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Benzisothiazolinone (BIT)

  • Preservatives
  • CAS 2634-33-5
  • IUPAC: 1,2-benzisothiazol-3(2H)-one

Benzisothiazolinone (BIT) (CAS 2634-33-5) appears in 14 of the 1,812 car-care products CarCareTruth tracks (as of June 2026).

H302 (harmful if swallowed), H315 (skin irritation), H317 (skin sensitization Cat 1), H318 (serious eye damage) at ingredient level. The H317 sensitization classification is the primary concern at product use concentrations — even trace amounts can elicit reactions in already-sensitized individuals.

Benzisothiazolinone (BIT) is a broad-spectrum biocide preservative used in water-based detailing chemicals to prevent microbial growth in the bottle. It carries the H317 (skin sensitization) classification at the ingredient level, which is a threshold effect — the sensitization potential persists at concentrations far below those that would trigger product-level GHS classification. EU has restricted BIT to <0.05% in leave-on cosmetic products for this reason.

In leather cleaners, BIT typically appears at 0.01–0.05%. At those levels the product-level SDS often does not classify the finished product, but the ingredient is still flagged in CCT health scoring per the H317 deduction in the chemical health rubric.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
yes
Biodegradable
no
Bioaccumulative
no
Persistent
yes
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
3/5
Purpose: Broad-spectrum biocide preservative for water-based formulations; replaces older formaldehyde donors and isothiazolinones

Common questions about Benzisothiazolinone (BIT)

What is Benzisothiazolinone (BIT) used for in car care?
Broad-spectrum biocide preservative for water-based formulations; replaces older formaldehyde donors and isothiazolinones
Is Benzisothiazolinone (BIT) a VOC?
No. Benzisothiazolinone (BIT) is not classified as a volatile organic compound (VOC).
Is Benzisothiazolinone (BIT) on California's Proposition 65 list?
No. Benzisothiazolinone (BIT) is not on California's Proposition 65 list.

14 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.