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One frequently asked question is whether individuals living or working near shale gas development (SGD) 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. One common class of potentially harmful emissions from oil and gas development is “volatile organic compounds” (VOCs). While there are blood and urine tests available to assess exposures to VOCs, the results can be misleading, resulting in either false reassurance or unnecessary alarm. Before undergoing testing, it is important to understand the nature and limitations of these tests.
Some limitations in biomonitoring testing in the SGD setting include:
Most of the chemicals associated with SGD 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 an SGD-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.
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 information you can share with your patients and clients, check out our factsheet on biomonitoring.
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