Posted By Enrique Garcia on April 29, 2001 at 16:33:53:

I wonder if anybody can help me out with this:

I have been testing organic and aqueous extracts of sludge derived from a printing industry which uses azo-pigments (mostly diazo).
The organic extract (methylene chloride and subsequent solvent exchange to DMSO)has yielded positive results in Ames's test on strain 98, especially with S9 metabolic activation, however aqueous extracts do not give positive results.
I imagine that this is a problem of availibility of the normally very insoluble pigment to the S9 enzyme sistem and to that of the bacteria themselves. In a suitable organic vehicle the azo bond is probably reduced leading to the production of aromatic amines.
Has anybody had a similar case. How does legislation in the US or elsewere treat this issue ?, would you consider this muyagenic effect which only takes place after using an unnatural extraction system, as risk. This is important, as I feel that probably this problem is common to most azo dyes and pigments. Considering the relevance of this sector, does anybody have something to say. Is this an issue anywhere ?.

Thank you in advance to all. Any help will be most appreciated.

Enrique García
Environmental Toxicologist

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