Determination of the oestrogenic (uterotrophic) activity of extracts of 'general purpose polystyrene (GPPS)' using immature female rats

In Japan there is growing concern about the possible adverse effects of consumption of food from styrene containers (mainly those made from polystyrene paper) due to the alleged oestrogenic activity of styrene oligomers (dimers and trimers), which may migrate into the food. To examine the possible oestrogenic activity of styrene dimers and trimers, extracts were made from 'general purpose polystyrene (GPPS)' and administered orally to immature female rats over a 4 day period. Increase of uterus weight (wet and blotted) was used for assessment of possible oestrogenic activity. To establish the sensitivity of the test method, immature rats were treated with diethylstilboestrol (DES), a well-known oestrogenic compound. It was found that treatment of rats with levels of up to 60 microg of styrene dimers and 930 microg of styrene trimers per kilogram body weight per day did not give any statistically significant increase of the uterus weight (wet or blotted), whereas DES caused statistically significant, dose-related increases in uterus weight at levels as low as 0.89 microg kg(-1) body weight day(-1). It was concluded that, compared with the estimated maximum human daily intake of styrene trimers of 1 microg kg(-1) body weight day(-1) from polystyrene food containers, the risk of adverse human health effects with respect to oestrogenicity may be considered negligible.