Edda Villaamil Lepori

Arsenic exposure in Latin America: Biomarkers, risk assessments and related health effects

In Latin America, several regions have a long history of widespread arsenic (As) contamination from both natural and anthropological sources. Yet, relatively little is known about the extent of As exposure from drinking water and its related health consequences in these countries. It has been estimated that at least 4.5 million people in Latin America are chronically exposed to high levels of As (>50 μg/L), some to as high as 2000 μg/L--200 times higher than the World Health Organization (WHO) provisional standard for drinking water. We conducted a systematic review of 82 peer reviewed papers and reports to fully explore the current understanding of As exposure and its health effects, as well as the influence of genetic factors that modulate those effects in the populations of Latin America. Despite some methodological limitations, these studies suggested important links between the high levels of chronic As exposure and elevated risks of numerous adverse health outcomes in Latin America--including internal and external cancers, reproductive outcomes, and childhood cognitive function. Several studies demonstrated genetic polymorphisms that influence susceptibility to these and other disease states through their modulation of As metabolism, with As methyltransferase (AS3MT), glutathione S-transferase (GST), and genes of one-carbon metabolism being specifically implicated. While the full extent and nature of the health burden are yet to be known in Latin America, these studies have significantly enriched knowledge of As toxicity and led to subsequent research. Targeted future studies will not only yield a better understanding of the public health impact of As in Latin America populations, but also allow for effective and timely mitigation efforts.

Riesgo sanitario de la población vulnerable expuesta al arsénico en la provincia de Buenos Aires, Argentina

OBJETIVO: Analizar la concentracion de arsenico en agua recolectada en localidades de la provincia de Buenos Aires, Argentina, y su relacion epidemiologica con factores de susceptibilidad y patologias asociadas. METODOS: Se cuantifico la concentracion de arsenico en 152 muestras provenientes de 52 localidades de Buenos Aires durante el periodo 2003-2008 mediante generacion de hidruros-espectrofotometria de absorcion atomica. Se construyo un indice compuesto de salud (ICS) considerando el contenido de arsenico, el porcentaje de hogares con necesidades basicas insatisfechas (NBI) y el de viviendas sin acceso al agua de red. A partir del ICS se definieron zonas de riesgo que fueron asociadas con la mortalidad por tumores malignos relacionados con el arsenico. RESULTADOS: Las concentraciones de arsenico se ubicaron en un rango amplio, desde 0,3 hasta 187 µg/L, con una mediana de 40 µg/L. El 82% de las muestras presentaron niveles de arsenico superiores al valor limite aceptable de 10 µg/L, y mas de la mitad de ellas provenian de agua de red. La mortalidad promedio (defunciones/100 000 habitantes) por tumores en los departamentos estudiados fue mayor en los varones que en las mujeres: vias respiratorias (310 frente a 76), vias urinarias (44 frente a 11) y piel (21 frente a 11), respectivamente. Las regiones de mayor concentracion de arsenico y pobreza, junto con la falta de agua de red, presentaron un riesgo relativo incrementado de 2 a 4 veces. CONCLUSIONES: La caracterizacion realizada a traves del indice compuesto de salud sintetizo el riesgo sanitario de la exposicion al arsenico de la poblacion con niveles de carencia socioeconomica de una amplia region de la provincia de Buenos Aires.

Relationship between exposure, body burden and target tissue concentration after oral administration of a low-dose mixture of pyrethroid insecticides in young adult rats

Pyrethroids (PYRs) are synthetic insecticides increasingly used in agricultural and household pest control. Little is known on how the toxicity of highly effective bolus doses of single compounds compares to more realistic scenarios of low-level exposure to PYR mixtures. In this study, we examined a quaternary mixture of two noncyano (tefluthrin, TEF; bifenthrin, BIF) and two cyano (α-cypermethrin, α-CPM; deltamethrin, DTM) PYRs in young adult rats. These compounds are mostly composed of PYR isomers ranking top ten in acute lethality in rats. Concurrently, we administered near-threshold levels of the four PYRs dissolved in corn oil by oral route. Six hours later blood was collected and the liver and cerebellum were dissected out to determine PYR concentrations in these tissues using Gas Chromatography with Electron Capture Detector (GC-ECD). The mixture caused mild-to-moderate changes in non-locomotor behaviors and subcutaneous body temperature (up to +1.2-1.5 °C increase at 2-4 h after dosing, respectively, compared to pre-dosing records). The most toxic PYRs BIF and TEF reached higher concentrations in the cerebellum than the cyano-compounds α-CPM and DTM. In addition, PYR concentrations in the cerebellum were correlated to single compound proportions in the dosing solution and changes in body temperature. Our results suggest that aggregate exposures resulting in a target tissue burden of ∼10-1 nmoles PYR/g may be toxicologically relevant, expanding the evidence on exposure-dose-effect relationships for PYRs, and serving to design convenient pharmacokinetic models for environmentally relevant exposures to PYR mixtures.