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The Dose Transcript for November 21, 2024

Host: Dr. Brian Goldman

BRIAN GOLDMAN: Hi, I'm Dr. Brian Goldman. Welcome to The Dose. A recent article in The Atlantic caught my eye because of a photo. Well, the content of the article, but also this photo. It depicts a very familiar kitchen utensil made of black plastic that has partially melted. It's something that I've seen in my own kitchen. The article's title is 'Throw Out Your Black Plastic Spatula. It's probably leaching chemicals into your cooking oil.' And that got me thinking. You know, cutlery, food trays, single-use coffee lids. Even kids' toys. And many, many other products are made from, or at least partly made from black plastic. And there's growing evidence that that black plastic that's all around us and sometimes we're consuming is hazardous to people. So this week we are asking: How does black plastic affect my health? Hi, Tiz. Welcome to The Dose.

TIZAZU MEKONNEN: Hi, Brian. Thank you for inviting me.

BRIAN GOLDMAN: So how much black plastic do you have in your home?

TIZAZU MEKONNEN: Quite a bit. [chuckles] I try to be careful as much as possible. I'm trying to reduce my black plastic footprint as much as possible these days, but I do have quite a bit still.

BRIAN GOLDMAN: And I'm looking around in my office here and I've lost count of the number of items that I've got. So the idea that they may be hazardous to our health is of paramount importance to us, or at least it should be. So I'm looking forward to this conversation. But before we begin, can you give us a hi, my name is? Tell us what you do and where you do it.

TIZAZU MEKONNEN: Thank you, Brian. Again, my name is Tiz Mekonnen. I'm an associate professor in the Department of Chemical Engineering at the University of Waterloo. I also hold the Canada Research Chair in Sustainable Multiphase Polymers. I research in the safety, health and sustainability of plastics.

BRIAN GOLDMAN: So what do they mean by black plastic?

TIZAZU MEKONNEN: As the name implies, black plastics are those plastics that has a black colour. The main reason for their black colour is they have an ingredient called carbon black, which is produced from high-temperature processing of petroleum residue that makes them black. But the concern we have with black plastics is not necessarily the ones that has black colour, but those that are made from recycled plastics.

BRIAN GOLDMAN: And what is it about recycled plastics that causes greater concern?

TIZAZU MEKONNEN: In many cases, when we come across black plastics in our kitchen, they are made from recycled electronic components -- that includes, you know, cell phones, old computers, laptops -- that are not intended for human food application. When you use plastics in electronics, you usually add special additives to avoid burning. So they are flame retardants. The main components of these flame retardants are brominated compounds. In other cases, they also contain heavy metals like cadmium, mercury -- heavy metals that are toxic to humans. When you recycle these plastics and use them in food utensils like spatulas, coffee stirrers, coffee lids, even, you know, thermos lids, they come with these chemicals. And these chemicals tend to leach out these brominated compounds, heavy metals. In other cases, there is a special component called plasticizers that can leach into our food and cause major concern on our health.

BRIAN GOLDMAN: Let me back up just a bit. Why does the plastic industry manufacture black plastic in the first place?

TIZAZU MEKONNEN: It has a practical purpose in many cases. So number one, black plastics, you like the colour just for the look of it. In other cases, it's functional. The carbon black gives the colour. Number two, it is a UV retardant. So you want your plastic component to stay for a long time. For instance, your computer, you don't want to degrade it within a year, right? You want to keep it for as long as possible, for five years, ten years. Your TV, your cell phone and that kind of thing. So you add the black component called carbon black. And the other additives like the brominated compound is to avoid burning of the plastic. You want it to stay stable under heating, right? Your electronic component can heat up quite a bit and you don't want your plastic to melt down. So you add those components to it. For those reasons, you manufacture black plastics.

BRIAN GOLDMAN: So you've started to talk a little bit about how black plastics enter consumer products that are, for instance, in the kitchen or might show up in toys, that in some cases they have originated in electronics and the black plastic has been recycled and placed into kitchen utensils --like the spatula that I mentioned off the top of the show. Are black plastics ever deliberately introduced into kitchen utensils, for instance?

