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 http://www.osha.gov.

October 6, 1978

Lawrence D. Kornreich, Ph.D.
Environmental Health Associate
ITT World Headquarters
320 Park Avenue
New York, New York 10022

Dear Dr. Kornreich:

This is in response to your letter concerning the applicability of the standard for occupational exposure to inorganic arsenic to operations involving chromated copper arsenate (CCA) wood preservative. Please accept my apology for the delayed response.

On the basis of your telephone conversation with Mr. Gail Brinkerhoff on approximately September 15, 1978, it is understood that you are referring to the manufacture of CCA wood preservative for internal plant use only. It is also understood on the basis of that telephone conversation that the preservative is prepared in a mixing (or reaction) vessel from base chemicals. The preservative is then pumped to a holding vessel from which it is pumped into the vessel where the treatment of the wood takes place. When the treatment of wood is complete, the preservative remaining in the treatment vessel is then recycled back to the holding vessel.

The Environmental Protection Agency's regulations do not apply at any stage in a process where wood preservatives are manufactured for internal plant use only and are not sold as a commercial product. Occupational Safety and Health Administration standard 29 CFR 1910.1018, published in the Federal Register on May 5, 1978, applies up to the point where the CCA wood preservative enters the pipeline running from the holding vessel to the treatment vessel.

The answers to your specific questions assuming manufacture of CCA wood preservative for internal plant use only are as follows:

1. An employee mixing CCA and applying it to the wood is covered by 29 CFR 1910.1018 until he/she moves beyond the preservative holding vessel. Neither EPA or OSHA regulations apply beyond the holding vessel.

2. An employee mixing CCA is covered by 29 CFR 1910.1018 during all stages of the operation.

Thank you for your interest in occupational health.


Bruce Hillenbrand
Acting Director,
Federal Compliance
and State Programs