Hidden dangers: The cancer risks of environmental injustice

Hidden dangers: The cancer risks of environmental injustice

0:00:43.0 Justin Colacino: Cancer disparities are when we see differences in cancer incidents, outcomes, or mortality across different demographic groups. And so this could be differences by gender, this could be differences by age. This could be differences by locations, sexual orientation, or differences in race or ethnicity. One classic example that our lab has been studying and many other groups are studying is trying to understand breast cancer disparities, which is one of the biggest public health problems that we know about in the cancer epidemiology field. And so what we know is that Black women in the US are much more likely to die of breast cancer than women of, for example, White background or Asian American background.

0:01:20.7 JC: They're also more likely to be diagnosed with an aggressive subtype of breast cancer that's very hard to treat, called triple-negative breast cancer. And so many researchers and public health professionals have been trying to figure out, why do these cancer disparities exist? And so multiple different factors have been examined. What my lab studies specifically is understanding how pollution and environmental exposures might impact this. So thinking about how the air that we breathe, the water that we drink, the food that we eat, and what's in that food, and even the things that we use around the house on a daily basis, how these different factors can promote the development of these health disparities because of these differences in chemical exposures.

0:02:03.4 Host: Hello and welcome to Population Healthy, a podcast from the University of Michigan School of Public Health. Join us as we dig into important health topics, stuff that affects the health of all of us at a population level. From the microscopic to the macroeconomic, the social to the environmental, from cities to neighborhoods, states to countries and around the world. Why are certain populations unequally impacted by chemical exposures and how do those increased exposures impact cancer disparities between different communities? To help shed light on these big questions, we have Justin Colacino, associate Professor of Environmental Health Sciences and Nutritional Sciences at the University of Michigan School of Public Health. He studies how environmental and dietary factors lead to chronic diseases like cancer. He begins with some background on how cancer impacts different populations in different ways.

0:03:04.3 JC: We can look at things like where people live. Some of you in the audience maybe have heard about how your zip code actually is a better predictor of health outcomes than your genetic code. So we know that where you live makes a big difference. We know that the food that we eat can make a big difference. Like access to healthy food, of course makes a huge difference. There's these areas called food deserts where it's very difficult for people to go to the grocery store and obtain healthy food. We also know that there's social factors, especially determinants like systemic racism and chronic stress. These also seem to be really important risk factors for the development of health disparities and cancer disparities. What causes cancer is still a question that we don't a hundred percent understand the answer to. So some of this is genetics.

0:03:48.9 JC: So some of us are more susceptible to getting cancer. And in breast cancer, somewhere between like 10 to 15% of breast cancer risk is solely due to an individual's genetics. What we are trying to understand is what are the drivers that are promoting this process? So we do know that exposure to things like hormone supplements can do it for breast cancer 'cause these can be driven by hormones like estrogen. And so there's like a set of characteristics that cancers tend to develop that seems to be similar across all these different types of cancer. And so cancers are characterized by cells growing out of control. So things that make cells divide really fast, that could be one way that we're promoting cancer. Cancers also are defined by their ability to invade into other tissues surrounding the cancers. That invasion process is another one of those hallmarks. And then, really the reason that people end up dying from cancer is because of this process called metastasis where cancer cells leave a tumor and then spread throughout the body and then grow in different sites. And so oftentimes when people die from breast cancer, it's because those breast cancer cells have spread throughout the body and start to grow in organs like the lungs or the brain or their bones.

0:05:00.6 Host: Colacino's lab looks at many different kinds of environmental contamination, including air pollution to detect which chemicals are linked to increased cancer risk.

0:05:09.7 JC: One exposure that many people are looking at now with respect to cancer risk is air pollution. And so air pollution comes from industrial sources. It can come from things like forest fires. We have good strategies to estimate somebody's air pollution exposure. There's air pollution monitors all over the place. And so we can then see, where does somebody live? And we can see where do they live relative to these other air pollution monitors. And then we can kinda like estimate an individual's exposure. This has been historically one of the, I would say, huge success stories of environmental health is using these types of data and then linking air pollution exposure to all of these different outcomes for like mortality cancer. People are looking at Alzheimer's disease and and starting to see these relationships. And then the EPA, the EU have dropped the level of air pollution that's allowable in the air down.

