It has been observed that in the previous decades, male infertility has ostensibly been on the rise, accompanied by increases in testicular cancer and hypospadias - a congenital defect in which the opening of the urethra is on the underside, rather than at the end, of the penis. Taken together, these three conditions have been termed testicular dysgenesis syndrome. This may explain periodic reports of a worldwide decline in sperm count and quality.

Environmental chemicals known as phthalates, some researchers say, may be the cause of the problem. Used in the manufacture of plastics, phthalates at sufficiently high levels have been seen to interfere with male fetal development. Some studies have found that hypospadias are more prevalent among male infants today than they were 30 years ago.

Now, a team of researchers based at NewYork-Presbyterian Hospital/Columbia University Medical Center and Children's Hospital of Philadelphia have taken a fresh look at the data and have found no rise in rates of hypospadias in New York State from 1992 to 2005. Similar findings have been reported by researchers looking at state-level data in Washington and California.

These studies break the link between the purported cause -- phthalates -- and their presumed effect -- impaired male reproductive health, says Dr. Harry Fisch, director of the Male Reproductive Center at NewYork-Presbyterian Hospital/Columbia University Medical Center and professor of clinical urology at Columbia University College of Physicians and Surgeons.