Estimating external chemical exposures and disease pathways from biomonitoring data


The goal of this study is to use mechanistic modeling to estimate external exposure levels and sources of exposure for the chemical biomarkers measured in the US National Health and Nutrition Examination Survey (NHANES). This study will also evaluate the biological pathways and the potential health risks associated with these exposures.

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We are potentially exposed to more than a million hazardous chemicals through many different sources, including work, the environment, the food we eat and the products we use. Determining which chemicals pose health risk, and at what concentration, requires robust epidemiological evidence and reliable methods for assessing exposure.

The National Health and Nutrition Examination Survey (NHANES) is a program that assesses the health and nutrition of people in the US. The goal of the survey is to determine the prevalence of major diseases and disease risk factors in the United States, in order to improve public health policies, direct health programs and services, and drive prevention. Each year, about 5,000 people participate in NHANES, which includes an interview to collect demographic, socioeconomic, dietary and health-related information, as well as an examination to collect medical, dental and physiological measurements. Laboratory tests (such as blood tests) are also administered. Blood and urine samples collected between 1999 and 2014 from 82,091 participants have been analyzed for 541 different chemical biomarkers.

While biomonitoring studies like NHANES are useful for identifying which chemical biomarkers are present in the body, they do not tell us what the source of the exposure was, or the level of exposure. This type of information is needed in order to inform prevention strategies to reduce or eliminate exposure.


This study will use NHANES biomonitoring data on levels of 541 chemical biomarkers in blood and urine samples from 82,091 participants collected between 1999 and 2014. The study will use the PROTEX mechanistic model to estimate external exposure levels that could result in the measured levels of chemical biomarkers in blood and urine. PROTEX estimates the contribution of multiple routes of exposure including ingestion (diet, drinking water, dust ingestion), inhalation (indoor and outdoor air), and skin absorption. The model adjusts for factors such as body mass index (BMI), fat percentage, age, race and time spent indoors that may affect the impact of external exposure levels on measured levels in blood and urine.

The study will also use the MetaboAnalyst “omics” platform to investigate biological disease pathways. It will identify possible metabolites and metabolic pathways for the chemicals measured in NHANES in order to better understand their potential health impact.


Biomonitoring studies like NHANES provide some indication of chemical exposure, but in order to be useful for prevention, data on external exposure sources and levels of exposure are needed. Results from this study can be used to help determine which chemicals pose a health risk, and at what levels. This information can be used to improve public health policies, direct health programs and services, and drive prevention. For example, differences in biomarker levels by demographic factors may indicate the contribution of specific chemical exposures on observed health outcome disparities in the US.

Progress (updated April 2023)

Mechanistic models have been developed for compounds. Additional analyses are ongoing.

Research Team
Joseph Okeme
OCRC, McMaster University
Victoria Arrandale
University of Toronto
Paul Demers
Lily Yang
Vy Nguyen
University of Michigan, Harvard Medical School
Li Li
University of Nevada
Yizhi Zhang
University of Toronto
Timothy Rodgers
University of British Columbia