Meet our 20 Pioneers under 40 in Environmental Public Health: Allan Just, PhD
In a way, Allan Just, PhD has come full circle. He is now a professor and researcher at Mount Sinai, but developed his interest in children’s health after hearing a CHE webinar at the start of his career.
“There was a CHE Call in 2005, it was moderated by Michael Lerner, and it was about early life exposures and their role in the developmental origins of disease, really it was focused on cancer. But, I listened to that CHE call, and it made so much sense to me. You are going through this developmental period early in life, as a fetus and as a young child, and you are getting set up on this trajectory of who you are going to become, and if you perturb that, that is going to have consequences down the road. I thought about how all the studies that I was involved with at the time were really focused on adults. And, if you were interested in chronic diseases, which can have extremely long latencies, the relevant time period, if you are interested in the environmental contribution, might be decades before you can distinguish who does and doesn’t go on to develop disease. And, I thought ‘well it’s sort of a little bit crazy to look at adults then, because if we are interested in the environmental role, it’s too late,’” Dr. Just recalls.
In February he got to present on a CHE webinar himself, talking about his own work focused on children’s environmental health. Specifically, the topic of his webinar, and one of the main focuses of his research now, is how epigenetics and the process of DNA methylation can be used to gain insights about various epidemiologic phenomena.
“Most of what I do in epigenetics is with DNA methylation. DNA methylation is a chemical modification on the DNA that acts like a dimmer switch that can modulate how much of our genes are turned off or on, but in a more continuous fashion. So, it is related to the regulation of gene expression that can be impacted by our environment, and also is definitely impacted by our gene sequence itself. It is a pretty complicated phenomenon, but what I think is exciting from the standpoint of environmental health is that we can see fairly stable associations that are pretty consistent between exposures and patterns of methylation in particular locations in the genome,” Dr. Just explains.
More specifically, his work looks at many different methylation sites within the DNA to get a better understanding of people’s health outcomes in relation to environmental exposures.
“We are using epigenetic measures to try to understand the relationship between environmental exposures and health. That’s a whole new emerging field… Nowadays, we are measuring 850,000 different methylation sites on every one of our samples, and we are doing that with hundreds or thousands of samples. So, the volume of data is incredible, and interpreting it is hard. And, fun and challenging. Just the amount of data makes us change a little bit the way we interact with that data. I have been working with my lab group on some tools to facilitate how we look at that kind of data, how we understand that kind of data, and interpret our findings when we do see these sort of fingerprints of environmental exposure,” Dr. Just says.
Because this field is relatively new and growing so quickly, it allows Dr. Just and his team to be at the cutting edge of some of this research. He explains how these epigenetic projects open opportunities for doing more nuanced science.
“It lets us use new epidemiologic methods or more recently advanced epidemiologic methods to try to understand more about the relationship between an exposure and an outcome, so really trying to tease apart the timing of the susceptible windows for these types of things,” Dr. Just explains.
Because his interest has been on children’s health for most of his career, he is really looking at critical windows related to the growth and development of children. One specific example of his work has been looking at how exposure to air pollution at different times during development can impact children.
“When we look, for example, at air pollution during pregnancy and some health effect in the children, like development of respiratory diseases as they grow up, we can actually reconstruct what the ambient exposure was at different times. We can ask which of those times are most important epidemiologically in explaining that association, and that can start to hint at the biology. We know that one of the reasons children are more susceptible is that they are going through these periods of development and that means that there is particular timing when they might be more susceptible. That can clarify the epidemiologic associations that we see by examining if they are specific to a particular time period, and then also it can maybe point at when we need to do our interventions. Who are the people we need to target and when do we need to target them for public health impact”, Dr. Just says of his work with epigenetics and air pollution.
Through all of his work with epigenetics and DNA methylation, he is working to look at someone’s epigenome and determine what exposures they have had. A hope would also be that they would be able to analyze an epigenome to be able to predict what might come in the future. While that is harder to do, identifying exposures is still quite interesting and useful.
“We look at a biomarker that might be an early manifestation or an early change on a pathway towards disease. And, in the same way, sometimes we see methylation changes that we think are predictive of later developing a disease. Now, that’s hard to do, primarily because you need to collect the samples before someone has the disease because we certainly know that disease states change your methylation. We are interested in methylation that predicts what your later disease state will be. For example, if you just compare the methylation of people you know with obesity versus those without obesity, some of the differences in methylation are due to the obesity. It would be more interesting to look at the methylation and see, does any of the methylation before people develop obesity predict [who] will go on to develop obesity, and that is actually something that I am undertaking,” Dr. Just says.
Dr. Just’s work is multifaceted and has the potential to tell us more about how exposures to various inputs can affect our bodies to create differing health outcomes. The next step is determining how these exposures occur and developing policy to affect change.
“We need regulators to adopt precautionary and forward-looking approaches because I think it is too much to pass this on as a responsibility to individuals to research and understand and avoid exposures to the many unregulated chemicals that we encounter in our daily lives,” Dr. Just says.
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.
In February, we held our sixth 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.