Dioxins and dioxin-like compounds in selected food products – April 1, 2014, to March 31, 2019

Targeted surveys are used by the CFIA to focus its surveillance activities on areas of highest health risk. The information gained from these surveys provides support for the allocation and prioritization of the agency's activities to areas of greater concern. Originally started as a project under the Food Safety Action Plan (FSAP), targeted surveys have been embedded in our regular surveillance activities since 2013. Targeted surveys are a valuable tool for generating information on certain hazards in foods, identifying and characterizing new and emerging hazards, informing trend analysis, prompting and refining health risk assessments, highlighting potential contamination issues, as well as assessing and promoting compliance with Canadian regulations.

Food safety is a shared responsibility. We work with federal, provincial, territorial and municipal governments and provide regulatory oversight of the food industry to promote safe handling of foods throughout the food production chain. The food industry and retail sectors in Canada are responsible for the food they produce and sell, while individual consumers are responsible for the safe handling of the food they have in their possession.

There are over 400 different structural forms of dioxins and dioxin-like compounds. The compounds are separated into 3 groups of chemicals with toxicological and chemical similarities. These groups are dioxins (also known as polychlorinated dibenzo-p-dioxins or PCDDs), polychlorinated dibenzofurans (PCDFs or furans) and polychlorinated biphenyls (dioxin-like PCBs or DL-PCBs). Only some of these compounds are of concern to human health; 29 of these (also known as targeted congeners) are the focus of this report^{Footnote 2}.

Dioxins and furans are mainly formed as by-products of industrial processes (manufacturing of chemicals, pulp and paper bleaching processes, exhaust emissions and incineration, etc.), but can also occur naturally (such as through volcanic activity or forest fires)^{Footnote 3}. These contaminants are not deliberately manufactured. PCBs are also man-made, and often contain furan contaminants. PCBs were historically used in many industrial applications (such as for their electrical insulating properties), but their production is now banned globally. PCBs are still present in certain types of electrical equipment and, despite strict controls on handling, storage and disposal of existing PCBs, accidental release into the environment is still possible. When released into the environment, dioxins, furans, and PCBs can be transported long distances from their source^{Footnote 2, Footnote 3, Footnote 6}.

The primary exposure to dioxins and dioxin-like compounds is through the consumption of foods of animal origin. These pollutants enter the livestock food chain through foraging and animal feed contamination and accumulate in the fatty tissues of the livestock^{Footnote 1, Footnote 2}. They then enter the human food chain through the consumption of contaminated foods of animal origin, particularly higher fat foods, such as dairy products, meat, and some fish and shellfish^{Footnote 4}.

Dioxins and dioxin-like compounds are associated with various health effects such as skin disorders (for example, chloracne), liver and thyroid problems, impairment of the endocrine, nervous, reproductive and immune systems, developmental effects and certain types of cancers^{Footnote 3, Footnote 4, Footnote 6}. The type and occurrence of these health effects typically depend on the level and duration of exposure.

In food, dioxins and dioxin-like compounds are found mainly in dairy products, animal tissues/fats and eggs^{Footnote 1, Footnote 2, Footnote 3, Footnote 4}. They can also be found in products made from oily plants due to their accumulation in soil and on plant surfaces^{Footnote 2}. These compounds accumulate in the liver and fat tissues of humans through consumption of food products containing dioxins and dioxin-like compounds^{Footnote 1, Footnote 3, Footnote 4, Footnote 5}. Dioxins and dioxin-like compounds are not destroyed by heating or cooking. The best method of minimizing dietary exposure to dioxins and dioxin-like compounds is prevention and reduction of contamination in foods and animal feeds^{Footnote 2, Footnote 3, Footnote 7}. This survey focused on vegetable oils and animal fats, meat and meat products, fish and seafood, ready-to-eat meals for children and adults, dairy products, infant formula, nuts and seeds and their products, meal replacements and protein powders available on the Canadian retail market.

A variety of domestic and imported vegetable oils and fats (vegetable oils, shortening, margarine, oil-based salad dressings, butter, mayonnaise, pork lard and goose fat), meat and meat products (frozen and canned), fish and seafood (frozen and canned), ready-to-eat meals (for adults, toddlers and infants), dairy products (cheese, yogurt, frozen yogurt, frozen dairy desserts, puddings and dairy-based salad dressings), nuts and seeds and their products (nut butters, seed butters and tahini), meal replacements (powders and liquids) and protein powders, and infant formula (soy-based and dairy-based formula in powder and liquid form) were sampled between April 1, 2014, and March 31, 2019. Samples of products were collected from local/regional retail locations in 6 major cities across Canada. These cities encompassed 4 Canadian geographical areas:

• Atlantic (Halifax)
• Quebec (Montreal)
• Ontario (Toronto and Ottawa)
• West (Vancouver and Calgary)

The number of samples collected from these cities was in proportion to the relative population of the respective areas. The shelf life, storage conditions, and the cost of the food on the open market were not considered in this survey.

