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Environmental Health Sciences Division's Caroline Smith Studying the Effects of Estrogenic Substances in Certain Household Products

Second year M.P.H. student Caroline Smith spent her summer in the Laboratory for Surgery, Obstetrics and Gynecology, studying the effect of certain plastic components on fetuses, infants and women. These components can leach out of plastic products, such as baby bottles and various forms of plastic packaging, when they are microwaved, autoclaved, or otherwise heated. These chemicals can also be released when the products are brand new and certain chemicals leach out of the incompletely polymerized plastic. The chemicals that Smith is looking at are estrogenic, meaning that they amplify the effect of naturally produced estrogen.

Smith mixes protein extract with a sample buffer before loading it onto a gel for separation. This is repeated many times before a current is applied to the gel and the proteins are "run" through it.

The leaching of certain chemicals out of plastic is one cause of endocrine disruption, in which synthetic or naturally occurring chemicals mimic natural hormones and either amplify or oppose their effect, disrupting the balance of hormones in the body and sometimes causing fetal malformations and health problems such as cancer. Ultimately, Smith would like to determine whether her research method this summer can lead to a "system to. identify potential endocrine disruptors."

To do her research, Smith is using a pharmaceutical model developed to study the effects of diethylstilbestrol (DES), a drug given to women in the 1940's and 50's to prevent miscarriage. DES, an estrogen mimic, caused reproductive tract cancers in the daughters of some women who were given the drug.

Smith is interested in the Homeobox (Hox) genes, developmental genes which are expressed along the reproductive tract. She is looking particularly at HOXA10, a developmental gene in the uterus.

To study the effect of in utero exposure to the plastic components she is studying, Smith is exposing pregnant mice to the chemicals late in pregnancy, when fetal reproductive tract development is occurring. When the female offspring mice are two weeks old, Smith prepares and stains slides of cross-sections of their reproductive tracts. A greater number of cells controlled by HOXA10 that have staining indicates a greater expression of the gene. As her data accrues, Smith will look for a correlation between the amount of staining in certain reproductive tract cells of the offspring and the dose of chemical received by their mothers. In addition, she is looking for anomalies in the placement and degree of expression of Hox genes along the entire course of the reproductive tracts of the female offspring mice.

To study the effect of the chosen chemicals on humans, Smith is using a human endometrial cancer cell line to examine the effect on Hox gene expression of different concentrations of the chemicals she is studying.

"Even though I’m doing laboratory work," Smith says, "I want to bring that back to my public health experience. Because in the wider view, I want to know how many different types of compounds [are endocrine disruptors] and should we find some way to regulate them? Should they not be used? Should we find some way to prevent exposure?"

Smith designed the project and secured funding with the help of Dr. Hugh Taylor, Associate Professor of Obstetrics and Gynecology and the principal investigator on the project, who co-applied for a grant from the Society for Gynecologic Investigation with her. Smith’s work is also supported by a Jan A.J. Stolwijk Fellowship from EPH.

Smith graduated from Fordham University in 2002 and spent a year as a research assistant in an immunology lab at the Rockefeller University in Manhattan prior to coming to EPH.

-Story by Christy Gordon, based on interview with Caroline Smith on July 15, 2004.