Study links occupational exposures with risk of miscarriage

Anesthetic gases, radiation, pesticides are areas of concern for pregnant workers
Published on May 01, 2008
information-circle This article is more than 3 years old

A new study out of Australia suggests that pregnant veterinarians who have occupational exposures to anesthetic gases, radiation, or pesticides may have twice the risk of miscarriage.

Similar studies in the United States, however, have found only that occupational exposures to radiation or anesthetic gases have a weak or insignificant association with the risk of miscarriage among veterinarians or other veterinary personnel.

IVeterinariann general, the AVMA as well as U.S. veterinary specialists in radiology and anesthesiology do recommend that pregnant veterinary personnel pay special attention to protective measures for reducing occupational exposures.

"It's something that we just need to be reminded of," said Dr. Pete Bill, director of the Purdue University Veterinary Technology Program and a former member of the AVMA Committee on Veterinary Technician Education and Activities. "We shouldn't become complacent."

The Australian study came to the same conclusion.

"The Australian Veterinary Association is concerned about the results of this study," said Marcia Balzer, AVA national communications manager. "Occupational health and safety have been a high priority for the AVA for many years."

The study, "Maternal occupational exposures and risk of spontaneous abortion in veterinary practice," appeared online ahead of print in the British Medical Journal: Occupational and Environmental Medicine. The study analyzed self-reported occupational exposures in relation to miscarriage among Australian veterinarians during 940 pregnancies from 1960-2000.

The authors reported finding significant associations between risk of miscarriage and having occupational exposure to unscavenged anesthetic gases for one or more hours per week, performing more than five radiographic examinations per week, or using pesticides at work.  

In practice

Veterinarians and other veterinary personnel often work through pregnancy without any problems, of course. 

Dr. Barbara F. Monaghan is the mother of three school-age children and co-owner of two animal hospitals in Birmingham, Ala., as well as a member of the AVMA Council on Veterinary Service.

"I practiced right until the day I delivered, times three, and I really didn't change a whole lot," Dr. Monaghan said. "We did update and go from a passive scavenging system to an active scavenging system because I do a lot of surgery, but I don't know that that was absolutely necessary."

Dr. Monaghan said radiation and pesticides pose safety issues more for her pregnant veterinary technicians and kennel workers, so the staff tries to cross train in other job responsibilities. She considers a veterinary clinical practice to be a safe work environment for pregnant personnel because the risks are manageable.

Dr. Laurel Kaddatz, owner of Pound Ridge Veterinary Center in New York and vice chair of the CoVS, said the recent Australian study keeps precautions foremost in people's minds.

"For me, looking at this study as a practitioner, it reaffirmed the safety measures we take in our hospital," he said. "We have active scavenging systems for anesthetic waste gases; personnel aren't in the X-ray room during film exposure; and we don't do any topical pesticide application here, either."

Dr. Kaddatz said his hospital does not need to do pesticide dips any more because of the development of effective injections and topical applications, the latter of which he can send home with clients.

Dr. Kaddatz said precautions in most practices have improved since he graduated from veterinary college 31 years ago—with the advancement of medical treatment, increasing awareness of employee safety, and development of governmental regulations and guidelines. 

In policy

On the recommendation of the CoVS, the AVMA last updated the information and language of the "AVMA position on veterinary facility occupational risks for pregnant workers" in late 2004.

"For me, looking at this study as a practitioner, it reaffirmed the safety measures we take in our hospital. We have active scavenging systems for anesthetic waste gases; personnel aren't in the X-ray room during film exposure; and we don't do any topical pesticide application here, either."


The policy starts by stating: "Although scientific data concerning the reproductive health effects of many occupational exposures is limited, the goal of creating a safe work environment for pregnant workers can be facilitated by awareness of inherent risks and then adopting procedures to minimize risk exposure."

The policy lists radiologic, biologic, and chemical exposure as areas of concern for pregnant workers. The policy states that pregnant workers ideally should avoid exposure to X-rays, anesthetic gases, and pesticides. The policy also notes biologic risks to pregnant workers from rabies, tetanus, toxoplasmosis, and other diseases as well as from animal bites.

