[devereaux]

And when it's mixed with benzoic acid? (the 'salting' process mentionned)

From Bing:

Is benzoic acid a carcinogen?

It is considered safe only at less than a .1% concentration in a finished product (Source) When benzoic acid and vitamin C (ascorbic acid) or citric acid are present, under the right conditions of heat and light, these two ingredients can combine to create the known carcinogen, benzene.