| SUBJECT |
ONE OF THE STUDIES the plastics council refers to was conducted by Rochelle W. Tyl, research director for reproductive and developmental toxicology at Research Triangle Institute (RTI). In this research, 8,000 Sprague-Dawley rats were fed a diet containing bisphenol A at levels ranging from lower than those tested by Hunt to more than 1,000 times higher. No evidence for reproductive or developmental effects was found at any environmentally relevant dose [Toxicol. Sci., 68, 121 (2002)]. But the RTI study has design problems. The Sprague-Dawley strain of rat that Tyl chose has been shown in several published articles to be insensitive to BPA. Those studies show that BPA binds in the vagina of the Sprague-Dawley rat, but causes no effect on the organ. This is the only rat known to be unresponsive to BPA, vom Saal says. In addition, Tyl also used no positive control. In most low-dose studies of estrogenic substances, such a control is used to test whether the animals, under the experimental conditions, respond to a known strong estrogen, such as diethylstilbestrol. For a test of reproduction and development, "what we want is the most sensitive animal, and the most sensitive outcome in that animal, in order to assess the greatest probability of human harm," vom Saal says. In contrast to the claims of the plastics council, there are 35 studies that do show physiological effects in rodents from BPA exposures at and even below the doses Tyl used |
| UPDATE | 05.03 |
| AUTHOR | Rochelle W. Tyl, research director for reproductive and developmental toxicology at Research Triangle Institute (RTI). |
|
Want more information ? Interested in the hidden information ? Click here and do your request. |