A
recent
analysis of published data on human exposure to bisphenol A (BPA) revealed more
than 140 studies with over 85,000 data points from 30 countries.  Taken together the data show that exposure to
BPA around the world is hundreds to thousands of times below the
science-based safe intake limits set by government bodies.

That’s
already far more data than is available for most chemicals, but the data just
keeps on coming.  Health
Canada recently released an important new report with data
on exposure of Canadians to a variety of chemicals.  Along with BPA, the Fourth
Report on Human Biomonitoring of Environmental Chemicals in Canada
provides exposure data on 53 other environmental chemicals for more than 2,500
participants throughout Canada.  

It’s
important because without knowing how much of which chemicals we’re exposed to,
it’s difficult to know whether those chemical exposures are safe or not.  After all, dose does matter.  If you’re not sure about that, imagine taking
a bottle of aspirin next time you have a headache.  You might get rid of your headache, and a lot
more.  In particular you might get rid of
your life since two aspirin are safe and effective for the headache but a whole
bottle of aspirin could kill you.

The
new report is the fourth in a series that together provide data on BPA exposure
to the general Canadian population (ages 3-79 years) over 8 years
(2007-2015).  The new data confirms that
exposure of Canadians to BPA continues to be very low.  Similar to what has been reported in other
countries, typical exposure to BPA in Canada is more than 1,000 times below the
safe intake limit set by Health Canada. 

In
addition, the new data adds to what is probably the most comprehensive database
on exposure to BPA for any country. 
Canadian researchers have also published results from four large-scale
exposure studies on potentially sensitive subpopulations (pregnant women and infants)
and the First Nations people.

The
data from all reports consistently show that exposure of Canadians to BPA is
far below Health Canada’s safe intake limit for all of the populations
studied.  Importantly, the temporal data
indicates that exposure to the general Canadian population is decreasing with
time, moving in the direction of a higher margin of safety.

What Did Health Canada Do?

Since
2007, the Canadian government has conducted the Canadian Health Measures Survey
(CHMS) to collect information on the general health of Canadians.  The survey collects baseline data and risk
factor information relevant to general health, chronic and infectious diseases,
fitness and nutritional status. 

The
survey also collects blood and urine samples in its biomonitoring component for
analysis of various environmental chemicals, which is where BPA enters the
picture.  It’s primarily used to make
polycarbonate plastic and epoxy resins and those materials are widely
used
in products that make our lives better and safer every day.  Our use of those products raises the
potential for exposure to trace levels of BPA. 
Along with benchmarking chemical exposures, the biomonitoring data can
be used to assess the need for policies to protect the health of Canadians from
exposure to chemicals.

What Did The Media (Mis)Report?

Most
likely you didn’t see any of the limited media coverage on the report, but you
didn’t miss much since it appears the media didn’t actually read the
report.  The headlines proclaimed that
Health Canada found BPA in the blood of more than 90% of Canadians.  That may be an eye-catching headline, but
Health Canada didn’t actually look for BPA in blood, and for good reason.  Had they done so, they almost certainly would
not have found any.

It’s
well
known that our bodies efficiently convert BPA to a
biologically inactive metabolite after exposure.  Because what goes in (exposure) is quickly
eliminated in urine where it’s easy to measure, experts from around the world
agree that “urine
is the best matrix for epidemiological assessment of exposure to BPA.”
 And that’s exactly what Health Canada
did.

What Does The Data Mean (And Not
Mean)?

Perhaps
the most glaring omission from the media stories is a point so important that
Health Canada included it in its short “Backgrounder”
on the report.

“It
is important to note that the presence of a chemical in a person’s body does
not necessarily mean that it will affect their health.”

The
report documents that BPA, in the form of its metabolite, is present in urine, which
means exposure did occur.  But what does
that data mean for our health?

Fortunately
for BPA, it’s relatively easy to interpret the data with respect to
health.  Along with other government
bodies, Health Canada has already determined a safe
intake level for BPA. 
In a previous study, Health Canada researchers further determined the
amount of BPA that would be measured in urine if exposure occurred at the safe
intake level.  That value is known as the
Biomonitoring
Equivalent (BE) for BPA.

Comparison
of the new data with the BE reveals that typical exposure to BPA in Canada is
fully 1,000 times below the safe intake level set by Health Canada.  The data strongly supports Health Canada’s earlier
conclusion that “Bisphenol
A does not pose a risk to the general population, including adults, teenagers
and children.”  But you wouldn’t have found that in the media
coverage either.

How Does The Data Compare With
Previous Studies?

With
the data provided in this new
report, Health Canada now has data on exposure of the
general population of Canadians to BPA over an 8-year period from
2007-2015.  Although Health Canada has
previously concluded that BPA does not pose a risk to the general population,
exposure data over extended periods of time is important to know whether there
are any significant changes in exposure. 
Changes are not necessarily good or bad, but might be signals that
further evaluation is needed.

A
trend towards higher exposure might suggest the need to reevaluate Health
Canada’s conclusion, or to consider whether any policies should be implemented
or revised to limit exposure.  In
contrast, a trend towards lower exposure strengthens the conclusion by
increasing the margin of safety and indicates that existing policies are
adequate to control exposure.

The
data on BPA exposure from the four reports shows a clear trend towards lower
exposure over time.  Although the data
cannot inform on the specific source of exposure or why exposure is decreasing,
the data does indicate that current use patterns for BPA and policies to
control exposure are adequate to ensure a wide margin of safety. 

 In addition to the series of reports on the general
population of Canadians, other Canadian government researchers have published
four other studies that provide BPA exposure data on potentially sensitive
subpopulations.  These include three
studies on pregnant women (1, 2, 3), one of which
included data on infants,
and a study on the First Nations people.  Perhaps not
surprisingly, exposures are similar for all populations examined with the
notable exception of infants. 

It is generally believed that most exposure to BPA is
through the diet.  Since infant diets are
generally different from adult diets and more limited, infant exposure to BPA
will not necessarily be the same as adult exposure.  Although data is limited to one study, infant
exposure is significantly lower, which suggests that existing policies to
control exposure are adequate for infants as well as adults.  The data also indicates that Health Canada’s
conclusion that BPA does not pose a risk to Canadians is applicable to infants.

How
Does The New Data Compare With The Rest Of The World?

It’s
not just Canadians who need not be concerned about BPA.  A recent
analysis from a group of researchers in China revealed that
exposure to BPA is very low in every one of the 30 countries where it’s been
measured. 

That
analysis included data from studies on exposure to BPA that have been published
in the peer-reviewed scientific literature. 
All told, the researchers found more than 140 studies with data on over
85,000 participants in 30 countries.  The
results from the new Health Canada study reaffirm that exposure of Canadians to
BPA is similar to the exposure levels measured in the rest of the world. 

The
extensive data on exposure to BPA from all of these studies leaves little doubt
that human exposure to BPA is extremely low and far below science-based safe
intake limits.  Perhaps the US Food and
Drug Administration says it best in a Q&A on its website:  Is
BPA safe? Yes.