Toxicologic Review of Selected Chemicals - 526

Before 1985, OSHA regulated wood dust under its nuisance dust standard of 15 mg/m3 (29 CFR 1910.1000, Table Z-3). However, in a 1985 enforcement proceeding before the Occupational Safety and Health Review Commission, wood dust was held not to be covered by the nuisance dust standard. It held that the standard only covered inorganic dusts. (12 OSHC 1785). The Agency did not regulate this substance after this decision. Consequently, OSHA had no PEL for wood dust when this generic rulemaking was undertaken. The ACGIH has a TLV-TWA of 1 mg/m3 for hard wood dust, and a TLV-TWA of 5 mg/m3 and STEL of 10 mg/m3 for soft wood dust. OSHA proposed a 1 mg/m3 8hour TWA for hard wood dust and a 5 mg/m3 8-hour TWA for soft wood dust. In the final rule, OSHA is establishing a single 8-hour TWA of 5 mg/m3 and a STEL of 10 mg/m3 for all hard wood and soft wood dusts except Western red cedar. For Western red cedar, a highly allergenic species of soft wood, the Agency is establishing an 8-hour TWA limit of 2.5 mg/m3. Wood dust is defined as any wood particles arising from the processing or handling of woods. Hard woods derive from the deciduous broad-leaved flowering species of trees, and soft woods include the coniferous species that do not shed their leaves in the winter.