Canadian Occupational Safety

August/September 2014 19 cardiac and circulatory birth defects. Pregnant workers face these risks in a variety of industries, including phar- maceuticals, health care and mining. Breathing diffi culties aren't the only hazard for pregnant workers and their fetuses. Workers can also inhale dan- gerous drugs that cause birth defects. For example, pregnant nurses who administer aerosolized pentamidine and aerosolized ribavirin to pneumo- nia patients put their fetuses at risk of developing physiological abnormali- ties, according to Marion Rita Alex, an associate professor at Saint Francis Xavier University School of Nursing in Antigonish, N.S. Pregnant workers can also inhale dangerous gases. Sandra Dorman, associate professor of human kinetics at Laurentian University in Sudbury, Ont., has studied respira- tory dangers for pregnant workers in mining. She says some of the worst hazards come from diesel engines used to power vehicles on mining sites. "Some of the byproducts of the exhaust are particulate matter and the particulate is a Class-1 carcinogen. But there's also carbon monoxide and the nitrogen oxide family. They're all hazardous." Carbon monoxide is probably "the scariest one," Dorman says. The gas is common and has an enormous effect on fetal development. She explains that fetal hemoglobin — the substance in red blood cells that carries oxygen — is different from adult hemoglobin. In the fetus, hemoglobin is designed to capture oxygen from the mother's blood rather than from the air. That enhanced ability to capture applies to carbon monoxide as well, which is dangerous. If a pregnant woman inhales carbon monoxide, the gas is completely concentrated in the fetus. "And it takes a long time to unbind, so you're basically inducing hypoxia," Dorman says. "In a normally ventilated mining environment, carbon monox- ide levels shouldn't cause signifi cant adverse effects." But if the vents fail or carbon monoxide builds up for some reason, powered air-purifying respirators (PAPRs), face masks and other per- sonal protective equipment (PPE) can help fi lter the toxins and allow the worker to get herself and her unborn child to safety. proBleMs WitH ppe That said, respirators are complicated for the pregnant worker. "(They are) breathing for two," Dorman says. "They have to bring in more oxygen and expel more carbon dioxide. At the same time, the baby is growing and pressing up into the (mother's) lungs." As the baby grows, mom can't draw air as far down into her lungs. This is why women in the third trimester sometimes feel breathless. The condi- tion may be exacerbated if the worker wears a respirator. "With a respirator, you may have to generate extra force to breathe," Dorman says. The harder it is for someone to breathe, the more tired that person's breathing muscles will become, more quickly. "The concern is if you're fatigued and you don't take in enough oxygen or push out enough carbon dioxide, it's going to be worse for the fetus than for the mom." Respirator fi t is another challenge, according to the United States' Centers for Disease Control and Prevention. "Some respirators must be fi tted to your face to make a tight seal," the organization says on its website. "Weight changes, including weight gained during pregnancy, can affect how a respirator fi ts. If a respirator does not fi t correctly, it may not pro- tect you… We suggest talking to your doctor and safety offi ce to make sure you can wear your respirator safely and correctly throughout pregnancy." Sometimes PPE just won't cut it at all. In 2011 the Canadian Union of Public Employees (CUPE), which represents 474,000 public sector employees across Canada, issued a health and safety bulletin about cytotoxic drugs, which are used in chemotherapy treatment. These drugs may cause tumors and damage or alter DNA. According to the union, the only safe exposure level is zero, and it recommended employers reassign pregnant workers to tasks that don't expose them to these drugs. speak up sooner Even if PPE isn't always the solution, information certainly plays a key role. For instance, although they usually don't disclose their pregnancies to employers until after the fi rst trimester, women might want to reconsider that common practice. "A lot of the critical fetal develop- ment occurs in the fi rst trimester," Dorman says. "That's the time when the fetus develops its spinal cord, brain and heart, as well as other key organs." If a pregnant employee's work involves substances that are danger- ous to a fetus, exposure could be especially damaging during those fi rst few months. Of course, part of the reason a worker doesn't want to tell her employer before 12 weeks about her pregnancy is that the risk of a miscarriage is high in that time, Dorman notes. "You don't want to tell people you're pregnant and then have to explain that you're no longer pregnant in the worst case. Still, I would encourage people to go see their occupational support personnel, such as the hygienist, for advice," she says. "And I think it's important for the employer to provide information about who employees can contact to confi dentially disclose their pregnancies, so best practices can be implemented immediately." accommoDation Accommodating pregnant workers need not be diffi cult. In fact, doing so should be a matter of regular health and safety procedures. That was the situation for Stacey Ritz when she studied at McMaster University in Hamilton. Her PhD research involved examining the molecular and cellular pathways of early allergic responses in the lungs to understand the triggers that lead to allergic disease. Part of her work involved extracting RNA from cells and tissues to analyze gene activation. One standard proto- col for RNA extraction involves the use of a chemical solution called TRIzol, which contains phenol and chlo- roform to help separate the various compounds. Phenol and chloroform have adverse effects on the lungs and the central nervous system in humans, and there is some evidence they may increase the risk of birth defects or miscarriage, Ritz explains. So she always used the fume hood when conducting these experiments. "When I became pregnant, toward the end of my PhD, I didn't change my behaviour because we were already taking precautions to protect ourselves from these chemicals." Companies should keep these matters in mind when creating preg- nant-worker policies to help ensure employees stay safe and their children arrive without experiencing detrimen- tal effects from damaging gases, drugs and other airborne hazards. And what Corman says of her daughter is what every employer wants to hear: "She's smart, energetic and healthy. I don't think my work had any effect on her." Stefan Dubowski is a freelance writer based in Ottawa. He can be reached at dubowski@stiffsentences.com. 2

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