Do you want to know your ‘body burden’?

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Publication Date: 
Mon, 2014-03-03

Measuring the chemicals within through biomonitoring

By Dolon Chakravartty and Robyn Lee

We are exposed to both naturally occurring and commercially produced toxic substances in a variety of ways every day. We may inhale them, swallow them in contaminated food or water, or in some cases, absorb them through our skin. Recent research indicates that all human beings carry varying amounts of chemicals in our bodies, with health effects that are not yet known. Each person’s risk of developing health problems related to environmental chemicals is tied to a combination of exposure, genetics, sex, age, nutrition and lifestyle. And an individual’s exposure to environmental pollution can be analyzed through a process called “biomonitoring.”

As analytical methods become more sophisticated, we are able to detect minute amounts of chemical presence in human tissue. A number of studies have used biomonitoring techniques to determine levels of chemicals in the body and concerns have emerged around disclosing results. While some argue that reporting results of the presence of chemical substances causes unnecessary alarm, others advocate for the right to know, even if the possible health effects are unclear. This raises ethical issues related to reporting biomonitoring results to study participants.

Biomonitoring, a scientific technique for assessing human exposures to natural and synthetic chemicals, is based on sampling and analysis of a person’s tissues and fluids. It measures contact with and absorption of toxic chemicals in the body through detection in human blood, urine, semen, amniotic fluid, breast milk, saliva, breath, hair, fingernails or other tissue. Samples are analyzed by assessing the concentration of the “parent chemical” and the products created when the “parent” breaks down (metabolites), as well as the products that the parent chemical reacts with. In this way, biomonitoring results are a detailed measure of exposure from multiple sources and routes. 
“Body burden”—also called the internal or absorbed dose—is the amount of chemical compound present in the human body at a given point in time. 

Biomonitoring was originally used to detect exposure to chemicals in occupational settings, but its use became more widespread during the 1970s through the detection of lead levels in the blood linked with leaded gasoline, lead paint and lead solder in canned food. This method for assessing exposure has recently become less expensive and more widely available with advances in molecular biology that have allowed for more specific, sensitive and biologically relevant tests. With these advances, biomonitoring research is becoming more common in academic and governmental settings, as well as in environmental advocacy and research organizations that use these studies to promote more stringent regulation of toxic chemicals.

However, because little is known about the potential health related outcomes of many of the pollutants studied, there are ethical challenges regarding whether and how to report results to individual study participants when clinical effects are uncertain.

Nationwide studies and sources

In the United States, the Centers for Disease Control and Prevention began a nationwide biomonitoring study in 1999, which is now updated every few years. Two major national biomonitoring studies are currently underway in Canada. The Canadian Health Measures Survey (CHMS) carried out by Health Canada and Statistics Canada includes a biomonitoring component. The CHMS is a population-based household survey that is currently assessing 91 chemicals and their metabolites in a Canadian sample to determine baseline amounts. Blood and urine specimens are being analyzed for a number of different classes of substances, including metals, phthalates, polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs), organochlorine pesticides, organophosphate insecticide metabolites, phenoxy herbicides, cotinine, perfluorinated compounds and bisphenol-A. The survey also includes a questionnaire, which allows for the analysis of risk factors related to exposure to these environmental chemicals.

Another Canadian study, the Maternal Infant Research on Environmental Chemicals (MIREC) study is examining approximately 2,000 pregnant women and their babies’ exposures to a variety of chemicals such as phthalates, PBDEs, pesticides, etc.

Brominated flame retardants (BFRs) and phthalates are two types of chemicals that are increasingly found through biomonitoring. Some chemicals, such as polychlorinated biphenyls (PCBs), dioxins, and Polybrominated Diphenyl Ethers (PBDEs) are considered “persistent,” remaining in the body for long periods of time as they adhere to fatty tissue. Others, such as volatile organic compounds (VOCs) and phthalates are processed by the body and expelled through urine.

