What Happens To BPA In Your Body? Are We Sure We Know?

Steven Hentges, Ph.D
Thursday, September 28, 2017

If you browse around on this website, you’ll quickly find the answer to the first question. The
most common way we encounter BPA is through our diet and, after oral exposure, BPA isquickly absorbed into the body through the intestine.

Before it can go anywhere in the body, BPA is efficiently converted to a biologically inactive
metabolite by enzymes that are plentiful both in the intestinal wall and the liver. That
inactive metabolite is then quickly eliminated from the body through urine.

If you look for BPA in the body, you probably won’t find it. But you probably will find low
levels of the metabolite in urine.

But how sure are we about that? After all, this is an internet site and you know you can’t
believe everything you read on the internet. That’s where a recently published study and a
key principle of the scientific method come into play.

Simply speaking, the scientific method is the systematic way in which we acquire newknowledge. Scientists conduct experiments through which they gather data and, as aresult, we learn something we didn’t know before.

To confirm what we learned, a key principle of the scientific method is the concept ofreplication. If an experiment cannot be replicated to get the same result, the original result
may be an error. Conversely, if an experiment is replicated with the same result, we havemore confidence that the result is valid.

Recently a pair of researchers from Sweden and Canada published a study in which they
dosed a group of human volunteers with a small amount of BPA that was placed on a1/2cookie. The researchers then monitored what happened to BPA as it passed through thebody.

They did not find any BPA in the blood of the volunteers after the exposure. What they did
find is the metabolite of BPA in the volunteer’s urine very soon after exposure.

These new results aren’t really unexpected but they are very reassuring. They’re exactly
what we would expect based on three previous studies on human volunteers. According to
the scientific method, our confidence in knowing what happens to BPA in the body is further
increased by replication of results across all four studies.

In this case, the four studies were conducted independently by four different groups ofresearchers. The first study, dating back to 2002, came from academic researchers inGermany. That was followed by two studies in 2015, the first from researchers at the PacificNorthwest National Laboratory, which is a U.S. government lab, and followed by a study
from the U.S. National Toxicology Program, another U.S. government lab.

Along with being a good example of how the scientific method works, the results from thesefour studies are important for consumers who regularly contact trace amounts of BPA
through our diets. Thanks to this normal process of metabolism, BPA is not likely to beharmful at the low levels to which we’re exposed since our bodies are very good at
eliminating it before it could build up or do us any harm.

Now that you’re tuned in to the scientific method and the important principle of replication,
you might be questioning that reference to trace amounts of BPA. How do we know thatand how sure are we? After all, you are reading this on an internet site.

In this case, more than 140 studies conducted in 30 countries worldwide have consistentlyreported that human exposure to BPA is hundreds to thousands of times below safe intake
limits set by government bodies worldwide. With more than 85,000 data points from thesestudies, we can be quite sure that human exposure to BPA is very low.

It’s not always the case that scientific studies and their findings are replicated as they havebeen in the examples discussed here. Before believing the latest scientific result that you
read on the internet, it’s worth asking the question. Has it been replicated?

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