Inhalation exposure calc

Canuk lsegal at sprint.ca
Sat Jul 3 13:07:56 EST 1999

"Laughlin, Sherry" <Sherry.Laughlin at METROKC.GOV> wrote in article
<33E3BCF0DCBDD21198B800805FE6DEA903642CDA at kcmail3.metrokc.gov>...
> I have yet to see an entry in the NIOSH RTECS for inhalation rat LC50 in
> units other than mg/m3/x-Hr.  Can mg/m3 be converted to mg/L without
> compromising any toxicological value?  Chemistry wise, 1 mg/m3 = 1000
> Would this be apples and oranges in the toxicology world?  Any help is be
> greatly appreciated.  Thanks

The LC50 value in mg/L can be converted to mg/m3 using the fromula you have
listed above.  Therefore, an LC50 of 2.5 mg/L = 2500 mg/m3.  The exposure
duration is an important factor when comparing LC50 values.  If I'm not
mistaken, the exposure duration recommended in the OECD Test Guideline for
acute inhalation toxicity is 4 hours.  The conversion from ppm to mg/m3 or
mg/L is a bit more complicated.

Lawrence Segal, Ph.D.
Health Protection Branch
Health Canada
Ottawa, Canada

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