How does our environment impact our health? Unravelling the exposome
The air we breathe, our social interactions and lifestyle choices all play a key role in our health. (Four Corners: Rob Hill)
In short:
Australian and international research efforts are underway to better understand the health impacts of the physical, chemical, psychological and social exposures we face over our lifetime.
Collectively, these factors are known as the "exposome".
In May, scientists gathered in the US to lay the groundwork for a global research initiative that aims to map the entire human exposome to improve health and prevent disease.
With around 125,000 children and parents enrolled, Generation Victoria — or GenV — is set to become one of the largest health studies of its kind in the world.
But its scientific director, Melbourne paediatrician Melissa Wake, says at its heart is a "simple idea".
"At a population level, more people are dying from diseases that we ought to be able to prevent … and it's now become clear that children are likely to face shorter life spans than their parents," Professor Wake says.
"We asked ourselves: How can we change the life trajectories of our population through research? How can we help people to live their longest and healthiest lives?"
In 2021, Professor Wake and her colleagues at the Murdoch Children's Research Institute began recruiting for Generation Victoria or GenV, a major long-term study that will track the health of more than 50,000 babies born in Victoria between 2021 and 2023 — and their parents — over their lifetime.
GenV will follow babies and their parents to help tackle problems like asthma, obesity, and mental illness. (Pixabay)
The aim of the research is to understand what shapes health and wellbeing across our early years and mid-life, and to identify factors that contribute to the development of disease.
"We're interested in long-term [health] outcomes … things like cancer, heart disease, stroke, osteoporosis and Alzheimer's," Professor Wake says.
"But also things that children experience now — like poor mental health, asthma, ADHD, autism and obesity."
While other large studies have set out to answer similar questions, Professor Wake says technological advances mean researchers are now able to capture health data in more detail at vastly bigger scales.
"The idea is to work with people across an entire population, try and measure all of the layers that we know are important to health, and then learn how we can actually improve [disease] prevention pathways."
To do this, researchers will capture information about participants' DNA, as well as the physical, chemical, psychological and social conditions they're exposed to — known collectively as the human "exposome".
What is the exposome?
The exposome is a measure of all the environmental or external exposures we face over our lifetime and the ways in which these impact our health.
It includes everything from diet, lifestyle, education and income to air pollution, chemical exposures, and climate conditions.
"Many of [these factors] overlap and happen in unequal ways, so if you're born and grow up in a poor area, your exposome is likely to be shaped by external stressors, air pollution, fewer opportunities and less income," Professor Wake says.
It also encompasses internal processes, such as your microbiome (or gut bacteria), inflammatory processes and metabolic factors, that are shaped, at least in part, by external exposures.
Johns Hopkins University researcher Fenna Sillé says while almost all diseases have a genetic component, the exposome often plays a critical role, particularly in the development of chronic diseases.
"It's estimated that up to 70 per cent — and for some [chronic] diseases even 90 per cent — of the risk is due to environmental exposures," Dr Sillé told the Health Report.
Loading...In May, a group of international researchers, including Dr Sillé, convened in the US to establish the Human Exposome Project — a global effort to "systematically map the totality of environmental exposures and their effects on human biology".
"The idea has lived for a while now of starting something that complements the Human Genome Project, but it's obviously not a small feat," she says.
"If the genome is your biological blueprint, the exposome is the lifelong record of how the world interacts with that blueprint."
The field of exposomics research has grown in recent years, particularly in Europe, where researchers have been investigating the relationship between environmental exposures and conditions such as chronic obstructive pulmonary disease, type 1 diabetes, coeliac disease, allergies and asthma.
While studying how environmental factors influence human health is not a novel idea, advancements in AI and computational models mean scientists can "really start to deal with" the complexity of overlapping and interacting exposures, University of Queensland epidemiologist and toxicologist Nick Osborne says.
"In the past, we'd look at one toxin … and we'd see what the effect was. But, of course, that's not the real world," says Dr Osborne.
"In the real world … there are a lot of [exposures] happening at once.
"[The exposome] is about having an understanding that the body is a very complex system but it's also interfacing with a very complex environment."
Exposome research could shed light on cancer questions
In Australia and other high-income countries, dramatic increases in cancer rates among young people in recent years have prompted concern that widespread environmental changes are contributing to earlier diagnoses.
Research suggests a surge in obesity, sedentary lifestyles, and increased exposure to plastics may all be playing a role, as well as changes to young people's gut bacteria from eating ultra-processed food and using more antibiotics.
"There's a very strong relationship between our gut bacteria and our immune system and brain and many of the functions in the body," Dr Osborne says.
"We're finding more and more that chronic inflammation seems to drive many of the 'big five' diseases we're confronted with — mental health, diabetes, cancer, heart disease and asthma."
But untangling the effects of different exposures is challenging, Dr Osborne says, in part because many diseases appear to be the result of a complex interaction between our environment and our genes.
"Quite often you might have the 'bad' genes, but if you're not exposed to the 'bad' environment, you don't get the disease," he says.
"It could be some pretty subtle changes in genetic make-up combined with what's happening in the environment … which then leads on to many of these diseases."
While it's impossible to document and study everything humans are exposed to, Professor Wake says the goal of GenV was to understand and act on the most important disease pathways and exposures.
"It would be nice to know everything, but what we really need to know are the most important things, and we need to act on the most important things."
Measuring environmental health impacts
The ways in which researchers measure the health impacts of different exposures vary, and in some cases, involves looking at an individuals' physiological processes, Dr Sillé says.
"Even though you can't measure everything every day … there are the exposures, both internal and external, that leave some sort of imprint."
Epigenetic effects, which include changes to the way your genes work as a result of your behaviours and environment, are one example.
"But also your metabolism, for example … is affected by things that happened in your past."
Initially, GenV researchers will mostly rely on existing clinical records and biological samples that are routinely collected during pregnancy and early childhood, such as blood samples.
Researchers will be able to use GenV data to find out how we can better prevent and treat health problems. (ABC News: Mark Leonardi)
Parents will also be invited to provide saliva and breastmilk samples, as well as information (through an app) about their children's physical and mental health during their early years.
"Our ethos has been that if you have 125,000 [participants] … it has to be very easy for them to take part," Professor Wake says.
As the children in the study grow up, more detailed health data will be collected from them at ages 6, 11 and 16, as well as from their parents.
"We'll be trying to measure those important [disease] development pathways for children and parents," Professor Wake says.
"Things like: what's happening to their blood pressure? What's happening with their growth, their body composition? What's actually happening in their brains?
"What we are wanting to do is actually measure the health signals that lie between risk factors and the long-term outcomes we care about."
The many layers of the exposome
Alongside measuring health markers, Professor Wake says researchers will collect family- and community-level data, as well as information about "air quality, climate, built environments, shopping opportunities, food supply" and other layers of the exposome.
To do this, they will rely on things like satellite maps, ambient monitors in classrooms and homes, environmental datasets and "social and policy mapping" tools.
"As people go through life, we can work with them and say, 'What's happened to your pathways as opposed to [another person's] pathways, and can we actually alter that?'"
A key advantage of the study, Professor Wake says, is the ability for researchers to not only observe changes over time, but also test the effectiveness of different health interventions.
"One of the ways to make discoveries is to undertake interventions," she says.
"We are particularly interested in … actually testing: can we change [disease] risk? How much can we change risk? Does it make a difference to the outcomes that matter? Who for? And is it fair?
"And because we've got that long-term horizon, we should be able to look 20, 30, 40 years down the track."