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Ochratoxin A in Wheat Products, Oat Products, Rice Products and Other Grain Products - April 1, 2018 to March 31, 2019

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Targeted surveys provide information on potential food hazards and enhance the Canadian Food Inspection Agency's (CFIA's) routine monitoring programs. These surveys provide evidence regarding the safety of the food supply, identify potential emerging hazards, and contribute new information and data to food categories where it may be limited or non-existent. They are often used by the Agency to focus surveillance on potential areas of higher risk. Surveys can also help to identify trends and provide information about how industry complies with Canadian regulations.

Wheat products, oat products, rice products, and other grains (for example, barley, quinoa) are consumed in varying degrees by some or all populations in Canada. These products can be naturally contaminated with mycotoxins, which are toxic secondary metabolites of fungi. Ochratoxin A (OTA) is a toxin released by mould that can grow on agricultural products as a result of warm, wet climate conditions during storage.

Considering the factors mentioned above and their relevance to Canadians, grains were selected for this targeted survey. The purpose of targeted surveys is to generate a snapshot of the occurrence and levels of chemical hazards in food. Over the course of this study (April 1, 2018 to March 31, 2019), a total of 495 samples were collected from retail locations in 6 cities across Canada and tested for OTA.

OTA was found in 45% of samples tested. Wheat products, oat products, rice products, and kamut products (kamut is a type of wheat) are subject to a maximum level of 3 parts per billion (ppb), which has been proposed by Health Canada (HC) (see Appendix 1 for more information). The compliance rate for these products was 99.8% (n=420 samples). There are currently no established limits for OTA in other grains. Levels above historical results (previously submitted to HC and deemed safe) in the specific grains are reviewed by HC to determine if OTA levels are harmful to consumers. Levels in these samples did not pose a health risk to Canadian consumers and there were no product recalls resulting from this survey.

Overall, our survey results suggest that grains are safe for consumption. Regardless, these foods are a known potential source of OTA contamination and as such, safe handling practices are recommended for producers, retailers and consumers.

What are targeted surveys

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.

Why did we conduct this survey

Chemical hazards in foods can come from a variety of sources. This report provides the results of a chemistry survey that was carried out to detect a toxin (ochratoxin A) produced by moulds. Various strains of Aspergillus and Penicillium moulds can infect foods in storage. Wet, warm weather conditions in storage will favour the development of OTAFootnote 1. OTA only forms after harvest and is most commonly found in in cereal grains (wheat, corn, oat, and barley), green coffee, grape juice, beer, wines, cocoa, dried fruits, and nutsFootnote 2. OTA is not easily destroyed by heating so it survives under normal cooking or processing conditionsFootnote 3,Footnote 4.

The International Agency for Research on Cancer (IARC) has classified OTA as a possible human carcinogenFootnote 5, especially in the kidneys. In animal studies, OTA has also been shown to have negative effects on the kidneys, the developing fetus, and the immune systemFootnote 5. HC completed a risk assessment for OTA, and as a result, has proposed maximum levels for OTA in various food commoditiesFootnote 6 as well as an industry guidance value for OTA in unprocessed cereal grainsFootnote 7.

The main objectives of this targeted survey were: to generate additional baseline surveillance data on the levels of OTA in foods not routinely monitored under other agency programs but available on the Canadian retail market; to assess compliance with proposed Canadian regulations; and to compare the prevalence of OTA in foods in this survey with that of previous targeted surveys, where possible.

What did we sample

A variety of domestic and imported wheat, oat, rice products, and products of other grains were sampled between April 1, 2018 and March 31, 2019. Samples were collected from local/regional retail locations located in 6 major cities across Canada. These cities encompassed 4 Canadian geographical areas: Atlantic (Halifax), Quebec (Montreal), Ontario (Toronto, Ottawa) and the 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.

Table 1. Distribution of samples based on product type and origin
Product type Sample types Number of domestic samples Number of imported samples Number of samples of unspecified Table Note a origin Total number of samples
Wheat Baked goods, baking mixes, cookies, granola/cereals bars, breakfast/infant cereals, crackers, crispbreads, pasta 23 62 111 196
Oat Cookies, granola/cereals bars, breakfast cereals, cookies, crackers, bran, grain, oatmeal, oat products 37 38 25 100
Rice Grain, flavoured rice 8 40 50 98
Buckwheat Grain, groats, flour 8 10 7 25
Kamut Breakfast cereals, crackers, grain, flour, pasta 3 7 16 26
Quinoa Flour, grain, flakes, pasta 5 7 13 25
Rye Bread, crackers, crispbreads, flour, flakes 9 5 11 25
Grand total All 93 169 233 495

Table Notes

Table Note a

Unspecified refers to those samples for which the country of origin could not be assigned from the product label or available sample information.

