Canada banned the manufacture, import, advertising or sale of baby bottles that contain BPA to protect infants. (Jonathan Hayward/Canadian Press)

Women should be counselled about reducing their exposure to environmental hazards such as bisphenol A in some plastics, U.S. obstetricians say, on the heels of the first measurements of the chemicals in pregnant women in Canada.

Researchers in the U.S. found one in five of the 2,500 physicians surveyed routinely asked pregnant women about their exposure to toxic chemicals such as bisphenol A and phthalates that can have harmful reproductive effects.

Bisphenol A (BPA) is used to make polycarbonate plastics and can be found in food and drink packaging. BPA is widespread and some animal studies suggest effects in fetuses and newborns exposed to the chemical, even at low doses.

Phthalates are found in air fresheners and dish soap, and have been linked to obesity and miscarriages.  

"Obstetricians feared broaching the topic of environmental health with patients, especially regarding chemicals other than lead and mercury. They felt they did not have adequate knowledge and understanding to answer patients’ questions about exposures, and that this conversation would take time away from easier topics to address, like nutrition," said Dr. Naomi Stotland, an obstetrician and researcher at the University of California, San Francisco School of Medicine. She and her team did the study in this week’s issue of journal PLOS One, published by the Public Library of Science.

About 78 per cent of obstetricians agreed they could reduce patient environmental exposures by talking to them about the topic. But less than 20 per cent regularly ask about phthalates, BPA, pesticides and PCB.

In contrast, virtually all of the doctors, 99 per cent, said they routinely counselled pregnant women about cigarette smoking, alcohol, weight gain and diet or nutrition.

BPA banned in baby bottles

Since 2010, Canada has banned the manufacture, import, advertising or sale of baby bottles that contain BPA. Both BPA and a phthalate called Di(2-ethylhexyl) or DEHP are on Health Canada's list of prohibited and restricted cosmetic ingredients.

Last week, Health Canada published the first results of its Maternal-Infant Research on Environmental Chemicals study that looked at phthalate and BPA exposure among pregnant Canadian women.

Exposure to the chemicals among pregnant women is “comparable to, and in some cases lower” than what was found in a national survey of women of reproductive age.​

Phthalate breakdown products or metabolites were found in over 95 per cent of the urine samples.

Health Canada will continue to monitor Canadians’ exposure to BPA through biomonitoring studies such as the Canadian Health Measures Survey, a spokeswoman said in an email. As part of the study, the department will also work with academic scientists "to examine the associations between maternal exposure to BPA and potential effects, if any, on the health of mother and baby."

Exposures 'widespread but low'

"Given the evidence from laboratory animal studies that these chemicals can disrupt hormone systems leading to developmental changes, it is important to keep doing research on these chemicals," said Scott Venners, a professor in the faculty of health sciences at Simon Fraser University. He’s studied environmental endocrine disruptors and human reproduction and now applies biomonitoring studies to inform public health policy research.

"We can see clearly now that exposure to BPA and phthalates in pregnancy is widespread, but low," Venners said in an email.

The time from conception to birth is one of the times when we’re most sensitive to these chemicals. To limit exposure before birth would require harder policy steps to protect all women of reproductive age, he said.

There are steps that women can take to reduce their exposure. In the U.S. study, obstetricians participating in a focus group commented on the barriers they face.

Preventive steps

"The information has to come in two pieces, like what does it mean for you and what can you do about it if you want to avoid it," one doctor said in a focus group for the study.

Environmental Defence, which lobbies governments and corporations for environmental policy changes, said it’s important that the Canadian research has been done.

Tim Gray, the group’s executive director, said endocrine disruptors mimic the behaviour of hormones that cause our bodies to mature. Tiny amounts can send confusing messages.

Gray gave some suggestions to reduce exposure:

  • Avoid using plastic and stick to containers with 2, 4 or 5 in the recycling symbol.
  • Air out your house.
  • Try to avoid products with BPA and phthalates.
  • Connect with provincial and federal governments to ask for clear labels and changes to the rules that allow products on the market without testing.

The U.S. study was funded by New York Community Trust, Passport Foundation, Johnson Family Foundation, the U.S. National Institute for Environmental Health Sciences and the U.S. Environmental Protection Agency.

With files from CBC's Marijka Hurko