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CarCareTruth

Amorphous Silica

  • Abrasives
  • CAS 7631-86-9
  • IUPAC: Silicon dioxide (amorphous)

Amorphous Silica (CAS 7631-86-9) appears in 4 of the 2,039 car-care products CarCareTruth tracks (as of July 2026).

OSHA classifies amorphous silica as a nuisance particulate (TWA 15 mg/m³ total dust, 5 mg/m³ respirable). Distinct from crystalline silica (quartz): amorphous silica is not classified as carcinogenic by NTP or IARC. Wet-sanding applications minimize inhalation exposure.

Amorphous silica (fumed or precipitated silicon dioxide, CAS 7631-86-9) is the form of silica used as an abrasive in automotive rubbing compounds and polishing pastes. It is distinct from crystalline silica (quartz or cristobalite) — the IARC Group 1 carcinogen form — and is not classified as carcinogenic under repeated exposure. OSHA treats amorphous silica as inert nuisance particulate.

In headlight restoration compounds, amorphous silica provides the abrasive cutting action at 15–40% concentration. Wet-sanding and wet-application processes reduce inhalation exposure substantially compared to dry abrasive use.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
no
Bioaccumulative
no
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
3/5
Purpose: Micro-abrasive polishing agent in rubbing compounds and light-cut polishes

Common questions about Amorphous Silica

What is Amorphous Silica used for in car care?
Micro-abrasive polishing agent in rubbing compounds and light-cut polishes
Is Amorphous Silica a VOC?
No. Amorphous Silica is not classified as a volatile organic compound (VOC).
Is Amorphous Silica on California's Proposition 65 list?
No. Amorphous Silica is not on California's Proposition 65 list.

4 products contain this

Related

Health and environment notes translate the manufacturer Safety Data Sheet, the GHS classification, and authoritative regulatory listings (California Prop 65, EPA). Not medical advice. They describe the ingredient itself; whether a hazard applies to a finished product depends on its concentration and how it's used.