A father's farm work, especially if it involves pesticides, may put his unborn child at risk of a rare liver disorder, according to a new epidemiologic study. Although the finding is very preliminary, it may help scientists track down the origins of this often deadly defect.
Children with biliary atresia are born with missing or underdeveloped bile ducts. Normally, these tubes carry bile from the liver to the small intestine. But in infants with biliary atresia, the bile backs up, causing liver inflammation, yellowing of the skin and an inability to properly digest fatty foods. Surgery can sometimes correct defective ducts, but in many cases the damaging inflammation recurs. Unless these children receive a successful liver transplant, they may face early death.
Scientists know very little about the causes of biliary atresia, which strikes about one in every 25,000 babies born in the United States. Now, researchers report a statistical link between a father's farming occupation and his offspring's risk of the birth defect.
At the Johns Hopkins University School of Hygiene and Public Health in Baltimore, Carol Magee and her co-workers contacted pediatric surgeons across the United States and located 267 families of children born with the disorder between 1982 and 1987. They also recruited a control group of 245 families whose children had been treated for other conditions by the same pediatric surgeons, in most cases for hernia repair. All parents filled out detailed questionnaires asking about their age, personal habits and occupational history, including past exposure to pesticides.
Statistical analyses revealed no link with biliary atresia for most of the factors on the questionnaire. However, the team discovered that fathers of children with biliary atresia, compared with control fathers, were about twice as likely to have worked on a farm, and these men were more than twice as likely to report pesticide exposure than were farm-working fathers in the control group. A link between farm work and biliary atresia also showed up on the maternal side, but this trend was statistically weaker than the paternal association, says Magee, now at the University of Maryland in Baltimore. She presented the results last week at the Teratology Society's annual meeting in Boca Raton, Fla.
Magee suspects that farm chemicals handled by the father reach the developing fetus via the mother. For example, women who handle clothes dusted with pesticides may absorb the chemicals through their skin -- an indirect route to the fetus. On the other hand, she says, pesticide exposure might somehow alter the father's sperm, affecting the fertilized egg directly.
But she cautions that her survey does not prove a cause-and-effect relationship between farm pesticides and biliary atresia. "I don't think we know enough to issue a public health alert," she says. "We have a lot more work to do." Among other things, Magee wants to identify specific pesticidal chemicals that would prevent normal development of the bile ducts.
COPYRIGHT 1991 Science Service, Inc.
COPYRIGHT 2004 Gale Group
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