OSHA requirements are set by statute, standards and regulations. Our interpretation letters explain these requirements and how they apply to particular circumstances, but they cannot create additional employer obligations. This letter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep apprised of such developments, you can consult OSHA's website at https://www.osha.gov.

February 21, 1989

Mr. Marshall Lee Miller
Bishop, Cook, Purcell and Reynolds
Law Offices
1400 L Street, N.W.
Washington, D.C. 20005-3502

Dear Mr. Miller:

This letter is in response to your January 12, letter to the Occupational Safety and Health Administration (OSHA). In your letter you ask that OSHA consider a regulatory clarification concerning commercial carbon black.

Staff members of several Agency directorates have read the report you supplied and your December 1, 1988 letter concerning the potential cardiopulmonary effects from exposure to airborne commercial carbon black. The report is well organized to summarize the previous human and animal studies that have been conducted for carbon black.

In your January 12 letter you asked the Agency to distinguish between two different substances- harmful soots and chars and commercial carbon black. After a thorough review of the available health information, OSHA agrees that there is a difference between commercially produced carbon black within the United States and substances identified as soots and chars and not manufactured by the same process. Soots and chars may have could exposed workers to a carcinogenic hazard. Airborne exposure present a similar hazard. Your request to modify the entry in and a significant amount of resources. Carbon black is not on OSHA's list of priorities to conduct rulemaking. Therefore, OSHA will not at this time undertake an effort to modify the X list. We will, however, modify the current entry in an Agency publication to our compliance officer entitled the Chemical Information Manual (OSHA Instruction CPL 2-2.43) to separate out different health effects for substances identified as soots and chars and those of commercial carbon black. Agency acknowledgment of theses differences should clarify any misunderstanding the health effects of the material may have with soots and chars and OSHA's hazard communication standard.

Finally, your letter mentions that carbon black should be classified as a nuisance dust and that exposure to it does not produce serious health effects. OSHA believes that the seriousness of the exposure hazard is related to the airborne concentration and duration of worker exposure. At this time OSHA is not convinced that the present classification of the health Manual is inappropriate. Therefore, the designation of "cumulative lung damage (HEIO)" and "cumulative heart damage (HES)" must remain.

I hope that this letter clears up the misunderstanding and adequately addresses your request.


John A. Pendergrass
Assistant Secretary