Cleaning
Pressure-Treated
Lumber
Is It Hazardous?
by Peter Marentay
B
Photos courtesy of Blue Ridge Pressure Washing.
6 • November 2005 • CleanerTimes
etween late 2001 and
early 2002, headlines appeared in
USA Today and other publications that
announced to the general population
that there was danger lurking in
their backyard. Pressure treated
lumber, used all over the country in
homes and for decks, fences, children’s play sets, and other outdoor
structures, was the latest target of an
EPA investigation.
One major article came out at
the time of the annual PWNA convention in Orlando, FL, and all of the
contractors involved in residential
pressure washing could not talk
about anything but this topic for
the three days we were together.
Would PT lumber be banned? Would
we be prevented from working?
Were we in any danger? Had we
been exposed to something that
would haunt us later? The questions were endless.
The CCA Issue
The controversy was centered
on the chemical used to treat the
lumber, called CCA (Chromated
Copper Arsenate). The EPA suspected that the poisonous arsenate
could leach from the wood when it
was exposed to water, such as during a rain or during the power wash
process. The arsenate compounds
could be picked up innocently by
simply touching the wood after a
rain. There was also concern that the
leaching would contaminate the
soil near the wood. Since children
were the most at risk, playgrounds
were immediately considered to be
the most dangerous use of CCA
lumber. The belief at the time was
that this represented a significant
health risk and warranted a direct
government study to determine the
extent of the problem.
Why was CCA lumber so scary?
Consider these statistics: A lethal
dose of arsenic to humans has been
estimated to be about 42 mg within
a day for a 150-lb adult. For a 20-lb
child, this works out to 6 mg. To put
this in perspective, an 8-ft long 2x4
contains about 11,000 mg of arsenic.
However, the actual amount of
arsenate compound available on
the surface of a piece of CCA lumber after a rainfall is extremely low,
with the amount depending on the
age of the wood and how far the rain
went into the wood. The poison is
potentially ingested by transfer
from hands to mouth, a behavior
common to young children. It could
also potentially be ingested by
breathing contaminated dust on a
playground.
The lumber industry countered
that there were no clearly identifiable
cases of arsenic poisoning that could
be attributed directly to CCA lumber. The industry entered into a voluntary agreement at the time with
the EPA to phase out CCA lumber
and replace it with lumber treated
with one of several readily available
substitutes. The agreement reached
called for the phase-out to take place
over the following two years. It was
reported at the time that this action
would probably eliminate the EPA’s
desire to conduct a study.
EPA’s Recommendation
The most interesting part of
the announcement was the EPA’s
recommendation of how to deal with
the existing lumber in use all over the
country. It was estimated that 80–90
percent of all decks in the country
were built with PT lumber. The EPA
suggested to the general public that
treating the wood by sealing it
would prevent the leaching of the
arsenate—big collective sigh of relief
from all of the power wash folks.
The EPA issued a press release that
stated in part that EPA did not advise
homeowners to remove existing
decks and other structures made
with wood. However, regularly
coating the lumber with sealant was
suggested as a way to reduce any
arsenic risks.
The EPA recommendations went
on to say that parents should make
sure that children who play on or
near decks or play sets should always
wash their hands thoroughly after
contact with treated wood, especially prior to eating and drinking,
and ensure that food does not come
into direct contact with any treated
wood. The agency also said that
CleanerTimes • November 2005 • 7
workers should take some precautions when handling pressure treated wood. They should wear gloves
when handling wood, wear goggles and dust masks when sawing
and sanding, always wash hands
before eating, and never burn CCA
treated wood.
EPA and CPSC Studies
In spite of the agreement with
lumber producers, the EPA, in a
joint effort with the Consumer
Product Safety Commission, went on
to do a two-year study. Beginning in
2003, these agencies investigated
the effect of sealing wood as a preventive for the leaching. Fast forward
to 2005, and that study is just finishing up. The final results are
expected to be released several
months from now. Preliminary
results are just becoming available,
8 • November 2005 • CleanerTimes
and the power washing industry is
again holding its breath.
The agencies studied both new
wood and aged wood. The EPA
concentrated on evaluating sealers
on old wood while the CPSC concentrated on studying the effects
of sealers on new wood. Their primary concern was
whether or not
sealing the wood
with many of the
popular brands
of sealers would
effectively reduce
the occurrence of
leaching of the
arsenate. Children
were considered to
be the most vulnerable to this
problem because
of their body size
and their proximity to play sets constructed of pressuretreated lumber.
