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Previous by Date: Subject: Chemical Safety Workshops, March 2005, San Diego, California Date: Tue, 15 Feb 2005 09:21:37 -0500 Author: List Moderator |
Next by Date: Subject: Pigeon Droppings and Perchloric Acid hood Date: Tue, 15 Feb 2005 12:51:50 -0800 Author: Debbie Decker |
Gail - You do not have to measure exposure. The OSHA Regulation, 29 CFR 1910.1450, Occupational Exposure to Hazardous Chemicals in Laboratories, says, in the (non-mandatory) Appendix A, E.1.n: "As a rule of thumb, use a hood or other local ventilation device when working with any appreciably volatile substance with a TLV of less than 50ppm." (I personally use 100ppm as the threshold for requiring that work be done under the hood, even if the substance is not particularly volatile.) Under this criteria, hexane would have to be used in the hood, whereas ethyl acetate would not. However, on the bench-top, you do not have good control over how vapors move and the location of ignition sources. Since ethyl acetate has a flashpoint of -4 degrees C, I would recommend that it be used under a hood where vapors are continually removed, and because you can limit the ignition sources. (As a side note, odor can be used as another criteria for use in the hood. Even if the chemical is relatively non-hazardous but it has an obnoxious smell, it has to be used in the hood.) Do you have a chemical hygiene plan in place? What does it say? The goal should be that the lab should be safe for the population considered the most sensitive, pregnant females. Suzanne (Just my opinion, and it does not represent anyone else's opinion here at UMDNJ.) Suzanne M. Kupiec, MPH, CSP Senior Industrial Hygienist (and Lab Safety Specialist) Environmental & Occupational Health & Safety Services Univ. of Medicine & Dentistry of New Jersey 675 Hoes Lane, Tr. #1 Piscataway, NJ 08854 (732) 235-4058/ fax - (732) 235-5270 http://www2.umdnj.edu/eohssweb/eohss.htm At 04:00 PM 2/14/2005, you wrote: >I am at a small college and trying to give good advice to researchers >about when work needs to be done in the hood. The chemicals we work >with typically have PEL or similar values listed on the MSDS but, of >course, I have no meter to measure those levels in the lab. Lacking >such hard data, is there any reasonable standard I can offer bench >chemists to help them decide when work needs to move to the hood? I >currently have researchers doing column chromatography with hexanes and >ethyl acetate on the bench outside the hood. When I express concerns, >the response starts "when I was in grad school, we did it this way . . >." I did lots of things in grad school that I couldn't defend then, let >alone now. Without the ability to measure (or estimate?) levels, I >can't do much to change behavior. > >Thanks, >Gail
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