A
common definition of the word dust refers to fine, dry particles of
matter.  From dust storms on earth to
cosmic dust, just about everywhere that any form of matter is present, dust
will also be present.  That includes the ubiquitous
household dust that seems to magically appear in our homes on every surface and
in the form of dust bunnies under furniture.

Household
dust consists of particles of most every form of matter that is present in our
personal environment, including particles of us.  From skin cells and hair, to fabric fibers,
to pollen and soil particles, household dust has it all.

Although
it may be just an annoyance to you, household dust is a topic
of research for some scientists.  Of particular scientific interest is the
presence of trace levels of environmental contaminants that are found in
household dust.  Understanding which
contaminants are present in dust and how they got there can provide important
information about the contaminants in our environment and how they move around.

Household
dust can also be a source of human exposure to environmental contaminants and,
thus, a potential health risk.  This is
especially so for infants and toddlers who spend a lot of time on the floor and
are prone to put everything in their mouths. 

One
of the environmental contaminants that has been measured in household dust is bisphenol A (BPA), which is primarily used to make polycarbonate plastic and epoxy
resins.  Clear and highly
shatter-resistant, polycarbonate is used in common consumer products such as
bicycle helmets, sunglass lenses and CDs. 
Epoxy resins are tough, durable materials that excel as protective
coatings used to prevent corrosion of metal products.

Recent
studies have reported BPA in household dust samples from 15 countries in North
America, South America, Europe, Asia and the Middle East.  Importantly though, the levels of BPA have
consistently been reported to be very low, in the range of one part per million
(ppm) or below. 

Along
with reporting the levels of BPA in household dust, many of the researchers
also estimated the level of human exposure to BPA from dust.  Even more importantly, these researchers also
consistently report that household dust is a minor source of exposure to BPA
and the levels of exposure from dust are far below safe intake limits for BPA set
by government bodies worldwide. 

With
the very sensitive analytical methods available today it is possible to detect
ultra-trace levels of BPA in dust along with a wide variety of other
contaminants.  At least for BPA though, dust
may still be annoying but it’s not a health concern.

Why Do Scientists Study Dust?

People
spend as much as 90% of their time in indoor environments.  Consequently, our indoor surroundings can be
a significant source of exposure to environmental contaminants simply by virtue
of the amount of time we spend there.  A
comprehensive understanding of health risks posed by environmental contaminants
thus requires an understanding of which contaminants are present in our indoor surroundings,
how they get there, and how much exposure occurs.

Household
dust is ubiquitous and essentially is a form of debris that represents a
cross-section of everything that enters the indoor environment, regardless of
how it got there.  In that regard, household
dust can provide a snapshot of contaminants that are present in the indoor
environment from all sources.

In
addition to providing clues to what is present in the indoor environment, household
dust can also be a vector for exposure to environmental contaminants.  We may not intend to eat dust, but a small
amount of dust probably finds its way into every one of us.  Household dust may be a particularly
important vector for infants and toddlers due to their proximity to the floor
where dust tends to accumulate, and their frequent hand-to-mouth behavior.

One
of the first environmental contaminants found in dust was lead, which at the
time was likely present due to its common use in paint and as a fuel additive.  Since those early reports more than 40 years
ago, scientists have conducted a growing number of studies that document the
presence of a wide range of environmental contaminants in household dust.

Is BPA Present In Dust?

One
such contaminant that has been studied is BPA, which has been measured in
household dust samples collected from 15 countries in recent years:  Belgium,
China,
Columbia,
Germany,
Greece,
India,
Japan,
South
Korea, Kuwait, Pakistan,
Romania,
Saudi Arabia, Sweden,
United States,
and Vietnam.  In most studies, dust was collected from vacuum
cleaner bags and extracted with a solvent to generate samples that could be
analyzed with sensitive analytical instruments.

In
general, BPA was found in nearly all dust samples, but only at very low
levels.  Typical levels of BPA were
similar across the 15 countries with median concentrations of 1 part per
million or less (0.1-1 microgram BPA/gram dust). 

Most
of the studies also looked for other common environmental contaminants in dust,
although the studies were not consistent in the selection of contaminants for
analysis.  Perhaps not surprisingly since
dust collects most everything present in our surroundings, other contaminants
were also frequently reported to be present. 
However, measuring the presence of contaminants doesn’t tell us where
they came from and, most importantly, whether their presence poses a health
concern.

Are The Levels Of BPA In Dust A
Health Concern?

Beyond
simply measuring the presence of BPA in dust, most of the studies also aimed to
evaluate whether the levels found are a health concern.  To do this, estimated intakes of BPA were
calculated using standard assumptions for ingestion of dust by different age
groups.  Dust ingestion rates for infants
and toddlers are higher than for adults due to different behavior patterns for
the different age groups. 

The
importance of BPA exposure from ingestion of dust can then be evaluated in two
ways.  First, exposure from dust can be
compared with estimates of exposure to BPA from all sources to determine
whether dust is a significant source of exposure.  Second, exposure from dust can be compared to
safe intake limits for BPA that have been established by government bodies
worldwide to determine whether exposure to BPA from dust is a health concern.

Not
surprisingly, given the low concentrations of BPA found in dust, the
researchers consistently report that dust is a minor contributor of BPA
exposure compared to other sources.  From
many other studies, it’s known that our diet is by far the biggest source of
exposure to BPA.  In comparison, dust is
estimated to comprise less than 5-10% of overall exposure to BPA.

Most
importantly though, exposure to BPA from household dust is far below safe
intake limits set by government bodies.  Even
the highest estimated exposure to BPA from dust for all age groups is
approximately 5,000 times below the safe intake limit set by U.S. government
bodies.  For example, the U.S. Food and
Drug Administration (FDA) answers the question “Is
BPA safe?” with the straightforward answer “Yes.”

These
studies are reassuring in that the results and conclusions indicate that
exposure to BPA from dust is not a health concern.  Nevertheless, any lingering concerns
regarding BPA or other environmental contaminants in dust can be further
mitigated through proper cleanliness and hygiene practices.  Dust may magically appear but it doesn’t have
to remain.