Easy to scare, harder to prove

There is no doubt that people have died after consuming L-tryptophan, an essential amino acid. But biotech opponents may find it convenient to ignore the fact that scientists have ruled out genetic engineering as a cause of the deaths.

The FDA, regulators in other countries and scientists who have spent years studying the issue still don't know precisely why an L-tryptophan product manufactured by Showa Denko K.K. over a six month period in 1988 and 1989 caused scores of people to get sick and more than 30 to die. But according to Gerald Gleich of the Mayo Clinic