Although the blood samples cannot be tested for alcohol or drugs until the subject gives permission, those who refuse will be subject to prosecution.
The requirement for obtaining informed consent of individuals in this study was waived by the IRB because radioactivity in blood samples cannot be used to identify personal information.
More importantly, primary blood samples cannot be continually passaged or easily manipulated, resulting in limited flexibility to generate iPS cells.
In epidemiology studies, this requirement often means that whole blood samples cannot be frozen prior to arrival at the central location and subsequent processing.
Blood samples cannot be frozen or stored in preservation buffer for these approaches prior to processing and hence these methods are impractical for field-based investigations of natural, free-ranging populations.
Thus, considering the limitations in sensitivity of the analytic procedures, the potential contamination issues, as well as the discomfort associated with the blood sampling procedure, blood or serum sampling cannot be recommended for surveying phthalate exposure in the general population.
However, as blood samples cannot feasibly be collected prior to diagnosis in a case control study, there is little that can be done to mitigate this limitation.
However, flow cytometry has important practical limitations: (a) results vary dramatically because of differences in specimen handling, (b) blood samples have to be analyzed immediately and cannot be stored for later analyses, and (c) samples cannot be collected from health-care units without laboratory equipment for flow cytometry.
Furthermore, sampling the gut mucosa remains an invasive procedure compared to blood sampling, it cannot be performed as frequently and standardization to the exact sampling location is difficult.
