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May 17, 2002
- To everyone's surprize, Florida researchers
have discovered that wood treated with chromated copper arsenic (CCA)
becomes more toxic as it ages.
While annual or biannual application of oil-based sealants can reduce
CCA leaching, the problem remains unresolved: should the wood be classified
as hazardous waste, as is the case in Europe, thereby increasing the
cost of waste management and encouraging illegal dumping?
Paradise for termites and molds, Florida is likely the first market
in the Western world for this popular greenish wood. By 2020, about
30,000 tons of arsenic used in wood whose service life has ended will
wind up in the environment.
In Gainesville, home of the University of Florida where CCA (an insecticide,
fungicide and algicide) has been tested since the 1930s, highly contaminated
soil was discovered last year below playground equipment made of treated
wood. A child, whose body does not eliminate arsenic as well as an adult's,
runs a higher risk of cancer by breathing or ingesting contaminated
sand, experts have concluded.
Last winter, the United States and Canada convinced industry to voluntarily
drop CCA use of residential wood by 2004, in favor of copper-based products,
which are nonetheless toxic to aquatic life.
It has long been known that treated wood sawdust, and especially smoke
and ashes, were highly toxic; repeated food, drinking water and skin
contact with treated wood has also been discouraged by Health Canada
since 1990, but consumers were never properly informed in retail outlets.
"Treated wood is not classified as hazardous waste because up until
now, the industry said it only used arsenic V (pentavalent arsenic or
arsenate- less toxic, but still a carcinogen), and we always presumed
that new wood leached less than old", Bill Hinkley, head of the
Florida Department of Environmental Protection, explained in an interview.
"High levels of arsenic are leached for the first six months and
they stabilize at a lower level for four to five years", confirmed
Tony Ung, a wood researcher at the University of Toronto.
But Dr. Tim Townsend, professor of Environmental Engineering at the
University of Florida, tested CCA-treated wood weathered for at least
ten years. He presented his results May 13 to a technical advisory committee
on which Bill Hinkley sits, who reports: "He discovered that the
old wood emits much higher levels of arsenic III (highly toxic trivalent
arsenic or arsenite) than As V, well above the limit for non-hazardous
waste. As it ages, the wood's lignin decomposes and releases the chemicals."
Dr Townsend only found As V in new wood and he does not know how it
converts
to As III. He also discovered that when used in alkaline conditions
(pH above 8), for example in contact with concrete, treated wood emits
large quantities of highly toxic hexavalent chromium, made popular by
the film "Erin Brockovich".
Lawyers Simien & Simien, of Baton Rouge, who successfully sued tobacco
manufacturers for the State of Texas, have launched a $4 billion dollar
class action suit against the treated wood industry last year. Even
the State of California is suing treated-wood picnic table and playground
equipment manufacturers.
In 1987, an American who was handicapped after sawing treated wood indoors
for two days, was awarded $767,000 in damages. Treated wood manufacturer
Koppers has known since 1968 that workers fell ill after breathing treated
wood sawdust.
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