Boletín de la RSEHN. Sección Biológica

El consumo de aguas contaminadas con arsénico (As) produce la acumulación de este en los tejidos, provocando daños en los organismos que se encuentran expuestos a él. El objetivo de nuestro trabajo es conocer qué cantidades de As pueden llegar a acumularse en los tejidos y cómo se distribuyen en el organismo tras el consumo directo de aguas contaminadas, o indirecto, a través de la placenta y la leche materna; así como la influencia que la administración de un suplemento vitamínico tendría sobre la bioacumulación del compuesto.

Para ello, tomamos dos grupos de ratas Wistar gestantes, cuya agua de bebida fue contaminada con arsenito sódico en una dosis de 50 ppm o con una mezcla de arsénico y el suplemento vitamínico (vitamina C, E y zinc). Al final de la lactancia, se extrajeron los órganos y se cuantificó la cantidad de As acumulado utilizando un método colorimétrico basado en el protocolo de Gutzeit (Merck).

Según los resultados obtenidos, la bioacumulación de As es significativamente mayor en las madres; en cuanto a su distribución, parece tener una clara preferencia por el bazo, frente a hígado, riñón y cerebro. Por último, el suplemento vitamínico administrado a las madres parece ser el responsable de una disminución del 30% en la cantidad de As acumulado.

Arsenic (As) is a metalloid widely distributed worldwide. This element appears in rocks of the Earth´s crust, where it passes to groundwater depending on changes in pH, oxygen concentration and temperature of the water percolating through the ground. The use of this water results in the accumulation of As in plant and animal tissues, entering in the food chain and causing damage to the organisms that are exposed to it. In humans, consumption of this water is associated with the appearance of certain types of cancer, cardiovascular and metabolic diseases and nervous system and reproductive function disorders.

The aim of our study was to determine what amount of As may be accumulated in tissues after consumption of contaminated water directly, or indirectly through the placenta and breast milk, and investigate the influence that vitamin supplementation would have on the bioaccumulation of this element. For this purpose, we polluted the drinking water of pregnant Wistar rats with sodium arsenite at a dose of 50 mg / l during the period of gestation and lactation. The other group, in addition of the dose of arsenic, has been administered an antioxidant supplement consisting of vitamin C (2000 mg/l), vitamin E (500 mg/l) and zinc (20 mg/l).

At the end of lactation (postnatal day 21), the organs were dissected: liver and spleen of mothers, and liver, spleen, kidney and brain of the pups. These organs were mineralized by dry digestion; they were maintained at 600- 650 °C until were reduced to ashes. These ashes were resuspended in 10% sulfuric acid for the quantification of arsenic using a colorimetric method based on the Gutzeit protocol (Merck).

According to the results obtained, about the distribution of arsenic in the body of the pups, we observed that the arsenic tends to accumulate preferentially in the spleen compared to the organs of the study (Fig. 3). This result could be explained on the basis of the capacity of this element to bind itself to red blood cells, and the spleen being the primary organ of clearance of the latter.

On another note, the bioaccumulation of As is significantly higher in mothers than in pups (Fig. 1), which shows only 10-20% of the total accumulated by their mothers; a possible explanation is that the pups have only received As through the placenta and during the 21 days of lactation excreted part of the arsenic accumulated.

Finally, the antioxidants administered to mothers seems to be responsible for a 30% decrease in the amount of As accumulated in comparison to the mother who only received arsenic in drinking water (Fig. 2). This result suggests that the antioxidants we have administered have a barrier effect on the absorption of arsenic and they could facilitate its metabolism and excretion, thus reducing the levels of this toxic in the organism.