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Interpretation Response #07-0173 ([Umicore USA, Inc] [Mr. Gary Sommer])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Umicore USA, Inc

Individual Name: Mr. Gary Sommer

Country: CA

View the Interpretation Document

Response text:

Sep 21, 2007

Mr. Gary Sommer                               Reference No. 07-0173

Environmental Health and Safety Manager

Umicore USA, Inc.

P.O. Box 5097

4261 Mainway Drive

Burlington, Ontario

Canada L7R 3Y8

Dear Mr. Sommer:

This is in response to your August 21, 2007 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) for determining if a material meets the definition of a hazardous substance. Specifically, you ask if the method you use to determine the particle diameter of your zinc powder is acceptable under the HMR.

In your letter, you state that you use a laser diffraction method to determine the particle size of your zinc powder. You are correct in your understanding that there are no requirements under the HMR specifying how the particle size must be determined. Under the HMR, zinc meets the definition of a hazardous substance when more than one thousand pounds is contained in one package and when the metal particles have a diameter smaller than 100 micrometers (0.004 inches). Any method used to determine the metal particle diameter, including the laser diffraction method described in your letter, is acceptable.

I hope this information is helpful. If you have further questions, please do not hesitate to contact this office.


Hattie L. Mitchell

Chief, Regulatory Review and Reinvention

Office of Hazardous Materials Standards


Regulation Sections

Section Subject
172.101 Purpose and use of hazardous materials table