Arsenic

Policy and Guidance

EPA regulates arsenic and its compounds under a variety of statutes that include the Clean Air Act; Clean Water Act; Safe Drinking Water Act; Resource Conservation and Recovery Act; Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA); Superfund Amendments and Reauthorization Act; and the Federal Insecticide, Fungicide, and Rodenticide Act. Besides directly regulating arsenic and its compounds in different industrial and environmental settings, the main impact of these statutes on CERCLA activities is the requirement under the National Oil and Hazardous Substances Pollution Contingency Plan (NCP) to consider them as potential applicable or relevant and appropriate requirements (frequently referred to as ARARs).

Clean Air Act. Under 40 CFR 61, National Emission Standards for Hazardous Air Pollutants, arsenic is designated a hazardous air pollutant. An air emissions permit obtained for thermal desorption and destruction of a co-contaminating organic constituent would also have to address the potential for the vaporization of arsenic from the soil.

Clean Water Act (CWA). A number of arsenic compounds have been designated as hazardous substances by regulations (40 CFR 116, Designation of Hazardous Substances) promulgated under the CWA. These compounds have been assigned reportable quantities under 40 CFR 117. The list of hazardous substances and their reportable quantities developed under CERCLA (40 CFR 302) incorporated those developed under the CWA. 40 CFR 131 provides for the development of water quality standards for each water body in the country. The standards are usually developed by the state and are directly applicable to Superfund cleanups that involve surface waters. The National Recommended Water Quality Criteria provides a list of current federally recommended criteria for the protection of aquatic life and human health in surface water. Though old, Ambient Water Quality Criteria for Arsenic (10.6MB/213pp/PDF) provides a good background reference. When conducting a cleanup action, the state regulations should be consulted to determine those criteria. Finally, the Clean Water Act creates the National Pollutant Elimination System (40 CFR 125), which governs the point-source discharge of chemicals into surface water bodies. Any cleanup action taken at a site that involves the discharge of treated water to a surface water body should comply with the state discharge regulations for that specific water body with regard to arsenic and any other regulated material that might remain in the effluent after treatment.

Safe Drinking Water Act. The Safe Drinking Water Act provides for the setting of maximum contaminant levels (MCLs) for chemicals found to be hazardous and in the water supply (40 CFR 141). The NCP, which is the implementing document for Superfund, specifically names MCLs as Superfund ARARs. The federal MCL for arsenic was changed to 10 micrograms per liter (µg/L) on January 22, 2001, and public drinking water systems must comply with this number by January 23, 2006. General drinking water standards and policies are available on the EPA website. Note that state drinking water standards are also ARARs and can be different from the federal standards. For example, California has developed a public health goal of 4 parts per trillion for arsenic, and this health goal will be used to develop a California MCL that may be different from the federal MCL. The Safe Drinking Water Act also regulates the injection of fluids into the ground (40 CFR 144). The program is usually administered by the states, and permission is generally required to return treated water to an aquifer or apply in situ chemical oxidation or flushing.

Resource Conservation and Recovery Act (RCRA). RCRA governs the treatment, storage, and disposal of chemicals or process wastes that have been designated by the government to be hazardous. There are some 10 waste or process waste streams that are specifically named (40 CFR 261.31 and 40 CFR 261.32) as hazardous under RCRA because of potential arsenic content. In addition, any material that contains arsenic that will leach 5 mg/L total arsenic under the Toxicity Characteristic Leaching Procedure (40 CFR 261.24) is considered a characteristic RCRA hazardous waste. These sections of RCRA are Superfund ARARs and have the potential to govern on-site treatment requirements and offsite disposal of arsenic-containing wastes and soils.

Comprehensive Environmental Response, Compensation, and Liability Act. CERCLA, as amended, requires the reporting of accidental spills of hazardous substances. Arsenic and arsenic-containing compounds are listed as hazardous substances with reportable quantities. Many of these quantities are adopted from 40 CFR 302.4 of the CWA. The Emergency Planning and Community Right-to-Know Act of 1986 contains a citizen's right-to-know section that requires manufacturers who handle hazardous substances to report any release of these substances to the environment. In many cases, these releases involve fugitive emissions and permitted releases, such as discharge permits issued under the CWA. EPA keeps the information gathered by this requirement in its Toxics Release Inventory Program database. Data on arsenic and arsenic compounds released by any facility can be found in the database. The NCP contains provisions that require EPA to conduct risk assessments to determine appropriate cleanup levels for hazardous substances (including arsenic and arsenic compounds) and to take into account any other law or regulation that may be an ARAR, or other information or guidance that needs to be considered. Because arsenic and its compounds are directly regulated by several other acts, there generally will be ARARs that affect arsenic cleanup under CERCLA.

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). FIFRA licenses and regulates the use and application of pesticides. Historically, arsenic has been used in agricultural applications to control insects on fruit trees, as a cotton defoliant and weed control agent, as a rat poison, and as a component of wood treating compounds. Its use has been declining in most applications as equally effective but less persistent pesticides are developed and applied and EPA restricts the licensing of arsenic-containing compounds.

