production.
This week, in an online report in Toxicological Sciences, researchers showed that dioxin has a profound effect on breast tissue by causing mammary cells to stop their natural cycle of proliferation as early as six days into pregnancy, and lasting through mid-pregnancy. In tissue samples from mice, exposure to dioxin caused a 50-percent decrease in new epithelial cells. This is important, Lawrence said, because mammary glands have a high rate of cell proliferation, especially during early to mid-pregnancy when the most rapid development of the mammary gland occurs.
Researchers also found that dioxin altered the induction of milk-producing genes, which occurs around the ninth day of pregnancy, and decreased the number of ductal branches and mature lobules in the mammary tissue.
The timing of dioxin exposure also seemed to be significant, the study noted. For example, when exposure occurs very early in pregnancy but not later, lab experiments showed that sometimes the mammary glands can partially recover from the cellular injury. However, although it is important to understand timing of exposure for research purposes, it is irrelevant for humans, who cannot really control their exposure to dioxins, Lawrence said.
"Our goal is not to find a safe window of exposure for humans, but to better understand how dioxins affect our health," she said. "The best thing people who are concerned about this can do is think about what you eat and where your food comes from. We're not suggesting that we all become vegans -- but we hope this study raises awareness about how our food sources can increase the burden of pollutants in the body. Unfortunately, we have very little control over this, except perhaps through the legislative process."
Much of Lawrence's research focuses on a transcription factor known as aryl hydrocarbon receptor, or AhR. When pollutants enter the body they bind to AhR, which then turns on certain g
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| Contact: Leslie Orr leslie_orr@urmc.rochester.edu 585-275-5774 University of Rochester Medical Center Source:Eurekalert |
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