Recent clinical studies indicate that BFRs may impact early stages of human development and at least one outcome is abnormalities of the reproductive system. Levels of BFRs in the environment and in humans in North America are on the rise. The body burden of BFRs in North Americans has risen sharply since the early 1990s to reach a level among the highest in the world. Most of the consumer products containing BFRs are found in homes and offices, since the substances are used to reduce flammability of carpet fibers, foam, mattresses, wiring, computers and other electronics. We spend over 80 per cent of our time indoors and the indoor environment has 1.5 to 50 times greater levels of BFRs compared to the outdoor environment.

A wide variety of consumer products contain phthalates. These include products made of flexible polyvinyl chloride plastic (PVC), cosmetics and other personal care goods, pesticides, building materials, lubricants, adhesives, and film, among other items. Phthalates are released into the environment during manufacturing processes and leach from consumer products. Human exposures are commonplace as a result of worldwide ecosystem contamination and direct contact with products containing phthalates.

Reporting results

Communicating study results is one of the greatest ethical challenges facing researchers who conduct biomonitoring studies. It is unclear what type of information to relay to study participants, but it is also unclear how it should be done. In many cases, study participants are now demanding to see their individual results, despite the lack of knowledge about individual health effects due to exposures.

Reporting study results to individuals is particularly difficult because participants usually want to know if they are healthy. Biomonitoring studies are not designed to answer that question. Biomonitoring accurately measures exposures, but the data do not indicate a particular state of health, nor do they indicate an individual’s likelihood to develop an illness. Also, for many of the chemicals measured in contemporary exposure studies there is no readily available range of acceptable levels of concentrations in human blood, urine, or other biological specimens.

Researchers have a duty to limit risk and must consider the potential harm of reporting results. Individuals may experience fear, worry, or stigma; there are legal and economic complications, such as effects on health insurance or property values related to chemical contamination; and the possibility of unnecessary or counter-productive interventions. Because responsible reporting is expensive (financial costs include creating a customized report for each individual and often a face-to-face meeting), it may cause unintended harm, not to mention the use of resources that would otherwise be spent on health or services (Read “Improving Disclosure and Consent").

Currently, scientists or community-based research collaborations receive minimal guidance on the matter of reporting results. According to the clinical ethics model, researchers should only communicate individual results if exposure levels are deemed significantly high or if the exposure level is clearly linked to a harmful outcome, such as in the case of lead. In some studies only physicians are permitted to share the results and are meant to adequately explain risk levels associated with the chemicals in question.

If a participant’s biomonitoring results are below the regulatory levels, even if evidence suggests health concerns at lower levels, the clinical model does not allow for precautionary action. For the majority of chemicals tested in biomonitoring studies no adverse health outcomes are conclusively linked to low-level exposures. However, not reporting individual results may become a problem as new research continues to link exposures and health outcomes in the future. Even in the absence of regulatory benchmarks, individuals could compare their results with average exposure levels in the general population.

Reporting individual results may have negative consequences. For example, recent studies on the presence of PBDEs, PCBs and other toxins in breast milk have raised concerns that if women have knowledge of high levels of toxins, they will stop breastfeeding. However, research shows that appropriate biomonitoring study design, including clear communication about individual results and the benefits of breastfeeding, can prevent these negative impacts on breastfeeding.

The clinical model policies also make researchers into gatekeepers of participants’ information instead of offering participants the opportunity to decide for themselves what research information they want to know. Failing to report biomonitoring results to participants treats individuals as sources of scientific data without considering their interest in receiving information about themselves. Research shows that the prevalence of distress caused to participants by disclosure is low and that most participants find disclosure of test results beneficial, regardless of the actual result or accompanying distress.

An alternative to the clinical model is community-based participatory research (CBPR), which assumes that reporting individual and aggregate study results can empower individuals and communities to act on scientific research. CBPR encourages as much dissemination of information as possible and asserts that the collected data belong primarily to the study participants.

