May 8, 2007 -- Add farmed fish to the list of animals that have been fed melamine-tainted food made from Chinese ingredients -- but pose little risk to humans, according to the FDA.
Melamine is a nitrogen-containing molecule that has several industrial uses. It has been used as a fertilizer in some parts of the world, but melamine isn't a registered fertilizer in the U.S.
"We have discovered melamine in fish [feed]," the FDA's David Acheson, MD, told reporters in a news conference today.
Acheson, who is the FDA's assistant commissioner for food protection, explains that the tainted ingredients came from the same two Chinese companies linked to melamine-tainted pet food and animal feed fed to U.S. hogs and poultry.
Those Chinese companies shipped the tainted ingredients to Canada, which produced fish feed that was then shipped to several U.S. fish farms.
Acheson said he doesn't know how many fish (or what types of fish) might have eaten the tainted fish feed.
"This is a new finding. It's a very active part of the investigation," Acheson says.
Low Risk to Humans
"At this point, based on the risk assessment and the levels that we know of in the fish [feed], as with the hogs and the poultry, we do not believe that this poses any significant human health threat," Acheson says.
"Even if these fish have been fed this fish [feed], we believe that the risk to humans is low," Acheson says.
"We know of a number of firms that received this fish [feed], and our investigators are getting out there to determine exactly what they are doing with the fish that have been fed this fish [feed].
"We have so far managed to get to one of these establishments, where we confirmed the positive finding," Acheson says. "That particular establishment is dealing with very small fish ... these are tiny fish that are not yet ready for human consumption."
Tainted Wheat Flour
At the news conference, Acheson also announced that FDA tests on melamine-tainted Chinese ingredients already under investigation were conducted on mislabeled products.
The labels said the products contained wheat gluten and rice protein concentrate. But they actually contained wheat flour.
"I realize this is a perfect storm for total confusion," Acheson says. "Even though it's labeled gluten and we all thought it was gluten -- [and] it was used as gluten -- it wasn't. It was mislabeled and was actually wheat flour.
"The material that was tested that we found to be the wheat flour was the same sample, the same material that had been tested positive for melamine," Acheson says. "It does not represent new batches from different companies, different countries, with yet another problem. It is the same melamine-contaminated material which we have just taken to a next level of testing analysis."
Acheson doesn't rule out further scrutiny of wheat flour, but he says there is no evidence of a wider problem with wheat flour.
There continues to be no sign that melamine-tainted products are in human food, except for the tainted animal feed, according to Acheson.
"We do not believe that any of these ingredients have gone directly into the human food chain. None of that has changed," Acheson says.
Theory on Mislabeled Flour
Acheson described what he called a "plausible hypothesis" about why the wheat flour was mislabeled as wheat gluten.
"Now, this is the point at which we become speculative, but it may throw some light onto how does this all fit together," he says.
Wheat flour contains wheat gluten, which is high in protein. "Rather than taking the trouble to extract the wheat gluten ... you simply grind up the wheat, put it all together, and then artificially create the appearance of it being high in protein by adding a high-nitrogen-containing compound such as melamine."
Yesterday, the FDA and USDA announced that melamine-tainted animal feed fed to hogs and poultry posed "very low" risk to humans. Based on test results, the USDA has begun to clear some hogs and poultry that had temporarily been held from the market due to the tainted animal feed.