Protocols to preclude extraneous exposure and cross-contamination between cohorts of animals as previously described [27] incorporated protective shower-in requirements, Tyvek™ clothing, masks, head covers, and footwear, while maintaining stringent husbandry.
Difficulty in interpreting some of the existing research arises because of the incipient state of knowledge regarding boron nutriture, to analytical problems associated with determining accurately the small quantities of boron in feed and tissues, and to technological difficulties in controlling extraneous exposure of experimental animals to boron.
A biomarker should be chosen to best represent usual personal exposures and not recent, adventitious, or extraneous exposures.
Finally, alcohol biomarkers in general, and in particular EtG because of the potential for extraneous exposures, should not be used as the only determinant of alcohol use, including potentially problematic use 2. The research on EtG as an alcohol biomarker is growing.
If used as a treatment monitoring tool, patients and clinicians need to be informed regarding possible extraneous, ethanol-containing exposures 1, 29.
This, together with the notion that the variability seen between different Vitrocell VC10's may dependent on the service (maintenance) status of the smoking machine [25], supports our view that the most significant sources of variability are extraneous to the Vitrocell® exposure system.
One type of confusion may arise from the distortion of the effect of an exposure of interest by some extraneous factor when the effect of the extraneous factor is mistaken for or mixed with the actual exposure effect.
One potential source of bias is confounding [ 15], where an extraneous factor is associated with both the exposure under study (e.g., treatment) and the outcome of interest, but is not affected by the exposure or outcome [ 16].
Nevertheless, we recognize that in a correlational study it is never possible to assess all extraneous variables that might be correlated with exposure and provide alternative explanations for observed effects.
To further increase model efficiency and eliminate variables that were extraneous (i.e., nonconfounders, not correlated with both exposure and outcome), we included only covariates that were correlated with both exposure and outcome at p < 0.20.
After 45 min exposure to this stimulus pattern, the extraneous signal acquired the same effect as the depth cues that were contingent during the exposure.