TIZAZU MEKONNEN: They are. In that case, it's a bit controlled, right? The concern would be only the carbon black, the black component. Which is relatively safer compared to the recycled one because it wouldn't contain the brominated compound I mentioned earlier. There is also a special component called plasticizers, and the common plasticizer is phthalates that are known to be carcinogenic. So if you are intentionally designing it for kitchen utensils, it wouldn't have this component. It only have the black component. But the black component itself may also have a smaller risk. It contains polycyclic aromatic hydrocarbon, called PAHs, which may leach out to a lower level. And the risk of this leaching may be associated with the use of this plastic component at elevated temperature. For instance, if you are using a fork to deal with your grill or your barbecue, for instance, which can go to a very high temperature, it will leach out some of the chemicals, right? So you have a risk there. But compared to those that are recycled, it's a much lower risk.

BRIAN GOLDMAN: The problem, of course Tiz, is that, you know, when you're holding that black plastic utensil, you don't know how much of the black plastic in it was intended for consumer use and how much consists of that recycled stuff that you were talking about before.

TIZAZU MEKONNEN: That's correct.

BRIAN GOLDMAN: So how does black plastic get inside our bodies?

TIZAZU MEKONNEN: There are various pathways. The main concern is when you use black plastics for our food contact material applications. One, when we buy food from the grocery store, for instance, some of them are microwaveable food. Many of them come in black plastic. And you expose it to microwave radiation, which would leach out some of the components that we discussed earlier into the food, and we consume the food. That's one. The other one is when you expose your black spatula, your black fork to high temperature -- grill, the barbecue I mentioned, or even dishwasher which exposes the plastic to high temperature -- it will leach out some of the component, or leach out to the surface. When you bring it in contact with the food, it will contaminate the food, and it goes to our body. That's one common pathway that it contaminates our food and gets into our body.

BRIAN GOLDMAN: So partly you're consuming foods that have now become contaminated with black plastic.

TIZAZU MEKONNEN: Exactly. Exactly. In other cases, when you are using, for instance, a coffee stirrer that's made from black plastic, and you are exposing the black plastic to heated water, heated coffee, heated tea, which will leach out the component to our drinks. In other cases, your thermos lid is made of black plastic again. The heating would increase the free volume of the polymer, which would allow the components, the chemicals, into our drink as one. That's another pathway. In other cases, like toys, kids tend to put their toys in their mouth, which would be quite a concern as well.

BRIAN GOLDMAN: Can you inhale residue of black plastic? Does it get into our dust and air that's circulating in our homes?

TIZAZU MEKONNEN: It has minimal risk in that aspect, unless you are exposing the black plastic directly to a very heated surface, you know, temperature above 260°C. It has very low risk of evaporating into the atmosphere and creating a fume. Usually, it's leaching to the food. That's a common concern.

BRIAN GOLDMAN: You know, I know, Tiz, that recently, there was a study a few months ago that found that microparticles or even nanoparticles of plastic end up in the plaque of arteries and that the presence of those micro- or nanoparticles is associated with an increased risk of heart attack. That doesn't prove cause and effect, but it does seem to be a worrisome association. And it makes you wonder how those particles are able to get into blood vessels.

TIZAZU MEKONNEN: Yeah, that's a separate problem, but connected to the topic we are discussing. Microplastics, nanoplastic contamination of our ecosystem is unbelievable. I also saw a study which shows that nanoplastics and microplastics were found in human breast milk. You know, that's beyond the bloodstream, right. So plastics, they stay in the environment for hundreds of years. Having said that, they doesn't stay as an integral component. They slowly disintegrate, releasing micro- and nanoparticles. That goes into the agriculture industry, the food industry. With the water filtration system also is not capable to deal with micro- and nanoplastics. So we drink it and it can be metabolized and it goes into our bloodstream. It's quite concerning.

BRIAN GOLDMAN: And you mentioned something there that I want you to elaborate on. You started to mention something that reminds me that I've heard that some of these particles are 'forever chemicals.'

TIZAZU MEKONNEN: Yes, they're polyfluoroalkyl substance called PFAS. Those are compounds that are known to stay for a very, very long time. One pathway we come in contact with PFAS or PFAS molecules is when you use cookwares that contain non-stick layer or coating material to it. So it's a common practice to use pans that are coated with Teflon -- that's a common name for it as well. What happens is Teflon by itself can be a dead molecule, but when exposed to very high temperature, it degrades to small molecules that can leach into our food. That's one pathway. It stays in our bloodstream and it outlives us. The impact is being well established, but we have not been studying it for a long time so the concern is there.

BRIAN GOLDMAN: Let's get back to black plastic. What does research show about how black plastic cookware is harmful to our health?

