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3.3.4. Method sensitivity
With this element, the instrument seeks to capture whether there is a sufficient percentage of the measurements above the limit of detection to enable a reasonable assessment of exposure/outcome relationships. Because the methods for measurement of urinary BPA are well-established and BPA was measurable in a large percentage of the study populations, reviewers were generally consistent in assigning publications to Tier 1 for this element. However, one publication was categorized as Tier 2 because the percent detected was not given. We recommend reassessing this SCH727965 using literature on a different biomarker that is more difficult to measure. This may help better define what constitutes a “sufficient” percentage of measures above the limit of detection.
3.3.5. Biomarker stability
3.3.6. Sample contamination
Contamination in the field and/or the laboratory has been shown to affect research that uses human or animal tissue samples; precautions must be taken to avoid or at least minimize this problem (Calafat and Needham, 2009). This BEES-C element is of considerable importance in assessing the quality of studies of short-lived chemicals such as BPA, which are ubiquitous in the environment and the laboratory (Ye et al., 2013) and are often components of sampling and laboratory equipment. The reviewers were generally in agreement that the publications fell into either Tier 2 or 3 due to lack of documentation demonstrating avoidance of sample contamination. The key ambiguity with this element pertains to the distinction between not using proper QC procedures and possibly using — but not documenting — the procedures. We suggest the following modification to Tier 2 (Table 2): Incomplete documentation of QC steps taken to avoid contamination.