title: The oxidation states of arsenic in well-water from a chronic arsenicism area of northern Mexico.
abstract: Aquifers in the Región Lagunera in northern Mexico are heavily contaminated with arsenic. The range of total arsenic concentrations in 128 water samples analyzed was 0.008 to 0.624 mg litre(-1), and concentrations greater than 0.05 mg litre(-1) were found in 50% of them. Approximately 400 000 people living in rural areas were exposed to high As concentrations. Most of the As was in inorganic form and pentavalent arsenic [As(V)] was the predominant species in 93% of the samples. In 36% of the samples, however, variable percentages (20-50) of trivalent As [As(III)] were found. Organic arsenicals were present in very small amounts. Since As(III) is several times more toxic than As(V), we suggest that periodic studies be performed on the As(III)/As(V) ratio in wells whose total As concentrations are above 0.05 mg litre(-1), in combination with epidemiological studies to evaluate possible differences in health effects produced by different As species.
authors.affiliation: Departmento de Farmacologia y Toxicologia, CINVESTAV-IPIN, AP 14-740, Mexico, DF 07000, Mexico.
authors.forename: L M
authors.initials: LM
authors.lastname: Del Razo
authors.forename: M A
authors.initials: MA
authors.lastname: Arellano
authors.forename: M E
authors.initials: ME
authors.lastname: Cebrián