OTTAWA, Ont. — The U.S. is phasing out the use of arsenic-treated lumber, meaning Canadian producers will have to do without the use of a pesticide aimed at protecting wood from decay and insects.

Either that, or take yet another hit from its largest trading partner.

The Environmental Protection Agency (EPA) has already made it mandatory to label all chromated copper arsenate (CCA). But it plans to take that one step further and ban its use altogether, in fear that it could pose a health threat to people.

CCA is commonly used on pressure-treated lumber used for fences and decks. EPA says that it’s possible arsenic leaches into the ground, contaminating the soil.

Health Canada says that the method of protecting wood has proven to be safe, but there will be more research on the way to determine that.

Meanwhile, if Canadian producers hope to continue selling CCA-treated lumber south of the 49th, they must immediately find a new way to treat the wood.

A new chemical process called CBA, which uses copper, boron and azole and which contains no arsenic, has been approved for use in Europe and the United States. But it is not approved for use in Canada.