Effect of selected organopolysiloxanes on male rat and rabbit reproductive organs

Abstract

Male rabbits were treated dermally at doses of 200 mg/kg/day for 28 consecutive days with dimethylpolysiloxane (Dow Corning ® 200 fluid), trimethyl end-blocked dimethylphenylmethylpolysiloxane (Dow Corning ® 550 fluid), tris-(trimethylsiloxy)phenylsilane (Dow Corning ® 556 cosmetic grade fluid), and trifluoropropylmethylpolysiloxane (Dow Corning ® FS-1265 fluid). Testicular atrophy and reduced testicular function did not occur as observed with 19 batches of an equilibrated copolymer of mixed cyclosiloxanes, cyclic [(PhMeSiO) x (Me 2SiO) y] where x + y = 3 to 8 (PMxMMy) given at a dose of 50 mg/kg/day for 20 consecutive days. PMxMMy was found to produce significant ( P < 0.01) atrophy of rat seminal vesicles after po administration (17 out of 23 batches) of 3.3 ml/kg/day for 7 days. With the exception of 2, the remaining 6 batches of PMxMMy did produce atrophy of the seminal vesicles, but to a lesser degree ( P < 0.05). Dow Corning ® 200 fluid, Dow Corning ® 550 fluid, Dow Corning ® 556 cosmetic grade fluid, and Dow Corning ® FS-1265 fluid, 1,1,3,3-tetraphenyl-1,2,2,3-tetramethyltrisiloxane (Dow Corning ® 704 diffusion pump fluid), and methylhydrogenpolysiloxane (Dow Corning ® 1107 fluid) were investigated in like manner. They did not significantly alter absolute seminal vesicle weights or seminal vesicle to body weight ratios when compared to the saline-treated control animals. Numerous production lots of Dow Corning ® 556 cosmetic grade fluid were investigated dermally on rabbits and po in rats and resulted in no significant effect relative to the parameters investigated. Human subjects dermally exposed to Dow Corning ® 200 fluid, Dow Corning ® 556 cosmetic grade fluid, or Dow Corning ® FS-1265 fluid at doses of 50 mg/kg/day for 10 days showed no absorption as indicated by absence of elevated silicon levels in blood or urine.