Nov 13

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Meet our 20 Pioneers under 40 in Environmental Public Health: Courtney Carignan, PhD


Courtney Carignan, PhD, got interested in the field of environmental health, and toxic chemicals more specifically, while she was doing work as an environmental consultant and risk assessor after college. One day when she was doing some indoor air monitoring she had to remove chemicals and paint cans in order to do the testing and wondered about their safety.

“We have regulations on chemicals in our ground water and air but it was unclear to me what was known about exposures and safety of these products. … So, I went back to school to get my PhD related to that concern and also to be able to help communities understand what it can mean for their health to have such exposures,” Dr. Carignan explains.

Since getting her PhD, a lot of her work has focused on flame-retardants, which are another class of chemicals that are often brought into the home willingly and possibly without realizing the potential health effects they can have.

“Some concerning findings about flame retardants are that prenatal exposure (in the womb) can affect child neurodevelopment and may be obesogens. Also, I recently published a study that found women with higher exposures to the organophosphate flame-retardants were less likely to become pregnant. In adults, some flame-retardants have been associated with changes in thyroid function, for example the level of thyroid hormone that we measure in blood. Also, recent studies have reported possible associations with thyroid cancer incidence.,” Dr. Carignan says.

With many types of flame-retardants in the world today, there are many adverse health effects that researchers are still discovering and worrying about. A related worry is that while flame-retardants such as the polybrominated diphenyl ethers (PBDEs) were banned and phased out of use they have been replaced with other flame-retardants such as the organophosphates, which were marketed as safer but are being found to have similar health concerns. While they do have some improvements, like leaving our bodies more quickly, scientists don’t know enough about the health effects of these replacements to be sure they won’t be regretted later down the road.

Flame-retardants as a class are specifically worrisome because “they are not chemically bound, they are just added [to the final product]. Because they are semi-volatile, they essentially evaporate from those products and can pass right through fabric or even leather it seems,” Dr. Carignan explains. 

Not only do they evaporate from these products, but also they are good at attaching to other things in the environment and entering our bodies.

“I like to think of [flame-retardants] as sticky. They basically stick to your hands, dust, and pretty much any surface. Because they stick to our hands one of the main ways they get into our bodies is through accidental dust ingestion - since we all ingest a little bit of dust every day. This is true for everyone, and particularly true for young children who also do a lot of mouthing behaviors,” Dr. Carignan says.

Unlike other chemicals that can leave the body quickly, the chemicals found in flame-retardants, even newer ones, can take years to exit. In fact, “some of these flame-retardants like PBDEs accumulate in your body over time, and have been doing so since you were in [your mother’s womb],” Dr. Carignan warns.

While this may sound scary, there are some ways to reduce your exposure and lessen the amount of these chemicals that accumulate in the body over time.

The first thing is to know what types of products contain flame-retardants. This helps people become a more informed consumers and look or ask for better options. According to Dr. Carignan, some of the most common products with flame-retardants in them are:

  • Polyurethane foam like that in couches, office chairs, carpet padding, vehicle seat, plane seats, baby car seat, certain baby cribs, and mattress pads/toppers
  • Gymnastics safety equipment like landing mats and the foam pit
  • Building insulation like blue board and spray foam
  • Tents for camping or children’s play time
  • Plastic casings on electronics that get warm like audiovisual equipment, television sets, laptops, CPU towers
  • Nail polish

The next step is to look at the tags on those products and understand what they mean. Some tags may say, “free of harmful flame retardants.” That means this product “might contain organophosphates because for a while, they were not considered harmful,” Dr. Carignan says.

Other tags may read “Free of additive flame retardants.” Those are “likely free of PBDEs and the organophosphate flame retardants, but might contain one of these newer chemically bound flame retardants, that hopefully are safer,” Dr. Carignan explains.

One other tip from Dr. Carignan, beyond becoming an informed consumer, is to use iodized salt.

“We know that flame-retardants can act on thyroid hormones and iodine is a micronutrient that is important for proper thyroid function. Iodized salt is good because it helps [people stay] iodine sufficient, and we need iodine. You don’t want to have too much iodine, that’s bad, but using iodized salt should help keep your iodine levels in the right place,” Dr. Carignan shares.

Ideally, the solution regarding flame-retardants would be to make sure that chemicals that are in products and on the market are safe. This is tough because while products might meet current standards, these standards can be outdated. 

“The field [of environmental health] has evolved, and now we know more but the standards haven’t really caught up,” Dr. Carignan says.

So, until legislation changes to match what scientists have discovered, the safest thing to do is to become informed consumers and ask your representatives to push for updated and stronger safety standards.

Takeaway Tips from Dr. Carignan:

  • Check your products and avoid flame retardants when you can
  • Wash your hands regularly, especially before you eat, to remove flame retardants that may stick to them during daily activity
  • Use iodized salt

We wanted to find the best young researchers and advocates who might change the future of environmental health. So, we asked a panel of luminaries in environmental health to nominate rising stars who are doing pioneering work. After a rigorous selection process, we invited 20 of these nominees to be our 20 Pioneers under 40 in Environmental Public Health.

This month, we held our second webinar in the series. In addition to these presentations, we got to sit down and learn a little bit more about the researchers. While we did talk about their research, we also learned how they first got interested in the field and what this work means to them, plus a few tips for staying healthy.


Tags: built environmentthyroidflame retardantswebinarsreproductive health