While it was not part of the design of our study, the protocol may well provide an answer to a paradoxical question posed by researchers in 2009 who found indications that Bisphenol A (BPA) may not be eliminated from the body as quickly as thought.
Most studies of the half-life of Bisphenol A (BPA) in the human body have concluded that the primary exposure comes through food and beverage, and that it is rapidly eliminated from the body.
Indeed, in our study & protocol approved by the Committee on Human Research at the University of California, San Francisco Medical School, we referenced (footnote 8) an oft-cited study to that effect.
A study in Environmental Health Perspectives back in 2009 challenged that widely held notion: Bisphenol A Data in NHANES Suggest Longer than Expected Half-Life, Substantial Nonfood Exposure, or Both.(Stahlhut, Welshons, and Swan).
That study analyzed data from the 1,469 adult participants in the 2003–2004 National Health and Nutrition Examination Survey conducted by the Centers for Disease Control.
The study results indicated:
“Overall, BPA levels did not decline rapidly with fasting time in this sample. This suggests substantial nonfood exposure, accumulation in body tissues such as fat, or both. Explaining these findings may require experimental pharmacokinetic studies of chronic BPA exposure, further examination of BPA levels and effects in fat, and a search for important nonfood sources.”
Our Study May Provide An Answer
The results of that previous study have not been tested before because it is considered unethical to deliberately expose humans to potentially harmful substances. This is the case even for those chemicals (like BPA) that are ubiquitous in the environment and have been deemed safe by federal regulators.
Our study protocol, however, calls for the controlled and staged reduction of chemicals to which most of the population is continually exposed. (See 15.1 in our study protocol).
BPA Half-Life Indications
While we had not designed the study to test for BPA elimination, the ability to do that requires the simple step of moving Class 4 of our test substance elimination (non-food exposures) to last. This is something we will do.
The BPA levels in the urine and serum samples taken at the end of that final week may offer insight on the half-life of elimination.
BPA Retention Possibilities
One measurement which has been added to the protocol since its approval by the UCSF-CHR is the measurement of the actual BPA load consumed in foods and beverages.
From that metric, it should be possible to calculate any degree of retention in the body, if any.
Because this measurement id not performed on human subjects, its addition doesn’t require the CHR’s re-examination