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Synonyms: D5; cyclosiloxanes; polysiloxanes; cyclomethylsiloxanes; polydimethylsiloxanecyclic pentamer; organosilcone fluid; silicones
OSHA IMIS Code Number: M207
Chemical Abstracts Service (CAS) Registry Number: 541-02-6
Chemical Description and Physical Properties:
molecular weight: 370.85
vapor pressure: 30.002 mmHg @ -6.6°C
molecular formula: C10H30O5Si5
boiling point: 209.9°C
melting point: -40.9°C
Potential Symptoms: No human data available; INHAL CHRONIC (RATS): slight liver enlargement, weak "phenobarbital-like" induction of cytochrome P450 enzymes; significantly increased lung weight (at 160 ppm or higher).
Health Effects: Potential cumulative lung damage (HE10)
Affected Organs: Lungs
- OSHA does not have a PEL for this chemical, which is used primarily in consumer product applications (e.g., bath oils, lotions, shampoos, shaving products, sprayed powders).
- The NOAEL for systemic toxicity in rats inhaling decamethylcyclopentasiloxane (D5) 6 hours/day for 28 days was reported to be 75 ppm.
- Two major, three minor and other trace metabolites were found in the urine of rats given a single oral dose of 14C-labeled D5. The major metabolites, which accounted for about 75% of total radioactivity in urine, were dimethylsilanediol and methylsilanetriol. The enzyme responsible for demethylation at the silicon-methyl bond has not been identified.
- A one-month recovery period did not reverse the focal macrophage accumulation and interstitial inflammation in lungs of rats that inhaled an average of 233 ppm, 6 hours/day, 5 days/week for 13 weeks.
- One year after a single injection of a mixture of cyclosiloxanes in female mice, D5 appeared to be retained to a greater extent than other cyclosiloxanes in lymph nodes, ovaries and abdominal fat.
- Burns-Naas, L.A., et al.: Toxicology and humoral immunity assessment of decamethylcyclopentasiloxane (D5) following a 1-month whole body inhalation exposure in Fischer 344 rats. Toxicol. Sci. 43(1): 28-38, 1998.
- Burns-Naas, L.A., Mast, R.W., Meeks, R.G., Mann, P.C. and Thevenaz, P.: Inhalation toxicology of decamethylcyclopentasiloxane (D5) following a 3-month nose-only exposure in Fischer 344 rats. Toxicol. Sci. 43(2): 230-240, 1998.
- Kala, S.V., Lykissa, E.D., Neely, M.W. and Lieberman, M.W.: Low molecular weight silicones are widely distributed after a single subcutaneous injection in mice. Am. J. Pathol. 152(3): 645-649, 1998.
- McKim, J.M., Jr., et al.: Induction of hepatic xenobiotic metabolizing enzymes in female Fischer-344 rats following repeated inhalation exposure to decamethylcyclopentasiloxane (D5). Toxicol. Sci. 50(1): 10-19, 1999.
- Varaprath, S., McMahon, J.M. and Plotzke, K.P.: Metabolites of hexamethyldisiloxane and decamethylcyclopentasiloxane in Fischer 344 rat urine - a comparison of a linear and a cyclic siloxane. Drug Metab. Dispos. 31(2): 206-214, 2003.
Date Last Revised: 02/17/2005
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