Nurses who worked with chemotherapy drugs or sterilizing chemicals were twice as likely to have a miscarriage as their colleagues who didn't handle these materials, in a new study.
Lead author Christina Lawson, a researcher at the National Institute for Occupational Health and Safety (NIOSH), said she was not too surprised that exposure to certain chemicals would be tied to lost pregnancies.
"What surprised me the most was that (chemotherapy) drugs are something we've been trying to educate nurses on, about the hazards, and we're still finding exposures during the first trimester," Lawson told Reuters Health.
Because chemotherapy drugs typically target rapidly dividing cells, such as those in a tumor -- or a fetus, they have been a concern for pregnant women who come into contact with them, Lawson said.
Not all previous research has agreed on whether nurses' exposures at work are tied to more miscarriages, though.
To help resolve the issue, Lawson and her colleagues set out to do a larger study than the earlier ones.
They surveyed nearly 7,500 nurses who had had a pregnancy between 1993 and 2002.
The nurses were asked to remember how often they worked with certain chemicals or equipment, such as X-rays, anesthesia, anti-cancer drugs and disinfectants, during each trimester.
One out of every 10 nurses ended up losing her pregnancy before the half-way point, 20 weeks.
Lawson said that number seems similar to the rate of miscarriages in the general population.
However, among nurses who handled chemotherapy drugs for more than an hour a day, that rate was double - about two out of every 10 nurses lost her pregnancy.
NIOSH is the organization that provides safe-handling recommendations for workers who use chemicals.
Barbara Sattler, a nursing professor at the University of Maryland, said the results reflect a lack of adherence to those safety guidelines.
"I know most hospitals try to do the best they can, but if all these nurses are lining up with spontaneous abortions...it's a significant issue to be addressed," said Sattler, who was not involved in this study.
Nurses who gave patients X-rays had a slightly higher risk of miscarriage too, about thirty per cent larger than nurses who didn't work with X-rays.
And nurses who handled sterilizing agents, such as ethylene oxide or formaldehyde, more than an hour a day also had a doubled risk of miscarriage, but only during the second trimester.
Lawson said that miscarriages during the second trimester might result from a toxin affecting the mother's ability to carry the baby, whereas a miscarriage in the first trimester suggests the toxin is affecting the fetus.
She added that it's difficult to determine the cause of the miscarriages seen in the study because the researchers don't know which chemicals each woman had contact with, and for how long.
Additionally, the current study only drew a link between the chemicals and the miscarriages, but did not prove that the materials caused the women to lose their pregnancies.
The surveys asked nurses to remember back sometimes as far as eight years, which leaves room for inaccuracies as well.
Lawson said her group is working on a follow-up study to get more precise information on exposures at work.
There are two million female nurses in the United States, making up four per cent of the female workforce, the researchers write in the American Journal of Obstetrics and Gynecology.
Nurses aren't the only ones exposed to chemotherapy drugs and sterilizing chemicals, they note. Pharmacists, drug manufacturers and veterinarians, to name a few, also handle these materials.
Sattler said it's important that nurses and their employers stick to safety guidelines, and that perhaps more strict enforcement of occupational regulations by the government might help protect workers.