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New research presented at the Endocrine Society's annual meeting in San Francisco has suggested that fetal exposure to bisphenol A (BPA) is linked to undescended testicles in newborn boys. The study does not prove a direct cause-effect relation between the exposure and the condition, researchers note.

However, the study found a link between BPA exposure and low levels of a developmental hormone that is associated with undescended testicles. Results from the early study add to the growing list of concerns linked to the chemical, which is commonly found in food packaging and a range of other consumer goods. Approximately 92 percent of the U.S. population have detectable levels of BPA in their bodies, the researchers stated.

The study focused on newborn boys with a condition known as cryptorchidism, commonly called undescended testicles. This means that the testicles remain stuck in the abdominal cavity but in many cases they descend on their own within about six months after birth. Typically, the condition affects between two percent and five percent of all newborn boys and if it does not resolve itself the condition requires surgery to be corrected. Scientific data suggests that boys who have suffered the condition are more likely to experience fertility problems and testicular cancer when they are adults.

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According to researchers, the level of the hormone insulin-like 3, or INSL3, one of two hormones that regulate descent of the testicles, was lower in boys with cryptorchidism that also had high levels of BPA in their fetal cord blood. Still, a direct link could not be drawn between BPA and cryptorchidism because the newborns with undescended testicles did not have significantly higher levels of BPA, compared with babies without the condition. However, researchers found that the level of the chemical in newborns' cord blood inversely correlated with the level of INSL3, meaning that the higher the BPA level, the lower the level of the important testicular hormone.

Meanwhile, the level of testosterone, the other hormone involved in testicle descent, was not influenced by the level of BDA detected in the body.

For their research, scientists analyzed 12 studies published between 1980 and 2010 that looked into the link between cryptorchidism and testicular cancer. Based on the findings of those studies, the researchers then calculated that boys with cryptorchidism were almost three times more likely to develop testicular cancer later in life than those without the birth defect. Their conclusions raise the question of whether these boys should be regularly monitored in an attempt to reduce their potential risk of developing testicular cancer, the researchers said.

Dr. Patrick Fenichel, head of reproductive endocrinology at the University Hospital of Nice, France, commented that this was the first study to link BPA to cryptorchidism in humans. Previous research on animals has suggested an association between fetal BPA exposure and a higher risk of reproductive problems, among other health issues.