Environmental implications of fluoride presence in drinking water along the southeastern of El Bajío Guanajuatese, Guanajuato, Mexico: sources and health effects

Chronic exposure from drinking water with naturally high concentrations of fluoride (F⁻) has serious health consequences in several regions across the world including north-central Mexico as Guanajuato State, where the rural population is particularly dependent on untreated groundwater pumped from wells that have natural F- concentrations higher than those allowed by national and international regulations. The contaminated aquifers in the area are usually located in fractured volcanic environment that interacts with sedimentary basins and have a carbonate basement. Few studies focused on identifying the origin and hydrogeochemical processes related to fluoride release and mobilization have been developed, and even fewer that quantify the natural content of F in the geological environment. In this study, an evaluation of fluoride in volcanic rocks collected from 11 sampling sites along the Sierra de Codornices (Guanajuato State, Central Mexico) was carried out. The fluoride content is disseminated in volcanic rocks and the highest contents were obtained in felsic rocks. According to results obtained of a sampling campaign of 32 wells in 2019 their statistical and hydrogeochemical evaluation suggest that F- mobilization in groundwater from Juventino Rosas and Villagran municipalities, is a product of volcanic glass dissolution, a process involved in alkaline desorption occurring on the surfaces of F-containing minerals, and possibly on ion exchange occurring in minerals and some clays or even in deep fluids enriched in F. All these processes may be accelerated by the geothermal characteristics of the groundwater in the study area. The hydrogeochemical results and the epidemiological survey conducted indicate that children and older adults of Praderas de la Venta are at risk of exposure to F- due to the high concentrations ingested over a long period of time, to the toxicity of the element and its ability to accumulate in the bones. Prolonged exposure to high concentrations increases the risk.

Genomic epidemiology of Salmonella enterica circulating in surface waters used in agriculture and aquaculture in central Mexico

Salmonella enterica (SE) can survive in surface waters (SuWa) and the role of non-host environments in its transmission has acquired increasing relevance. In this study, we conducted comparative genomic analyses of 172 SE isolates collected from SuWa across three months in six states of central Mexico during 2019. SE transmission dynamics were assessed using 87 experimental and 112 public isolates from Mexico collected during 2002-2019. We also studied genetic relatedness between SuWa isolates and human clinical strains collected in North America during 2005-2020. Among experimental isolates, we identified 41 SE serovars and 56 multi-locus sequence types (ST). Predominant serovars were Senftenberg (n=13), Meleagridis, Agona, and Newport (n=12 each), Give (n=10), Anatum (n=8), Adelaide (n=7), and Infantis, Mbandaka, Ohio and Typhimurium (n=6 each). We observed a high genetic diversity in the sample under study, as well as clonal dissemination of strains across distant regions. Some of these strains are epidemiologically important (ST14, ST45, ST118, ST132, ST198, and ST213), and were genotypically close to those involved in clinical cases in North America. Transmission network analysis suggests that SuWa are a relevant source of SE (0.7 source/hub ratio) and contributes to its dissemination as isolates from varied sources and clinical cases have SuWa isolates as common ancestors. Overall, the study shows SuWa act as reservoir of various SE serovars of public health significance. Further research is needed to better understand the mechanisms involved in SuWa contamination by SE, as well as develop interventions to contain its dissemination to food production settings. Study importance Surface waters are heavily used in food production worldwide. Several human pathogens can survive in these waters for long periods and disseminate to food production environments, contaminating our food supply. One of these pathogens is Salmonella enterica , a leading cause of foodborne infections, hospitalizations and deaths in many countries. This research demonstrates the role of surface waters as a vehicle for the transmission of Salmonella along food production chains. It also shows some strains circulating in surface waters are very similar to those implicated in human infections and harbor genes that confer resistance to multiple antibiotics, posing a risk to public health. The study contributes to expand our current knowledge on the ecology and epidemiology of Salmonella in surface waters.

Phytoplankton Biodiversity in Two Tropical, High Mountain Lakes in Central Mexico

Lakes El Sol and La Luna, inside the crater of the Nevado de Toluca volcano, Central Mexico, are the only two perennial high mountain lakes [HML] in the country. HML are considered among the most comparable ecosystems worldwide. These lakes are “extreme” environments with diluted, oligotrophic, and cold waters exposed to high UV radiation doses. In this paper, we document the phytoplankton species inhabiting these two extreme tropical ecosystems. The phytoplankton diversity of Lakes El Sol and La Luna is low compared to the global phytoplankton diversity from other Mexican inland waters. Nonetheless, the phytoplankton diversity turned out to be high compared to other HML worldwide, both temperate and tropical. The phytoplankton community in Lake El Sol was formed by 92 morphospecies and in Lake La Luna by 63; in both, the most diverse groups were Bacillariophyceae and Chlorophyceae. All species found in Lake La Luna were present in Lake El Sol, but 29 species present in Lake El Sol were absent in Lake La Luna. Nevertheless, 57% of the most frequent and abundant taxa in Lake El Sol were rare in La Luna, and 47% of the most frequent and abundant taxa in Lake La Luna were rare in Lake El Sol. Associated with their shallowness and polymictic thermal pattern, 87.5% of the Bacillariophyceae morphospecies are tychoplantonic, while the remaining 12.5% are truly planktonic. Dominant taxa were Chlorophyceae in Lake El Sol and Cyanobacteria in Lake La Luna. The most extreme conditions of Lake La Luna (ultraoligotrophy, very low pH, high ultraviolet radiation) most likely explained the differences in the dominant species composition and lower species richness compared to Lake El Sol. Herein, we provide for the first time a taxonomic list of the phytoplankton community of Lakes El Sol and La Luna. This information constitutes a baseline needed to use these HML as sentinels of global and climate change.

Review of Cooperative health in the COVID-19 era

The governance of migratory flows, understood as a system of co-management co-responsibility between institutional and private, political and social actors with respect to their identity and occupational health is addressed in the present non-experimental, exploratory and cross-sectional work with a non-probabilistic sample selection of 100 former migrants from central Mexico. From a structural model seven factors were established regarding framing, demands, resources, risks, opportunities, capabilities and employment. Based on the literature consulted, the limits, scope and lines of research aimed at deepening the effects of the variables and factors in an intercultural scenario are noticed.

Prescriptions For The Control Of A Clonal Invasive Species Using Demographic Models

Until recently, little focus has been given to determine the population dynamics of invasive species and evaluate their genetic variation. Consequently, not much is known of what drives clonal invasive species and their demography. Here we describe the population dynamics of Kalanchoe delagoensis (Crassulaceae), considered invasive to several countries. We quantified the demography of a population in central Mexico using integral projection models (IPM) in a population that reproduced asexually exclusively through plantlets. The effect of clonal recruitment on λ was evaluated by changing plantlet survival and simulating management scenarios that used previous data of watering and seven experimental herbicide treatments. The finite rate of population increase indicated that this Kalanchoe delagoensis population is growing (above one) with significant potential increases that correlated with water availability. The IPM showed that plantlet survival and recruitment were the most critical steps in the cycle for the population and simulations of different management scenarios showed that reducing plantlet survival significantly decreased λ only in two out of the seven herbicides used.