ARTICLE NO. TX982441 Inhalation Toxicology of Decamethylcyclopentasiloxane (D5) Following a 3-Month Nose-Only Exposure in Fischer 344 Rats

D5 is a low-molecular-weight cyclic siloxane used for industrial and consumer product applications. The objective of the present study was to evaluate the subchronic toxicity of D5 following a 3-month nose-only inhalation exposure. In addition, animals from both sexes of the control and high dose groups were allowed a 4-week recovery period to observe reversibility, persistence, or delayed occurrence of any potential adverse effects. Male and female Fischer 344 rats were exposed for 6 h/day, 5 days/week for 3 months to target concentrations of 0 (30/sex/group), 26 (20/sex/ group), 46 (20/sex/group), 86 (20/sex/group), and 224 (30/sex/ group) ppm D5. Recovery groups (0 and 224 ppm) comprised 10 rats/sex/group. Body weights and food consumption were moni-tored at least twice weekly over the course of exposures. Approx-imately 16 h preceding euthanasia, animals were transferred into metabolism caging for urine collection and were fasted. Rats wer