Arsenic Concentrations in Household Drinking Water: A Cross-Sectional Survey of Pregnant Women in Tacna, Peru, 2019.

The World Health Organization (WHO) estimates that around ~150 million people in 70 different countries have been consuming water with arsenic levels higher than the recommended limit of 10 µg/L. Here we describe the concentrations of inorganic arsenic in drinking water in homes of pregnant women living in the province of Tacna, near the southern border of Peru. 161 pregnant women were enrolled in their second trimester of pregnancy. A total of 100mL drinking water was collected in each household from the source of most common use. Inorganic arsenic was categorized into 3 levels with a commercial kit. Thirty percent of women had drinking water ≤10 µg/L (the WHO recommended level), 35% had 25 µg/L, and 35% had greater than 50 µg/L. Low arsenic levels were found in the southernmost homes, supplied by groundwater, while high levels were found in the northern and metropolitan homes supplied by river water.

Arsenic levels in groundwater and its correlation with relevant inorganic parameters in Uruguay: A medical geology perspective.

The aim of this work was to perform a groundwater quality monitoring in Uruguay, from the Medical Geology perspective, focusing attention on arsenic levels and its correlations with other relevant inorganic parameters. For this purpose, a total of 46 groundwater samples from private wells, out of the scope of the state-run water utility company, were analyzed. The accuracy of the analytical methods was ensured by using certified reference materials. Arsenic concentration range was 1.72-120.5 µg L-1, half of the samples being above the limit of 10 µg L-1 recommended by WHO for drinking water, with the corresponding risks for human health. Pearson correlations were performed, resulting in strong positive correlations for the pairs As/Cl-, As/F-, As/Na and As/V. These relationships between arsenic and other inorganic parameters in groundwater should be deeply studied, to prevent long-term health effects.

Unraveling the antibacterial mode of action of a clay from the Colombian Amazon.

Natural antibacterial clays can inhibit growth of human pathogens; therefore, understanding the antibacterial mode of action may lead to new applications for health. The antibacterial modes of action have shown differences based on mineralogical constraints. Here we investigate a natural clay from the Colombian Amazon (AMZ) known to the Uitoto natives as a healing clay. The physical and chemical properties of the AMZ clay were compared to standard reference materials: smectite (SWy-1) and kaolinite (API #5) that represent the major minerals in AMZ. We tested model Gram-negative (Escherichia coli ATCC #25922) and Gram-positive (Bacillus subtilis ATCC #6633) bacteria to assess the clay's antibacterial effectiveness against different bacterial types. The chemical and physical changes in the microbes were examined using bioimaging and mass spectrometry of clay digests and aqueous leachates. Results indicate that a single dose of AMZ clay (250 mg/mL) induced a 4-6 order of magnitude reduction in cell viability, unlike the reference clays that did not impact bacterial survival. AMZ clay possesses a relatively high specific surface area (51.23 m(2)/g) and much higher total surface area (278.82 m(2)/g) than the reference clays. In aqueous suspensions (50 mg clay/mL water), soluble metals are released and the minerals buffer fluid pH between 4.1 and 4.5. We propose that the clay facilitates chemical interactions detrimental to bacteria by absorbing nutrients (e.g., Mg, P) and potentially supplying metals (e.g., Al) toxic to bacteria. This study demonstrates that native traditional knowledge can direct scientific studies.

Developing medical geology in Uruguay: a review.

Several disciplines like Environmental Toxicology, Epidemiology, Public Health and Geology have been the basis of the development of Medical Geology in Uruguay during the last decade. The knowledge and performance in environmental and health issues have been improved by joining similar aims research teams and experts from different institutions to face environmental problems dealing with the population's exposure to metals and metalloids and their health impacts. Some of the Uruguayan Medical Geology examples are reviewed focusing on their multidisciplinary approach: Lead pollution and exposed children, selenium in critically ill patients, copper deficiency in cattle and arsenic risk assessment in ground water. Future actions are also presented.