Silicone rubber nipples: effects of sesame-oil extract on reproduction in mice.

The authors investigated a type of silicone rubber (SR) nipple for toxicity, caused by chemical migrants, on reproduction and pregnancy outcomes. They followed an extraction method (set forth in the 20th revised edition of the United States Pharmacopeia) in which sesame oil was a vehicle. They prepared the extract daily and administered it orally (50 ml/kg of body weight) into pregnant Swiss albino mice from gestation Day 0 until delivery. They gave a control group of mice the pure vehicle that was subjected to the same conditions. The authors recorded pregnancy weight gain, gestation period, litter size, stillbirths, and offspring sex ratio. They performed an enzyme-linked immunosorbent assay for pregnancy hormones (progesterone, estradiol, and prolactin) for each trimester and monitored birth weight, growth rate, and sex hormone levels (follicle-stimulating hormone, luteinizing hormone, and estradiol in females; testosterone in males) in offspring. The authors detected SR-extractable chemicals by means of gas chromatography and mass spectrometry. The decrease in weight gain from Day 6 of gestation until delivery and the shortness in the gestation period were significant in dams (p< or = .05). Newly born pups demonstrated a significantly (p < or = .05) lower body weight that continued with age, and this became highly significant (p< or = .01) from Day 6. Blood hormone levels in dams and offspring indicated no significance. In conclusion, the studied SR nipples indicated leachability, which could affect reproduction, without a manifest endocrine modulation.