STANFORD, Calif. A study of several hundred chemicals used in commercial pesticides has found only weak evidence that any of them are associated with a common birth defect in male infants.
The study, led by epidemiologists at the Stanford University School of Medicine, analyzed thousands of birth records and commercial pesticide application records for eight counties in California's heavily agricultural Central Valley. The researchers aimed to determine whether children were at increased risk of hypospadias if their mothers had lived in relatively close proximity to where pesticides were used while pregnant. Hypospadias is a genital malformation in which the urethral opening is on the underside of the penis rather than on the tip.
In the most detailed study of the largest data sets done to date, 292 individual chemicals and 57 groups of structurally similar chemicals were analyzed. Of those, the study identified 15 that had possible associations with hypospadias. But the researchers say further studies need to be done.
"We didn't see many chemicals that suggested an increased risk, and of those that did, most of them were infrequently used," said Suzan Carmichael, PhD, associate professor of pediatrics and lead author of the study to be published Oct. 28 in Pediatrics. "It is good news that such exposures are rare, but at the same time, when exposures are rare, it makes studies harder to do."
Approximately five of every 1,000 male infants are born with hypospadias, but the cause is usually unknown.
Most previous studies of pesticides and hypospadias focused on risks associated with occupations that involve the use of pesticides. Some studies have suggested slightly increased risks for infants whose mothers or fathers work around pesticides, but many studies suggest no association.
The researchers worked with data on births in the counties of Fresno, Kern, Kings, Madera, Merced, San Joaquin, Stani
|Contact: Louis Bergeron|
Stanford University Medical Center