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After reviewing available published literature, NIOSH provided comments to OSHA on August 1, 1988, regarding the "Proposed Rule on Air Contaminants" (29 CFR 1910, Docket No. H-020).


In these comments, NIOSH questioned whether the PELs proposed (and listed below) for the following substances included in the Pocket Guide were adequate to protect workers from recognized health hazards:


  • Acetylene tetrabromide [TWA 1 ppm]
  • Chlorobenzene [TWA 75 ppm]
  • Ethyl bromide [TWA 200 ppm; STEL 250 ppm]
  • Ethylene glycol [Ceiling 50 ppm]
  • Ethyl ether [TWA 400 ppm; STEL 500 ppm]
  • Fenthion [TWA 0.2 mg/m3 (skin)]
  • Furfural [TWA 2 ppm (skin)]
  • 2-Isopropoxyethanol [TWA 25 ppm]
  • Isopropyl acetate [TWA 250 ppm; STEL 310 ppm]
  • Isopropylamine [TWA 5 ppm; STEL 10 ppm]
  • Manganese tetroxide (as Mn) [TWA 1 mg/m3]
  • Molybdenum (soluble compounds as Mo) [TWA 5 mg/m3]
  • Nitromethane [TWA 100 ppm]
  • m-Toluidine [TWA 2 ppm (skin)]
  • Triethylamine [TWA 10 ppm; STEL 15 ppm]


At that time, NIOSH also conducted a limited evaluation of the literature and concluded that the documentation cited by OSHA was inadequate to support the proposed PEL (as an 8-hour TWA) of 10 mg/m3 for alpha-alumina, benomyl, emery, glycerine (mist), graphite (synthetic), magnesium oxide fume, molybdenum (insoluble compounds as Mo), particulates not otherwise regulated, picloram, and rouge.


Adapted from: NIOSH Publication Number 2005-149


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