One frequently asked question is whether individuals living or working near unconventional oil and gas development (UOGD or “fracking”) sites such as well pads, compressor stations, or production facilities should undergo biomonitoring (blood or urine tests) to determine if they have harmful chemicals in their body as a result of exposures from these operations. While biomonitoring tests may be appropriate in a few cases, EHP does not routinely recommend them for every potentially exposed individual because of the limitations of the available tests.
Results of biomonitoring testing in the UOGD setting are often misleading for several reasons:
- Most of the chemicals associated with UOGD activity are cleared rapidly from the body, so a test may not show the presence of a chemical or metabolite even if someone is exposed to a pollutant. This may result in a “false negative” result, which can be inappropriately reassuring.
- Some metabolites of potentially harmful chemicals are also metabolites of common foods or medications. Consequently,the presence of these substances in blood or urine may not result from a harmful chemical and thus may present a “false positive” result, which can be inappropriately alarming.
- Many chemicals have multiple sources of exposure in the environment. Because of this, it can be difficult to determine if a positive result is from a UOGD-related exposure or from some other exposure.
- Some toxic chemicals do not have an associated, measurable metabolite in the blood or urine that is specific to the chemical of concern. In this scenario, even if an exposure to environmental pollutants did occur, there may be no way to detect that exposure.
- Even if a chemical can be appropriately measured in blood or urine, for most chemicals or metabolites, there are no reference values to indicate whether the amount detected poses a health risk.
Although no specific testing protocol currently exists for monitoring low levels of environmental exposures, healthcare providers are encouraged to perform routine periodic blood and urine tests to monitor kidney, liver, and thyroid function as well as hematologic status. When patients are experiencing new symptoms, these should be evaluated in a thorough fashion, recognizing that environmental exposures may be contributing to the symptoms, but without automatically assuming that environmental exposures are responsible.
An additional note is that although the results of biomonitoring results in individuals are often difficult to interpret and therefore not routinely recommended, biomonitoring of populations, where results are average over a large group of individuals, may provide useful information regarding comparative levels of exposures to particular communities.
For more information, check out our factsheet on biomonitoring.
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CDC/ATSDR Guidance on the Interpretation and Use of Blood Laboratory Analyses for VOCs