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August 28th, 2015
Fall certainly feels to be in the air this past week. Cool nights and mornings. A healthy blanket of fog and dew when we wake up. And football seasons kicking off around the Valley. For many of us, this is the time of the year when we start buttoning up our homes for winter, cleaning out the gardens, disconnecting the hoses, giving the lawn one last seeding and weeding, and often times power washing our wooden decks. A new University of Florida study shows we need to approach this last task with extreme caution. Because power washing that old wooden deck in your back yard might make it look better, but by doing so, you may be creating a significant cancer hazard that puts you, your children and your pets at risk in the process.
You see wooden decks manufactured before 2004 are made almost exclusively with a chemical wood preservative called Chromated Copper Arsenate (“CCA”). As the name implies, CCA-treated wood, contains arsenic and chromium, which are both classified by the International Agency for Research on Cancer as Group 1 carcinogens, meaning they have been scientifically proven to cause cancer in humans (and not just animals). And the recent University of Florida study shows that wet wood releases arsenic at three times the rate of dry wood. Not only that, but using bleach to power wash, a common practice to get that deck really clean and shining, causes the wood to release chromate, another carcinogen.
Although the EPA pressured industry to stop using CCA to treated wood used in residential construction in 2003, current estimates put the number of CCA-treated decks on American homes at 20 million or more. CCA was widely used, because it is highly resistant to termites, which should have been a clue that it is no good for humans. After all, if even the termites won’t go near it . . . . But even though this practice has been discontinued CCA-treated wood can last up to 40 years, so most of the decks built with it are still in active use today.
Even just mopping the deck puts you at risk. The Florida study demonstrated that water alone caused three times more arsenic to form on the surface of the wet wood than that of dry wood. They also found much higher levels of arsenic and chromate, if bleach was used, in the rinse water. Dumping this rinse water can also pollute the soil around the decks and present an additional exposure risk. And of course, applying highly pressurized water to a CCA-treated deck only magnifies the risk of harm. If your deck absolutely needs cleaning, do everything you can to avoid skin contact with wet decking, particularly right after cleaning with bleach. The Florida study also offers some additional tips for concerned homeowners, including not growing vegetables on soils near the CCA-treated deck, keeping children and pets off the deck when its wet, washing children’s hands after they play on or near the deck and avoiding giving kids finger foods while outside playing near the deck.
If you’re inclined to remove a CCA-treated wood deck, the Florida study advises not to cut it into pieces. The study showed that sawdust is high in arsenic that dissolves easily into the soil. For the same reason, avoid burning the wood. The arsenic in the resultant smoke can also harm humans and animals. If you live in a home with a deck built before 2004, chances are it contains CCA-treated wood. Ultimately you and your neighbors might just have to live with the deck’s appearance. A fresh coat of paint seems preferable to a good power washing. But no amount of aesthetic improvement is worth your health or your life.
