Diethylstilbestrol (DES)

Diethylstilbestrol is a synthetic nonsteroidal estrogen. It is also classified as an endocrine disruptor. Human exposure to DES occurred through diverse sources, such as dietary ingestion from supplemented cattle feed and medical treatment for certain conditions, including breast and prostate cancers. DES gained notoriety when it was shown to cause a rare vaginal tumor in girls and young women who had been exposed to this drug in utero.Subsequent studies have shown an approximate 40-fold increased risk of vaginal/cervical clear cell adenocarcinoma in women exposed in utero to DES. As a consequence of this evidence, DES is considered an established human carcinogen. DES was one of the first transplacental carcinogens discovered in humans, meaning a toxin could cross the placenta and harm the fetus.