The First Nations Biomonitoring Initiative (FNBI), which started in January 2011, is a health survey designed for First Nations populations living on reserve, south of 60 degrees. The initiative measures levels of trace metals, PCBs and also BFRs, pesticides, PFOs, BPA and phthalates using the community-based model. The initiative carries out body burden testing for the same chemicals with testing protocols that are complimentary to the Canadian Health Measures Survey (CHMS). First Nations communities on reserves are not included in the Canadian Health Measures Survey, despite their history of exposures to heavy pollution and toxicity. The FNBI will provide a baseline of chemical body burdens on First Nations reserves, and the communities will retain control over all resulting data. The First Nations Biomonitoring Initiative provides an information package to all participants to help them understand the results of their tests and individuals found to have an unusually high level of a chemical will be informed so that they can seek appropriate medical attention.

The results of community-based participatory research biomonitoring studies must be carefully disseminated and used to avoid potential adverse effects to communities and individuals who may be stigmatized as being “at risk” as a result of high chemical body burdens. Pitfalls can be avoided through appropriate study protocols and communication strategies developed together with the communities involved.

‘Advocacy biomonitoring’

The terms “data judo” or “advocacy biomonitoring” are used to describe a strategy in which study design and the communication of individual results are shaped primarily by policy goals to improve chemical regulation. This framework assumes that reporting results can boost public support for increased regulation of toxic chemicals and motivate individuals to engage in collective activism.

Participants in a California biomonitoring study examining indoor pollution used their individual data and aggregate results in testimony opposing a neighbouring oil refinery. Newer biomonitoring studies that report individual results as part of community-researcher partnerships emphasize participants’ right to know and right to act, and in some cases highly visible results reporting is central to activist strategies to stimulate policy change.

Biomonitoring can expose how your home is not a “refuge,” but “a dumpsite for the excesses of industrial capitalism” according to the authors of Through the Kitchen Window: The Politics of Home and Family. Participants in a household exposure study in California initially perceived their homes to be a safe haven, an assumption that biomonitoring disproved. This inspired many study participants to want to use their results to pressure government officials for more stringent regulation of toxics. The participants decided to take action by “writing to the city council, speaking at hearings, and supporting the passage of regulation, among others.” Sharyle Patton, from the environmental advocacy group Commonweal, argues that biomonitoring can be used to promote activism. Drawing on personal stories of individuals who have had their chemical body burdens tested, she described how migrant farm workers in California had developed a strong activist community as a result of biomonitoring. She described the tremendous impact of first person accounts when campaigning for greater regulation of chemical exposures.

Researchers at Brown University in the United States found that biomonitoring can demonstrate the ineffectiveness of individual changes in consumption patterns. Some of the study participants who changed their consumption patterns and yet saw no change in their chemical body burdens reported a desire to get involved in regional environmental health advocacy. The visible failure of consumption changes may help mobilize collective action. Body burden testing can demonstrate how shopping does not make us safe and how more sweeping regulatory changes are required that go beyond individual consumer choice.

Biomonitoring has limitations, since it can be difficult to identify the primary source of exposures and it is rarely possible to predict health outcomes based on chemical body burdens. However, respect for participants in research provides a strong impetus to report biomonitoring results. Research demonstrates that biomonitoring participants appreciate getting these results, and they are not necessarily alarmed or fearful about finding out about chemical exposures in their bodies. In fact, participants are often highly motivated to engage in collective environmental advocacy. Receiving biomonitoring results can be an important tool in campaigns to improve regulation of toxic chemicals.


Dolon Chakravartty is a PhD candidate at the University of Toronto in Public Health and collaborative program in Environment and Health.  She is also a team member on a CIHR team grant on Brominated Flame Retardants and Phthalates.

Robyn Lee has a PhD from York University in Social and Political Thought and is a team member of CIHR team grants on Brominated Flame Retardants and Phthalates.

Supported by grants RHF100625 from the Institute for Human Development, Child and Youth Health (IHDCYH), and CIHR Team Grant RHF-100626, Canadian Institutes of Health Research (CIHR).

Additional Resources:

Measuring Personal Chemical Exposures Through Biomonitoring: The Experiences of Research Participants by R. Washburn, published in Qualitative Health Research, February 2014

Northern Contaminants Program

First Nations Biomonitoring Initiative – National Results 2011 – Report published June 2013

Assembly of First Nations – Media release on FNBI

Cans not cancer campaign – Breast Cancer Fund 

Breast Cancer Action Montreal (BCAM)