0:06:01.7 JC: There's very strong evidence now that air pollution exposure is linked to lung cancer, especially in individuals who actually don't smoke. Unfortunately, that seems to be the case for multiple other cancers. And so folks are even starting to see relationships with air pollution exposure and things like breast cancer. Folks are also looking at differences in exposures to things that we call endocrine disrupting chemicals, or these are chemicals that look like hormones to our bodies. And so breast cancer is a special type of cancer and that oftentimes it's driven by hormonal signals either within our bodies or can come from outside of our bodies. And so many researchers, including folks like us in our lab, are now studying the impacts of some of these chemicals that can mimic hormones and trying to understand how those chemicals can drive the proliferation of cancers. And so these tend to be a pretty broad class of compounds. So classic examples of these are like pesticides.

0:06:56.8 JC: So these pesticides oftentimes are designed to act like this in our bodies. Unfortunately, a lot of the plastics that we're using on a daily basis also have the ability to mimic these hormones in our bodies. And so we're all sort of like bathed in this environment of the microplastics, these very small plastic particles that are found all throughout our environment. And now people in the last year or two have been finding these tiny plastic particles all throughout our bodies too. And so many of us in environmental health are trying to understand how these plastic pollutants might be impacting the risk of cancer largely through altering hormone pathways. Another class of chemicals that people are quite concerned about are called these PFAS compounds. These are these per-and polyfluoroalkyl alcohol substances. These are the compounds that make up really great state and water resistant things like Teflon and Scotchgard that are in all of our products.

0:07:53.8 JC: Some of these have now been outlawed because they're so dangerous. There's new regulations coming out from the EPA that's limiting the concentrations of this in our water. And that's because we know that these compounds can be quite hazardous to our health. There's even been some studies that have shown that extremely low levels of exposure to one of these compounds. The one that was classically found in Teflon when an individual is very young, can potentially alter the development of their breast tissue in a way that could later cause breast cancer. And so there's all of these different compounds that people have been studying, trying to understand how are these exposures potentially linked to cancer and then cancer disparities. And so one of the ways that our lab does this is we look across an entire population. We do what's called an environmental epidemiology study. We look at thousands of people or tens of thousands of people, and then we try to measure what chemicals we're detecting in those people's bodies.

0:08:47.9 JC: So we can look at all sorts of different chemicals. We'll take blood samples from these people, we'll take urine samples from these people and then we'll look for multiple different classes of chemicals in them. We'll look for things like those air pollutants I was talking about. We'll look for things like pesticides and these plastics and we'll look for these PFAS compounds. We'll look at heavy metals like lead and cadmium and arsenic, all of these different compounds that we think might be linked to an individual's cancer risk. And then we can look and compare and see, do we see differences in the levels of these chemicals in people's bodies based on different demographic factors. So we can see like, do we see differences by gender or by age? Do we see differences in these chemical profiles over time? Or do we see differences by race or ethnicity?

0:09:33.2 JC: And so by doing these types of studies, we can then prioritize chemicals that we see at higher concentrations in specific populations. And then if we also know that there's health disparities between those populations, that gives us an idea that that might be a really important place to look to try to understand that link between exposure to those specific chemicals and those outcomes like cancer disparities. People might not know that if a chemical is gonna make it onto the market, it doesn't need to be tested for safety first. It's our job as public health people to identify if a chemical is hazardous, that really makes it tricky because of the regulatory environment here in the US.

0:10:15.0 Host: So how do you go about pinpointing chemical exposures in large populations?

0:10:19.5 JC: The Centers for Disease Control run this really amazing study called the National Health and Nutrition Examination Survey, where they go around the country and they set up shop in a county, and then they recruit like 10,000 people to come in and they give them this very robust workup. It's like the most intense doctor's appointment of your life. They ask you all these questions about your health history, how you're feeling. They'll take blood samples and urine samples and they'll do all the clinical chemistry workups. Then they'll also measure a bunch of these pollution markers in your body and and the CDC goes and they make all these data publicly available. And so here's a very impressive resource that anybody can access. This is all data that the CDC makes available. It's an incredible resource for this type of work.

0:11:03.3 JC: But sometimes we wanna do a little bit more of a targeted study. And so as an example, what we're doing as part of our Michigan Cancer and Research on the Environment or Mi-Care Study, which is based outta the University of Michigan School of Public Health and brings together a team of researchers from the Department of Epidemiology and Biostatistics, Environmental Health Sciences and Nutritional Sciences, Health Behavior and Health Education where we're really trying to understand the link between these disproportionate exposures in cancer in the state of Michigan. And so there, what we want to do is really look in communities that we know have a historical environmental injustice, meaning that they have been disproportionately exposed to environmental pollution. So these are due to systemic racist processes like redlining, for instance, where we know that Black communities have been disproportionately located next to industry, historically, leading to these long-term exposures and potentially health consequences.

