From: bjgaed@bb1t.monsanto.com
Newsgroups: sci.chem
Subject: Re: TLV question
Date: 8 Sep 92 07:20:34 CST
Organization: Monsanto Company, St. Louis, MO

In article <1992Sep8.000626.10953@col.hp.com>, chrism@col.hp.com (Chris Magnuson) writes:
> How can I tell the TLV of 2-pentanone?  What is the number?  Is there a "public"
> document like the CRC or something that gives these TLV values?
> 
> chrism@col.hp.com
> 
For the *vast* majority of chemicals no TLV has been established.  
TLV's (Threshold Limit Values, the amount of a compound to which a 
worker may be exposed) are established by OSHA (Occupational Safety 
and Health Administration) through a baroque rule-making process 
involving hearings, public comment, lawsuits, etc.

The *only* truly accurate source of TLV's is the _Federal Register_, a 
weekly publication of *everything* going on in the Federal Government. 
Needless to say this may not be very helpful to anyone but an 
information expert or a lawyer.  The thing is just too huge for the 
average person to keep up.  

If you are using 2-pentanone at work, there *must* be available a 
Material Safety Data Sheet (MSDS).  This gives you all of the 
regulatory and toxicity data on the compound.  If you have an 
industrial hygienist or safety officer, they will direct you to the 
MSDS.  If you don't have these people where you work, check with your 
personnel department.  By law, an MSDS must be furnished with the 
compound by the supplier and must be kept on file and *available in 
the workplace* by the employer.

I just looked it up on our on-line MSDS database.  Here is the 
information:

 OSHA PEL FINAL:8H TWA 200 PPM (700 MG/M3);STEL 250 PPM (875 MG/M3)
     FEREAC 54,2923,89

Now, that is just one of many lines on this multi-page document!

Translation:

Occupational Safety and Health Administration/Permissible Exposure 
Limit/Final rule (after public comment and any court challenges)/8 
Hour Time Weighted Average/200 Parts Per Million (700 Milligrams per 
Cubic Meter);/Short Term Exposure Limit/250 Parts Per Million (875 
Milligrams per Cubic Meter/Federal Register Volume 54, Page 2923, 
1989.

Unless a rule has been made in the past year or two (unlikely), no TLV 
has been established for this compound.  The exposure limits are 
determined much less rigorously than a TLV because the penalties and 
liabilities are not nearly so severe.  Still, they are a useful guide. 
TLV's are usually reserved for much more toxic compounds or things 
to which very large numbers of workers are exposed.  

Can someone supply a better picture of the legal status of the 
exposure limits, as opposed to TLV's, please?

In any event, to put this in perspective, a permissible exposure limit 
for an 8 hour shift of 200 ppm is a compound of rather low toxicity.  
The LC50 for mammals by inhalation is 22 *grams* per cubic meter.  No 
mention was made of carcinogenic effects.

MSDS's do get out of date, and the usual disclaimer applies:  If an 
effect is not mentioned there is no gaurantee that a problem will not 
occur.

OSHA tends to regulate the more toxic and widespread compounds first.  
Unless there is a change in the toxicology picture through further 
testing (carcinogenic or mutagenic effects show up) I doubt if this 
compound will ever by regulated by a TLV.


-- 
--Electric Monk            (Bruce Gaede); 
                            e-mail: bjgaed@ccmail.monsanto.com

"...and then time started seriously to pass."
--Douglas Adams, _Dirk Gently's Holistic Detective Agency_
Newsgroups: sci.chem