Submitted to: Arsenic Exposure and Health Effects International Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: July 14, 2002
Publication Date: July 14, 2002
Technical Abstract: As is a natural constituent of soils and plants. The low soil As limit suggested by some (3.0 mg As/kg soil) is below natural background levels in US soils; thus validity of such limits is being questioned. Background As levels in US soils are 5-10 mg/kg, with range exceeding 20 mg/kg for acid sulfate soils; background As exceeds suggested soil As limits. Extensive contamination of soils with As by historic agricultural uses (orchard, cotton, and potato soils; tick treatment soils), mining, smelting, and the extensive use of Cr-Cu-As-treated lumber, indicate that over 50% of US surface soils would need to be replaced. It seems irrational to conclude that median background soils are causing human As risk thru soil ingestion. Rice accumulates As well compared to most plant foods. Rice accumulation of As from soils irrigated with As-rich water over decades was not increased in either As-sensitive or -resistant rice cultivars in a collaborative field test in Bulgaria indicating lower potential food-chain As risk than some suggest. Soil ingestion comprises greater risk than eating garden foods. The assumptions in soil As risk assessment are known to be faulty; one assumes that children consume soil at the rate of a 2-year-old child for one's lifetime; adjustment of risk estimates is needed for short term exposure of children by soil ingestion. Raised urinary As in children exposed to As in soil and dust found that soil As had to exceed 40-100 mg As/kg before there was a significant increase in urinary As from inorganic sources, suggesting that soil As would have to exceed this level before any increase in absorbed As would occur.