I’ve scrounged some old wooden shipping pallets for garden projects — compost piles and raised planting boxes. They appear to be untreated wood, but I’m feeling paranoid. Is there any way to know? Do companies that make pallets routinely spray them with any preservatives?
Great nations consider your humble garden pallets to be of vital economic importance. As world trade expands, the global market often rests, literally, on shipping pallets. Goods visit many shores before reaching the stores, and tiny little hobos — wood-boring insects such as the pine borer and the Asian longhorn beetle, which can destroy trees, forests, and economies — are only too happy to hop on board. As a result, the International Plant Protection Convention recently set standards for pallet manufacturers in hopes of controlling the migration of invasive and destructive insect species. (A few countries, such as China and E.U. nations, are already picky about what type of wood they will accept.) Hence, pallet makers will soon be obligated to bake or fumigate their wood if they wish it to be used internationally. Baking is benign; fumigating is not.
Domestic pallets do not face the same issues. I spoke with the Pallet and Container Research Laboratory in Virginia and was assured that most pallets are not treated with anything. The largest pallet market in the U.S. is the food service industry, which has no need or desire for chemically impregnated wood. There is a minute chance that any given pallet could have been fumigated with methyl bromide, a pesticide due to be phased out by 2005 under the Montreal Protocol for ozone-depleting substances. But for now, most pallets are still good, free garden supplies. In the future, when international regulations come into effect, you’ll be able to search your pallets for secret signs that they’ve been chemically treated. A crossed-out bug (take a look at the image below) and the initials “HT” indicate heat treatment, while “CT” indicates chemical treatment.
One final note: Kudos to you for reusing wooden pallets, which are a burden on the environment even without chemical treatment. According to a 2000 report by the Sierra Club, “Approximately 48 percent of all U.S. hardwood lumber production in 1992 was for use in shipping pallets, more than half of which are used just once and then end up in landfills.”