For background on this story, here are Part 1Part 2 and Part 3 of this three-part series. 

The Halifax Examiner has received responses from two federal departments involving the presence of a potent human carcinogen in Lafarge Brookfield’s cement kiln dust (CKD) — a product that is being sold as an agricultural soil amendment and is spread on farm fields in the province.

According to a spokesperson from Environment and Climate Change Canada (ECCC), the presence of the cancer-causing, and highly mutagenic N-Nitrosodimethylamine (NDMA) is considered “incidental” under the federal Act pertaining to toxic substances and therefore exempt from the regulations. In response to an Examiner “complaint” to its Pre-market Application Submissions Office, the Canadian Food Inspection Agency (CFIA), which regulates fertilizer additives, concluded that there was “no plausible risk pathway when the cement kiln dust is used as directed.” 

Cement kiln dust (CKD) storage at Lafarge Brookfield. According to CABOT member Lydia Sorflaten, from 1965 to 1994, the CKD was landfilled behind the plant without any containment measures in place. A barrier several metres high was later constructed around the perimeter to contain the material. Today not all CKD is landfilled on site—some is sold as a soil amendment and spread on farm fields. Photo courtesy Lydia Sorflaten.

 In Part 3 of The Halifax Examiner Series, “Concrete Capture,” it was reported that in the late summer of 2019, as part of the permitting process to burn scrap tires, Lafarge Brookfield hired ALS Global to test samples of its cement kiln dust (CKD). It should be noted that the CKD analysis pre-dated the burning of tires. The analysis revealed that all six samples of CKD exceeded the detection limit for NDMA, a human carcinogen that is believed to pose a significant risk to human health even in very small concentrations.  

It should also be noted that in 2007, when officials from Nova Scotia Environment (NSE) collected samples of the CKD from Lafarge’s landfill for testing, the analysis found the “material not appropriate for disposal in a municipal landfill.”  

Despite this, the company sells the “limestone derivative” for use in various fertilizer products, which eventually make their way onto farm fields in the province.  

As previously reported, to make some sense of the matter, the Examiner contacted Douglas Hallett, an internationally renowned toxicologist of more than 40 years. He was retained as an expert witness in the 2007 environmental review tribunal when Lafarge’s plan to burn alternative fuels, including scrap tires, at its Bath plant in southern Ontario was challenged by local environmentalists, including Gord Downie of the Tragically Hip.  

Recall that Hallett’s expertise was also sought here in Nova Scotia, when the Citizens Against the Burning of Tires (CABOT) — many of them residents who live near the Brookfield plant — requested that new information from Hallett be admitted as part of the evidence in a judicial review of the Minister’s 2017 decision to approve the burning of tires. The group argued the Minister’s decision should be re-visited because the tire-burning proposal was ill-advised, not based in any science, and hazardous to nearby residents and the environment. But as previously stated, Hallett’s offer to provide a report that would “fully consider” the outstanding issues was denied by the court.  

Hallett’s 2017 affidavit zeroed in on the “ash residuals” or CKD. How might its composition change with the addition of tires” he asked.  

“There is a real and substantial risk that groundwater may become a contaminated source of drinking water if the ash residuals contain [N-nitrosodimethylamine] NDMA and products of incomplete combustion of tires,” writes Hallett, who points to the spectacular way in which this occurred in areas of Ontario from both the manufacturing of chemicals and synthetic rubber for tires, as well as from the Hagersville tire fire, when 10 million tires burned for 17 days.  

Little did Hallett know, NDMA was already present in the CKD — even before scrap tires were included in the fuel mix.   

When the Examiner sent Hallett a copy of the analysis for NDMA, his response was simply, “All of the samples are positive for NDMA well above the detection limit … This means that NDMA is definitely there … and what you’ve got is one of the most powerful carcinogens ever found.” 

Satellite photo of Lafarge Brookfield showing cement kiln dust (CKD) landfill. Robert Cumming says the storage site design, which includes a clay cap “ensures we meet the regulatory performance requirements without the need for a liner.”

When asked about the sale of CKD as an agricultural amendment in the province, NSE officials pointed me to the Canadian Food Inspection Agency (CFIA) and to Lafarge.  

Robert Cumming, the company spokesperson, downplayed any potential harms associated with the CKD, despite the fact that company publishes this safety datasheet, which states the product can cause severe skin burns, eye damage, respiratory irritation, damage to organs, and cancer (if inhaled). It can also be harmful to aquatic life. “Avoid release to the environment,” reads the safety datasheet. 

