Traces of the antibiotic nitrofuran, which is thought to cause cancer, have been found in a number of samples of imported poultry and shrimp, according to the Swiss Federal Office of Public Health.

Forty-three of 121 tested samples of poultry and shrimp imported from Asia and South America were found to contain levels of nitrofuran that were above the safe limit.

Switzerland imposed a safety limit on levels of nitrofuran on 14 August 2002, after traces of the antibiotic were found in poultry imported form China, reported Swiss News Digest.