Return to table note a referrer

How were samples analyzed and assessed

Samples were analyzed by an ISO/IEC 17025 accredited food testing laboratory under contract with the Government of Canada. The results are based on the food products as sold and not necessarily as they would be consumed.

In 2009, HC proposed maximum levels (MLs) for OTA in a variety of foods. These MLs as well as an industry guidance value for OTA in unprocessed cereal grains are still under consideration and remain in "proposed" statusFootnote 7. The proposed Canadian standards and guidance value for OTA, and the established international maximum levels for OTA in foods are presented in Appendix 1.

In the absence of established tolerances or standards for OTA in foods, elevated levels of OTA in specific foods may be assessed by HC on a case-by-case basis using the most current scientific data available.

What were the survey results

Of the 495 samples that were tested, 55% were free from contamination by OTA. Of the 45% of samples where OTA was detected, there were various ranges of contamination as seen in Table 2. Average levels of OTA were highest in buckwheat, and lowest in rye products.

Table 2. Levels of OTA in wheat products, oat products, rice products, and other grains
Product Total number of samples Number of positive samples Number of samples with non-compliant/elevated levels Min (ppb) Max (ppb) Average level (ppb) of positive results
Buckwheat 25 11 0 0.060 7.6 2.4
Kamut 26 10 0 0.050 1.2 0.48
Oat 100 55 0 0.050 1.6 0.26
Quinoa 25 8 0 0.054 5.8 1.3
Rice 98 13 1 0.049 11 1.1
Rye 25 15 0 0.050 1.9 0.24
Wheat 196 107 0 0.042 2.2 0.27

Only 1 (0.2%) sample had non-compliant/elevated levels of OTA. A sample of brown rice had a  level of 11 ppb. The proposed maximum limit for rice is 3 ppb.

The results for the elevated sample, along with the entire dataset, were forwarded to HC for a safety assessment. Adverse health effects are associated with long-term exposure to OTA. Periodic, short-term exposures to elevated OTA levels in a limited number of foods would not be considered to pose a safety concern. HC is of the opinion that the levels of OTA in the products analyzed in this survey were unlikely to pose a health risk. No product recalls were warranted given the low risk to human health.

What do the survey results mean

In this survey, 55% of samples of selected foods analyzed were free of detectable levels of OTA. Tables 3-6 present a comparison of the maximum, minimum and average OTA levels in specific food categories observed in this study vs. previous agency surveysFootnote 8,Footnote 9,Footnote 10,Footnote 11,Footnote 12. Please note that only the detectable values of OTA were included in the calculation of the minimum, maximum and average OTA levels for agency surveys.

Table 3. Summary of current and previous targeted survey data on OTA concentrations in wheat products
Food Year Number of samples Number (%) of positive samples Minimum OTA levels (ppb) Maximum OTA levels (ppb) Average OTA levels (ppb)
Baked goods 2018-2019 1 1 (100) n/a 0.073 n/a
Baked goods 2016-2017 100 64 (64) 0.040 65 1.2
Baked goods 2012-2014 48 48 (100) 0.39 5.3 2.0
Baked goods 2011-2012 19 13 (68) 0.043 0.35 0.13
Baking mixes 2018-2019 28 9 (32) 0.051 0.46 0.16
Baking mixes 2012-2014 247 163 (66) 0.042 6.1 0.28
Granola/cereal bars 2018-2019 9 6 (67) 0.080 1.3 0.36
Breakfast cereal (wheat) 2018-2019 31 13 (42) 0.050 2.0 0.32
Breakfast cereal (wheat) 2012-2014 361 208 (58) 0.042 7.0 0.38
Breakfast cereal (wheat) 2011-2012 80 59 (74) 0.041 1.8 0.37
Breakfast cereal (wheat) 2010-2011 56 26 (46) 0.040 2.8 0.56
Infant cereal (wheat) 2018-2019 28 5 (18) 0.050 0.17 0.077
Infant cereal (wheat) 2012-2014 259 111 (43) 0.041 2.2 0.57
Infant cereal (wheat) 2011-2012 25 9 (36) 0.041 0.76 0.30
Infant cereal (wheat) 2010-2011 10 1 (10) n/a 0.22 n/a
Infant cereal (wheat) 2009-2010 75 19 (25) 0.30 4.1 0.82
Cookies 2018-2019 31 22 (71) 0.042 1.0 0.23
Cookies 2016-2017 198 136 (69) 0.042 2.6 0.24
Cookies 2012-2014 102 86 (84) 0.041 4.4 0.23
Cookies 2010-2011 30 20 (67) 0.049 3.8 0.50
Crackers/Crispbreads 2018-2019 40 30 (75) 0.047 2.2 0.41
Crackers/Crispbreads 2016-2017 100 73 (73) 0.048 1.7 0.28
Crackers/Crispbreads 2012-2014 147 121 (82) 0.045 2.8 0.32
Crackers/Crispbreads 2011-2012 10 10 (100) 0.044 3.2 0.94
Pasta 2018-2019 28 21 (75) 0.049 0.34 0.18
Pasta 2016-2017 262 132 (50) 0.040 1.9 0.32
Pasta 2012-2014 159 96 (60) 0.041 2.8 0.26

