Federal government sources have funded, and Federal scientists have recently performed, a clinical study of human BPA exposure, using a controlled diet and blood testing - not just urine tests, as other well publicized studies have relied upon.
Here, as touted by a canning industry trade group - they are naturally excited about the findings - is a summary of what the findings may mean:
"In the paper to be published this month in the Journal of Toxicological Sciences, researchers found that even when a typical diet was altered to ensure that high concentrations of BPA were ingested, the levels of non-metabolized BPA (i.e., "free" BPA) in blood were below the level of detection. That is several orders of magnitude lower than levels associated with potentially adverse health effects."
On to the facts as published.Below, as presented on the US National Library of Medicine website, is the cited study's full abstract.
Notes: The last sentence of that abstract was made bold by me. LOD means "level of detection" which is the lowest concentration at which a laboratory can measure presence of the substance with standard procedures.
Toxicol Sci. 2011 Sep;123(1):48-57. Epub 2011 Jun 24.
Twenty-Four Hour Human Urine and Serum Profiles of Bisphenol A during High-Dietary Exposure. Teeguarden JG, Calafat AM, Ye X, Doerge DR, Churchwell MI, Gunawan R, Graham MK.
Source: Fundamental and Computational Sciences, Pacific Northwest National Laboratory, Richland, Washington 99352.
AbstractPMID: 21705716 [PubMed - in process]
By virtue of its binding to steroid hormone receptors, bisphenol A (BPA, the unconjugated bioactive monomer) is hypothesized to be estrogenic when present in sufficient quantities in the body, raising concerns that widespread exposure to BPA may impact human health. To better understand the internal exposure of adult humans to BPA and the relationship between the serum and urinary pharmacokinetics of BPA, a clinical exposure study was conducted. Blood and urine samples were collected approximately hourly over a 24-h period from 20 adult volunteers who ingested 100% of one of three specified meals comprising standard grocery store food items for breakfast, lunch, and dinner. The volunteers' average consumption of BPA, estimated from the urinary excretion of total BPA ((TOT)BPA = conjugated BPA + BPA), was 0.27 μg/kg body weight (range, 0.03-0.86), 21% greater than the 95th percentile of aggregate exposure in the adult U.S. population. A serum time course of (TOT)BPA was observable only in individuals with exposures 1.3-3.9 times higher than the 95th percentile of aggregate U.S. exposure. The (TOT)BPA urine concentration T(max) was 2.75 h (range, 0.75-5.75 h) post-meal, lagging the serum concentration T(max) by ∼1 h. Serum (TOT)BPA area under the curve per unit BPA exposure was between 21.5 and 79.0 nM•h•kg/μg BPA. Serum (TOT)BPA concentrations ranged from less than or equal to limit of detection (LOD, 1.3 nM) to 5.7 nM and were, on average, 42 times lower than urine concentrations. During these high dietary exposures, (TOT)BPA concentrations in serum were undetectable in 83% of the 320 samples collected and BPA concentrations were determined to be less than or equal to LOD in all samples.
Now back to the press release issued by North American Metal Packaging Alliance, Inc.
I'm assuming that the study findings as presented by the trade association are factually in bounds and not too far extrapolated from.
People have heard that 93% of the U.S. population have BPA in them, but the mere presence of BPA doesn't mean it is harmful," Dr. Rost continued. "What people aren't told is that the BPA is measured as the BPA-metabolite in urine, which means the human body is metabolizing and clearing it efficiently and effectively from the body."
The study results indicate that the human body is extremely efficient at processing BPA from the body and is so effective that levels of free BPA are undetectable.
-- Free BPA was below the limit of detection in all 320 blood samples analyzed by the CDC lab, even for samples with detectable total BPA. Based on their results, the authors note that high levels of BPA in blood reported in other studies are unlikely to be valid.
-- Total BPA was detected in only 14% of the 320 blood samples, only one of which was above 1 part per billion (ppb). Total BPA was below the sensitive limit of detection (0.3 ppb) for 86% of the samples.
The work of Teeguarden et al. demonstrates for the first time in a large clinical study that because of the way BPA is processed in the body, it is highly unlikely that BPA could cause health effects. Moreover, the findings call into question other studies reporting high levels of BPA in spot testing of urine or blood. The authors suggest that "infrequent positive determinations near the detection limit should be suspect" and "thus, some attributions of high blood BPA concentrations from oral exposure seem implausible."
Don't sweat the little stuff.
You might want to wait for the full study to be released, but here's my take.
The occasional recipe made from a can of tomatoes won't detonate your (adult) hormone system into a gender-bent, reproductively damaged future.
I would still be cautious about baby formula in cans but let's see what the authors may have to say about how applicable their findings are to children.
Get that BPA-lined aluminum bottle back out from the corner of the garage and fill it to the brim with water.
And, above all, there's no need to feel guilty for donating canned goods to the food drive. If people are hungry, feed them.
Footnote: Tea Partiers and Libertarians, because they are unlikely to give credence to work done by government scientists, are at risk of discounting these important study findings and refusing to eat canned food. That's why I included excerpts from the trade group release in my post. (No one should have to go hungry, even if they have a bizarre world view.)