Q's and A's

1. Is there any change in the regulatory status of Parabens?
No. No changes were done in the authorized use concentrations of Parabens.
The Maximum allowance in the EU according to the Annex VI of the E.C.D is 0.4% for 1 Paraben and 0.8% for a mixture of esters. These amounts are also allowed in the USA (C.I.R).

2. How Can a formulator use the MIC values to understand the efficiency of the preservative ?
The MIC values give an indication about the activity spectrum of a given preservative.
If, for example, the MIC values for molds are significantly higher than the MIC values for bacteria then the preservative is more effective against bacteria, and the addition of an anti molds preservative may be considered.
The MIC values can give a general indication about the concentration of the oreservative that should be used. One must keep in mind, however, that as growth inhibition of microorganisms is not sufficient and a stronger effect is desired, the concentration of preservative to be used should be higher than it's MIC.
As MIC values are obtained in standard laboratory conditions, they can serve for comparing the activity of different preservatives.
In order to exclude inactivation of the preservative by other components of the formulation a challenge test must be carried out when the formulation is finalized.

3. What kind of microorganisms should we use when we challenge a cosmetic formula?
The basic group of microorganisms that should be used for challenging formulations is given by the USP. This group includes 2 gram negative bacteria (Pseudomonas aeruginosa ATCC 9027, Escherichia coli ATCC 8739), 1 gram positive bacteria (Staphylococcus aureus ATCC 6538), 1 yeast (Candida albicans ATCC 10231) and 1 mold (Aspergillus niger ATCC 16404).
We strongly recommend to add microorganisms that were isolated from the producer environment and from used raw materials to the challenge test.

4. Do cosmetic raw materials have to be registered under REACH ?
Yes. However, as cosmetic raw materials are also subjected to the requirements of the European cosmetics directive (directive 76/768EC), a few exemptions apply.
The main exemptions are given under articles 2(6), 14(5b), 56(5) and 67(2).

5. What preservatives combinations can be suitable for wet wipes ?
Wet wipes preservatives blends suggestions –
Compatibility with the formulation and non woves should be verified.
* Phenochem (0.6%) + Bronopol (700ppm)
* Sharomix 300 (0.5 to 0.7%)
* Phenochem (0.6%-0/8%)) + PHMB (0.1% active)
* Phenochem (0.6%) + DMDMH (0.3-0.4%)
* Sharomix MCI (0.05%) + Bronopol or DMDMH
* Sharomix 702 (1-1.2%) + Sharomix MT (0.1%)
* Sharomix 705, 706 or 707 (1-1.2%)

In case long-chained parabens are unwanted you can replace the Phenochem with Sharomix 824 (MP, EP & PP) or Sharomix ME (MP & EP).
 

6. How can we maximize the preservation effect of organic acids in cosmetics?
As the anti microbial activity of organic acids is attributed to the undissociated form, their performance increases with the drop of pH.
As the pKa of an organic acid represents the pH in which 50% of the acid are in the undissociated form, one must keep in mind that at pH lower than the pKa less than 50% of the acid will be in the active form. The exact dissociation percentage of a certain organic acid at a given pH can be calculated by using the Henderson Hasselblach equation.
 

 

 

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