n/a = not applicable

Table 4. Summary of current and previous targeted survey data on OTA concentrations in oat products
Year Number of samples Number (%) of positive samples Minimum OTA levels (ppb) Maximum OTA levels (ppb) Average OTA levels (ppb)
2018-2019 100 55 (55) 0.050 1.6 2.6
2012-2014 314 141 (45) 0.040 21 0.9
2011-2012 31 22 (71) 0.042 1.2 0.32
2010-2011 17 13 (76) 0.042 0.74 0.23
Table 5. Summary of current and previous targeted survey data on OTA concentrations in rice products
Year Number of samples Number (%) of positive samples Minimum OTA levels (ppb) Maximum OTA levels (ppb) Average OTA levels (ppb)
2018-2019 98 14 (14) 0.049 11 1.1
2011-2012 1 1 (14) n/a 0.25 n/a

n/a = not applicable

Table 6. Summary of current and previous targeted survey data on OTA concentrations in other grains
Grain Year Number of samples Number (%) of positive samples Minimum OTA levels (ppb) Maximum OTA levels (ppb) Average OTA levels (ppb)
Buck-wheat 2018-2019 25 11 (44) 0.060 7.6 2.4
Buck-wheat 2017-2018 17 9 (53) 0.050 3.3 0.70
Buck-wheat 2012-2014 37 17 (46) 0.052 5.3 0.88
Buck-wheat 2011-2012 12 7 (58) 0.11 29 5.3
Kamut 2018-2019 26 10 (38) 0.050 1.2 0.48
Kamut 2017-2018 1 0 (0) n/a n/a n/a
Kamut 2012-2014 33 8 (24) 0.14 13 3.3
Kamut 2011-2012 15 7 (47) 0.047 2.3 1.0
Quinoa 2018-2019 25 8 (32) 0.054 5.8 1.3
Quinoa 2017-2018 22 10 (45) 0.043 1.3 0.52
Quinoa 2012-2014 32 13 (41) 0.12 12 2.6
Quinoa 2011-2012 24 9 (38) 0.045 0.70 0.25
Rye 2018-2019 25 15 (60) 0.050 1.9 0.24
Rye 2017-2018 3 1 (33) n/a 0.36 n/a
Rye 2012-2014 26 12 (46) 0.045 6.7 1.6
Rye 2011-2012 4 4 (100) 0.068 2.4 0.98

n/a = not applicable

When examining the baseline data collected from 2009 to 2017, rice typically had very low prevalence and low levels of OTA. Wheat, oat and other grain products had relatively high OTA prevalence, and the levels were variable.

In general, the OTA prevalence and average levels in the current targeted survey data were comparable or lower than those recorded in previous targeted surveys, except for oat products, rice products and buckwheat products. The scientific studies purchased local products while the CFIA studies included samples from at least 28 countries. This may account for some of the differences.

The OTA levels in all samples were assessed by HC, who concluded that the levels of OTA found in the products analyzed in this survey did not pose a health concern. No product recalls were warranted given the lack of a health concern.

Appendix 1

Proposed Canadian and established international OTA maximum levels/levels/guidelines in foods
Commodity Canada Table Note b (proposed) – see ref 7 United States European Union Codex
Raw/unprocessed cereal grains 5 Not specified to date 5 Not specified to date
Grains for direct consumption 3 Not specified to date 3 Not specified to date
Derived cereal products (for example, flour, bread, breakfast cereal) 3 Not specified to date 3 Not specified to date
Wheat bran 7 Not specified to date 3 Not specified to date
Cereal-based foods for infants and young children 0.5 Not specified to date 0.5 Not specified to date
Wheat gluten not sold directly to the consumer Not specified to date Not specified to date 8.0 Not specified to date

Table Notes

Table Note b

Proposed maximum level by HC

Return to table note b referrer

Levels reflect latest regulations in the USAFootnote 13, European Union (EU)Footnote 14 and CodexFootnote 15

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