Bronopol is used as a preservative in various cosmetic, pharmaceutical, toiletry and household preparations at concentrations of up to 0.1% (wt/vol) particularly because of its high activity against Gram-negative bacteria, especially Pseudomonas aeruginosa and other pseudomonad. 

History

Bronopol was invented by The Boots Company PLC in the early 1960s and first applications were as a preservative for pharmaceuticals. Due to its low mammalian toxicity at in-use levels and high activity against bacteria, especially Gram-negative species,bronopol became popular as a preservative in many consumer products such as shampoos and cosmetics. It was subsequently adopted as an antimicrobial in other industrial environments such as paper mills, oil exploration, and production facilities, as well as cooling water disinfection plants.

Production

Bronopol is produced by the bromination of di(hydroxymethyl)nitromethane, which is derived from nitromethane by a nitroaldol reaction.World production increased from the tens of tonnes in the late 1970s to current estimates in excess of 5,000 tonnes. Manufacturing today is the business of low cost producers, mainly in China.

Use

Bronopol is used in consumer products as an effective preservative agent, as well as a wide variety of industrial applications (almost any industrial water system is a potential environment for bacterial growth, leading to slime and corrosion problems - in many of these systems bronopol can be a highly effective treatment).

The use of bronopol in personal care products (cosmetics, toiletries) has declined since the late 1980s due to the potential formation of nitrosamines. While bronopol is not in itself a nitrosating agent, under conditions where it decomposes (alkaline solution and/or elevated temperatures) it can liberate nitrite and low levels of formaldehyde and these decomposition products can react with any contaminant secondary amines or amides in a personal care formulation to produce significant levels of nitrosamines (due to the toxicity of these substances, the term 'significant' means levels as low as 10s of parts per billion).

Manufacturers of personal care products are therefore instructed by regulatory authorities to avoid the formation of nitrosamines which might mean removing amines or amides from the formulation, removing bronopol from a formulation, or using nitrosamine inhibitors.

Bronopol has been restricted for use in cosmetics in Canada.