CONICET | Buscador de Institutos y Recursos Humanos

The Chaco Pampean Plain of central Argentina constitutes one of the largest regions of high arsenic groundwaters known, covering around 1x106 km2. The high-As groundwaters are from Quaternary deposits of loess (mainly silt) with intermixed rhyolitic or dacitic volcanic ash. One of the most affected region is the province of Cordoba, where As concentrations that exceed the maximum level of 50 µg/L for drinking water have been reported. The southeast of Cordoba is an important milk production zone in Argentina, where dairy products consumption is up to 192 equivalent milk L/inhabitant/ year. As an excretion of the mammary gland, milk can carry numerous xenobiotic substances, which constitute a technological risk factor for dairy products and above all for the health of the consumer. Nevertheless no studies on the incidence of high-As livestock drinking water in livestock health and its transfer to milk have been performed in Argentina. The aim of the present study was the determination of arsenic content in livestock drinking water and milk from dairy farms located in an area of high arsenic groundwaters, to analyse the relation between As uptake through water and its transfer to milk. Groundwater is the main source of livestock drinking water. In 54 % of the analysed wells, the phreatic water was found between 3 and 8 m, with extreme depths of 2 and 15 m, while the remaining wells range in depth from around 80 to 150 m (deep wells). Arsenic concentration in all phreatic water samples was over the suggested level for occurrence of chronic intoxication in cattle (0.15 mg/L) and 53% of them showed higher values than those recommended for livestock drinking water (0.5 mg/L). Arsenic concentration in deep wells was under 0.15 mg/L. As milk content ranged from 2.8 to 10.5 ng/g for dairy farms using phreatic groundwater, while a mean value of 0.5 ng/g was obtained for farms using deep wells. In order to analyse the relation between As uptake through water and its transfer to milk, four farms (Holstein dairy cows) were selected. Two of these stablishments where medium size (100-120 dairy cows) and two were small (10-20 dairy cows). One medium size stablishment with As water concentration of 0.04 mg/L was also selected for comparison. If As water content is considered as the only exposure dosis of As to milk, assuming steady state conditions, a biotransfer factor (BTF) may be calculated as: concentration of As in milk (mg/L) / daily animal intake of As (mg/day). The values obtained ranged from 5.2 x 10-5 to 1.8 x 10-4. No significant differences were found between the five farms analyzed, where food is the same in all cases and one of them has very low As water content.

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