The Canadian Food Inspection Agency (CFIA) is advising livestock producers across
Canada not to use chemically-treated wood structures near livestock feed or food-producing
animals because they can transfer potentially harmful levels of chemicals into animal
products, such as meat, milk and eggs.
As part of the CFIA's residue monitoring program, dioxin levels higher than background
were detected in raw milk from two British Columbia dairy operations. The dioxin was found
at levels that are not considered an immediate health risk by Health Canada. The levels
found did, however, trigger follow-up action to identify and eliminate the source of
contamination, in line with Canada's approach to managing dioxin in the food supply.
Dioxins are released into the environment through natural and industrial processes and are
commonly found in low levels throughout the food chain around the world.
The CFIA and the Province of British Columbia are collaborating on this issue. The CFIA
is also working with other provinces and territories to ensure this advice reaches all
livestock producers. The investigation indicated that chemically-treated wood used in some
silage bunkers (animal feed containers) may, in large part, be the source of the dioxin
detected. Exposure to wood treated with chemicals, such as pentachlorophenol (PCP), has
been shown to result in higher than background levels of dioxins in livestock feed, which
can then transfer into animal products. Further follow-up after precautionary measures
were implemented indicated lowered levels of dioxin.
Producers should ensure that livestock feed is not stored where it can come into direct
contact with chemically-treated wood structures. Animals should also not be allowed to
come into contact with chemically-treated wood, including sawdust or shavings that could
be used for bedding. At a minimum, bunker silos containing this wood should be lined with
a plastic tarp and untreated lumber. Gloves should be worn when handling any treated wood
and scraps must be disposed of in accordance with provincial/territorial and municipal
For more information on dioxins, visit the Health
Canada Web site at http://www.hc-sc.gc.ca/iyh-vsv/environ/dioxin_e.html or the CFIA Web site at www.inspection.gc.ca.