A growing body of evidence shows that pesticides have powerful repercussions beyond their intended use. Aside from killing pests that threaten farmers' crops, they may also be harmful to benign species and humans. These effects may be found among those who are directly exposed to pesticides, or they may occur in offspring.
Previously, a number of studies suggested that adults exposed to pesticides may be more likely than those who were not to have male children born with hypospadias, a birth defect in which the opening of the urethra is found somewhere on the penis other than the tip. However, conflicting evidence prompted one team of researchers from Stanford University Medical Center to conduct their own study on males born in eight California Counties between 1991 and 2004. They discovered that certain pesticides may be tied to the incidence of hypospadias, but concluded that the link they found was weak, as published in the journal Pediatrics.
What is the burden of hypospadias?
According to the Hypospadias and Epispadias Association, hypospadias affects as many 1 in every 125 live births in the U.S. The severity of the condition depends in part on where the urethral opening forms along the penis. In the mildest cases, it forms a short distance away from the tip of the penis, while in the most severe cases, the opening may appear closer to the scrotum. Additionally, this condition is often accompanied by an extreme curvature of the penis. The U.S. Centers for Disease Control and Prevention noted that hypospadias may make males unable to urinate standing up, and in severe cases, it may make sexual intercourse difficult.
There are no clear causes for hypospadias, but various studies have suggested several risk factors, including maternal obesity during pregnancy, advanced maternal age, fertility treatments and hormones taken either before or during pregnancy.
Most cases of hypospadias require surgical correction, which is done in stages while boys are between the ages of 3 and 18 months. The goal is to correct the placement of the urethral opening, reduce the curvature of the penis and replace the skin in appropriate places on the penis.
Rare exposures complicate research
To understand whether parental exposure to pesticides increases the risk of hypospadias in male children, the authors of the study reviewed 690 cases of the birth defect and compared them to nearly 2,200 randomly selected controls. The study population came from eight counties in California's Central Valley, which has one of the highest rates of pesticide use in the nation. This information was compared to information on maternal exposure to 292 chemical compounds and 57 groups of structurally similar chemicals, primarily between weeks one and 14 of pregnancy.
Ultimately, the researchers found slight connections between hypospadias and 15 chemical compounds. Other results showed that there is no evidence that maternal exposure to multiple pesticides at the same increases the risk of hypospadias.
"We did not see many chemicals that suggested an increased risk, and of those that did, most of them were infrequently used," Suzan Carmichael, Ph.D., associate professor of pediatrics and lead author of the study, said in a statement. "It is good news that such exposures are rare, but at the same time, when exposures are rare, it makes studies harder to do."
According to the CDC, expectant mothers can take steps to help reduce the likelihood their sons are born with hypospadias. These include taking a multivitamin that contains at least 400 micrograms of folic acid, and refraining from alcohol consumption and tobacco use.
