Landmark Exposome Study Reveals Cumulative Impact on Health

Researchers, led by scientists at Harvard Medical School, conducted one of the largest studies to date quantifying the relationships between environmental exposures and health outcomes. The study tested over 100,000 associations and demonstrated that examining exposures in aggregate provides a more comprehensive understanding of variations in human health than analyzing individual exposures.

Examining environmental exposures in aggregate provides a more comprehensive understanding of variations in human health than analyzing individual exposures.

The Exposome Concept

For decades, genetic factors have been studied for their role in disease. However, genetics represent only a partial explanation. The remaining influence comes from the exposome, which encompasses all external and internal exposures an individual experiences throughout their life, including pollution, infections, diet, and lifestyle, as well as the body's biological response to these factors.

Study Methodology and Findings

Utilizing 20 years of existing data from the U.S. National Health and Nutrition Examination Survey (NHANES), the team analyzed more than 115,000 associations between 619 environmental exposures and 305 clinically relevant health outcomes. These exposures included pollutants and nutrients, while outcomes covered metrics such as body mass index, blood sugar levels, and lung function.

The study identified over 5,600 statistically significant associations. Individual exposures accounted for less than 1 percent of the variation in health outcomes. However, considering up to 20 exposures simultaneously increased this explanatory power to an average of 3.5 percent across 120 health outcomes, a contribution comparable to that of some individual genetic variants.

One significant finding highlighted a combination of 20 specific exposures—including trans fats, polychlorinated biphenyls, and vitamin E levels—which explained 43 percent of the variation in people's triglyceride levels, a known risk factor for heart disease.

The researchers emphasized that while there was a range of explanatory power, most combinations showed only a modest influence on variations between individuals.

Implications and Future Directions

Chirag Patel, associate professor of biomedical informatics at HMS, noted that the cumulative effect of exposures can be as influential as DNA in determining disease risk.

The findings, published in Nature Medicine, underscore the value of using existing data for exposomics research and the need for further large-scale studies.

The research provides foundational insight for future exposome studies, with goals to expand the scope of exposures and outcomes, and to investigate connections between early life exposures and later-life diseases. The team has made its data and software openly available through The Phenome-Exposure Atlas of Health and Disease Risk to facilitate further investigation.

The scientists envision a future where exposomic information could be integrated into precision medicine and real-time health monitoring systems.