Skip to content
CarCareTruth

Bronopol (2-Bromo-2-nitropropane-1,3-diol)

  • Preservatives
  • CAS 52-51-7

Bronopol (2-Bromo-2-nitropropane-1,3-diol) (CAS 52-51-7) appears in 1 of the 2,122 car-care products CarCareTruth tracks (as of August 2026). It is readily biodegradable.

Ingredient-level classification includes Acute Tox. 3 (H301, H331), Acute Tox. 4 (H312), Skin Irrit. 2 (H315), Eye Dam. 1 (H318), and STOT SE 3 (H335) at pure-substance concentration. A known contact allergen and slow formaldehyde releaser. At the trace concentrations used as a preservative (typically 0.01-0.1%), these hazards do not carry into a finished product's mixture-level (SDS Section 2) classification unless the specific concentration limit for a given endpoint is met.

Bronopol (2-bromo-2-nitropropane-1,3-diol, INN) is a broad-spectrum antimicrobial preservative used at very low concentrations in water-based cosmetic and cleaning formulations. It works partly by slowly releasing small amounts of formaldehyde, which inhibits bacterial and fungal growth in the bottle.

At the pure-substance level, Bronopol carries a substantial hazard profile (acute oral/inhalation toxicity, skin and eye irritation, respiratory irritation), but it is formulated into finished products at trace concentrations, typically well under 0.1%, specifically because a little goes a long way as a preservative. At those concentrations, none of the ingredient-level hazard classifications carry through to the finished mixture's own SDS Section 2 classification unless the product's specific concentration limit for a given hazard endpoint is met. It is readily to inherently biodegradable and is not on California's Proposition 65 list.

Health & environment profile

VOC
no
Prop 65 listed
no
Asthmagen
no
EPA Safer Choice
no
Aquatic toxicity
yes
Biodegradable
yes
Bioaccumulative
no
Persistent
no
Ozone depleting
no
Microplastic
no
PFAS
no
Env. score
3/5
Purpose: Formaldehyde-releasing preservative used at trace concentrations to inhibit microbial growth in water-based formulations

Common questions about Bronopol (2-Bromo-2-nitropropane-1,3-diol)

What is Bronopol (2-Bromo-2-nitropropane-1,3-diol) used for in car care?
Formaldehyde-releasing preservative used at trace concentrations to inhibit microbial growth in water-based formulations
Is Bronopol (2-Bromo-2-nitropropane-1,3-diol) a VOC?
No. Bronopol (2-Bromo-2-nitropropane-1,3-diol) is not classified as a volatile organic compound (VOC).
Is Bronopol (2-Bromo-2-nitropropane-1,3-diol) on California's Proposition 65 list?
No. Bronopol (2-Bromo-2-nitropropane-1,3-diol) is not on California's Proposition 65 list.
Is Bronopol (2-Bromo-2-nitropropane-1,3-diol) biodegradable?
Yes. Bronopol (2-Bromo-2-nitropropane-1,3-diol) has a confirmed biodegradable profile.

1 product 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.