Definition: The measure of internal effects of exposures from the outside environment, or cellular changes that are predictive of later increased risk for disease development
Classification: Tool and technique for human study
Unlike traditional biomonitoring, which measures chemicals or their metabolites in a person’s body, these biomarker studies look at abnormal changes in an individual’s (?) DNA structure and function or metabolic pathways that precede the development of a diagnosable disease (Perrera, 2000).
One example relevant to understanding the relationship between environmental exposures and later development of breast cancer is the development of PAH-adducts in breast tissue following exposures to polycyclic aromatic hydrocarbons (PAHs). PAH-DNA adducts are created when PAHs bind to DNA and create problems with DNA repair in cells, one of the early hallmarks of tumor development (Poirier, 2012; Pratt, 2011).
Environmental chemicals, including several pesticides, can also bind to proteins, forming chemical-protein adducts, causing the proteins to transform into irregular 3-dimensional shapes that may interfere with how the proteins can behave in relation to other cells. These protein adducts inactivate the proteins, leading to changes in cellular function at many levels (Marsillach 2013).
Another example of a biomarker that is predictive of later development of cancer is the reliable rearrangement of nucleotides (the building blocks of the genetic code) within genes following exposure to low-grade radiation, including that found following exposure to radon or several occupational sources (Hande, 2003).
While still a relatively new research tool, biomarker monitoring allows scientists (and potentially clinicians) to monitor actual premalignant cellular changes in individuals in response to environmental exposures. Because these cellular changes are indicative of the first steps in the development of cancer, they are more accurate predictors of the increased risk for full development of a malignant tumor. As our understanding of these markers increases, so will our understanding of the complex progression from normal to cancerous states (Pratt, 2011). And as the techniques for assessing biomarkers become both more accurate and less costly, their use will increase for both research and diagnostic purposes, together yielding substantial databases (Marsillach, 2013).
Both the technology for biomarker monitoring and the scientific understanding of appropriate cellular markers to measure are still in the early stages of development. If the tissue of interest is breast tissue, then this requires taking a breast biopsy or tissue from other breast surgical procedures. It is critical that scientists study multiple cell types in various organs or tissues, use fresh (not frozen) samples, and validate assays within and across samples. And particular biomarkers need to be demonstrated to be stable during the assay procedures so that determinations are accurate and reliable (Levenson, 2013). All of these issues are standard scientific concerns, but scientists are in the early stages of addressing them for this particular approach (Pratt, 2011). Until these standardized assays are adopted across laboratories, the methods can be quite expensive and time consuming (Marsillach, 2013).