A new scale to estimate the “burden,” or cumulative exposure, of a family of the thousands of synthetic chemicals we encounter in daily life with potentially adverse health effects, has been created by a team of researchers at Mount Sinai.

In a paper published in Environmental Health Perspectives, the team reports that its sophisticated tool could have clear advantages for epidemiologists and researchers who routinely measure exposure levels to this class of chemicals, known as PFAS (per- and polyfluoroalkyl substances), which have been linked to high cholesterol and liver and thyroid damage. Disease and hormonal disorders.

There are a few current methods for determining the total exposure burden of individuals to the combination of PFAS chemicals present in our daily lives. For the first time we have developed a PFAS burden calculator that takes into account exposure patterns for many chemicals within the PFAS family, not just the individual chemical concentrations that current methods focus on. As a result, this powerful tool can be very useful for vital monitoring by regulatory agencies, and for disease and health risk assessment.”

Shelley Liu, PhD, lead study author and assistant professor, Center for Biostatistics, Division of Population Health Science and Policy, Icahn School of Medicine at Mount Sinai

PFAS is a class of more than 5,000 chemicals that the fluorine-carbon bond gives the ability to repel oil and water. This construction has made them an integral part of a growing number of industrial and consumer products applications in recent decades, such as stain and water repellents, Teflon nonstick utensils, paints, detergents, and food packaging. Furthermore, PFAS chemicals do not break down in the environment or in our bodies. Instead, they build up in our surroundings and in the blood, kidneys, and liver, as confirmed by a 2007 Centers for Disease Control and Prevention study that found PFAS can be detected in the blood of 98 percent of the US population.

Mount Sinai researchers used national biomonitoring data from the National Health and Nutrition Examination Survey to develop an exposure burden score using element response theory. The item response theory was developed in the educational test literature for standardized test scoring, and was first used by Mount Sinai researchers in environmental epidemiology to develop the exposure burden score, highlighted by this interdisciplinary investigation. Specifically, they used serum concentrations of eight common PFAS chemicals taken from adults and children. By combining the participant’s baseline biomarker concentrations with their much broader ‘exposure pattern’, that is, their relative exposure to other PFAS biomarkers within the entire chemical class, the researchers were able to estimate the cumulative or summary exposure burden of PFAS. This statistical methodology can be accessed by researchers and other epidemiologists by simply plugging their data sets into the PFAS burden calculator, available online.

The benefits are great. Explains Dr. Liu, whose research focuses largely on environmental health through latent variable modeling and longitudinal data analysis. Furthermore, the calculator provides a straightforward way to include exposure biomarkers with lower detection frequencies, and to reduce exposure measurement errors by considering both participants’ concentrations and their exposure patterns to estimate the exposure burden of chemical mixtures.

“By capturing individual biomarker changes, we essentially keep the exposure meter stable so that it can be used in a variety of applications,” says Dr. Liu. “These could include, for example, research across populations to determine if there are differences in exposure burden across racial/ethnic or socioeconomic classes, or whether exposure burdens are the same between people in the United States or Canada. Or looking across Physiological systems and health outcomes—such as cardiac metabolism, hormones, and immunity—to see which are more troublesome than exposure to PFAS chemicals. This range of applications takes us far beyond anything currently available in population health.”


Mount Sinai Health System

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