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

Tetrachloroethylene Toxicity
What Are the Standards for Tetrachloroethylene Exposure?

Learning Objectives

Upon completion of this section, you will be able to

• identify the Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for tetrachloroethylene and
• identify the U.S. Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) for tetrachloroethylenein drinking water.

Introduction

Government regulations and standards have been developed for tetrachloroethylene. These are designed to protect the public and workers from potential adverse health effects.

Workplace Standards

OSHA has established a PEL in workplace air of 100 ppm measured as an 8-hour TWA (Table 1).

NIOSH recommends that tetrachloroethylene be treated in the workplace as a potential human carcinogen and that occupational exposure be reduced to the lowest feasible level (Agency for Toxic Substances and Disease Registry 1997).

The American Conference of Governmental Industrial Hygienists (ACGIH)(American Conference of Governmental Industrial Hygienists. 2001) recommends a threshold limit value (TLV) of 25 ppm and an 8-hour TLV/TWA of 100 ppm. ACGIH has also established the following biologic exposure indices (BEIs)

• 10 ppm tetrachloroethylene in end-exhaled air, sample collected before the last shift of the workweek,
• 1 mg/L tetrachloroethylene in blood, specimen collected before the last shift of the workweek, and
• 7 mg/L trichloroacetic acid in urine, specimen collected at end of the workweek

A BEI is a recommended “warning level,” not an absolute threshold. It may be underprotective or overprotective, depending on individual susceptibility, body habits, level of activity, and concomitant exposures.

Environmental Standards

Air

EPA intends to propose air emission standards for tetrachloroethylene, but such standards have not yet been promulgated.

Water

The current EPA drinking water regulation for tetrachloroethylene is 5 ppb.

American Conference of Governmental Industrial Hygienists

Air: workplace

25 ppm

Advisory; TLV/TWA^† STEL^‡ of 100 ppm

National Institute for Occupational Safety and Health

Air: workplace

Not available

Advisory; lowest feasible level because of carcinogenicity

Occupational Safety and Health Administration

Air: workplace

100 ppm

Regulation; PEL^§ over an 8-hour workday

U.S. Environmental Protection Agency

Air: environment

None

Listed as a hazardous air pollutant under Section 112 of the Clean Air Act

Water: environment

5 ppb

Regulation; maximum level allowed in drinking water

^*ppm: parts per million; ppb: parts per billion.

^†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 exposed.

^‡STEL (short-term exposure limit): usually a 15-minute sampling period.

^§PEL (permissible exposure limit): highest level, averaged over a normal workday, to which a worker may be exposed.

Key Points

• EPA has established a drinking water maximum contaminant level (MCL) for tetrachloroethylene of 5 ppb (US Environmental Protection Agency 1986).
• The current OSHA’s 8-hour TWA for tetrachloroethylene is 100 ppm.
• NIOSH considers tetrachloroethylene a potential carcinogen and recommends exposure in the workplace be reduced to the lowest possible level.

Progress Check