Siloxane D5 in Dry cleaning Applications
                  Fact Sheet
        EPA has received results of a cancer study on Siloxane D5 in rodents, submitted under TSCA section 8(e).
        The results of this study indicate that there may be a cancer hazard associated with D5. However, the
        Agency has not conducted a risk assessment for D5, and, therefore, is not in a position to characterize
        potential risks to human health or the environment associated with D5 use in drycleaning.
What is "Siloxane
Have other studies
been conducted?
What were the
preliminary results
of the study?
Decamethylcyclopentasiloxane, or D5, is an odorless, colorless liquid that has many
consumer and industrial applications.  D5 is used as an ingredient in a number of personal
health and beauty products, including deodorants, antiperspirants, cosmetics, shampoos,
and body lotions. It is also used as a drycleaning solvent and in industrial cleaning.

The subject cancer study is one of a broad range of toxicological studies on D5 and several
other siloxanes that are being conducted voluntarily by the Dow Corning Corporation under
a Memorandum of Understanding signed with EPA in 1996.

In February 2003, EPA received from Dow Corning the preliminary results of a two-year
chronic toxicity and carcinogenicity study on D5 using rats.  In this study, groups of 60
male  and 60 female Fischer 344 rats were exposed to vapor concentrations of 0,  10, 40, or
160 ppm of D5 for  6 hours per day, 5 days per week, for 24 months. The preliminary results
show that female rats exposed to the highest concentration of D5 exhibited a statistically
significant increase of uterine tumors.

In July 2005, EPA received the final results of the two-year study in rats, which confirmed
the significant increase in uterine tumors following exposure to 160 ppm of D5, the highest
concentration tested in the study. No significant increase in tumors was observed at lower

Dow Corning submitted the results of their study under section 8(e) of the Toxic  Substances
Control Act (TSCA). Section 8(e) requires that U.S. chemical manufacturers notify EPA of
information that could support a conclusion of substantial risk of injury to health or the
environment. Section 8(e) submissions most often contain toxicity data, but may also
contain information on exposure, environmental persistence, or actions being taken to
reduce human health and environmental risks.

EPA has received the work agreed upon in the MOU and a Public Docket has been
established to make data and information developed through this MOU available to the
public.  The docket number EPA-HQ-OPPT-2009-0180 can be accessed through Docket materials include more than 88 reports assessing
potential toxicity and exposure, annual progress reports, science briefings, and related
TSCA section 8(e)  notices and additional submissions concerning D5 and five other
siloxanes that were subject to the MOU.
        Office of Pollution Prevention and Toxics (7404)
        August 2009
How were the results
How will EPA follow