0:12:01.5 JC: And we have some colleagues at the School of Environmental Sustainability that went and generated a map of environmental injustice across the state. And we can see that communities across the state like Detroit and Kalamazoo and Flint and Saginaw and Lansing and Grand Rapids, all are at higher risk of environmental injustice. So more exposure to environmental pollutants, more exposure to traffic pollution, more exposure to hazardous waste sites. And we know that there's communities across the state that are disproportionately burdened by pollutants. And so what we want to do is try to work with those communities to understand what is their exposure. Then also, are they disproportionately experiencing cancer?

0:12:40.8 JC: Because we know that there's some action that we can take there. If we can identify these links between disproportionate pollution exposure in cancer, there's regulatory action that can be taken to decrease those levels of exposure. This can translate into things like the Clean Air Act and the Clean Water Act, which have had substantial impacts on the health of our environment and impacted literally the health of everybody in the US. This is really what we try to do in the field of environmental health sciences, is understand these exposures. Figure out who's the most exposed, why they're the most exposed, understand if there's links to health outcomes, and then take those data and try to translate them into policy to try to reduce exposures in those communities.

0:13:21.0 MK: So what can people do in their daily lives to help reduce their exposures to cancer causing chemicals?

0:13:26.3 JC: One is thinking about, especially if you're on well water is get your water tested for contaminants like PFAS and you can install a water filtration system. This can be huge. Those of us that are on city water, the city is in charge of making sure that the water quality is good. People that are on well water don't have the same federal regulatory oversight. Similarly, you can install air filters in your home, and we know that these air filters can be very, very effective at decreasing indoor air pollution. So these can be like particulate matters or volatile organic compounds, things that we know that can cause diseases like cancer or just general respiratory issues. And then another one that people don't think about that much is something as simple as is vacuuming. If you look at the composition of dust, oftentimes, it's very highly made up of some compounds like flame retardants that just come off of our electronics and our furniture.

0:14:18.4 JC: Keeping the level of dust in your house low can decrease the amount of dust that you then ingest and get into your body. So that sounds kind of gross when I say it, but unfortunately, it is true. And then the other things that we can do to help our bodies remain resilient, get a good night's sleep, super important. A lot of the enzymes that are involved in processing pollution are what we call circadian regulated. They like go up and down with our sleep cycle. And so having a good sleep cycle is super important for our body to protect itself. Eating a well balanced diet, high in fruits and vegetables can also give us some of the micronutrients necessary to protect ourselves. And then making sure that you're exercising. All of these are ways that we can help promote public health to reduce our individual risk.

0:15:00.4 JC: And then there are other strategies that we can do on an individual level, making sure that you're getting vaccinated for some of these diseases like HPV and Hepatitis, those are cancer fighting vaccines, which is pretty amazing that we can give people a shot that helps them not get cervical cancer or not get liver cancer. That's pretty incredible. So making sure you're up to date on those. Yeah, and then making sure you're seeing your doctor. There's new tests that are coming down the line that are allowing us to detect cancers earlier and earlier. The earlier we detect the cancers, the easier they are to treat. And so making sure that you're talking to your primary care physician about cancer screening and cancer risk and what you can do to reduce your risk, all of these are things that individuals can do. The other thing that folks that live in these communities can do is work closely with their local representatives to try to get awareness raised and laws changed. And so right now, for instance, the EPA is putting a lot of money in towards environmental justice and remediating some of these communities where we're seeing environmental injustice. And so this is really our chance to make some big differences while there is some political motivation now to address these historic injustices.

0:16:16.4 Host: Thanks for listening to this episode of Population Healthy from the University of Michigan School of Public Health. Visit our website, population-healthy.com for more resources on the topics discussed in this episode, and to find more episodes. If you enjoyed the show, remember to subscribe, rate and review wherever you listen to podcasts. Be sure to follow us on social media and consider sharing this episode with friends. Population Healthy is produced by Andrea LaFerle, Brian Lillie, and Crissy Zamarron and hosted by Michael Kasiborski. Hope you can join us for our next episode where we'll dig in further to public health topics that affect all of us at a population level.