At Children's Hospital of Philadelphia, surgeon Howard Snyder says he and his colleagues repair the genitalia of roughly 300 baby boys every year - about double what they did when he started his practice 30 years ago.
He's not the only doctor who's noticed an increase in this kind of birth defect.
The most common of them, hypospadias, nearly doubled in the United States between the late 1960s and early 1990s, according to researchers from the Centers for Disease Control and Prevention.
Snyder suspects that while in the womb, some of these boys may have been affected by hormone-disrupting chemicals called phthalates, found in dozens of consumer products.
These chemicals give plastics flexibility, prevent perfumes from losing their scents, and keep nail polishes from chipping.
But in lab rats and mice, doses comparable to those we humans absorb from the environment can disrupt the formation of male genitals and otherwise feminize male animals. One small study from the University of Rochester also linked these chemicals to irregularities in male genital development.
Despite that, phthalates are added to numerous products ranging from deodorants to shower curtains to IV tubing in hospitals.
While the European Union has banned one type of phthalate in nail polishes and several others in children's toys, the U.S. Environmental Protection Agency is "assessing the toxicity of several phthalates," and awaiting results of a National Research Council study, expected next year, a spokesman said.
The specific problem that concerns Children's Hospital's Snyder - hypospadias - is considered an incomplete development of the male organs, causing a boy's urethra to exit the underside of his penis. In most cases, surgeons can reroute the urethra, but it can take several difficult operations.
While there's yet no direct link between this defect and phthalates, the dramatic increase in cases and the animal data have many doctors concerned.
The American Chemistry Council, a trade group, defends the compounds, saying that the animal data may not apply to humans.
Chris Bryant, a council spokesman, cited a council news conference, stating that dozens of studies found no link between phthalates and adult diseases.
Industry and federal toxicologists also questioned the validity of the one human study, he said, because it was small and flawed in its methods.