TIZAZU MEKONNEN: Some of them, like the brominated components, are suspected to be carcinogenic. In other cases, they are hormone disruptors, right. They resemble testosterone in men and estrogen in women as well. So they disrupt our fertility. They can cause brain development in children as well. They can be quite concerning.

BRIAN GOLDMAN: I read recently, there was a paper a few months back that surveyed various consumer products that contain black plastic, and some of them increase the risk of dying of cancer 300%. So we're talking about a significant risk, aren't we?

TIZAZU MEKONNEN: Yes, we are. We are. Especially in black plastics, the amount of the components we mentioned, including, you know, the polycyclic aromatic hydrocarbon release, the brominated compound, the plasticizers, can be up to 200% more than typical plastics, right? So the risk is huge.

BRIAN GOLDMAN: As you've mentioned, black plastic is especially toxic when heated up. But what about doing something like cleaning plastic utensils? Is that harmful?

TIZAZU MEKONNEN: Yeah. If you are using dishwasher in a very heated temperature for cleaning, that will also cause the leaching of some of the components. So the wisdom there is to reduce our footprint of black plastic in the kitchen. Anything that has to do with food, it's recommended that we avoid the use of black plastic.

BRIAN GOLDMAN: We'll get to some of that prescriptive information in a few moments. But a question that comes to mind, I'm sure that our listeners are going to be wondering this. Does it have to be black plastic to be harmful?

TIZAZU MEKONNEN: Yes. So black plastics have a much higher risk compared to other plastics. There are other plastics that are known to be safe. Plastics are popular because, in a way, they have a number of benefits, right? They are lightweight, they are easy to manufacture, easy to ship, and also fairly safe in many cases. Now, if you take polypropylene lunch container, for instance, it doesn't have too many additives to our knowledge. It's designed purposefully for food containment. It's approved and it's fairly safe. Now, black plastic, one of our concerns is they are not intended for human food, right? And there is no regulation on the recycling of electronic components into our food utensils and containers. That's where the concern is. But there are plastics that can be of concern that are not black plastic, but there are regulations developed. One example along those lines is the liner that's applied on our tomato containers. You know, tomato is acidic, for instance, right. If you directly put it in a metal can, it will corrode the metal easily. To mitigate that, it's very common to coat the can with epoxy resin, which contains bisphenol A, right. There is a huge concern with that, and there are regulations coming up right now. So there are examples where some plastics that are not black can be of concern.

BRIAN GOLDMAN: Are there any other coloured plastics that are either more or less harmful?

TIZAZU MEKONNEN: So the challenge is our knowledge is limited by the amount of study we conducted. We have now an attention on black plastics and studies are coming out. Black plastics seems to be the highest risk at this point, not the others. But having said that, it doesn't necessarily mean that the other plastics are entirely safe.

BRIAN GOLDMAN: Of course, you're not a clinician, and I don't expect you to be able to answer clinical questions. But when it comes to the risk to humans, what are some of the big unknowns, the research that we're going to need to have in the coming years to show more clearly the risk to humans through the inadvertent consumption of black plastic?

TIZAZU MEKONNEN: I think hormone disruption is widely established, I would say. And the impact of plastic components in causing cancer is also coming up. But it looks to us that cancer seems a blanket word. There is no direct correlationship, or the cause and effect is not very well established. I think we have to work on that. But the other major concern is the impact of plastic components on brain development in children. That's probably something that keeps me awake at night.

BRIAN GOLDMAN: What's the risk that you're talking about that makes you so concerned?

TIZAZU MEKONNEN: Some of these components are known to have an impact on brain development in children. And we don't know for sure which components exactly at what level, what concentration and what exposure routes as well, right? So we need to establish that very well.

BRIAN GOLDMAN: So what should we do about black plastic? You started to talk about it, but let's get all of your advice in one place. What should we do about the black plastic in our homes and especially in our kitchens?

TIZAZU MEKONNEN: I think we have to reduce our black plastic footprint. That's the number one thing. Especially when it comes to black plastic that comes in contact with our food. We should stop it as soon as possible, completely avoid, because there are so many unknowns. And until Health Canada catches up with regulations, we have to monitor ourselves. If you go to the grocery store, you can still find food that are contained in a black plastic and that you can microwave, right? We have to stop doing that right away. Hopefully the regulations will catch up very, very soon.

BRIAN GOLDMAN: What are safe alternatives to black plastic in the kitchen, for instance?

