Understanding how environment impacts health will empower us to make the lifestyle changes that matter most, from what foods to buy to fragrances to avoid
Exercising and eating better as part of our new year health kicks are great, but we should also think more deeply about the role the environment plays on our health. As a professor of environmental medicine, I believe this is an exciting new area of study that will play a big part in the future of personalized medicine.
Consider this, every day we are bombarded with messages: genes that cause cancer, supplements that prevent Alzheimer’s disease, diets that prevent asthma, chemicals that make us gain weight. But while headlines frequently proclaim “game changing” new findings, over the last 20 years in the US and Europe our health status as a population has seriously deteriorated. Rates of obesity, diabetes, heart disease, cancer and learning disorders continue to rise. Genetic variation may be part of the puzzle that explains why we get sick, but clearly there are missing pieces.
After all, 20 years of increasing obesity and diabetes represents only a single generation. If our genes didn’t change in the last 20 years, then our environment must have.
Genes never work in isolation. Instead, they determine how we react to our diet, social surroundings, physical environment, infections and chemical exposures. Environment is the missing piece of the puzzle.
The old 20th-century concept of nature v nurture needs to be redefined, as genetics and environment do not compete, they work hand in hand, sometimes to our benefit and sometimes to our detriment. The correct formula is really nature times nurture. Right now the nurture part of that equation is largely unknown, but that may soon change.
Exposomics – a new science
Recently, a new concept has arisen, the science of the “exposome”: the measurement of all the health-relevant environmental factors across the lifetime.
The exposome is to our environment what genomics is to our genetics. Most of what we know about environment and health is still a “black box” consisting of yet to be discovered risk factors we too often attribute to “bad luck” – ie because we don’t measure the environmental cause, the problem appears random.
But most of what we now understand about genetics was also a black box in the 20th century.
Physicians see the role of environment daily even if it is not clear to them that environment is the cause. For example, a child with autism develops more frequent combative oppositional behaviors and emotional outbursts. An adult with diabetes can’t seem to control her blood sugar despite higher doses of insulin. A newborn is born with blue skin but a normal heart.
For each of these cases, sequencing the genome would not have identified the cause. The autistic child had lead poisoning because of pica brought on by autism, the diabetic adult used perfumes high in phthalates, chemicals that affect metabolism and the newborn baby drank formula mixed with well water contaminated by fertilizer runoff that reacted with his hemoglobin.
In each case, genomics would not have given us the correct answer, but if we had the tools to measure the exposome, we would have made the correct diagnosis. Just as importantly, because the underlying causes were environmental, we can treat the problem with interventions.
Furthermore, in most diseases, environment and genetics work in combination. It’s very rare to have a genetic variant that “causes” Alzheimer’s disease, but it is fairly common to have a genetic variant that makes us susceptible to environments that can cause Alzheimer’s. The different between those with the genetic variant who get sick and those who don’t is their different environments.
Imagine a visit to your physician in which you begin by handing over your smartwatch to have its data downloaded, followed by a blood draw to measure your chemical environment and nutritional status, then you update your lifetime home address and occupational history into a secure computer that houses your genomic data. This then computes your personalized risk score for heart disease, diabetes and other diseases. Or, if you already have one of these diseases, computes the ideal treatment regimen based on this “big data”. This is how we will be able to personalize medicine.
We are not there yet, but the technology to measure the exposome is far more advanced than the general public, and even many researchers, realize. There are now lab tests that can demonstrate the presence of thousands of chemicals in our bodies and satellites that record our daily weather, air pollution, light exposure and built environment. Public records have data on water quality, age of housing, local crime statistics, outdoor noise levels and even where disease clusters are occurring. Cellphones are ubiquitous and can link our daily behavior and movement patterns with the quality of the local air and water while simultaneously measuring our heart rate, physical activity and sleep quality.
Computational science has advanced to a point where storage of terabytes of data is routine and computer clusters are found in every major university and methods to bring these databases together are no longer science fiction. Artificial intelligence and other big data approaches to genomics also provide a roadmap for analyzing exposomic data.
Understanding how environment affects your health will empower people to make the changes in their lifestyle that will matter most. To understand what food to buy, which fragrances to avoid, where and when to exercise, etc. All the pieces to solve this puzzle are beginning to come together. What is needed is the grand vision to invest in and integrate exposomic science into public health and clinical medicine. This is the final piece of the puzzle. Once we understand our exposome and integrate it with our genome, we will finally understand why and how chronic diseases have become so common and how we can start to reverse their trends in society.
Dr Robert Wright is a pediatrician, medical toxicologist, environmental epidemiologist and director of the Institute for Exposomic Research at the Icahn School of Medicine at Mount Sinai
Read more: www.theguardian.com