PHBA alkyl esters

PHBA alkyl esters are more effective against moulds and yeasts than bacteria, however, they are also useful for the control of bacterial growth. As membrane-active microbicides, their primary mode of action is based on nutrient transport... 

Chemical and physical properties of PHBA alkyl esters... 

Contact dermatitis caused through PHBA alkyl esters occurs occasionally, especially in cases where the esters are used at higher concentrations (5%). At concentrations of 0-5% allergic skin reactions in general fail to appear. As preservatives for pharmaceuticals, cosmetics and food, PHBA alkyl esters are normally used at an average concentration of 0-2%. WallhSusser (1984) mentions an allergy quota of 0-3-0 8% for PHBA alkyl esters. 

Table 67. Minimum Inhibition Concentrations (MIC) of PHBA Alkyl Esters in Nutrient...

The application of PHBA butyl ester as a preservative in cosmetics and pharmaceuticals is, in spite of its high activity, very limited because of the low water solubility and is restricted to the application in combination with other PHBA alkyl esters (see Sections 6.1.10.1-6.1.10.3). PHBA butyl ester is permitted for use in cosmetics (EC list). 

These are mainly in the preservation of foods, pharmaceuticals and cosmetics, although there is a certain sensitization potential. PHBA alkyl esters are also used for the in-can protection of technical functional fluids, when one looks for particular odourless and colourless preservatives. Using PHBA alkyl esters for the protection of non-ionic surfactant solutions one has to bear in mind that binding effects may occur which reduce the antimicrobial efficacy. This is valid for anionic alkaline detergent solutions, too. Macromolecules, e.g. saccharosee-sters, polyoxy-40-stearate, polyvinyl-pyrrolidone, methylcellulose and carboxymethylcellulose, are also able to... 

---