Messaggio
da paracelso » ven gen 27, 2006 1:40 pm
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It is demonstrated that in aqueous solutions, imidazolidinyl urea, diazolidinyl urea sodium
hydroxymethyl glycinate and benzylhemiformal release some or all of the formaldehyde they
contain, and thus, they may not be available for analysis as parent compounds in cosmetic
products.
A MEKC method is published for the analysis of imidazolidinyl urea, in which it was not
established that the chromatographic peak obtained by the analysis of imidazolidinyl urea was in
fact the intact compound. The method could not be reproduced in another testing laboratory.
Similarly, a HPLC method is published for the analysis of diazolidininyl, in which it was not
established that the chromatographic peak obtained by the analysis of diazolidinyl urea was
infact the intact compound. Furthermore, the applicability of the HPLC method validated for the
analysis of diazolidinyl urea in an experimental cream has not been demonstrated for the analysis
of this compound in the marketed cosmetics. HPLC, CZE and NMR studies have indicated that
both imidazolidinyl urea and diazolidinyl urea may be a mixture of isomers. It appears that it is
impossible, with present state of knowledge, to develop a method(s) for the analysis of
imidazolidinyl urea and diazolidinyl urea as parent compounds in cosmetic products.
Sodium hydroxymethyl glycinate and benzylhemiformal, present in a cosmetic product,
theoretically should release all of the formaldehyde they contain. Thus, an analytical method(s)
for the identification and quantification of these preservatives in cosmetic products is not
necessary.
The maximum authorised concentrations of imidazolidinyl urea, diazolidinyl urea, sodium
hydroxymethyl glycinate and benzylhemiformal in cosmetic products are based on the Opinions
of SCC/SCCNFP. Only in the case of benzylhemiformal, SCCNFP considered complete
decomposition of the preservative releasing total formaldehyde of the compound as free
formaldehyde. The decomposition product of Sodium hydroxymethyl glycinate, e.g. sodium
glycinate cannot be considered harmful. As regards the decomposition products of
imidazolidinyl urea and diazolidinyl urea, it may be considered that they were present in the test
solutions used in the experiments performed for the elucidation of toxicity of the parent
compounds. And thus, the safety profile of the decomposition products has been elucidated
together with that of parent compounds.
A possibility to overcome the unavailability of the analytical method(s) for these 4 formaldehyde
releasers may be to determine total formaldehyde content in a product and relate this amount to
the amount of the formaldehyde releaser. But this approach can only be used when the
formaldehyde releaser in a product can be unequivocally identified, and when it is guaranteed
that there is only one source of formaldehyde in the product. Both of these conditions appear to
be impractical.
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aggiungo che ho varie esperienze di formaldeide libera , in forma gassosa fino a gonfiare il packaging, in cosmetici mal formulati :-)))