Samples were analyzed by ISO 17025 accredited food testing laboratories under contract with the Government of Canada and were reported as they were sold (not prepared according to directions prior to analysis). Although the detection methods often test for 35 or more compounds, only 29 of these (also known as targeted congeners) are the focus of this report^{Footnote 2}. The list of compounds reported as part of this survey are shown in Table A-1 in the Appendix of this report. The concentration of each dioxin or dioxin-like compound detected, reported as picograms per gram of sample (pg/g, in total sample weight unless otherwise stated), is multiplied by its respective World Health Organization (WHO) 2005 consensus Toxic Equivalency Factors (TEFs)^{Footnote 8, Footnote 9} to calculate the individual toxic equivalency (TEQ) concentration in picograms TEQ per gram of sample (pg TEQ/g). Refer to Table A-1 in the Appendix for the TEFs used in this survey. Each of the calculated individual TEQ concentrations are then added together to arrive at a total TEQ concentration, which is an estimate of the total relative potency of all the dioxins and dioxin-like compounds detected in the sample.

Consistent with international reporting practice, total TEQ results are calculated and reported in terms of both lower bound TEQ (LB TEQ) and upper bound TEQ (UB TEQ) levels of dioxin and dioxin-like compounds. This allows for interpretation of both a best-case (LB TEQ) and a more conservative, worst-case scenario (UB TEQ) estimate of the total TEQ of a sample. LB TEQ levels represent solely the sum of all detected congeners multiplied by their respective TEFs, and congeners not detected are given a value of zero. UB TEQ levels represent the sum of detected forms multiplied by their respective TEFs, plus the sum of the limit of detection (LOD) contributions for all congeners that were not detected, also multiplied by their relevant TEFs. This method of calculating the UB TEQ incorporates levels that may be present below the LOD but still contribute to the total toxicity value. The true TEQ value will be somewhere between the LB TEQ and UB TEQ levels. At very low concentrations, the LB TEQ and UB TEQ values can span a larger range due to measurement uncertainty at low toxicity levels, but the higher the concentrations of the congeners, the closer the LB TEQ and UB TEQ values will be. In an abundance of caution, most global guidance and regulations use the UB TEQ value for compliance^{Footnote 1, Footnote 10, Footnote 12, Footnote 18}.

There are no Canadian regulations for total TEQ of dioxin-like compounds (furans and PCBs) for foods other than fish, which has a maximum level of 20 ppt for the specific congener 2,3,7,8-TCDD^{Footnote 11}. In the absence of established tolerances or standards for dioxins in foods, elevated levels in specific foods may be assessed by Health Canada on a case-by-case basis using the most current scientific data available. Currently, Health Canada is using the Joint Expert Committee on Food Additives' (JEFCA) recommended tolerable monthly intake of 70 picograms of dioxins and dioxin-like compounds per kilogram of body weight per month to assess the safety of foods while they are updating their risk assessments for these compounds^{Footnote 6}.

Of the 3115 samples analyzed in this survey, 95% (2951 samples) contained dioxins and dioxin-like compounds. The range of levels found is presented in Table 2. Among the 8 product types in the survey, the highest levels were found in fish, seafood, oils and fats, and the lowest were found in infant formula, nuts, seeds, and ready-to-eat meal products.

Ready-to-eat meals

The ready-to-eat meals that were tested consisted of 341 meals intended for adults, such as frozen dinners, canned soups and stews, frozen pizza products, and 282 frozen and jarred meals for infants and toddlers. The average UB TEQ for adult meals was 0.0910 pg TEQ/g, the average UB TEQ in infant/toddler meals was 0.0679 pg TEQ/g, and the average UB TEQ in the whole ready-to-eat meal category was 0.0805 pg TEQ/g. There were no detected levels of dioxins and dioxin-like compounds in 6% of the infant/toddler foods and in 4% of the adult meals.

Nuts, seeds and nut/seed butters

Dioxin and dioxin-like compounds were found in 288 of the 320 nuts, seeds and nut/seed butter samples surveyed, or 90% of samples. Samples tested included 267 nuts and nut butters, and 53 seeds and seed butters (or pastes, such as tahini). The average level in nuts and nut butters (UB 0.114 pg TEQ/g) was slightly higher than the average levels in seed and seed butters (UB 0.0.0999 pg TEQ/g). There was no significant difference in the average results between the different types of nuts or seeds.

Meat and meat products

Samples in this category consisted of processed meat in cans, jars or pouches and frozen meat products. Dioxins and dioxin-like compounds were detected in 95% of the samples. Beef products had higher average TEQ values (UB 0.116 pg TEQ/g) than the poultry, pork, and mutton samples (UB 0.0838 pg TEQ/g) analysed in this survey.

Meal replacements and protein powders

This survey tested 95 samples of liquid and powdered meal replacements and nutritional protein powders. There were detected levels of dioxins and dioxin-like compounds in 85 samples (89%). Dioxins and dioxin-like compounds were found in 96% of powdered samples, compared to 83% of liquid meal replacement samples. Powdered samples had an average UB TEQ level 0.0912 pg TEQ/g. Liquid samples had an average UB TEQ level 0.0915 pg TEQ/g.

