Bronopol is a preservative and antiseptic used in cosmetics and topical medications. It is used as a preservative in paints, textiles, cooling towers, humidifiers, and hide processing. Used as a preservative antiseptic in cleaning agents, paints, and shampoos and other hair products.
Bronopol is widely used as a bactericide, e.g. in the cosmetics and pharmaceutical industries and in paint, in cutting fluids and for water treatment. In these preparations, bronopol commonly features in concentrations of about 0.01 to 0.1%.
The substance is also used for slime control in paper making machinery systems, for which purpose it has to be approved the National Chemicals Inspectorate. Concentrations in slime control agents are about 10-20%, i.e. much higher than in the preparation first mentioned.
The main cause of slime formation is said to be the growth of certain species of bacteria, but also certain fungi.
Bronopol is effective in pH 5-8 and presumably more so in alkaline environments where it is also more rapidly degraded. The mechanism is to form disulphide bonds in the proteins of the micro-organisms, which then inhibit the metabolism of the organism.
Bronopol from Union Carbide also contains the contaminant 2-hydroxymethyl-2-nitropropane-1,3-diol in concentration of 3-3.5% by weight, i.e. 25% of the total Bronopol content. This contaminant is formed in the synthesis of Bronopol and is a known formaldehyde former. It is used as a biocide in other connections, e.g. in cutting fluids. Concentrations for biocide effect are then 1,000-2,000 ppm, and the effect is achieved through formaldehyde formation. Figures reported concerning the contaminant suggest that it does not contribute towards the effect of Bronopol.
A trial was carried out to test the efficacy of bronopol against infection of rainbow trout broodstock with the fungus Saprolegnia species. Replicate groups of 20 fish were held in each of four raceways.
Two groups were treated in baths containing 20 mg bronopol/litre for 30 minutes on 15 consecutive days, and the other groups were treated in a similar way with a placebo. In the treated groups the percentages of infected fish decreased during the trial from 70 per cent and 40 per cent to 0 per cent, whereas the percentages in the placebo groups increased from 45 to 74 per cent and from 35 to 55 per cent; the severity of the infection also increased in the placebo groups.