Ask EWG: Arsenic on my new house's deck?

Question: My husband and I are thinking of buying this great old house with a big back deck, but I remember reading something about how wood used on decks can be dangerous. We've got a two year old. Should I be worried? Answer: There are reasons to be concerned, but if you’re set on the house, there are a couple of steps you can take to minimize exposures. First, however, a quick recap of the problem. Wood destined to remain outside faces harsh elements and can succumb to insect damage and rot. Pressure treated wood is injected with chemicals in order to protect it from the elements and the insects, and one of those chemicals is chromated copper arsenate (CCA), an insecticide that is 22 percent arsenic. Arsenic is a carcinogen, and EWG research indicates that little ones crawling across a deck or playing on an old wooden swing set may ingest potentially hazardous levels of CCA leached out of the wood.

In part because of EWG’s advocacy and research, EPA banned arsenic-treated wood for decks and playsets in 2004. But because the pesticide was the standard in outdoor lumber for 30 years, 70 percent of all homes in the U.S. still have old, arsenic-treated wood porches and decks. You can learn if your wood contains arsenic by using a simple test kit available on our website.

If your wood contains arsenic, the best solution would be to rebuild your deck with materials naturally resistant to rot and insects, or wood treated with arsenic-free preservatives. If that’s not in your budget right now there are other ways to minimize your family’s risk of exposure:

  1. Seal the wood at least every six months with standard penetrating deck treatments.
  2. Replace sections of potential high exposure like handrails, steps, or deck boards with non-arsenic alternatives.
  3. Wash your hands and your children’s hands after every exposure to arsenic-treated wood, especially before eating.
  4. Keep children and pets away from the soil beneath and immediately surrounding arsenic-treated wood structures.
  5. Cover arsenic-treated picnic tables with a tablecloth before using.
  6. Do not pressure wash to clean the surface of arsenic-treated wood. Instead use a soap and water solution, with disposable cleaning supplies. Pressurized water will blast off the upper surface of the wood and spray arsenic-contaminated particles over your yard.
  7. Do not allow children to play on rough wood surfaces. Arsenic-treated wood splinters can be dangerous.
  8. Never sand arsenic-treated lumber. If wood is smooth enough that splinters are not a risk, avoid sanding a deck to prepare the surface for sealing—use a simple soap and water wash instead. Wood dust formed by sanding contains arsenic that is easily ingested by a child, or can wash off the surface to contaminate the soil below.
  9. Do not store toys or tools under the deck. Arsenic leaches from the wood when it rains and may coat things left there.
  10. Do not use commercial “deck washing” solutions. These solutions can convert chemicals on the wood to a more toxic form.

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