Banned rat poison may still pose threat

A highly toxic rodent poison, banned worldwide since 1984, may still pose a risk to public health due to its continued illegal sale and use, according to a team of medical experts.

TETS, short for tetramethylenedisulfotetramine, is an odorless, tasteless, lethal chemical that was once used worldwide as a rodenticide. The substance is still illegally sold in China, where it has been used, on numerous occasions, in intentional mass poisonings.

As recently as April 2004, for example, 74 people in Tongchuan City were poisoned after consuming scallion-flavored pancakes that were tainted with TETS. In September 2002, about 400 people were poisoned by TETS-contaminated food, and 38 people died.

Yet, the illegal use of TETS does not appear to be confined to China. In May 2002, TETS poisoning, albeit unintentional, occurred in New York City as well. As Reuters Health previously reported, a 15-month-old infant developed permanent brain damage as a result of exposure to the highly toxic substance.

The little girl had been playing in an area that her parents had recently sprinkled with the rodent poison, which they had purchased in China. She was taken to the hospital after she began developing seizures.

While this is the only known case of TETS poisoning in the United States, it points to the "special public health risk in large urban areas with significant immigrant populations whose members may have used these substances successfully as rodenticides in their countries of origin," writes Dr. Kenneth Scott Whitlow of the Virginia Commonwealth University Health System in Richmond and colleagues.

TETS, a white, crystalline powder that dissolves easily in water, is so potent that it meets the World Health Organization's criteria for "extremely hazardous" pesticides, the authors note in their report published online February 21 in the of Annals of Emergency Medicine.

China banned its use in 1984, due to its toxicity to humans, but it is still easily obtainable on the black market. The chemical was never registered for use in the United States.

And the 2002 incident suggests that some people in the United States may currently be using the banned chemical. "If this one couple brought it in, maybe someone else could as well," he said. "Now we know that people are getting it here, the question is how many people have it and what are they using it for."

Most people may use the chemical "for its original purpose (and) may not understand it's banned here," Whitlow said.

It's a "great rodenticide - it does what it is supposed to do," he added. "The problem with the drug is its high toxicity to humans." While it cannot be absorbed through skin unless it is cracked or otherwise wounded, a person can die from ingesting as little as 10 milligrams of the substance, Whitlow said, adding that "any exposure could considerably cause problems." There is no known cure for TETS poisoning.