According to the policy, any worker who cannot avoid X-ray exposure should wear shielding and a monitoring badge. To reduce exposure to anesthetic gases, veterinary facilities should maintain anesthetic machines to ensure leak-free operation and use efficient scavenger systems to remove waste gases.

To reduce pesticide exposure, ventilation is essential, and pregnant workers should wear protective clothing to minimize absorption of pesticides through the skin. The AVMA policy adds that handling hormones and chemotherapeutic agents requires the same precautions.

Radiation safety 

Dr. Robert D. Pechman Jr., executive director of the American College of Veterinary Radiology and a visiting professor at the Oklahoma State University Center for Veterinary Health Sciences, said every veterinary professional is aware that radiation is dangerous. 

"Everybody is taught to wear aprons and gloves; we're all taught to stay out of the X-ray beam," Dr. Pechman said. Yet, even though radiation safety is a standard part of veterinary curricula, veterinary professionals may become lax about precautions. "I get radiographs all the time with bare fingers on them."

Dr. Pechman said pregnant women stay out of the radiography room at Oklahoma State University. The university's radiation safety officer checks radiographic equipment and protective gear—gloves, aprons, thyroid shields, and film badges. The state and federal governments also regulate radiation safety.

Dr. Pechman noted that more than half the radiologists with whom he currently works are women, and accommodating pregnant workers isn't always simple. He said veterinary faculty place a high priority on radiation safety, nevertheless.

Several studies of U.S. veterinary personnel have linked radiation exposure with risk of miscarriage.

The 1996 study "Occupational exposures and risks of spontaneous abortion among female veterinarians," which appeared in the International Journal of Occupational and Environmental Health, found a weak association between risk of miscarriage and radiation exposure among small animal practitioners.

The 1990 study "Adverse reproductive outcomes among female veterinarians," which appeared in the American Journal of Epidemiology, found that veterinarians who performed five or more radiographic examinations per week had a marginal elevation in the risk of miscarriage.

Anesthetic gases

Dr. Robert E. Meyer, a diplomate of the American College of Veterinary Anesthesiologists and associate professor at the Mississippi State University College of Veterinary Medicine, said the safety issue isn't as straightforward with anesthetic gases.

Much of the research on anesthetic gases and reproductive health has consisted of studies relying on self-reporting of occupational exposures, Dr. Meyer said. He said these epidemiologic studies may find a link but not necessarily a cause-and-effect relationship because of confounding factors such as stress, fatigue, and work hours.

The 1987 study "Effect of waste anesthetic gas and vapor exposure on reproductive outcome in veterinary personnel," which appeared in the Journal of the American Industrial Hygiene Association, did not find a significant association between exposure to anesthetic gases and adverse reproductive outcome after adjusting for radiation exposure. For nitrous oxide specifically, though, the study did find a significant association between exposure and risk of miscarriage in veterinary assistants and in wives of male veterinarians who had exposure.

In 1996, the JAVMA published "Commentary and recommendations on control of waste anesthetic gases in the workplace," by a committee of the ACVA. The report recommended implementing control programs for anesthetic gases despite conflicting evidence on the dangers of exposure.

"I still think we should be emphasizing that people should be scavenging their waste anesthetic gases," Dr. Meyer said.

The federal government does not regulate safety measures for exposure to anesthetic gases, though the Occupational Safety and Health Administration does provide guidelines on the subject.  

Pesticides, informational resources

As for pesticides, the Environmental Protection Agency has not regulated occupational use by veterinarians or veterinary staff. Last year, the EPA was considering a certification requirement for occupational users that might have included veterinarians. The AVMA urged the EPA to continue exempting veterinarians from certification because of their skills and knowledge relevant to pesticides. 

The EPA's human-health risk assessments for many pesticides are available online at, under "Facts" to the far right of each chemical name. The National Pesticide Information Center also provides fact sheets at

Information from OSHA on other worker safety and health topics, including ionizing radiation and waste anesthetic gases, is at The ACVA report on control of waste anesthetic gases is available at by clicking on "Professional Links" and then on "Position Statements."

The AVMA policy on pregnant workers is online here. The policy urges workers who become pregnant or plan to become pregnant to consult with their obstetrician and inform their employer as soon as possible.