Hormone-Disrupting Toxin Found in Polystyrene Containers 

Kyodo Tokyo 27apr98

Polystyrene,   -(CH2CH-benzene ring)-

Officials of the National Institute of Health Sciences in Japan were cited as saying Sat. that polystyrene containers, commonly used in the packaging of instant noodles and fresh foods in supermarkets, have been found to contain toxic substances known to disrupt the reproductive functions of animals and humans.

The story says the substances, grouped under the term ''environmental hormones,'' may contaminate food through absorption. The chemicals, which mimic hormones, are styrene polymers called styrene dimmer and styrene trimer. Styrene, a colorless, toxic liquid used in making plastics and rubbers, is also known as phenylethylene or vinylbenzene. The institute's study is the first to confirm through lab tests the possible elution of styrene foam, a commonly used material whose residual effects have thus far escaped close examination.

Yoko Kawamura, head of an institute office in charge of food additives, said tests have found high concentrations of the polymers in 25 types of polystyrene containers, with an average of 9,509 micrograms and a maximum of 21,430 micrograms per gram. One microgram equals 1-millionth of a gram.

In a series of tests, researchers simulated the effect of high-fat foods in cups and bowls found to contain the highest concentrations of the toxins in order to determine how much of the chemical compound would dissolve into an organic solvent. They found that no less than 43.9 micrograms of styrene trimer dissolved in 1 square centimeter of the material.

Impact resistant polystyrene was found to have contained particularly high amounts of dissolved substances. Tests did not detect any traces of the substances in containers holding water heated to 60 C. The institute will announce the test results at a meeting of the Food Hygienic Society of Japan in Tokyo starting May 13.

''While we do not know much about polymers as a hormone-disrupting substance, we have to be careful about the presence of the substances in containers that come into direct contact with the food we eat,'' Kawamura said.

She said she wants to conduct more tests to find out how much of the dissolved substances contaminate food. Last year, an Environmental Agency research team counted more than 67 environmental hormones as having an adverse effect on the normal functioning of hormonal systems.

One type of toxin, known as bisphenol-A, affects a living organism by mimicking estrogen or sex hormones and causing hormonal reactions like lowering sperm production in males and reducing the number of full-term pregnancies.