water according to the Vietnamese standard and theWHOguideline are
10 μg/L (Ministry of Health of Vietnam, 2002;WHO, 2004). Chakraborti
et al. (2003) reported that the concentration of drinking water
predicting arsenic skin lesions is 300 μg/L. In Ly Nhan, arsenic concentrations
in any of the groundwater samples (311 - 598 μg/L) exceeded
this threshold value; 86% of the wells at Hoai Duc did not meet the
criteria for drinking established by Vietnam (Ministry of Health of
Vietnam, 2002) andWHO(WHO, 2004) and 51% of thewells contained
arsenic at levels higher than 300 μg/L (Chakraborti et al., 2003). At Dan
Phuong, 69% and 38% of groundwater samples had higher arsenic concentrations
than the criteria of theWHO and Vietnam, and skin lesions,
respectively. These results suggest that groundwater arsenic contamination
is widely distributed in the Red River Delta and the high risk of
arsenic toxicity is of great concern for residents in this region.