Arsenic drinking water maximum standard

Although not as widespread as arsenic, barium also occurs naturally in the environment in some areas. It can also enter water supplies through hazardous industrial waste discharges or releases. Small doses of barium are not harmful. However, it is quite dangerous when consumed in large quantities. The maximum amount of barium allowed in drinking water by the standard is 1.0 mg/L of water. 

Maximum contaminant levels (MCLs) Drinking water standards for various contaminants that are enforced by the United States Environmental Protection Agency (US EPA) that take into account the risks of human health effects and the costs of cleaning the water (Appendix E). The current MCL for arsenic is 10 pg E 1 (40 Code of Federal Regulations 141.62). 

A Fischer assay simulates the conversion of oil shale to usable fuels in an above-ground retort. The results of an extensive program of chemical analysis of major and trace elements in spent shale, oil, and water collected from the Fischer assay of a standard oil shale are presented. The concentration of major elements in raw and spent shale can be determined only to 10% in this study. Two criteria show that fluorine and zinc may have been mobilized during the assays. The concentrations of arsenic and selenium in the Fischer assay retort water exceed the maximum permissible concentrations for drinking water. 

In contrast to stream water, groundwater in the Warrior coalfield may have elevated arsenic concentrations. Waters produced during methane recovery from coal (n=28) were found to have a mean arsenic content of 25 ppb with a maximum of 475 ppb (O Neil et al., 1993). These production waters are typically saline and not potable. However, the presence of elevated arsenic in the deep groundwater samples indicates that arsenic may be mobilized from the coal into solution. Shallow drinking-water wells in the Warrior coalfield are lower in arsenic than the production waters, having a mean of 2 ppb and a maximum of 44 ppb (n=35)(0 Neil et al., 1993). The highest of these arsenic contents exceed the present drinking water standard and indicate the potential for at least isolated arsenic contamination. 

The arsenic allowed under the EPA s proposed drinking water standard is a maximum of 10 ppb. 

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