Uses and Limitations of Biomonitoring Equivalents

Biomonitoring Equivalents (BEs) are screening tools for interpreting biomonitoring data in a public health risk assessment context.  BEs provide an estimate of biomarker concentrations that are consistent with existing exposure guidance values such as the United States Environmental Protection Agency’s (US EPA) Reference Dose (RfD) and for identifying populations with biomonitoring levels above or below the BE value associated with that exposure guidance value.  In conjunction with other information, the BE value allows biomonitoring data to be used to prioritize chemicals for risk management follow-up.

BE values are screening values.  They can be used to provide a screening level assessment of measured blood or urine levels of a chemical in population- or cohort-based studies.  Comparison of measured biomonitoring levels to BE values can provide an initial evaluation of whether the measured values in a given study are of low, medium, or high priority for risk assessment follow-up and inform whether there is a need for additional studies on exposure pathways, potential health effects, other aspects affecting exposure or risk, or other risk management activities. 

BE values are not diagnostic criteria or “bright lines” between safe and unsafe levels.  They cannot be used to evaluate the likelihood of an adverse health effect in an individual or even among a population.  Exposure guidance values are set at levels that are designed to be health-protective for daily exposure for a full lifetime of exposure, while, depending on the chemical, biomonitoring data may be informative only about recent exposure levels.  An exceedance of the BE value in a single sample of blood or urine may or may not reflect continuing elevated exposure and does not imply that adverse health effects are likely to occur, but can serve as an indicator of relative priority for further risk assessment follow-up.

BEs are not bright lines between safe and unsafe levels of chemicals in the body and do not represent regulatory standards. Rather, BEs are tools that can be used in conjunction with other information to prioritize chemicals in a risk assessment and risk management context.