Introduction

The earliest evidence of asbestos-associated disease in workers was found in the 1930s by British studies [Lee and Selikoff 1979]. We now know that the toxic effects of asbestos depend on the nature and extent of exposure, particularly on the:

• Concentration of asbestos fibers involved in the exposure,
• Duration of exposure,
• Frequency of exposure,
• Type of asbestos fibers involved in the exposure, and
• Dimensions and durability of the asbestos fibers.

The Center for Disease Control and Prevention/National Institute for Occupational Safety and Health (NIOSH) and OSHA began establishing standards for asbestos in the 1970s. U.S. regulatory agencies such as EPA and OSHA recognize six asbestos and asbestiform minerals, i.e.,

• Actinolite asbestos,
• Amosite asbestos,
• Anthophyllite asbestos,
• Chrysotile asbestos,
• Crocidolite, and
• Tremolite asbestos

Asbestiform minerals are defined as crystal aggregates displaying these characteristics: groups of separable, long, thin, strong, and flexible fibers arranged in parallel [ATSDR 2001a].

Currently there is discussion underway to include asbestiform minerals that may have similar health effects to the previously mentioned forms of asbestos as regulated substances. However, nothing has been finalized at this time [OSHA 1992; NIOSH 2011a].

Currently, there are standards for asbestos in

• Drinking water,
• Schools,
• Some consumer products, and
• Workplace air.

Occupational Standards

In 1986, OSHA in Standard 29 CFR 1910.1001 established the current permissible exposure limit (PEL) for asbestos in the workplace: (0.1 fibers/cc of air as a time weighed average) [OSHA 2012]. PELs are allowable exposure levels in workplace air averaged over an 8-hour shift of a 40 hour workweek. There are also OSHA standards (29 CFR 1915.1001) for shipyards and construction (1926.1101).

Additionally, OSHA standards (1915.1001 and 1926.1101) requires employers of all workers whose work exposes them to asbestos above the PEL or excursion limit (1.0 f/cc over 30-minute period) to

• Provide training in the engineering controls, work practices, and proper use of personal protective equipment (PPE),
• Train workers in safety before beginning work and annually,
• Train workers regarding the health effects of asbestos exposure, and
• Inform workers of the relationship between smoking, asbestos exposure and increased risk of lung cancer.

In addition, OSHA requires employers of workers who are exposed to asbestos above the PEL and who are employed in certain asbestos industries to

• Provide and make sure of correct use of PPE (respirators, protective clothing like coveralls and goggles),
• To undergo medical surveillance in order to identify those with signs of asbestos-associated disease, remove them from further exposure,
• Comply with regulations requiring documentation for work-related injury claims, and
• Provide information to workers about where they can go for help to stop smoking.

Components of the required medical surveillance include

• Chest radiograph,
• Physical examination,
• Spirometric test, and
• Standard questionnaire.

Further information about OSHA requirements is available at http://www.osha.gov/SLTC/asbestos/standards.html.

For further information about protection guidelines, contact NIOSH via 1-800-CDC-INFO or via http://www.cdc.gov/niosh/contact/.

Environmental Standards

ATSDR does not consider the use of OSHA's PEL for workplace exposures to be appropriate for environmentally exposed populations since residential and/or environmental exposures are 24 hours a day year round, much longer than the typical 8-hour day and 40-hour workweek exposures of workers. Children and the elderly, who are not typically exposed in the workplace, may be more susceptible to exposure.

EPA has established a maximum contaminant level (MCL) for asbestos in drinking water of 7 MFL (million fibers per liter > 10 µm in length) in drinking water [EPA 2011]. Asbestos in drinking water comes from two main sources:

1. Decay of water mains constructed of asbestos-containing cement, and
2. Erosions of naturally occurring asbestos deposits into watersheds [EPA 2012a].

In addition, EPA has

• Banned spraying of asbestos in building interiors (for fireproofing and ceilings),
• Developed guidelines for proper treatment of in-place asbestos in old buildings,
• Recommended "no visible emissions" of asbestos,
• Regulated demolition of buildings with asbestos (NESHAP rules), and
• Regulated uses of asbestos in industrial products and construction.

More information on EPA rules and regulations regarding asbestos is available at
http://www2.epa.gov/asbestos/asbestos-laws-and-regulations

Schools

The Asbestos Hazard Emergency Response Act of 1982 (CFR 40, Part 763, Subpart E) requires that local education agencies

• Inspect schools for asbestos-containing material using certified inspectors,
• Analyze these materials for asbestos content,
• Post results and notify parents and employees if asbestos is found,
• Test air levels following clean-up,
• Develop appropriate management plans,
• Communicate openly about any asbestos abatement needed, and
• Maintain appropriate records [EPA 2012c].

EPA also warned school authorities that power buffing and power stripping of asbestos-tile floors in schools produces significant airborne asbestos levels. Floor maintenance must be performed by hand to prevent release of asbestos fibers.

Progress Check