An ecological soil screening guidance (1.7MB/128pp/PDF) specific to arsenic was published in 2005. The general soil screening guidance is useful for estimating cleanup levels at specific sites that have arsenic contamination relevant to human health. Also, the Regional Screening Levels (RSLs) website provides some guidance on arsenic cleanup levels for various land use scenarios.

For Further Information

Ambient Water Quality Criteria for Arsenic
U.S. EPA, Office of Water.
EPA 440-5-80-021, 213 pp, 1980.

Arsenic and Clarifications to Compliance and New Source Monitoring Rule: a Quick Reference Guide
U.S. EPA, Office of Water.
EPA-816-F-01-004, 2 pp, Jan 2001
Contact: Safe Drinking Water Hotline, hotline-sdwa@epa.gov

Chromated Copper Arsenate (CCA)
U.S. EPA, Office of Pesticide Programs.
Contact: Susan Laing, laing.susan@epa.gov

This CCA page provides guidance and information on its use, alternatives, and risks.

Compilation and Review of Data on Relative Bioavailability of Arsenic in Soil
U.S. EPA, OSWER 9200.1-113, 58 pp, 2012

EPA evaluated literature relevant to estimating a relative bioavailability (RBA) value of arsenic in soil and reached the following conclusions: (1) Currently available research information suggests that an RBA of arsenic in soils can be expected to be less than 100%; (2) the upper percentile of U.S. data gives a default RBA arsenic in soil value of 60%; and (3) the default RBA for arsenic in soils should be used only if site-specific assessments for arsenic RBA are not feasible. See also the Recommendations for Default Value for Relative Bioavailability of Arsenic in Soil and separate reports on relative bioavailability of arsenic in specific soil types at the bottom of the bioavailability Web page.

Guidance for Developing Ecological Soil Screening Levels, Interim Final
U.S. EPA, Office of Emergency and Remedial Response.
OSWER Directive 9285.7-55, 128 pp, 2005.
Contact: Stephen J. Ells, ells.steve@epa.gov

Implementation Guidance for the Arsenic Rule: Drinking Water Regulations for Arsenic and Clarifications to Compliance and New Source Contaminants Monitoring
U.S. Environmental Protection Agency, Office of Water
EPA-816-K-02-018, 83 pp, 2002
Contact: Safe Drinking Water Hotline, hotline-sdwa@epa.gov

Guidance for Arsenic in Soil
Policy Memo 00-01, Rhode Island Department of Environmental Management, 2000

National Primary Drinking Water Regulations; Arsenic and Clarifications to Compliance and New Source Contaminants Monitoring
Federal Register, Vol. 66, No. 14, p 6975-7066, 22 Jan 2001
Contact: Safe Drinking Water Hotline, hotline-sdwa@epa.gov

The Scenarios Approach to Attenuation-Based Remedies for Inorganic and Radionuclide Contaminants
Truex, M., P. Brady, C. Newell, M. Rysz, M. Denham, and K. Vangelas.
SRNL-STI-2011-00459, 111 pp, Aug 2011

This document was developed as a technical resource to guide interested parties through the process of evaluating attenuation-based remedies for sites contaminated with inorganic or radionuclide contaminants. The six scenarios are based on aquifer geochemical properties: oxidation-reduction potential, cation exchange capacity, and ferric iron oxide content. Section 1 steps the reader through using the scenarios approach, including how to choose a scenario, the parameters on which the scenarios are based, and worksheets to organize data. Section 2 discusses specific attenuation processes affecting contaminant mobility, shows how to use a scenario to develop a site conceptual model, discusses how to apply MNA and EA to specific scenarios, and ties the scenarios approach to U.S. EPA's four tiers of evidence for demonstrating MNA. Section 3 provides detail on attenuation mechanisms and development of conceptual models, discusses the EPA four-tiered approach in more detail, and includes additional information on geochemical reactions, monitoring, remediation, and costs. Appendix B contains a synopsis of mercury chemistry.

Study of State Soil Arsenic Regulations
L. Baldwin and H. McCreary
Association for the Environmental Health of Soils, 40 pp, 1998.

Soil Screening Guidance: A User's Guide
U.S. EPA, Office of Solid Waste and Emergency Response.
EPA 540/R-96/018, OSWER Directive 9355.4-23, 49 pp, 1996
Contact: David Cooper, cooper.davide@epa.gov

Attachments A-D

Supplemental Guidance for Developing Soil Screening Levels for Superfund Sites
U.S. EPA, Office of Emergency and Remedial Response.
OSWER Directive 9355.4-24, 106 pp, 2002.
Contact: David Cooper, cooper.davide@epa.gov

Attachments A through C

Web Sites

U.S. EPA, Office of Water, Arsenic in Drinking Water Web Site