Why is exposure to VOC relevant to health?
Volatile organic compounds (VOC) are common products of incomplete combustion, occurring widely in air pollution, vehicle exhaust, and tobacco smoke. VOC are also common constituents of cleaning and degreasing agents, deodorizers, dry cleaning processes, paints, pesticides, and solvents. Increased concentrations of VOC in the body can, therefore, result from a variety of environmental exposures.
Prior studies indicate that exposure to VOC such as benzene, butadiene, and toluene throughout life, as well as during early childhood, increases the risk of a variety of diseases, including leukemia and retinoblastoma.
What types of questions can be answered?
Exposure to VOC can be measured by determining levels of their metabolites in urine or certain parent substances in blood. DNA adducts of some VOC can be measured in DNA from oral cells or leukocytes. Most humans have these substances in their blood or urine, as some of them are the results of endogenous metabolic processes.
How can VOC exposure be measured?
- Analytes: Many VOC such as acrolein, propylene oxide, and benzene are metabolized by the glutathione S-transferase pathway leading to the excretion of mercapturic acids in urine; these metabolites can be quantified. The mercapturic acid measurements in urine are particularly useful because the levels of these substances are generally well within the quantifiable range using current methods. Virtually all urine samples will contain these metabolites, but levels in exposed subjects may be significantly higher. Some VOC (parent compounds) can also be quantified in serum and whole blood. DNA adducts of VOC - including formaldehyde, acetaldehyde, and acrolein - can be measured in DNA from leukocytes or oral cells.
- Methods: Methods that couple chromatography with mass spectrometry are used.
- Types of biospecimens: Urine, serum, oral cells and leukocytes. Because urine concentrations vary, analytes measured in urine need to be corrected for urine dilution.
- Types of environmental samples: HHEAR does not provide analysis of VOC in environmental samples.
How does HHEAR ensure the quality of its analyses?
All bioassays are well validated with respect to accuracy and precision. All assays have embedded positive and negative controls. The positive controls are used to check assay accuracy within each set of samples. The negative controls are generally water blanks that are included to assess the possibility of any cross contamination in the assay procedure.
What sample quality and quantity are necessary?
This is highly dependent on the assay to be run, but in general a few milliliters of urine, 0.5 mL of serum, or 10 micrograms of DNA are required. Sample stability is of concern for VOCs in serum so be sure to consult with a HHEAR Lab Hub for these analyses.
References
Filippini T, Heck JE, Malagoli C, et al. A review and meta-analysis of outdoor air pollution and risk of childhood leukemia. Journal of Environmental Science and Health. Part C. Environmental Carcinogenesis and Ecotoxicology Reviews. 2015;33(1):36-66.
Hecht SS, Yuan JY, Hatsukami D. Applying tobacco carcinogen and toxicant biomarkers in product regulation and cancer prevention. Chemical Research in Toxicology. 2010;23(6):1001-1008.
Heck JE, Park AS, Qiu J, et al. Risk of leukemia in relation to exposure to ambient air toxics in pregnancy and early childhood. International Journal of Hygiene and Environmental Health. 2014;217(6):662-668.