No. 1031 - Miljøstyrelsen

• Immunotoxicity studies.
Human clinical studies:
• Determination of human response and assessment of relevance of animal
studies.
Exposure assessment studies:
• Workforce;
• Consumers;
• General public.
Information was specifically searched for the CAS numbers shown in the table
below.
Table 3.1 Siloxanes searched by CAS number
Chemical name CAS no. Synonym
Octamethyl cyclotetrasiloxane 556-67-2 D4; Part of cyclomethicone
Cas. no 69430-24-6
Decamethyl cyclopentasiloxane 541-02-6 D5; Part of cyclomethicone
Cas. no 69430-24-6
Hexamethyl disiloxane 107-46-0 HMDS
Octamethyl trisiloxane 107-51-7
1,1,3,3-tetramethyl-1,3-diphenyl disiloxane
56-33-7 Phenyl dimethicone
1, 1, 5, 5, 5- hexamethyl- 3- phenyl- 3-
[(trimethylsilyl)oxy] trisiloxane
2116-84-9 Phenyl trimethicone
Information has primarily been identified for D4, D5 and HMDS which besides
polydimethylsiloxane (PDMS) is part of the Siloxane Research Program.
For the other three siloxanes which are not part of the program, little or
no information has been found. This is also the situation as regards more general
information on toxicity related to small linear siloxanes and cyclic siloxanes.
A few studies are focussing on estrogenic and anti-estrogenic properties of D4
and HMDS, but in general data on endocrine disruption end points are
scarce.
3.2 Toxicity of siloxanes
Although siloxanes are used in many products including consumer products
and have been so for many years, there is relatively little information available
about their toxicity apart from the information provided by the Siloxane Research
Program. However, siloxanes have generally been regarded as safe in
consumer products, but new uses, e.g. in breast implants and focus on reproductive
toxicity and possible endocrine disrupting effects have focussed attention
on this group of substances.
Of the six siloxanes mentioned in Table 3.1 only D4 is on Annex I to the Substance
Directive (67/548/EEC) with a health classification as toxic to reproduction
in category 3. The German justification for classification of D4 with
regard to carcinogenic, mutagenic and reprotoxic effects is included in the
reference list.
45