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CarCareTruth

Sulfur Dioxide

  • Preservatives
  • CAS 7446-09-5
  • IUPAC: Sulfur dioxide

Sulfur Dioxide (CAS 7446-09-5) appears in 2 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is listed on California's Proposition 65.

Sulfur dioxide is listed under California Proposition 65 for developmental toxicity (birth defects or other reproductive harm), effective as a listed substance since 2011. It is also listed on the California Labor Code Hazardous Substances List and is IARC Group 3 (not classifiable as to carcinogenicity). It is a common trace byproduct or preservative-system residual in some surfactant and citrus-extract supply chains rather than an intentionally formulated cleaning active. This product's SDS names it directly in Sections 2.3 and 15 as triggering the mandatory California Prop 65 warning, without disclosing a concentration - per CCT's fail-safe scoring convention, an undisclosed concentration is treated as the highest exposure tier.

Sulfur dioxide (CAS 7446-09-5) is a California Proposition 65-listed substance (developmental toxicity, listed 2011) that this product's Safety Data Sheet names directly as a trigger for its mandatory Prop 65 warning, alongside 1,4-dioxane. It does not appear in the SDS's Section 3 ingredient/concentration table, meaning it is not disclosed as an intentional formulation component - manufacturers typically encounter sulfur dioxide as a trace residual from certain surfactant or citrus-extract supply chains, or from preservative systems, rather than adding it deliberately.

Because no concentration is disclosed anywhere in the SDS, CarCareTruth's scoring treats the exposure as the least-favorable (highest) tier rather than assuming a low trace level it cannot verify. This is a source-transparency gap in the manufacturer's own SDS, not a claim that the product's actual sulfur dioxide content is unusually high.

Health & environment profile

VOC
no
Prop 65 listed
yes
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
no
Biodegradable
no
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
3/5
Purpose: Process residual / preservative-system trace byproduct - not an intentional cleaning ingredient. Named in this product's SDS Sections 2.3 and 15 as a substance the product can expose users to, without a disclosed concentration or role in Section 3.

Common questions about Sulfur Dioxide

What is Sulfur Dioxide used for in car care?
Process residual / preservative-system trace byproduct - not an intentional cleaning ingredient. Named in this product's SDS Sections 2.3 and 15 as a substance the product can expose users to, without a disclosed concentration or role in Section 3.
Is Sulfur Dioxide a VOC?
No. Sulfur Dioxide is not classified as a volatile organic compound (VOC).
Is Sulfur Dioxide on California's Proposition 65 list?
Yes. Sulfur Dioxide appears on California's Proposition 65 list.

2 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.