Wooden structures like decks, bomas and lapas may be a potential threat to groundwater, contaminating both water and soil with high levels of arsenic. The characteristic green colour of gumpoles is created by chromated copper arsenate (CCA), which prevents termites and other organisms from destroying the wood.
A new study carried out by researchers from universities in Florida and Miami has found that arsenic contamination of rainwater runoff from a CCA treated deck was 100 times greater than that from an untreated deck.
Arsenic levels in the sand under the deck are 15 to 30 times higher. The research was published in the journal Environmental Science and Technology, and involved studying rainwater runoff from a CCA treated deck for a year.
They also studied simulated landfills and found that arsenic leaching continued in the landfill. This has serious implications for the disposal of old CCA treated wood items. One of the study authors, Helena Solo-Gabrielle, told the journal's online news section, "Only a small fraction leaches in any given year" but because the wood is in the ground for so long, "the impacts can be significant, especially given the high concentrations of arsenic in the wood itself."
The study estimated that in Florida alone, 4,600 tonnes of arsenic had been leached into the environment by 2000. In America, CCA treated wood may no longer be used in people's homes, but only for things like telephone poles and industrial timbers. This ruling was made after earlier studies identified the arsenic leaching problem.