Shanna Swan, professor and vice chair for research and mentoring at Mount Sinai Medical Center, pushed her research in the right direction by collecting extra samples.
Swan is known for her research on phthalates, the chemical used to make plastics flexible, and the effects they have on fetal development. She presented her research to the public at the Life Sciences and Society Symposium at MU on March 14.
In 1998, Swan began working on a study of semen quality in the partners of pregnant women. Although males were the focus of the study, she also asked pregnant women to provide urine samples during different stages of their pregnancies. This was fortuitous, because it provided data Swan needed later.
“This urine was ‘golden’ and allowed us to do the next study,” Swan said.
In a follow-up study, Swan focused on how prenatal phthalate exposure affected the reproductive organs of the babies in the previous study. She turned her to specifically scrutinize how levels of the MEHHP phthalate in the mother’s urine affected the baby’s Anogenital Distance (AGD), which is the distance between the anus and the genitalia.
In her studies, Swan found that males who had genital defects, such as hypospadias and cryptorchidism, had shorter AGDs compared to males who had no genital defects. Her research also showed males with a longer AGD had a higher sperm concentration, and those who were fathers had a significantly longer AGD than those who weren’t.
Ultimately, her research showed the more fetuses were exposed to phthalates, the shorter their AGD would be, compared to the fetuses who weren’t exposed to as many.
Now Swan is turning her eye to study how stress influences the effects of phthalates. She has found that stressful events during the mother’s pregnancy resulted in their girls having a more masculine AGD, while boys had a less masculine AGD.
Plastics and phthalates became more prevalent in daily life following World War II, when petroleum production soared. Now they are everywhere from the packaging of a deli sandwich to the plastic tubing used in hospitals.
“Plastics came everywhere in our homes and everywhere in our diets,” Swan said.
However, Swan’s research has encouraged the Center for Disease Control and Prevention to remove six phthalates from children’s toys.