BPA Exposure Tied to Undescended Testicles in Boys
Early study doesn't prove that common chemical causes the condition, experts say
By Dennis Thompson
MONDAY, June 17 (HealthDay News) -- Fetal exposure to the chemical bisphenol A (BPA) has been linked to low levels of a key developmental hormone in newborn boys with undescended testicles, according to an early new study.
The research adds to the list of growing health concerns related to BPA, which is widely used in food packaging. Government studies have shown that 92 percent of Americans have detectable levels of BPA in their bodies.
This study focused on boys with cryptorchidism, the medical term for undescended testicles. The condition occurs in 2 percent to 5 percent of newborn boys, according to the authors, and requires surgery to bring the testes out of the abdominal cavity. Boys born with cryptorchidism have an increased risk of fertility problems and testicular cancer in adulthood.
The researchers found that boys with cryptorchidism who had high levels of BPA in their fetal cord blood also had low levels of the hormone insulin-like 3, or INSL3, one of two hormones that regulate descent of the testicles.
The findings do not draw a direct link between BPA and cryptorchidism, as the newborns with undescended testicles did not have greatly increased levels of BPA compared with newborns without the birth defect.
Researchers found, however, that the BPA level in newborns' cord blood inversely correlated with the level of INSL3. That is, the higher the BPA level, the lower the level of the important testicular hormone.
The study was presented Sunday at the Endocrine Society's annual meeting in San Francisco. The data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
"Alone, our study cannot be considered as definitive evidence for an environmental cause of undescended testis," lead author Dr. Patrick Fenichel, professor and head of reproductive endocrinology at the University Hospital of Nice, in France, said in a society news release. "But it suggests, for the first time in humans, a link that could contribute to one co-factor of [unexplained] undescended testis, the most frequent congenital malformation in male newborns."
This appears to be the first study that shows a link between INSL3 levels and BPA, said Shanna Swan, a professor and vice chair for research and mentoring in the department of preventive medicine at the Icahn School of Medicine at Mount Sinai, in New York City.
"This hormone INSL3 has not been, to my knowledge, previously linked to any endocrine-disrupting chemicals," Swan said. "It's interesting, definitely, and it's an important step."
For the study, Fenichel and his colleagues studied 180 newborn boys between 2003 and 2005, including 52 boys born with one or two undescended testicles. They tested the infants' umbilical cord blood to measure levels of BPA and INSL3.