Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: April 15, 2011
Publication Date: September 23, 2011
Citation: Codling, E.E. 2011. Environmental impact and remediation of residual lead and arsenic pesticides in soil. Book Chapter. 9:169-180.
Lead arsenate (PbHAsO4) was used as a pesticide for over 50 years in orchards throughout the world, and residual lead and arsenic have been found in high concentrations in these orchard soils long after the pesticide use ended. These high concentrations of lead and arsenic may create a potential risk to public health when orchard lands are converted to other uses. Young children are especially at risk because of their unintentional consumption of soil. Children exposed to lead may develop neurobehavioral impairment, while arsenic is a human carcinogen. Humans can also be exposed indirectly to lead and arsenic through the consumption of vegetable crops grown on contaminated soils, although the bioavailability of lead and arsenic in vegetable crops consumed by human and animals is not known. Because hundreds of thousands of acres have been contaminated with PbHAsO4, removal of contaminated soil and replacement with clean surface soil is not economically feasible. Chemical in situ treatment with phosphorus, although effective in sequestering soil lead from other sources, has been shown to increase the leaching of arsenic this potentially may reach ground water in PbHAsO4-contaminated soils. Application of iron oxide has been shown to be effective in sequestering arsenic in PbHAsO4-contaminated orchard soils. Using plants to remove metals from contaminated soil (phytoremediation) is a method that is being considered for removing lead and arsenic from soils, but even if lead and arsenic accumulating plants are identified, this method may be too slow to be practical. Presently, each state has its own guidelines on the utilization of lead and arsenic contaminated orchard soils. However, with the increasing conversion of old orchard land to residential development or to other agricultural uses, a national effort is needed to prevent excessive human exposure to lead and arsenic.