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Toxic L-tryptophan: Shedding Light on a Mysterious Epidemic
by William E. Crist
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Japanese Identify Second Impurity in L-tryptophan
Copyright 1992 Asahi News Service
Asahi News Service
JUNE 23, 1992, TUESDAY
LENGTH: 595 WORDS
HEADLINE: JAPANESE IDENTITY SECOND IMPURITY IN L-TRYPT
DATELINE: TOKYO
KEYWORD: TRYPTOPHAN
BODY:
Japanese government researchers have identified a second chemical impurity in L-tryptophan, a dietary supplement that caused 38 deaths and more than 1,500 complaints of severe muscle pain and blood circulation problems in the United States, the researchers said June 23.
Some members of the science community say L-tryptophan could be the first major case of genetic engineering gone wrong.
However, the researchers said more studies need to be done to determine the source of the impurity and whether it can be linked to the side effects.
Showa Denko K.K., the producer of L-tryptophan, has reported only two cases of side effects in Japan to the Japanese government.
L-tryptophan is produced from an amino acid produced by genetically altered hay Bacillus bacteria. Showa Denko genetically altered the Bacilli to increase the bacteria's production of the serine used to manufacture L-tryptophan.
Mitsuru Uchiyama, head of the government research team and director of the National Institute of Hygienic Sciences, said the impurity detected was phenyl-amino-alanine [PAA]. The chemical is a combination of an aniline, a toxin, and a serine, a non-essential amino acid produced by the inserted gene.
Some environmentalists have said the impurity is probably a previously unaccounted for byproduct of the DNA recombinant bacillus that creates the chemical source for tryptophan, because the chemical structures of the phenyl-amino-alanine and a known product of the inserted gene are similar.
The other impurity, called Peak E has been identified in the United States.
"We still need more study before we understand how those two impurities were made during the manufacturing process," said Uchiyama. "Also, we should investigate the causal mechanism of the chemical."
"We did not use any analine compounds anywhere in the manufacturing process," said a spokesman for Showa Denko. "We should wait for more studies in order to identify the cause and effect relationship between the derivative (phenyl-amino-analine) and the symptoms."
Some researchers have said the tryptophan side effects might be an unforeseen outcome of genetic engineering.
"Although we still don't know where the aniline comes from, it is obvious that the serine should have a close relationship with the DNA recombinant bacillus," said Kiyoshi Toda, lecturer on environment studies at Tsurubunka University. "There is a possibility that the case was the first accident caused by DNA recombinant food products."
Shingo Shibata, professor of environmental sociology at Hiroshima University, said the case clearly illustrates the dangers of biotechnology.
"There are still a lot of unknown things around biotechnology," he said. "The case is a warning bell for high technology."
Showa Denko started exporting L-tryptophan in 1982 as a raw material for health foods. But it was also sold as a treatment for depression and insomnia in the United States.
Between 1988 and 1989 more than 1,500 Americans who ate health foods containing L-tryptophan developed severe side effects such as severe muscle pain and a rapid increase of the number of acidocytes, a type of immune cell.
At least 89 victims have suit against Showa Denko in the United States, seeking at least $810 million. Most of the cases have been already settled out of court. Showa Denko will not disclose the number of cases and how much compensation is being sought through the courts.
Distributed by The New York Times Special Features/Syndication Sales
Reprinted with permission of the Asahi Shimbun Company, Tokyo, Japan.
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