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Is Congo Red vegan?

Congo Red is a synthetic azo dye and the sodium salt of 3,3′-([1,1′-biphenyl]-4,4′-diyl)bis(4-aminonaphthalene-1-sulfonic acid). It is water-soluble, yielding a red colloidal solution, and was formerly used in the textile industry but has been largely abandoned due to its carcinogenic properties. It is still used as a histological stain and as a pH indicator.

Classifications are made to the best of our knowledge based on available scientific and regulatory sources. We cannot guarantee the accuracy of every entry, errors in the sources we draw from can always occur. This tool also cannot account for cross-contamination, which depends entirely on individual suppliers and producers. If you believe a classification is incorrect, you can report an issue.