Hypospadias, a congenital defect of the penis in which the opening of the urethra is on the underside of the penis, has been blamed on in utero exposure to chemicals known as phthalates, but a US study challenges this notion and says there is no evidence of a link.
The study, by researchers from NewYork-Presbyterian Hospital/Columbia University Medical Center and Children's Hospital of Philadelphia, notes that in recent decades male infertility has been on the rise accompanied by increases in hypospadias. Other studies have suggested plastics chemicals known as phthalates may be the cause of the problem.
Used in the manufacture of plastics, phthalates at sufficiently high levels can interfere with male fetal development. Some studies have found that hypospadias are more prevalent among male infants today than they were 30 years ago.
To explore this apparent association further, Dr. Harry Fisch, director of the Male Reproductive Center at NewYork-Presbyterian Hospital/Columbia University Medical Center and co-researchers took a fresh look at hypospadias rates in New York State from 1992 to 2005. Fisch says the team found no statistically significant increase during that period. He believes that poor quality data from earlier studies may be the problem. "It's all in the data," says 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."
Fisch's work challenges the link between the purported cause - phthalates - and their presumed effect - impaired male reproductive health. The only significant risk factor for hypospadias that emerged from 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.
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Source: NewYork-Presbyterian Hospital/Columbia University Medical Center