Research due to be published today by Which? magazine is expected to herald the latest in a long line of consumer panics over the safety of food on UK supermarket shelves. The Consumer Association tested 316 samples of raw, fresh chicken products from five of the country's major supermarkets and found that around one fifth of those surveyed were contaminated with bugs that can cause food poisoning. Two serious bugs, salmonella and campylobacter, were present in 16% of the meat pieces sampled, but experts warn that this figure may underestimate the true extent of contamination because the tests used are not the most sensitive.