Recent concerns in the United States about levels of heavy metals in fertilizers are not an issue in Canada because of government standards.
The standards were implemented in 1980 to deal with sewage sludge. They were changed in 1993 to apply to other products in response to an earlier problem.
“There was an incident in the United States where a company was found to be shipping high metal content fertilizer to a developing country,” said Darlene Blair, associate director of the fertilizer section for the Canadian Food Inspection Agency. “That twigged us to think, gee, maybe we’d better take a look at that.”
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The U.S. has no national standards for heavy metals such as lead, cadmium and arsenic in fertilizer. This has raised concerns about the safety of recycling some industrial waste by blending it with fertilizer.
Plants need small quantities of nutrients outside of the three common components of fertilizer – nitrogen, phosphate and potash. One of these micronutrients is zinc.
“(Zinc) has as one of its sources an industrial byproduct that would otherwise be classified as a hazardous waste,” said Ron Phillips, of the U.S. Fertilizer Institute.
The U.S. Environmental Protection Agency has ruled this waste product, an emmission control product from the steel manufacturer called baghouse dust, can be processed into products that can be sold for zinc micronutrient value.
“The problem with that is, it also contains some non-essential stuff, like lead.”
Phillips said less than one tenth of one percent of fertilizer sold in the U.S. contains a product considered to be hazardous waste.
“There’s an impression that has been left that we take recycled waste, put it into fertilizer and use that as a disposal method. That’s absolutely untrue,” he said.
There are some environmental arguments for using industrial byproducts in fertilizers. Phillips called the use of byproducts with nutrient value, like zinc, “a good form of recycling.”
Blair said a large amount of zinc is difficult to dispose of, but it can be effectively used as fertilizer.
But she cautioned that moderation is necessary. “The dose makes the poison. If you have enough, it’s good, if you have way too much, that could be bad.”
Recently, the U.S. has started looking to Canada for guidance in setting its standards.
Canadian standards are set by total cumulative additions of metals to the soil. Standards will change for different products depending on the rate of application, up to a maximum. Some provinces have additional guidelines for metal content in soils.
Still, it remains up to manufacturers and users to keep metal levels at acceptable levels. Manufacturers are expected to follow the standards, and users must use the product properly.
Any American fertilizer imported into Canada must meet Canadian standards.
