The Occupational Safety and Health Administration (OSHA) mandates permissible limits for occupational exposures. The permissible exposure limit (PEL) for arsenic is set at 10 micrograms of inorganic arsenic per cubic meter of air (10 µg/m³), averaged over any 8-hour period for a 40-hour workweek. The recommended exposure limit (REL) set by the National Institute for Occupational Safety and Health (NIOSH), is 2 µg/m³ for a 15-minute ceiling, based on classification of arsenic as a potential human carcinogen (Table 1).

Table 1. Standards and Regulations for Inorganic Arsenic

Agency	Focus	Level	Comments
American Conference of Governmental Industrial Hygienists	Air: workplace	10 µg/m³*	Advisory; TLV/TWA⁺
National Institute for Occupational Safety and Health	Air: workplace	2 µg/m³	Advisory; 15-minute ceiling limit
Occupational Safety and Health Administration	Air: workplace	10 µg/m³	Regulation; PEL⁺⁺over 8-hour day
U.S. Environmental Protection Agency	Air: environment	Not applicable	Not applicable
U.S. Environmental Protection Agency	Water	10 ppb	Regulation; maximum contaminant level in drinking water
Food and Drug Administration	Food	0.5-2 ppm	Regulation; applies to animals treated with veterinary drugs
*µg/m³: micrograms per cubic meter; ppb: parts per billion; ppm: parts per million. ⁺TLV/TWA (threshold limit value/time-weighted average): time-weighted average concentration for a normal 8-hour workday or 40-hour workweek to which nearly all workers may be repeatedly exposed. ⁺⁺PEL (permissible exposure limit): highest level averaged, over an 8-hour workday, to which a worker may be exposed.

Environment

Air

EPA limits emissions from copper smelters, glass-manufacturing plants, and other arsenic-using facilities; however, no ambient air standard for arsenic exists.

Arsenic is listed by EPA, under authorization of the Clean Air Act, as a hazardous air pollutant (defined as a substance that may cause an increased mortality or serious illness in humans after significant exposure). In 1986, EPA promulgated the National Emissions Standards for Hazardous Air Pollutants for three stationary source categories known to emit inorganic arsenic: primary copper smelters, glass-manufacturing plants, and arsenic plants. However, there is no ambient air standard for arsenic.

Drinking Water

EPA has set 10 ppb as the allowable level for arsenic in drinking water.

The EPA Office of Drinking Water has set a maximum contaminant level (MCL) for arsenic in drinking water of 10 ppb. The World Health Organization recommends a provisional drinking water guideline of 10 ppb.

Food

FDA currently has no tolerance levels for arsenic in food, except for the by-products of animals treated with veterinary drugs.

The U.S. Food and Drug Administration (FDA) has established tolerance levels for arsenic in by-products of animals treated with veterinary drugs. These permissible levels range from 0.5 ppm in eggs and uncooked edible tissues of chickens and turkeys to 2 ppm in certain uncooked edible by-products of swine.

Pesticides

In 1989, household ant killers containing sodium arsenate were banned because of danger of ingestion by small children.

In 1989, EPA began to phase out household ant poisons containing sodium arsenate because of the danger of ingestion by small children. The EPA Office of Pesticide Programs has restricted the use of inorganic arsenic to pressure-treated wood. It has also cancelled all registered uses of inorganic arsenic for nonwood preservative purposes.

Challenge

Would it be important to notify authorities about the patient described in the case study? Why?

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Revised 2000-10-30.

Agency for Toxic Substances and Disease Registry Case Studies in Environmental Medicine (CSEM) Arsenic Toxicity Standards and Regulations

Table 1. Standards and Regulations for Inorganic Arsenic

Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM)

Arsenic Toxicity
Standards and Regulations