Exposome: how your health is determined by your environment

If it is about your health, you tend to mostly look at your genetic make-up. But three quarters of your health is determined by environmental factors. Your environment determines your odds for a healthy life to a very high degree. How that works? Roel Vermeulen, Ulrike Gehring and Kors van der Ent explain. “Anyone who grows up in a poor neighbourhood, lives seven years shorter than someone who grows up in a rich neighbourhood.”

Exactly twenty years ago, the Human Genome Project was completed - an enormous milestone for science and healthcare. Because we now know how humans work genetically. The so-called ‘genome’ is our genetic blueprint and contains all hereditary information on the composition, growth and development of our bodies. Thanks to the cracking of our ‘code’, we could make enormous steps in the development of new medicines and treatment methods.

Now, twenty years later, the European Human Exposome Network is ongoing. In it, 24 European countries collaborate in order to, after the human genome, now chart the human exposome. The Utrecht professor Roel Vermeulen, who is also the Academic Director of the Institute for Risk Assessment Sciences (UU/UMCU), is one of the coordinators of this network.

"The exposome can be seen as the total of environmental factors we are exposed to throughout our lives, and which influence our health and illnesses. Think along the lines of factors such as air quality, living environment, and the social circumstances in which someone grows up.

So exposome research is very ambitious. Because it is about systematically charting the thousands of chemical substances and countless other matters which influence us every day. From there, we can better understand what makes us ill - and what does not. So we will know in the future which environmental factors are harmful and to which degree. In this, we also want to know in which combinations these environmental factors are harmful. And in which phases of our lives we are more vulnerable.

Because this involves so many different factors, there is not one single method which can measure all these factors, like in genetic research. Another matter is that in the exposome, unlike the genome, the circumstances change along with the passage of time. Exposome research is therefore multidisciplinary and uses Big Data."

Looking through a keyhole

To the field of medicine, the exposome is an eye opener, says Kors van der Ent, who is a paediatric-lung specialist in the WKZ (UMCU). “Practising traditional medicine is like looking through a keyhole - you only see the patient and - in my case - their lungs. You determine what the condition is and based on that, you decide what the treatment should be. New medicine is placing that condition in the context of the exposome. Which environmental factors influence those lungs and that condition? You include that in your treatment.”

But how do you know which environmental factors are relevant in such a case? That is where researchers like Ulrike Gehring come in. She is an associate professor (UU) and a researcher at the Institute for Risk Assessment Sciences (IRAS). She does research there into the influence of the environment on children's health. She especially focuses on the risk factors for asthma and allergies, and the effects of air contamination. 

Ulrike says: “We do long-term studies in which we follow big groups of participants, children and adults, throughout periods of dozens of years, sometimes from birth. This enables us to determine to which degree matters such as air pollution during a certain period in life predicts you will have an illness like COPD later in life.”

Roel adds: “Research on children is so important if you consider that for half the COPD patients, the causes are in the first years of life, in which the lung function could not develop properly, for instance, because the child grew up with smoking parents. But those parents make up only one of the many environmental factors. We also do specific research into chemicals and how these influence health, including lung health. There are over one million registered chemical substances. By now, we know that 100,000 of those are in all kinds of products we use. And that 5000 are very prevalent in our environment. That's still much and extensive. But along the way, we do discover better and better what we're exposed to. We can measure it better and better as well as chart it, and see whether or not they are related to our health.” 

Kors says: “In brief, it matters where your cradle was. If you grow up in a neighbourhood with little green, much air pollution and all kinds of social-societal problems, you live on average seven years shorter than someone in a neighbourhood where these problems do not exist at all. The difference in healthy years of life is even bigger. That can be 15 years shorter. Roel says: “Especially in the cities, you see huge health differences. And these differences are persistent. The shocking reality is that so far, we've been able to change little about that.”

It matters where your cradle was. If you grow up in a neighbourhood with little green, much air pollution and all kinds of social-societal problems, you live on average seven years shorter than someone in a neighbourhood where these problems do not exist at all

Smoke-free generation

That is of course no reason to give up. Exposome research is the reason behind many prevention and intervention programmes such as those often developed by the government and societal organisations. One such example is the campaign ‘Rookvrije generatie’ (Smoke-free generation).

Ulrike says: “Our research and the advices coming out of it result in more attention for matters such as schools next to crowded roads. And that policy makers are more consciously working on the planning of new neighbourhoods and the locations of schools.”

Roel says: “It's important that we work ‘solution based’. With that, I mean: how do we come to effective interventions? The first possibility is to inform people as well as possible. That can result in a better understanding and a change in behaviour. But there are limitations to that. You can inform about the usefulness of healthy eating and exercising. But if healthy food and the soccer club are too expensive for you, or your environment doesn't support different behaviour, you won't change your behaviour after all.

The second possibility is systematic change. A successful example of that is how we mostly banned smoking from our society - besides information, also with excise tax and regulations. Our role as researchers, I think, is that we gain relevant knowledge and ensure this knowledge is used in systematic change.”   

Blinders

Kors says: “May I give a final example? I see many patients with cystic fibrosis. The medicines for that are very expensive. We're talking along the lines of 1.5 to 2 hundred thousand euros per year per patient. But if that child grows up in a family in which the parents - for any reason - keep smoking, you know a big part of the treatment is pointless. So you do want to look into whether or not these environmental factors can be influenced - because that can be a huge benefit for the treatment. So I have to be alert to that as a doctor and actively try that. I must have more vision of reality. And I have to be able to take patients and caregivers, AND colleagues, along in that. The blinders are off.”