The preliminary
study results can
be seen on the
EPA’s own website.
The methodology
used to conduct the
study is outlined
on the CPSC website. In effect, each
of the agencies discovered that all of
the sealants tested
significantly reduced the occurrence of leaching for the first 12
months. (The preliminary results are
based on the first 12 months of results
only. The 24-month results will be released by the end of this year or early
next year.) It is expected at this time
that the leaching problem will be significantly higher during the second
year for many of the sealers tested.
Several different types of sealers were tested. The products tested included:
• “Film formers” such as paints
that form a film on the wood surface,
• Penetrating stains and sealants
which absorb into the wood, and
• Those designed to encapsulate
CCA (e.g., plastic-type products).
(It must be noted that a number of
consumer groups have already questioned the validity of the studies
and the techniques used to gather
results. The primary complaint about
the studies is that they concentrate on
the cause and effect of arsenate exposure without looking at chromium
exposure and its impact.)
The EPA’s website reports that
“While the top two performers were
film-forming coatings (e.g., paints),
the other more typical deck treatment
products—specifically sealants and
stains performed similarly in reducing the amount of dislodgeable
arsenic at the surface of the wood.”
The EPA went on to state that
film-formers like paint, even though
they performed well, were not the
best choice because of the potential
for chipping and flaking. They also
suggested that removing film formers
by sanding or power washing presented additional exposure hazards.
The EPA also commented that
the encapsulating vinyl products
were not the best choice since they
also chipped over time. Recoating
with these products might require
removing the old product before
the new coat could be applied, which
made the problem worse.
Penetrating sealers were the overall preferred solution to the problem,
according to the EPA preliminary
results. Most of the commonly used
oil-base wood sealers manufactured
today are defined as penetrating
sealers by the EPA.
A search of the CPSC’s study
indicates that the agency found very
similar results to the EPA study.
Sealing the wood reduced the
amount of available (dislodgeable)
arsenate on the surface of the wood
by as much as 98 percent.
The Present Scene
The voluntary phase-out of CCA
lumber means that pressure treated
boards made since January 1, 2004
do not contain CCA. The most common replacement is called ACQ (Alkaline Copper Quaternary) lumber,
which contains no arsenate or chromium derivatives. Since so many power
washing contractors do residential
work involving older structures,
exposure to CCA lumber day after
day is very likely. Understanding
the issues and using appropriate
caution is always a good idea.
At this time, the agencies are
sticking to the original prescription
for preventing exposure to the arsenate poison found in most pressure
treated lumber made prior to January
1, 2004. Both studies reach the same
preliminary conclusion: Regular
treatment of the wood with a quality wood sealer is still the best prevention technique known for consumers and property owners. Until
the studies are ready to be released,
the same common sense suggestions for handling and working with
PT lumber remain the best advice.
So where does that leave professional power wash contractors who
make their living cleaning this wood?
Common sense tells you that awareness is your best defense. Cleaning
methods and the precautions used
should address the cumulative effect
of this poison. Be careful to wash
your hands often during the day. You
should certainly avoid touching
your face or food without washing
your hands first. Gloves are necessary when you handle the wood, and
you should be very careful not to
inhale sawdust during the cutting or
sanding of old PT lumber.
Washing your clothes after
each use is probably a smart idea
as well. You should even try to
avoid tracking trace amounts of
arsenate onto the kitchen floor when
you go home at night, particularly
if you have small children that might
crawl on those surfaces. Their tolerance is very low because their
body size is small.
With all of these scary precautions,
is it time to walk away from this business? Most of us take more of a risk
just driving to the job than we do
from CCA lumber. While we can’t
protect ourselves from that other
driver, we can certainly protect ourselves from excessive CCA exposure. We are in the driver’s seat.
The Bottom Line
Once again this year the EPA
will make several public statements
to all citizens about the importance
of sealing decks and play sets. If
history repeats itself, the news services will be quick to jump onboard
with a few sensational headlines, too.
With the government encouraging
your customers to do this service
annually, you are in a great position
to gain new customers and make
your existing ones breathe easier. I
suggest that each of you add information on the importance of sealing
wood for safety reasons to your
customer presentation.
Ya’ll can exhale now.
Peter Marentay owns Sun Brite
Supply and is one of the authors of the
PWNA Wood Certification course and
a member of the PWNA Board. CT
For information circle 263
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