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Carbon Tetrachloride Toxicity
What Are Guidelines and Regulations for Carbon Tetrachloride Exposure?

Course: WB2888
CE Original Date: December 31, 2017
CE Expiration Date: December 31, 2019
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Learning Objectives

After completing this section, you will be able to

  • Describe current U.S. guidelines and regulations for carbon tetrachloride (CCl4) exposure.

Introduction

The U.S. government has developed regulations and guidelines for CCl4. These are designed to protect workers and the U.S. public from potential adverse health effects from CCl4 exposure. Table 1 summarizes the regulations and guidelines pertaining to CCl4.

*Note: At the time of publication of this CSEM, the listed guidelines and regulations were up to date. Guidelines and regulations are subject to change. For the most up-to-date information, see the following websites:

Workplace Standards

Air

The Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) is an 8-hour time-weighted average (TWA) of 10 parts per million (ppm) in workplace air. This is the highest level of CCl4 in air to which a worker may be exposed, averaged over an 8-hour workday for up to a 40-hour workweek.

The National Institute for Occupational Safety and Health (NIOSH) recommends a 60-minute time-weighted average (TWA) short-term exposure limit (STEL) of 2 ppm [NIOSH 2005]. The NIOSH immediately dangerous to life and health (IDLH) value for CCl4 is 200 ppm.

The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an 8-hour TWA of 5 ppm and a 15-minute STEL of 10 ppm [ACGIH 2017].

Environmental Standards

Air

CCl4 is on the list of 187 hazardous air pollutants listed in the Clean Air Act. The U.S. Environmental Protection Agency (EPA) classifies CCl4 as a hazardous air pollutant [EPA 2014].

Water

The EPA maximum contaminant level (MCL) for CCl4 in drinking water is 5 ppb [EPA 2008].

Federal regulations have banned the use of all pesticide products containing CCl4. An exception is the use of CCl4 on encased museum specimens.

Food

The U.S. Food and Drug Administration (FDA) classifies carbon tetrachloride as an indirect food additive for use only as a component of adhesives. FDA also monitors bottled water and uses a level of 5 μg/L as acceptable for bottled water [FDA, 2017].

Table 1. Regulations and Guidelines for Carbon Tetrachloride

Agency Focus Level Comments
American Conference of Governmental Industrial Hygienists (ACGIH) Workplace air 5 ppm (31 mg/m3) Advisory: 8-hour TLV- TWA* 10 ppm (63 mg/m3) = 15-minute TWA STEL; skin absorption notation
National Institute for Occupational Safety and Health (NIOSH) Workplace air 2 ppm (12.6 mg/m3) Advisory: REL (60-minute STEL†)
Occupational Safety and Health Administration (OSHA) Workplace air 10 ppm Regulation: PEL§ as 8-hour TWA; 25 ppm = acceptable ceiling concentration; 200 ppm = acceptable maximum peak above the acceptable ceiling concentration for an 8 hour shift (max duration = 5 minutes in any 4 hours).
U.S. Environmental Protection Agency (EPA) Drinking water 5 ppb (0.005 mg/L) Regulation: current MCL**
U.S. Food and Drug Administration (FDA) Food: Bottled drinking water allowable Indirect food additive: adhesives 5 μg/L Yes

*TLV-TWA (threshold limit value-time-weighted average) - ACGIH TLVs are listed in the order of 8-hour time-weighted averages (TWAs during a 40-hour workweek, unless otherwise indicated), short-term exposure limits, and ceilings levels, if available. A TLV is a level to which it is believed a worker can be exposed day-after-day for a working lifetime without adverse health effects. These are not regulatory limits unless OSHA adopts them as a PEL.

STEL (short-term exposure limit) - Unless noted otherwise, the STEL is a 15-minute TWA maximum exposure that should not be exceeded at any time during a workday (a single work shift) to prevent adverse health effects.

REL (recommended exposure limit) - NIOSH RELs are for up to 10-hour TWAs during up to a 40-hour work week, unless otherwise indicated (can also be a STEL or ceiling limit). These are not regulatory limits.

§PEL (permissible exposure limit) - OSHA PELs are 8-hour TWAs, unless otherwise indicated (can also be short-term exposure limits (STEL) or ceiling limits). The PEL represents an employee's average airborne exposure in any 8-hour work shift of a 40-hour work week, which shall not be exceeded. OSHA enforces these limits under section 5(a)(2) of the Occupational Safety and Health Act. The 8-hour TWA PEL is the level of exposure established as the highest level of exposure an employee may be exposed to without incurring the risk for adverse health effects.

Ceiling limit - A ceiling limit, unless otherwise noted, is a maximum concentration level of exposure that should not be exceeded at any time during a workday in an effort to prevent adverse health effects.

**MCL (maximum contaminant level) - The highest level of a contaminant that is allowed in drinking water.

Key Points

  • The U.S. government has developed regulations and guidelines for CCl4.
   

Progress Check

5. Which of the following statements is FALSE regarding U.S. regulations and guidelines for CCl4 levels?

A. Federal regulations allow continued use of pesticide products containing CCl4.
B. EPA has set a maximum contaminant level for CCl4 in drinking water.
C. NIOSH has recommended a 60-minute exposure limit on CCl4 exposure at the workplace.
D. None of the above.

Answer:

To review relevant content, see all content in this section.

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Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, Atlanta, GA 30341
Contact CDC: 800-232-4636 / TTY: 888-232-6348

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