[Indoor air guide values for 2-butanone oxime. Communication from the Ad-hoc Working Group on Indoor Guide Values of the Indoor Air Hygiene Commission and the States' Supreme Health Authorities].

The German Working Group on Indoor Guidelines of the Indoor Air Hygiene Committee and of the Supreme State Health Authorities is issuing indoor air guide values to protect public health. No reliable human studies are available for health evaluation of 2-butanone oxime in indoor air. In a well documented chronic inhalation animal study with rats and mice assessed as reliable, degenerative changes in the olfactory epithelium were observed, which led to a dose related increased incidence and severity, especially in mice. Using a benchmark approach the Working Group assessed a BMD10 of 13.8 mg 2-butanone oxime/m(3) for continuous exposure for the endpoint degeneration of the olfactory epithelium. For interspecies differences a reduced factor of 1 was applied due to the same susceptibility of rodents than human for this endpoint. By applying a factor of 10 for interindividual variability, and a factor of 2 to account for the higher respiratory rate of children compared to adults, a health hazard guide value (RW II) of 0.06 mg 2-butanone oxime/m(3) indoor air is obtained. A precautionary guide value of 0.02 mg 2-butanone oxime/m(3) indoor air is recommended.