TIZAZU MEKONNEN: We have to increase our use of stainless steel for forks, spoons, spatulas. Let's replace it with wood. In some cases, ceramics, right, in our cookware, to avoid the use of PFAS-coated material. Let's use our stainless steel pans. You know, apply some olive oil, which is a good fat. And we just, we just have to spend a bit more time with cleaning, but it's better to stay safe.

BRIAN GOLDMAN: And if we receive food in black plastic containers we've purchased, such as takeout or from the grocery store, what should we do as soon as we bring those foods home?

TIZAZU MEKONNEN: Transfer it to a ceramic container and microwave it if you have to microwave. But please do not microwave plastic at all, at any cost. Any plastic for that matter.

BRIAN GOLDMAN: And that would of course include coffee lids.

TIZAZU MEKONNEN: Yes, exactly.

BRIAN GOLDMAN: And do not attempt to recycle. Don't put black plastic products into the recycle bin. They should go into the trash, shouldn't they?

TIZAZU MEKONNEN: Whether we like it or not, it will go to the trash even though we put it in the recycle. The current technology of sorting plastic relies on infrared, and black plastics absorb the infrared radiation so they wouldn't be able to sort it. So it usually goes to the trash, whether we like it or not. So if you don't put it in the recycle bin, it's completely fine. That's the recommendation.

BRIAN GOLDMAN: Well, Professor Tiz Mekonnen, thank you so much for speaking with us on The Dose on this important subject.

TIZAZU MEKONNEN: Thank you.

BRIAN GOLDMAN: Tiz Mekonnen is an associate professor of chemical engineering at the University of Waterloo. He's also a Canada Research Chair in Sustainable Multiphase Polymers. Here's your dose of smart advice. Black plastic refers to products made of plastic that are coloured black due to the addition of carbon black. The latter is produced by the partial combustion of petroleum products. It's added to make the plastic stiffer and less likely to degrade. Black plastic is made using carbon black and can also contain plasticizers and brominated flame retardants. Black plastics are found in lots of consumer products, including kitchen utensils, kids' toys, coffee lids, takeout food containers, office supplies like pens and staplers, computers and cell phone cases, garbage and recycling containers, and small appliances. The most hazardous form of black plastic comes from recycled electronic devices like cell phones and computer sleeves, which contain brominated flame retardants or BFRs. Studies have shown that the chemicals contained in black plastic can leach out of consumer products and can be detected in wastewater and even the air we breathe inside our homes. When black plastic takeout food containers are heated up in a microwave or oven, these chemicals can leach into food. The residue of microplastics have been detected inside the human body. Carbon black contains lots of compounds that are potentially hazardous to your health. For instance, it contains polycyclic aromatic hydrocarbons, PAHs, which may be cancer-causing. The International Agency for Research on Cancer has designated carbon black as possibly carcinogenic to humans. A 2024 study published in JAMA Network Open found that people with the highest blood levels of polybrominated diphenyl ethers, the flame retardant I mentioned, which is derived from black plastic, were roughly 300% more likely to die from cancer. Researchers have also raised concerns that chemicals found in black plastic could act as endocrine disruptors, possibly affecting human reproduction and thyroid function. They may also affect brain development in kids. We need more studies to determine how black plastic affects specific cancers and how the chemicals in black plastic might affect brain development in children. Canada's Single-Use Plastics Prohibition Regulations remain in force, despite ongoing court proceedings. That includes food service wares containing carbon black, but not all black plastics. The implementation of the regulations has been staggered to allow the food industry time to adjust. The goal of these regulations is to remove all single-use plastic products by 2030. Here's what you can do in the meantime: Look for black plastic items in your home. Try to reduce your black plastic footprint by replacing plastic kitchen utensils with ones made of stainless steel and silicone. Don't microwave or otherwise heat black plastic containers with food. Don't dishwash or re-use takeout black plastic containers. Remove food from those containers and use containers made of glass, stainless steel or ceramics to reheat them instead. To remove household plastic contamination, dust, mop and vacuum frequently. And don't buy kids’ toys with black plastic pieces. If you have topics you'd like discussed or questions answered, our email address is thedose@cbc.ca. If you liked this episode, please give us a rating and review wherever you get your podcasts. This edition of The Dose was produced by Sameer Chhabra. Our senior producer is Colleen Ross. The Dose wants you to be better informed about your health. If you're looking for medical advice, see your health-care provider. I'm Dr. Brian Goldman. Until your next dose.

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How does black plastic affect my health? - Transcript

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