Guide values for 1-butanol in indoor air. Report of the German Ad Hoc Working Group on Indoor Guidelines of the Indoor Air Hygiene Committee and of the States' Supreme Health Authorities

Abstract

The German Ad Hoc Working Group on Indoor Guidelines of the Indoor Air Hygiene Committee and the States' Supreme Health Authorities is issuing indoor air guide values to protect public health. No human studies of sufficient quality are available for the evaluation of 1-butanol in indoor air. In a well-documented oral study on reproduction toxicity in rats, assessed as reliable, impairment of embryo development was observed. Benchmark modeling of the study data by US-EPA revealed a BMDL10 of 26.1mg/kg b.w. per day. The working group used this BMDL10 as the point of departure for the derivation of the guide value II. Considering a human respiration rate of 20m(3) per day and a human body weight of 70kg, this dose was converted into an inhalative concentration. Applying a factor of 0.6 to account for the inhalative absorption rate, an allometric extrapolation factor from rat to human (factor 4), an interspecies factor of 2.5 for toxicodynamics, and a factor of 10 to account for individual differences (intraspecies factor), results in a health hazard guide value (RW II) of 2mg 1-butanol/m(3). The benchmark dose calculation of the same study generated a BMDL05 of 12.4mg/kg b.w. per day. Applying the same assessment factors as for RW II, a precautionary guide value (RW I) of 0.7mg 1-butanol/m(3) indoor air is calculated.