ACGIH Ratifies Exposure Limits

Feb. 1, 2008
The American Conference of Governmental Industrial Hygienists (ACGIH) announced Jan. 31 that its board of directors ratified the 2008 biological exposure indices and threshold limit values for chemical substances and physical agents.

ACGIH committees review published and peer-reviewed literature in various scientific disciplines to conclude what level of exposure the typical worker can experience without suffering adverse health effects. These limit values and exposure indices provide health-based guidelines for industrial hygiene professionals, but are not designed to be used as standards.

The board ratified the following threshold value limits:

Physical Agents

  • Electromagnetic radiation and fields – light and near-infrared radiation
  • Electromagnetic radiation and fields – lasers

Chemical Substances

  • Aluminum and compounds
  • Aluminum metal and insoluble compounds
  • Aluminum oxide
  • Benomyl
  • Butenes, All isomers
  • Carbaryl
  • Emery
  • Hydroquinone
  • Indene
  • Iodine and iodides
  • Natural rubber latex
  • Polyvinyl chloride (PVC)
  • 1,1,1,2-Tetrachloro-2,2,-difluoroethane
  • 1,1,2,2-Tetrachloro-1,2-difluoroethane
  • Thiram
  • Trimellitic anhydride
  • Triphenyl amine

ACGIH also adopted the following biological exposure indices:

  • Tetrahydrofuran
  • Trichloroethylene

Additional Recommendations

When a limit or biological exposure index is proposed for the first time, it is added to the Notice of Intended Changes (NIC), where it will remain for approximately one year. If during that time the committee does not discover or receive substantive data that changes its scientific opinion, it may then approve its recommendation through the board of directors for adoption.

In 2008, the board proposed NIC recommendations for nearly 30 chemical substance threshold value limits, three physical agent threshold value limits and two biological exposure indices.

ACGIH welcomes comments on these proposals, as well as suggestions for other substances that could be considered for threshold limit values or biological exposure indices. ACGIH also maintains an “under study” list of substances that may need further consideration.

The complete list of substances, including the NIC list and substances under study, can be viewed at

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