Indoor air guide values for cyclic dimethylsiloxanes

To protect public health the German Working Group on Indoor Guidelines of the Federal Environment Agency and the States' Supreme Health Authorities is issuing indoor air guide values. For health evaluation of indoor air cyclic siloxanes no appropriate human data is available. Based on animal studies airway inflammation has been identified as crucial adverse effect following -inhalative exposure to cyclic siloxanes. Significant inflammatory lesions of nasal epithelium have been seen in F344 rats chronically exposed to D5 (LOAEL = 600 mg/m(3)). The lowest adverse effect level for continuous exposure is assessed by the Working Group as 107 mg D5/m(3). By applying an interspecies factor of 2.5 and an intraspecies factor of 10 a so-called health hazard guide value of 4 mg D5/m(3) indoor air is obtained. Regarding the limited data on inhalation toxicity of volatile cyclic siloxanes D3 to D6 a health hazard guide value of 4 mg/m(3) indoor air for the sum of cyclic siloxanes D3 to D6 is recommended. Additionally, a so-called health precaution guide value of 0.4 mg cyclic siloxanes D3-D6/m(3) indoor is recommended.