Bisphenol A or BPA is one of those synthetic chemicals that regularly hits the headlines.
It's used in polycarbonate plastics, food can liners
thermal till receipts and other everyday objects and most people have small
amounts of it it in their body
but are these levels safe or do we have a problem?
These are questions scientists the world over have been grappling with for
some time
and just recently the latest in a line by extensive expert reviews was
published by the European
Food Safety Agency or EFSA. The review
which analyzes and interprets the latest science on BPA and human health risks
is a whopping five hundred pages long. So on the assumption that most people are
more likely to use it as a
door stop than read every last word here are the highlights.
The review takes a weight of evidence approach to making sense of a large
number of published studies.
This is a bit like reconstructing a scene from a bunch of smart phone photos
some a crisp somewhat blurry some focus on a minute
details, while others so distant they lack any
detail all, you even have some selfies in there
none of them paint a complete picture and own their own some could be
downright misleading but stitched together they give a good idea of what's
going on.
In the same way a weight of evidence assessment
helps construct the likely risks associated with a chemical like
BPA from a series of scientific snapshots.
In this case the reviewers found evidence for a number of health related impacts
following exposure to BPA
including potential impacts on the liver, kidneys
and breasts. Many of these raised concerns but the one that dominated
all others at a given exposure level was kidney weight gain in mice.
This was identified as the critical endpoint.
The one that if dealt with would also means that the other potential health
impacts should be avoided.
Using data from mice the reviewers estimated that if an
even average person was exposed to 113 micrograms have BPA per day
for every kilogram that they weighed their health could be at risk.
That's around eight milligrams have BPA per day for an adult.
From here the next step was to work out what
an acceptably safe level would be in people. This is what's referred to as the
tolerable daily intake or TDI. Accounting for differences between mice and people
as well as differences between individuals the reviewers came up with a draft
TDI up 5 micrograms per day
per kilogram of body weight. From the available data they concluded that
at this level no significant health effects would occur
in most people even accounting for uncertainty in the current state of the science.
This does of course leave couple of questions...
What levels of BPA and most people exposed to?
And what if you're not most people?
The first question was addressed in an earlier report from EFSA that looked at
typical exposure levels. They found that teenagers seem to have the highest
exposure to BPA
within estimated upper level in this analysis of 1.3 micrograms per day per
kilogram body weight.
For comparison this is four times lower than the proposed safe level.
So for most people everyday exposure to BPA
a probably pretty safe but what if you not
the same as most people. In adults BPA is quickly converted into a relatively
benign form and got rid of pretty fast.
Researchers are indicating though embryos, fetuses in even young children
don't handle BPA in the same way as grown adults
which means that what is okay for most people
may not be quite as okay for the very young and the
unborn these are some other blue livery bits in the BPA safety picture that is still
being researched. That said at least we do have a picture of BPA safety
imperfect though it may be, which would seem to be better for making informed
decisions that having no picture at all
which is where we are with some alternatives to not using BPA in products.
If you have any thoughts on BPA's benefits and risks please join the
conversation in the comments
and remember to check out the additional resources in the blurb below.