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Arsenic in irrigation water is transferred to crops

A team of researchers from the University of Valladolid (UVA) and the Salamanca Institute of Natural Resources and Agrobiology (IRNASA-CSIC) has shown that potatoes irrigated with arsenic-rich water contain this element at levels up to 35 times higher than crops on which this water was not used. The scientists have also confirmed the impact of water with high arsenic content on beet, carrot and wheat crops.

The results show that arsenic levels, both in the ground (which reached levels of up to 36 milligrams/kg) and in the plants, were higher in the sites irrigated with water containing higher levels of this element in comparison to those in the control areas. The levels of dissolved arsenic in water reached 0.9 mg/kg in some samples, which is in excess of the 0.04 mg/kg limit set for agricultural use.

The scientists found arsenic levels in the potatoes to be 35 times higher in the crops irrigated with arsenic-laden water, while they also reached high concentrations in the beets (between 3.9 and 5.4 mg/kg).

Arsenic is a natural chemical element that may or may not be toxic to human beings depending upon the dose consumed and its origin. Arsenic combines with carbon and hydrogen in living beings to form organic arsenic compounds, which in general are not harmful. In the environment, however, this substance combines with oxygen, chlorine and sulphur, forming inorganic arsenic compounds, which are considered to be more toxic.

The maximum level of arsenic permitted in water for human consumption in Spain and the rest of the European Union is 0.01 mg/l, and the World Health Organisation (WHO) recommends this figure should not be exceeded. Levels of more than 0.05 milligrams of arsenic per litre of water (irrigation water rather than that for human consumption) were detected in all the sites analysed in this study, with levels at some sites reaching 0.136 mg/l.

by S. C.
22 may 2009, Technical Area > Science News