Biomonitoring Equivalents: A valuable scientific tool for making better chemical safety decisions

Among all the discussion and debate about improving how chemicals are managed to ensure the public and the environment are protected from potentially harmful exposures, at least one point stands out on which we can all agree: better access to information, as well as a greater understanding of that information, will help lead to better safety decisions.

Scientists today can detect even minute levels of a given substance in the body through tools such as biomonitoring. This has left some with the impression that more data, or just settling for more information regarding potential hazards, equals greater safety. That’s really not the case.

As the U.S. Centers for Disease Control and Prevention (CDC) noted in a 2005 report, “The presence of a chemical does not imply disease. The levels or concentrations of the chemical are more important determinants of the relation to disease, when established in appropriate research studies, than the detection or presence of a chemical.”

The question is, how should public health professionals and scientific researchers go about doing a better job of interpreting biomonitoring data on chemical exposures? One way is to use a recently developed tool called Biomonitoring Equivalents, or BEs.

What are Biomonitoring Equivalents?

BEs are tools that provide a credible estimation of how much of a health risk there is based on population biomonitoring results, thus allowing agencies, lawmakers and the public to better understand what the results actually mean.

Acting upon the recommendations of the National Research Council’s report “Human Biomonitoring for Environmental Chemicals,” scientists first developed the BE method to understand population-based biomonitoring results in a public health risk context. The surveys provide extremely valuable information on the public’s exposures to chemicals.

BEs have become a valuable tool to help risk managers interpret valuable biomonitoring data being generated by the CDC, the Canadian Government and the State of California. With the advent of the BE method, health professionals and risk managers can now interpret the public’s exposure levels via biomonitoring in a public health risk assessment context.

BEs are now readily available on the U.S. National Library of Medicine’s ToxNet website.

Sean Hays, Ph.D., President of Summit Toxicology, L.L.P., was an originator of the BE method, and has been driving the effort to develop BEs and make them easily accessible for everyone.

We had the opportunity to ask him a few questions about BEs and how the addition of BEs to ToxNet on the National Library of Medicine’s database will help public health professionals protect health and the environment.

Why were BEs added to the existing ITER database on ToxNet, and who will be using BEs?

Sean Hays, Ph.D.

The ITER database on ToxNet is a compilation of safe exposure limits set for chemicals by a range of regulatory agencies across the world. These safe exposure limits help risk assessors and risk managers interpret exposure information when the exposure estimates are based on chemical residues in air, water, food and consumer products. The BEs were added because they provide the corresponding concentrations of chemicals in people’s blood and/or urine that are associated with these same safe exposure limits. As a result, risk managers can now have easy access to the safe exposure limits in terms of biomonitoring levels that can be used to compare to actual population biomonitoring results. In addition to risk managers, researchers, public health experts and physicians will be able to readily access the BEs through the National Library of Medicine portal and use these to help them interpret concentrations of chemicals in blood and/or urine from study volunteers or patients.

How will this new information help improve safety decisions?

Biomonitoring data provides some of the most accurate indicators of human exposure to chemicals. BE values allow these biomonitoring data to be interpreted in the context of safe exposure limits. This will help regulators and companies alike to identify chemicals for which exposures may approach or exceed current safe exposure limits, as well as to identify those for which exposures are well below current safe exposure limits. Such information can assist in prioritization of further exposure and risk assessment evaluations.

Can BEs help eliminate some of the fear and confusion that is often associated with simply reporting the detection of a chemical in the environment or in the body?

Yes. Reporting that a chemical was found in a person’s blood and/or urine most often elicits two responses: how did I get exposed to that chemical? And, is it a hazard to my health? BEs cannot answer the first question, but it can help answer the latter. Just like having a benchmark to assess whether a person’s cholesterol level in their blood is too high, the BE allows scientists, health professionals and risk managers to identify chemicals for which exposure levels are below risk-based exposure guidance values and those for which exposure levels are potentially of concern.

What is the most important point that the public and or policymakers should know when it comes to properly understanding biomonitoring data?

As with exposures to all chemicals, natural and man-made, understanding the level of exposure relative to levels that produce health effects is of paramount importance. If levels of exposure are very low compared to levels that may produce a health effect, the exposures are negligible in a health risk context. Biomonitoring data provides some of the most important exposure information available for exposures to many chemicals, and interpretation of these data in the context of safe exposure limits set by regulatory agencies using BEs assists in making full use of the data. As biomonitoring for chemical exposures becomes even more cost effective and routine, health professionals and regulators will be required to more often interpret these biomonitoring data in a public health risk context, and BE values will become even more important in understanding the relative levels of chemical exposure.

Where can we learn more about how BEs have been used to evaluate human biomonitoring data?

We recently published a scientific paper, co-authored by leading scientists at EPA and CDC, where we used BEs to interpret CDC’s U.S.-wide biomonitoring results.

For scientists and health professionals, a complete list of BE publications can be found at

In addition, we recently evaluated initial biomonitoring data from California’s Environmental Contaminant Biomonitoring Program. We were invited by the Kids + Chemical Safety website to compare the data reported for the Maternal and Infant Environmental Exposure Project to BEs and to summarize the results in a post. We found that the levels detected in the California study were all lower than the BE values; thus exposures are within the safe range in the context of a population health risk assessment. Since many of the California Program’s measured biomonitoring levels were 100’s to 1000’s of times lower than the BE, there’s a wide margin of safety for these substances. Interested readers can find the complete post at:

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