Decamethylcyclopentasiloxane (D5; CAS No. 541-02-6) is a precursor in the production of siloxane polymers for industry and medicine and is a carrier ingredient in many toiletries and cosmetics. D5 has a relatively low order of toxicity following acute administration via the oral, dermal, and inhalation routes of exposure. It is not considered to be a dermal or eye irritant or a dermal sensitizer. There is no appreciable dermal absorption of D5 based on results from in vivo and in vitro studies. It has not been shown to be genotoxic/mutagenic when tested in a number of short-term in vitro and in vivo assays and did not cause reproductive or developmental toxicity in rats. Inhalation exposure of rats to 160 ppm D5 for up to 24 months produced adverse effects in the liver (weight changes and hepatocellular hypertrophy) and uterus (increased incidence of endometrial adenocarcinoma, endometrial adenoma, and adenomatous polyps in several animals); however, the results of recent mode-of-action studies are consistent with a uterine tumorigenesis mechanism that is not relevant for humans. Based on the results of the chronic inhalation study, 160 ppm was determined to be the no-observed-adverse-effect level (NOAEL) and was selected as the point of departure for the derivation of the workplace environmental exposure level (WEEL®) value. This NOAEL was adjusted to account for interindividual variability and residual uncertainty regarding upper respiratory tract changes still occurring at 160 ppm. The resulting 8-h time-weighted average WEEL value of 10 ppm is expected to provide a significant margin of safety against any potential adverse health effects in workers exposed to airborne D5.

中文翻译：

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十甲基环五硅氧烷（D5）。

十甲基环五硅氧烷（D5； CAS编号541-02-6）是生产用于工业和医学的硅氧烷聚合物的前体，并且是许多盥洗用品和化妆品中的载体成分。通过口服，皮肤和吸入途径急性给药后，D5的毒性相对较低。它不被认为是皮肤或眼睛刺激物或皮肤敏化剂。根据体内和体外研究的结果，没有明显的D5皮肤吸收。当在许多短期的体外和体内试验中进行测试时，尚未显示出它具有遗传毒性/致突变性，并且在大鼠中没有引起生殖或发育毒性。将大鼠吸入160 ppm D5达24个月，会对肝脏和肝脏产生不利影响（体重变化和肝细胞肥大）（增加子宫内膜腺癌，子宫内膜腺瘤和多发性息肉的发生率）；然而，最近的作用方式研究的结果与与人类无关的子宫肿瘤发生机制是一致的。根据长期吸入研究的结果，确定160 ppm为未观察到的不良反应水平（NOAEL），并被选作得出工作场所环境暴露水平（WEEL®）值的出发点。对该NOAEL进行了调整，以考虑到个体差异和关于上呼吸道变化的残留不确定性（仍在160 ppm时发生）。