Women workers who are exposed to low-level radiation emitted by video-display terminals do not appear to have a heightened risk of miscarriages, government researchers said.
A study involving 2,430 female telephone operators found no significant difference in the miscarriage rates between those who used the terminals and those who did not, Teresa Schnorr of the National Institute for Occupational Safety and Health in Cincinatti said Wednesday.Schnorr said the impetus for the study grew out of scattered reports of "clusters" of miscarriages among women workers who used computer terminals and thus were exposed to low-level electromagnetic radiation.
However, among 323 young women who worked with the terminals and became pregnant during a three-year period and 407 closely matched women who did not use the screens, the miscarriage rates were nearly identical, Schnorr and colleages reported in The New England Journal of Medicine.
The overall miscarriage rates were 14.8 percent for the VDT-exposed pregnancies and 15.9 percent for those not exposed, they said. Both figures fell within published estimates that somewhere between 11 percent and 20 percent of all pregnancies end in miscarriages, they noted.
"I think the study is reassuring for women who are concerned about working with VDTs and the subsequent risk of miscarriages," said Schnorr.
However, Dr. Donald Mattison, dean of the University of Pittsburgh's Graduate School of Public Health, said the results should be interpreted cautiously because the study relied on the women's recall of pregnancy outcomes rather than the results of pregnancy tests.
Mattison, whose research focuses on reproduction and toxicology, said that because a large proportion of miscarriages occur before a woman knows she is pregnant, such studies are likely to underestimate the miscarriage rate.
"Of the conceptions that occur, I believe probably 30 to 40 percent miscarry, with only about half taking place after the pregnancy is recognized," he said.
The rest of the time, miscarriages occur so early that a woman is likely to dismiss the event as the onset of menstruation, Mattison said.