through the consumption of contaminated food. A survey was applied to 384 Mexican school-age children (between 6 and 12 years old), to find out the type of food they eat most frequently, based on this, a research was made to know the concentration of phthalates contained in these foods. The daily intake had been calculated with the concentration of phthalates reported in food, obtaining: DEHP (19.50 μg/kg body weight/day), DnBP (5.52 μg/kg body weight/day) y for DEP (1.12 μg/kg body weight/day). The hazard index (HI) for DEP y DEHP was 0.49 to 42.5 for internal organs damage reported. HI for reproductive health damage due to exposure to DnBT and DEHP was of 0.04 to 5.58, so that there is a high probability that children's health is at risk. Therefore, it is necessary to a quantitative analysis of phthalates in food consumed in Latin American countries and establish the TDI of phthalates especially, to DEHP, which was obtained the higher HI.

¹³⁷Cs activity concentration in soil was analyzed yearly for 13 years (2010–2022) in an undisturbed area in Mexico. The temporal variation at 17 sampling points is consistent with the natural radioactive decrease of ¹³⁷Cs, excluding increased activity concentration detected after the Fukushima accident at 4 sampling points. Geospatial analysis was permitted to obtain ¹³⁷Cs activity concentration distributions for each year. The highest ¹³⁷Cs activity concentration was found at higher topography levels and close to intermittent water streams: 87.1 ± 5.5 Bq kg⁻¹ for the year 2011, which increased to 135.5 ± 14.5 Bq kg⁻¹ for the year 2013, and then ¹³⁷Cs decreased down to 46.4 ± 4.0 Bq kg⁻¹ by the year 2022. The lowest ¹³⁷Cs activity concentration was in the range of 0.6 ± 0.1 Bq kg⁻¹ to 13.5 ± 1.0 Bq kg⁻¹ at the points far from the undisturbed area, probably due to anthropogenic activities.

Radiological effects on population and environment due to fracking unconventional hydrocarbons is given in this study. Evaluation on environmental effects concerning extraction process is given. Effects on fauna and humans during fracking process, including on air, water and soil, are mentioned. Unconventional oil and gas extraction generates Natural Occurring Radioactive Materials (NORM); their associations to radiological aspects are comment. Our environmental radiological baseline studies at three prospecting fracking zones in Mexico showed no radiological hazard to population. The natural gamma radioactivity before fracking had a maximum equivalent dose rate of 1.83 mSv a⁻¹, in the low value of the acceptable background interval (1–13) mSv a⁻¹ stated by UNSCEAR. The 226Ra and 228Ra maximum concentration obtained in soil (59.2 ± 3.6 and 38.5 ± 5.0 Bq kg⁻¹, respectively) for this baseline are both in the average global-interval concentration reported by UNSCEAR; gross alpha and gross beta in water were all below the suggested limits by the World Health Organization of 0.5 and 1.0 Bq L⁻¹, respectively, for drinking water. An important conclusion is that water stress is an important issue before considering fracking activities in Mexico.

Por pruebas nucleares se liberaron 948 PBq de 137Cs entre 1945-1993, además se incorporó 137Cs al ambiente por los accidentes de Fukushima y Chernóbil. El 137Cs se incorpora a la biota, cadena trófica y ser humano; este trabajo utiliza el código RESRAD para determinar la dosis efectiva total anual y exceso de riesgo de cáncer al humano por 137Cs. Los cálculos se realizaron con concentraciones de 137Cs reportadas en Canadá, Estados Unidos de América y México. Los valores máximos reportados de 137Cs en el ambiente son 212 Bq kg-1, 111 Bq kg-1 y 20.4 Bq kg-1 para, Canadá, Estados Unidos de América y México respectivamente. Se tomaron los valores máximos y se consideró un área de suelo de 400 por 400 metros; se ingresaron al código datos de cada sitio. Los resultados fueron: dosis efectiva total anual de 5.7x10-4 mSv a-1 para Canadá, 3.0x10-4 mSv a-1 para Estados Unidos de América y 5.4x10-5 mSv a-1 para México. Estas dosis están muy por debajo de la dosis efectiva total anual 2.4 mSv a-1 a nivel global por fuentes de radiación natural.