CarCareTruth

Decamethylcyclopentasiloxane (D5)

  • Silicones
  • CAS 541-02-6
  • IUPAC: 2,2,4,4,6,6,8,8,10,10-decamethyl-1,3,5,7,9,2,4,6,8,10-pentaoxapentasilecane

Low acute human toxicity — H227 (combustible) is the only GHS code. No carcinogenicity, reproductive toxicity, or sensitization classifications. Environmental persistence (PBT/vPvB) is the primary concern, not personal health.

Decamethylcyclopentasiloxane (D5) is a cyclic volatile methylsiloxane (cVMS) used as a carrier solvent in auto-care glazes, silicone polishes, and trim coatings. It evaporates quickly from surfaces, delivering active ingredients and leaving behind a film. **Environmental concern:** D5 is classified PBT (persistent, bioaccumulative, toxic to aquatic environments) and vPvB under EU REACH. It does not biodegrade and accumulates in aquatic sediments. EU regulations restrict D5 in wash-off cosmetics above 0.1%. For leave-on automotive products, aquatic exposure is primarily through atmospheric deposition of vapors rather than direct drain discharge. Products containing D5 at significant concentrations (>10%) receive environmental score penalties. **Human health:** Low acute toxicity — the only GHS code is H227 (combustible liquid). No carcinogenicity, sensitization, or confirmed reproductive toxicity in humans. The PBT/environmental concern, not personal health risk, is the main issue with D5.

Health & environment profile

VOC
yes
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
yes
Biodegradable
no
Bioaccumulative
yes
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
2/5
Purpose: Volatile carrier solvent; delivers active glaze/silicone ingredients to the surface, then evaporates

5 products contain this

Health summaries are editorial — we synthesize from SDSs, peer-reviewed sources, and regulatory listings. Not medical advice.