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In recent decades, there have been periodic reports of a worldwide decline in sperm count and quality. 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.

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.

"It's all in the data," says Dr. Fisch. "For one, the entire method of collecting data on birth defects has changed. Statewide surveillance of birth defects has become the norm. This calls into question the value of the older data.

"Second," he adds, "we can't assume that these chemicals are harmful at low, environmentally allowable levels just because we've seen high rates of exposure to phthalates in utero have been linked to hypospadias in animal studies."

In the study, Dr. Fisch and and his colleagues reviewed the total number of cases of hypospadias in New York State from 1992 to 2005 and found no statistically significant increase during that interval. These findings have just been published in the May 2009 issue of the Journal of Urology. Co-authors included Drs. Terry W. Hensle and Grace Hyun of NewYork-Presbyterian Hospital/Columbia University Medical Center, and Dr. Sarah M. Lambert of Children's Hospital of Philadelphia.

When combined with recent research showing that sperm counts are not declining, the current study suggests that testicular dysgenesis syndrome may not be a problem in humans, contrary to earlier concerns.

The only significant risk factor for hypospadias that emerged from Dr. Fisch's research is maternal age. Children of mothers aged 35 years and older show higher rates of the birth defect — a finding that is consistent with other recent epidemiological studies.

Most hypospadias can be surgically repaired in the first year of life by a pediatric urologist.

More on Phthalates

In July 2008, Congress approved a ban on the use of phthalates in children's products, such as teething rings, rubber ducks, and soft toys. However, these chemicals are ubiquitous in today's environment. Also known as plasticizers, they are found in shampoo, pharmaceuticals, medical supplies, pesticides, plastic wrap, garden hoses, and plastic clothing, among other common products.

Given their suspected detrimental effects at high levels of concentration, questions arise around how to regulate phthalates and other human-made environmental chemicals.

"Environmental chemicals need to be regulated," says Dr. Fisch, "but policies should be based on science, not fear."

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Columbia University Medical Center

Columbia University Medical Center provides international leadership in basic, pre-clinical and clinical research, in medical and health sciences education, and in patient care. The Medical Center trains future leaders and includes the dedicated work of many physicians, scientists, public health professionals, dentists, and nurses at the College of Physicians & Surgeons, the Mailman School of Public Health, the College of Dental Medicine, the School of Nursing, the biomedical departments of the Graduate School of Arts and Sciences, and allied research centers and institutions. Established in 1767, Columbia's College of Physicians and Surgeons was the first institution in the country to grant the M.D. degree and is now among the most selective medical schools in the country. Columbia University Medical Center is home to the largest medical research enterprise in New York City and state and one of the largest in the United States. For more information, please visit www.cumc.columbia.edu.

NewYork-Presbyterian Hospital

NewYork-Presbyterian Hospital, based in New York City, is the nation's largest not-for-profit, non-sectarian hospital, with 2,242 beds. The Hospital has nearly 2 million inpatient and outpatient visits in a year, including more than 230,000 visits to its emergency departments — more than any other area hospital. NewYork-Presbyterian provides state-of-the-art inpatient, ambulatory and preventive care in all areas of medicine at five major centers: NewYork-Presbyterian Hospital/Weill Cornell Medical Center, NewYork-Presbyterian Hospital/Columbia University Medical Center, NewYork-Presbyterian Morgan Stanley Children's Hospital, NewYork-Presbyterian Hospital/The Allen Pavilion and NewYork-Presbyterian Hospital/Westchester Division. One of the largest and most comprehensive health care institutions in the world, the Hospital is committed to excellence in patient care, research, education and community service. NewYork-Presbyterian is the #1 hospital in the New York metropolitan area and is consistently ranked among the best academic medical institutions in the nation, according to U.S.News & World Report. The Hospital has academic affiliations with two of the nation's leading medical colleges: Weill Cornell Medical College and Columbia University College of Physicians and Surgeons.