FRIDAY, July 13, 2001 (HealthDayNews) -- Fathers whose jobs expose them to chemicals and irritants, like solvents and wood dust, may increase their children's risk of a rare childhood cancer.
Children of fathers exposed to lacquer thinner and other hydrocarbons had a 50 percent greater risk of contracting neuroblastoma, compared with children whose parents had no job exposure to the chemicals, say epidemiologists at the University of North Carolina. They studied the jobs of the parents of 593 children with neuroblastoma. On-the-job exposure to wood dust also increased the risk by 50 percent.Though mothers may not be completely out of the woods, too few women in the study were exposed to the pollutants to draw any conclusions, the researchers say.
Study author AnneClaire DeRoos says the findings, which are reported in the latest issue of The American Journal of Epidemiology, should be considered in perspective.
"Even if there is a 50 percent increase in risk for this disease, that is an increased risk from a very low risk in the first place because of the rarity of the disease," she says. "Further, this is the very first study that has ever looked at these exposures, and no conclusions can be based on the results of one study."
Neuroblastoma, a rare cancer of the nervous system, affects one of every 80,000 to 100,000 children, a third of whom contract the disease before they are 1 year old. It is the third most-common cancer in children, with about 550 new cases reported each year, says the American Cancer Society. When found early, the cure rate is high.
Until more research is done, DeRoos says workers should continue to follow all the safety measures printed on the containers of chemical products.
DeRoos and her colleagues conducted phone interviews with all the mothers and 405 of the fathers of 593 American and Canadian children who were diagnosed with neuroblastoma between 1992 and 1994. In addition, researchers interviewed 304 fathers whose children did not have the cancer as a control group.
Parents were asked about their occupations, the locations and dates of employment for the two years before the birth of their children and whether and how often they had been exposed on the job to chemicals, dusts, fumes, gases, vapors or oils.
Of the parents of ill children, 46 fathers and 17 mothers reported exposures high enough to analyze. Among fathers, exposures to hydrocarbons, particularly lacquer thinner, mineral spirits and turpentine, were associated with the highest increase -- 50 percent or more -- in the incidence of neuroblastoma in their children, compared with parents who did not have chemical exposures.
Fathers exposed to wood dust also showed a 50 percent increase in incidence of neuroblastoma. In addition, paternal exposure to several metals was associated with disease incidence, but too few men had the exposure to statistically matter.
Exposure to other chemicals, however, like oil and water-based paints and plastics didn't increase the risk of children getting the disease.
DeRoos says neuroblastoma develops in stages, and "that the first part could be the father's exposure to chemicals that are causing changes in sperm DNA."
University of Pennsylvania epidemiologist Timothy Rebbeck says, "It may be plausible that parents may be exposed to something that causes genetic damage, but it is notoriously difficult to do exposure assessments, and if you don't do it right, there is a lot of error."
He says one problem is recall bias, meaning the parents might report exposure to chemicals because they know their children have cancer. He says many other variables, from the questions that were asked to how exposure was measured, make repeat studies difficult, and those studies are needed to prove any theory.
DeRoos says though "it is hard to get good exposure information," the study could be a preliminary step in understanding the causes of neuroblastoma.
"Little is known about the causes of neuroblastoma, and parents' occupations is one area of research," she says. "It may be important because [so many children] are being diagnosed at young ages and pre-conception and pre-natal information is important."