As previously mentioned, the CKD is currently sold as a limestone derivative, approved by the CFIA for its use in fertilizer products. As previously reported, since 2008 a patented technology called N-Viro has been used at a Walker Industries facility located in Aerotech Park near the Halifax Airport to process Halifax’s sewage sludge — or biosolids — and turn it into fertilizer. In the process, cement kiln dust (CKD) is added to the dewatered sludge, as what’s called an “alkaline admixture.” The product is spread on farm fields in the province.  

A screenshot of a webpage advertising Nutri Lime, New!
Cement kiln dust (CKD) from Lafarge Brookfield is sold as a “liming agent” in this CFIA-approved product.

Also previously reported, at the suggestion of the CFIA, the Examiner sent the NDMA analysis to their attention as a “complaint” through the Pre-market Application Submissions Office, and if deemed appropriate, the matter would be investigated.  

But, gauging from the response, it appears a thorough investigation was not deemed appropriate. Here is the CFIA response: 

Thank you for bringing this issue to the attention of the Canadian Food Inspection Agency (CFIA). Protecting human, plant and animal health and the environment are the pillars of the CFIA’s mandate. The CFIA has completed a thorough toxicological assessment of the data (results of analysis) you provided together with additional information. The conclusion is that there is no plausible risk pathway when the cement kiln dust is used as directed. CFIA takes any reports of risk of harm posed by regulated products very seriously. CFIA scientists evaluate each case based on identified hazards and exposure scenarios to ensure that fertilizers and supplements imported or sold in Canada meet all prescribed safety standards. 

That there is “no plausible risk pathway” when CKD containing NDMA is spread on farm fields —  potentially making its way into groundwater, surface water, and food — is hard to believe.  

When pressed further on how it came to the conclusion that there was “no plausible risk pathway,” the CFIA replied that “The results of the analysis are inconclusive in terms of NDMA content in the cement kiln dust (CKD) produced by Lafarge Canada. Specifically, the NDMA testing appears to have been conducted for a tire-derived fuel (TDF) permit and there is no description of the actual sample material tested.” 

In my initial emails with the CFIA on the matter, it was made clear that the samples were CKD, as verified by both the NSE and Lafarge. That all six samples showed NDMA concentrations to be above detection limits indicates its presence as a matter of fact. How the CFIA could characterize that as being “inconclusive” of NDMA content is beyond comprehension. 

When pressed further, the CFIA response was: “Detection of a contaminant does not equate to a safety risk.” 

This might be true for some toxic substances, but not with NDMA. The mere detection of it should warrant further investigation. Its presence above detection limits in pharmaceuticals and in drinking water have led to full-fledged investigations and product recalls.    

“The CFIA has also reviewed the manufacturing process (controlled incineration process and temperature) of CKD at the Brookfield plant. At 1450°C the formation of nitrosamines is not expected to occur at toxicologically relevant levels.” 

Again, this does not amount to an investigation, but appears to be a review of some of Lafarge’s literature. It also does not consider the reality of there being kiln upsets or situations where incomplete combustion would result in the creation and release of toxic emissions or waste.   

“The application rate of the product to soil, along with the environmental fate of nitrosamines (degradation, half-life, persistence and bioaccumulation potential) were also considered,” says a CFIA spokesperson. 

But according to this US Environmental Protection Agency fact sheet on NDMA, the substance is “highly mobile” in soil with the “potential to leach into groundwater.” The “oral route, including consumption of contaminated food and water, is the primary human exposure pathway,” which raises the — I would think — obvious concern that since it’s being spread on farm fields, where produce for human or livestock consumption is grown, the potential for an oral pathway should clearly be flagged.  

In fact, according to this 2002 World Health Organization report, NDMA can be taken up by plants from the growth medium. “Lettuce and spinach absorb NDMA from sand, soil, and water,” says the WHO. And, as was reported previously in this series with regards to the contamination of Elmira’s drinking water supply, the WHO confirms that NDMA has the potential to leach into and “persist” in groundwater.   

The World Health Organization characterizes NDMA as “clearly carcinogenic” based on lab studies in which tumours were induced in all species at relatively low doses. There is also “overwhelming evidence that NDMA is mutagenic and clastogenic,” capable of obstructing DNA synthesis and damaging DNA, according to WHO.  

