Scientists now know that genetics, although important, are not everything and what people are exposed to in the environment matters a great deal for predicting disease risks and overall health. There is reason to believe it’s especially vital for pregnant women and babies, so much so that it’s driving a new emerging field of study known as exposome research, or the investigation of human exposures as they relate to health. New data indicates that children may be at risk for everything from early puberty, male infertility, high blood pressure, certain cancers, autoimmune diseases, and even autism, depending on what they come into contact with in the womb.
“There is probably a genetic component to autism, but it’s pretty clear that autism happens somewhere during fetal development at some critical time,” says Dr. Michael Snyder, a medical doctor and geneticist. “Understanding what the pregnant mom is exposed to and how that might lead to autism is a big deal and the answer is not really known. A lot of stuff is happening and it’s really important to know what moms are being exposed to. Prenatal exposures are very under-studied and very important to study.”
The good news is that recent advances have made studying environmental exposures more possible than ever before. The challenge is, they have a lot of work to catch up on. Snyder, who also teaches and runs the Snyder Lab at Stanford University, is currently working with his colleagues to catalog as many relevant chemical and biological compounds in order to figure out exactly what it means for parents and their developing children. Here, he shared what we know about how the environment, how it can hurt babies, and how much more there is left to be learned.
It’s probably safe to say the field of exposome research is not well understood by the general public. What can you tell me about how this research works and how the data is developing?
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Exposures can fall into different types. There are biological exposures, like allergens and things like that, and there are chemical exposures, called particulates. We’re just starting to classify them, but we haven’t broken down the composition so much. What’s special about our work is that we’re trying to understand it in more detail what we’re exposed to, and on an individual level. Most research before would just put a device in a neighborhood to see the exposures as a whole, but what we’re doing is trying to tell the difference between my exposure and yours.
Do you have any examples?
One of the most obvious examples of this is smoking. We tell pregnant women not to smoke because of the clear chemical carcinogens that are going to be dangerous to the fetus. Clearly, most pregnant women don’t smoke but they’re obviously exposed to lots of other things and I don’t think we know what all those things are.
And you’re seeing growing public interest in this research. Why?
People are realizing that autism is on the rise and it’s not just a matter of increased diagnosis anymore. It’s reasonable to think that environmental exposures might contribute to that. People are starting to care about chemical exposure in the environment now because we’re learning it affects their kids, but also they are making the connections between things like polluted rivers and cancer. Data on people getting cancer living near toxic dumps is really quite clear. That awareness helps.
What else are you finding in the research that parents should know about.
What we and others are finding is that plastics are everywhere, certain carcinogens are everywhere, VEET which is found in bug sprays is everywhere. Having said that, their concentrations range from one place to another. We’ve been able to show that location is probably the number one factor, but seasons are also a factor, especially when it comes to biological exposures, but to some extent chemicals as well.
Your exposure is pretty dynamic, meaning when you go from one place to the next there are very different exposures, some are chemical, some are more fungal. Some areas are loaded with more pesticides than others. If we can understand this better, we can reduce some of the exposures in bad areas.
What about plastics? Is the growing concern about the impact of plastics on our health warranted?
Most of us grew up during a time when plastic was everywhere and just assumed to be inert, meaning it didn’t move. But clearly there is stuff that leaks out of plastics, and it’s only been realized more recently that that stuff is getting into what we eat. That is a recent phenomenon compared to even a few years ago because now we can measure it. From our work, it was very eye-opening to see that plastics were in nearly every sample we looked at. I certainly didn’t expect that and it does raise concerns.
People hypothesize, but don’t conclusively know, that girls are going through puberty earlier. It’s been suggested that a lot of the stuff out there looks like estrogen related compounds that could be influencing that. A lot of these things are very similar to plastics.
What scientific advances have made it more possible to measure exposures?
Advances in DNA and RNA sequencing have helped us better identify the biological compounds — it’s getting cheaper and easier to do that. After wearing a device for two years, I was exposed to over 2,000 different strains and we can pick that up and quantify all that now. Same goes for chemical compounds. Mass optometry is getting more and more sensitive and our ability to detect and identify these chemicals has gone up. Those technologies have been very powerful in finding who’s been exposed to what.
Exposome research is getting a lot more attention in Europe and international communities. Why is the U.S. seemingly falling behind?
The European Union is rolling out a big initiative of environmental exposures. They’re just awarding grants now, but we haven’t seen, anything like that in the United States. China is very concerned about it as well. I think part of it is just how funding has gone for this. Most of the funding in the U.S. comes from the NIEHS, The National Institute of Environmental Health Sciences, and that’s a very small institute compared to the overall National Institutes of Health. Most of the funding for biomedical research comes from NIH, but it doesn’t fund environment research, because that is funded by NIEHS, and that is much smaller. It’s just the way the funding is set up in the U.S.
So how long will it take for the research to catch up with the environment? How many years off are we from knowing how exposures affect people, especially developing babies?
In fairness we’re still just cataloging this and our work is incomplete. Step one is to identify all these things and then step two is that we’re doing most of these studies with mice, which is helpful, but we need to start doing them with humans and we’re still a few years away.
Estimating an exact number of years is tricky because that can change, but I do think it will take a long time, at least several years, to get everything cataloged. Then to test their effects is going to take many more years, so it will take some time. Maybe a decade, but there will certainly be things we learn between now and the next ten years. There will just more to learn after ten years. If we knew the answers, it wouldn’t be science. Regionally, most of this will take 10 years or more, but I sure hope we can catalog everything in the next few years, and then once you know what you’re exposed to, you can determine its effects.
Based on what we currently know what are the safest places and seasons for pregnant women?
We don’t know much about seasons. Where we live in the Bay Area, we know that pine and eucalyptus peak in the late spring, early summer. So people with severe allergies may have a problem. But we know that there are other fungi that come in the fall, and if you’re allergic to that, it won’t be a good time for you. People in the northeast may avoid some of this in colder temperatures in the winter because they stay inside. Then there was a time when we heated homes with kerosene, and that wasn’t good for our health either. But we don’t know what this means for pregnancy.
Assuming it’s the same for fetuses everywhere, living near highways in cities, there are clearly a lot more particulates in the air, and that is generally perceived as bad. Toxic dump sites are not good either, and anywhere there is excessive amounts of pollution would be a place to avoid. But the reality is that most people don’t have a choice where they live. They can’t go buy a new house somewhere and they’re stuck where they’re stuck.
It’s very nuanced and I don’t think we know the effects all of these exposures have on people’s health. For all we know there is a major health hazard going around and no one is doing anything about it. It is all very concerning to me.