Some toxic metals (Al, As, Mo, Hg) from cow's milk raised in a possibly contaminated area by different sources.

Milk can be considered as an indicator of the degree of environmental contamination of the place where it is produced and this is especially important when assessing its content in toxic metals. Therefore, 36 bovine milk samples from 7 farms with a semi-extensive grazing system were analysed, located in Asturias (Spain), in an area with high probability of being highly contaminated due to a mining zone, with important industrial activity and near high-density highway traffic. The samples were lyophilised to achieve total dehydration, further analysed using inductively coupled plasma mass spectrometry (ICP-MS). The metals titrated were aluminium (Al), arsenic (As), molybdenum (Mo) and mercury (Hg) in the lyophilised samples and subsequently extrapolated their values to whole milk. All samples analysed showed levels of Al and Mo above the limit of detection, with mean values of Al of 140.89 ± 157.07 in liquid milk and 1065.76 ± 1073.45 in lyophilised milk and Mo of 20.72 ± 14.61 µg/kg and 152.26 ± 96.82 µg/kg in whole and lyophilised milk. Only As was detected in four samples with mean values of 18.45 ± 6.89 and 166.45 ± 42.30 µg/kg in liquid and lyophilised milk, respectively, and no Hg was found in any of them. In no case do the values found indicate a significant hazard to the population and are in agreement with those found in other investigations. Although the various anthropogenic activities of the area (industrial, mining, traffic density) could, a priori, indicate a possibly contaminated area.

Cadmium and lead in bovine milk in the mining area of the Caudal River (Spain).

The levels of cadmium and lead in 36 raw bovine milk samples were analysed. These samples come from seven farms with a semi-extensive grazing system and were collected between the autumn of 2007 and the winter of 2008. All the farms were located in Asturias (Spain), a zone of great industrial and mining activity in the proximities of the Caudal River. The samples were collected in sterile precleaned polypropylene tubes and frozen until the analysis. After a lyophilization process, the samples were treated with nitric acid and microwave treatment. Cadmium and lead determinations were carried out using inductively coupled plasma mass spectrometry with sensibility under 0.2 ppb for liquid matrix. The lead content was found to vary from 0.71 to 16.06 µg/kg wet weight (w.w.), and the cadmium was lower than 2 µg/kg w.w. The levels of lead in milk are higher in those farms near zones of storage of mining waste depots, thermal power and areas with high levels of traffic. All the values found are in concordance with research carried out at non-polluted areas, and those for the lead are well below the European Union limitations.