The WHO goes on to state that “major releases” of NDMA have occurred from the manufacture of pesticides, alkylamines, dyes, and rubber tires. Given that Lafarge is now burning scrap tires, the potential for an increase in the presence of NDMA in the CKD is certainly there.  

Fred Blois has been involved in Citizens Against the Burning of Tires (CABOT) since it began. He lives in Old Barns, as the crow flies about seven kilometres from the Lafarge plant. He was also one of the plaintiffs in the judicial review of the Minister’s 2017 decision to approve the tire-derived fuel (TDF) plan. He has also taken a keen interest in the safety of spreading bio-solids on farmland in the province.  

He’s “disappointed” that the CFIA has not taken a stronger stance on the issue. “It is all too evident that the CFIA cannot be trusted to ensure the safety of the food we consume,” he says.  

 “It would appear the CFIA is violating its own mandate.” 

As previously reported, the Examiner also sent Lafarge’s CKD analysis to Environment and Climate Change Canada (ECCC). According to its media spokesperson, at the federal level the Prohibition of Certain Toxic Substances Regulations prohibits the manufacture, use, sale, offer for sale, or import of NDMA, with a limited number of exemptions. NDMA is currently considered a toxic substance in Canada.  

According to the ECCC, “If the cement kiln dust contains NDMA, its sale would be prohibited.” 

The ECCC then began a review of the file to “verify compliance” with the Canadian Environmental Protection Act and the Prohibition of Certain Toxic Substances Regulations.”  

Here is how the ECCC concluded the matter:  

After reviewing the information, the presence of  N-Nitrosodimethylamine (NDMA) is considered incidental under subsection 4(1) of the Prohibition of Certain Toxic Substances Regulations, 2012 (PCTSR), and therefore exempt from the regulations. Regional Environment and Climate Change Canada (ECCC) Environmental Enforcement is aware of the information and will review to determine what steps are appropriate to ensure compliance.

From the ActSubsection 4(1) reads: “a person must not manufacture, use, sell, offer for sale or import a toxic substance set out in Schedule 1 or a product containing it unless the toxic substance is incidentally present.” 

After two attempts to gain clarity on how the ECCC defines “incidental,” The Examiner finally received the following response: 

Incidental presence is not defined in the Prohibition of Certain Toxic Substances Regulations, 2012 nor in the Canadian Environmental Protection Act, 1999. Incidental presence is a residual, a trace contaminant or impurity that was not intentionally added to the formulation. The regulations do not establish any quantity or concentration thresholds for the presence of NDMA in a product (i.e., there is no “de minimis” allowable concentration). 

In other words, even though NDMA has been deemed highly toxic to humans, even in small quantities, the fact that it was not intentionally added is enough to exempt it from the regulations. That there is no established threshold for the substance — one that could override the fact that it wasn’t intentionally added — is astonishing.  

I can’t help but wonder if this loophole isn’t an intentional one, to benefit the industrial sector at the expense of human and environmental health. I also wonder about the role the industrial sector played in developing these regulations in the first place, and to what extent this is more evidence of runaway regulatory capture, where our government agencies have become dominated by the interests they are intended to regulate.  

The question is, how will we capture it back?  

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Linda Pannozzo is an award-winning author and freelance journalist based in Nova Scotia. email:; Website:

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  1. Yet another “why am I not surprised?” in the long, sad history of environmental degradation here in Nova Scotia.

  2. The ‘logic’ around these exemptions is pretty absurd.
    Whether intentional or not there is a known potent carcinogen going into the food web where it could easily be kept out of it.
    Best practice would be to keep the carcinogen out of the food web. Period. That’s not a hard decision to make.
    There’s not only a risk to humans (if there is a plausible pathway into the food produced on farms that use this product), there is an even more direct risk to all species that live on and use those farms (birds, insects, mammals, reptiles, amphibians etc).
    The province should require tracking of where CKD is being applied and check soils and nearby water for concentrations of NDMA in order to establish whether plausible pathways into human food or ecosystems exist.

  3. Good work.

    The ancient Lefarge kiln is almost designed for “incomplete combustion”. Modern cement kilns are bad enough- and they use an entirely different and more efficient combustion technology.

    I dont know how many decades ago that old “toilet bowl technology” was left behind. But I worked on the construction of the cement plant in Bowmanville in 1990, and that cyclone technology was not new then.

    I’m sure all the modelling that has been done assumes a perfect combustion that plant mostly does not achieve.