Q. Calcium propionate and related preservatives belong to the GRAS list of chemicals, "Generally Recognised as Safe". The public has been assured for decades that the safety of these chemicals is conclusively proven. If indeed propionates are found to be unsafe, what assurance do we have of the safety of other food-additive chemicals on the GRAS list? - email, Sydney.

A. Additives are never tested for their behavioural toxicity, that is, their effects on children's behaviour or learning. There are no assurances regarding behavioural safety of any additives. There are 50 "safe" additives that have been associated with behaviour problems, see list on the website.