The workplace air standards mandated by the Occupational Safety and Health Administration (OSHA) include an 8-hour time-weighted average (TWA) of 200 ppm. The National Institute for Occupational Safety and Health (NIOSH) recommends a TWA of 100 ppm and a STEL of 150 ppm. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends a 8 hour TWA threshold limit value of 50 ppm.
The federal government has not established specific standards for toluene in ambient air. At least 10 states have guidelines or standards for acceptable ambient air concentrations of toluene.
Water
As of July 30, 1992, the U.S. Environmental Protection Agency (EPA) instituted a maximum contaminant level of 1 ppm (1.0 milligrams per liter [mg/L]) for toluene in drinking water. Approximately 10 states have drinking water standards or guidelines for toluene ranging from 0.1 to 2 ppm.
Biologic Standards
Biological exposure indices (BEI) are reference values established by ACGIH that are intended as guidelines for evaluating potential exposure hazards in the workplace. The BEI for the urinary metabolite of toluene (hippuric acid) is 2.5 g/g creatinine; the sample is collected at the end of the work shift. Hippuric acid is also a metabolite of other aromatic solvents and certain endogenous agents; therefore, it is not specific to toluene. The BEI for toluene in venous blood, collected at the end of the work shift, is 1.0 mg/L, whereas the toluene index in end-exhaled air (thecols residual air in the lungs after the person has exhaled normally), measured during the work shift, is 20 ppm. These biologic standards are useful as confirmatory tests for the effectiveness of workplace industrial hygiene practices, but are not useful for comparison purposes in cases of acute exposure.
American Conference of Governmental Industrial Hygienists
Air: workplace
50 ppm (375 mg/m3)
Advisory; TLV-TWA†
National Institute for Occupational Safety and Health
Air: workplace
100 ppm (375 mg/m3)
150 ppm (560 mg/m3)
Advisory; TWA STEL‡
Occupational Safety and Health Administration
Air: workplace
200 ppm (375 mg/m3)
Regulation; PEL§ as TWA
U.S. Environmental Protection Agency
Drinking water
1 ppm (mg/L)
Regulation; MCL¶
Health advisories
20 ppm (mg/L)
1 day (10-kg child)
2 ppm (mg/L)
10 day (10-kg child)
Longer term
2 ppm (mg/L)
Child
7 ppm (mg/L)
Adult
1 ppm (mg/L)
Lifetime Adult
*ppm: parts per million; mg/m3: milligrams per cubic meter; mg/L: milligrams per liter.
†TLV-TWA (threshold limit value time-weighted average): time-weighted average concentration for a normal workday and a 40-hour workweek to which nearly all workers may be repeatedly exposed.
‡STEL (short-term exposure limit): maximum level allowed in any 15-minute sampling period.
§PEL (permissible exposure limit): highest level in air to which a worker may be exposed, averaged over an 8-hour workday.
¶MCL (maximum contaminant level): enforceable level for drinking water.
Disclaimer