Infant formula

Dioxins and dioxin-like compounds were found in 83 (91%) of infant formula samples, which were tested and reported as they are sold (not diluted). These included dairy-based (powder and liquid) and powdered soy-based formulas. The average UB TEQ levels were similar in both soy-based and dairy-based infant formulas. In dairy-based infant formula, powdered samples' average UB TEQ value was 4 times higher than the UB TEQ average levels found in the liquid samples. This is due to differences in method performance when analyzing powdered samples compared to liquids and because they are meant to be diluted with water before being used. Therefore, for this category of samples, the UB TEQ is likely an inflated estimate of the total TEQ present. The LB TEQ values reflect the levels of dioxin and dioxin-like compounds that were found in the samples and are likely a better calculation than UB TEQ.

Oils and fats

This category consisted of 792 oil and fat samples from vegetable and animal sources. Vegetable oils included a variety of single oil types (for example, olive, sesame, canola), as well as blended oils, oil-based salad dressings and mayonnaise. Solid vegetable shortenings and margarines were also sampled. Animal-sourced fats included dairy butter, lard (pork fat) and goose fat. These categories are presented in more detail below.

Oils and fats - Vegetable-sourced oils, fats and dressings

A total of 551 vegetable-based oils and shortening style fats were tested, plus 76 samples of vegetable oil-based mayonnaise and 24 salad dressings whose primary ingredient was a vegetable-based oil. Dioxin and dioxin-like compounds were found in 92% of the vegetable-based oils and fats, 96% of mayonnaise samples, and in all of the oil-based salad dressings. The lowest average level was found in oil-based salad dressings (UB 0.0677 pg TEQ/g). The highest average level was found in rice bran oil (UB 0.353 pg TEQ/g).

Oils and fats - Animal-sourced fats

Animal fats consisted of 141 samples of lard (pork fat), goose fat and dairy butter samples. Dioxins and dioxin-like compounds were found in 98% of samples. The highest average level found in this category was goose fat (UB 0.190 pg TEQ/g), followed by butter (UB 0.102 pg TEQ/g). Lard from pork fat had the lowest average levels (UB 0.0299 pg TEQ/g).

Dairy products

The dairy products tested in this survey included a range of cheese varieties, yogurt, frozen dairy desserts (ice cream, frozen yogurt, cheesecake, gelato, cream pies), dairy-based puddings and dairy-based salad dressings. Dioxin and dioxin-like compounds were detected in 99% of the samples tested. The highest average levels were in cheese (UB 0.109 pg TEQ/g). Yogurt beverages had the lowest average levels (UB 0.0177 pg TEQ/g).

Fish and seafood

Fish and seafood products contained the highest average content of dioxin and dioxin-like compounds of all the food categories in this survey, and 97% of samples had detected levels. Samples included canned and frozen products and covered a wide range of fish and seafood. Canned products had a higher average level than frozen samples. Fattier species, such as herring and sardines, tended to have higher levels than leaner species, such as tilapia and basa, which is expected because dioxins and dioxin-like congeners accumulate in fatty tissues. Frozen or refrigerated samples had lower average levels than canned fish. All of the fish and seafood samples in this survey were compliant with the Canadian Food and Drug Regulations' ML of 20 ppt of 2,3,7,8-TCDD^{Footnote 11}, with 97% of the samples containing no detected 2,3,7,8-TCDD, and the highest result found was 0.147 ppt of 2,3,7,8-TCDD.

In this survey, 95% of samples contained detected levels of dioxins and dioxin-like compounds. Table 3 presents current survey data compared with previous CFIA surveys where dioxins and dioxin-like compounds were analyzed in similar commodities.

The average UB TEQ levels observed in ready-to-eat meals and infant formula were slightly higher than in previous surveys. The other categories had UB TEQ levels similar to, or lower than, previous surveys. When the LB TEQ values are compared, the ready-to-eat meals and meal replacement/protein powder categories have higher average values than in previous surveys, and all other categories showed a decrease in this survey.

These differences can likely be attributed to the types of samples tested in each survey period. Another contributing factor may be that the global dioxin and dioxin-like compound contamination of the environment is decreasing after Canada and many other countries began implementing regulations to prevent emissions and monitor environmental levels of these contaminants in the 1990s^{Footnote 6, Footnote 17}.

This was the first year that a targeted survey included meat and fish, and so there are no previous CFIA survey results available. For comparison, published data from the German total diet study (BfR MEAL Study; meat report from 2019^{Footnote 13}, fish report from 2023^{Footnote 19}) and the European Food Safety Authority (EFSA) 2012 Monitoring Program Report^{Footnote 12} are included in Table 3 for meat and fish. All fish samples tested in this survey complied with the Canadian Food and Drug Regulations for 2,3,7,8-TCDD maximum allowable level^{Footnote 11}. The average UB TEQ results from this survey are either comparable to or lower than both the German total diet study (BfR MEAL study) and the EFSA 2012 Monitoring Program Report, except for the BfR meat results, which were lower than the results found in this survey.

The levels observed in this survey were evaluated by Health Canada's Bureau of Chemical Safety and none of the samples were determined to pose a safety concern to human health. There were no recalls resulting from this survey.

The data will be accessible on the Open Government Portal.