Bronopol


 * Bronopol (C 3 H 6 BrNO 4 )**

It is suspected that this can cause skin or sense organs toxic hazards, it is also suspected that it can cause gastrointestinal and liver toxic hazards. It is harmful if it comes into contact with skin or if it is swallowed. Bronopol is dangerous for the environment, is extremely toxic to water organisms, and is an irritant. Bronopol is a preservative and antiseptic that is used in cosmetics and topical medications. It is used as a preservative in paints, textiles, cooling towers, humidifiers, and hide processing. It is used as a preservative/antiseptic in cleaning agents, paints, and shampoos and hair products. Symptoms from Bronopol can be coughing and sore throat if it gets inhaled. The skin can become red and irritated. There would be redness and stinging if it gets into the eyes.

In summary, bronopol can cause skin irritation, partially breaks down to formaldehyde, and is a severe eye irritant in its concentrated form (EPA R.E.D.). The LD50 for bronopol is approx. 300-350 mg/kg in rats. If exposure occurs, bronopol is rapidly absorbed & excreted from the body. Bronopol poses low risk of developmental or reproductive effects. Bronopol is not a carcinogen (EPA Group E). The environmental fate is highly dependent on ambient conditions, the half-life in water can range from 1.5 years (20 deg. C and pH6) to 3 hours at higher temperatures and pH. A major metabolite from degradation is formaldehyde. Bronopol is slightly toxic to avian species; slightly toxic to freshwater fish; moderately toxic to freshwater invertebrates; and moderately –highly toxic to marine invertebrates.

Bronopol is supplied as crystals or crystalline powder, which may vary from white to pale yellow in colour depending on the grade of material being offered. The yellow colouration is due to chelation of iron during the manufacturing process. As a pure material, Bronopol has a melting point of about 130°C. However due to its polymorphic characteristics, Bronopol undergoes a lattice rearrangement at 100 to 105°C and this can often be wrongly interpreted as the melting point. At temperatures above 140°C Bronopol will decompose exothermically releasing Hydrogen bromide and oxides of Nitrogen. Bronopol is readily soluble in water although the dissolution process is endothermic. Solutions containing up to 28% w/v are possible at ambient temperature. Bronopol is poorly soluble in non-polar solvents but shows a high affinity for polar organic solvents. Solubilities at 22–25°C
 * Appearance:**
 * Melting Point:**
 * Solubility:**
 * Solvent || %w/v ||
 * Water || 28 ||
 * Methanol || 89 ||
 * Ethanol || 56 ||
 * Isopropanol || 41 ||
 * Liquid Paraffin || <0.5 ||

Was used frequently in the 1980's in cosmetics and other toiletries, however the use in these substances has declined.


 * allergic contact dermatitis;
 * Bronopol (2-bromo-2-nitropropane-1,3-diol);
 * patch testing;
 * sensitization rate;[[image:3-250x250.jpg align="right"]]
 * multicentre trial;
 * cosmetics;
 * medicaments

A total of 8149 patients were patch tested with the preservative Bronopol in 7 European contact clinics. The Majority of patients (6507) were investigated in London. Reactivity was low, with a total of 10 irritant (0.12%) and 38 allergic reactions (0.47%). In only 17 cases (0.21%) was the patch test reaction to Bronopol considered to be of current or past clinical relevance. Concomitant sensitization to formaldehyde was present in about 1/3 of patients. Based on these figures, the present sensitization rate to Bronopol in Europe seems to be quite low, which may be related to its less frequent use as a preservative in cosmetics and medicaments in comparison to parabens or isothiazolinones.

When conditions are such that Bronopol decomposes in aqueous solution, very low levels of formaldehyde are produced. Liberated formaldehyde is not responsible for the biological activity associated with Bronopol. Amongst other decomposition products detected after Bronopol breakdown are, bromide ion, nitrite ion, Bromonitroethanol and 2-Hydroxymethyl-2-nitropropane-1,3-diol.

Applications
Today, 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 Nitrosamine Problem
Although fairly ubiquitous in our diet and the environment, and even produced within the [|stomach] from various foodstuffs, many nitrosamines are known or suspect [|carcinogens] and therefore should be avoided in manufactured goods. Nitrosamines are relatively easily produced from secondary [|amines] and [|amides] in the presence of [|nitrite] [|ions] (this is why they are formed in-vivo from foodstuffs). 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 thes 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

Degradation
When conditions are such that Bronopol decomposes in aqueous solution, very low levels of formaldehyde are produced. //Liberated formaldehyde is not responsible for the biological activity associated with Bronopol//. Amongst other decomposition products detected after Bronopol breakdown are, bromide ion, nitrite ion, Bromonitroethanol and 2-Hydroxymethyl-2-nitropropane-1,3-diol.