"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