Food microbiology – Targeted surveys – Final report
Summary
A targeted surveyFootnote 1 analysed 197 samples of imported fresh green onions over a 1-year period from April 1, 2019 to March 31, 2020. All samples were tested for the presence of Cyclospora cayetanensis (C. cayetanensis), Cryptosporidum species (spp.), and Toxoplasma gondii (T. gondii).
All 197 (100%) samples tested were found to be satisfactory. C. cayetanensis, Cryptosporidium spp., and T. gondii were not found in any samples.
Overall, our survey results indicate that imported fresh green onions sold in Canada are generally safe for consumption. However, as with all foods, and especially with those that are consumed raw, good hygienic practices are recommended for producers, retailers, and consumers.
Why was this survey conducted
The survey was conducted to provide enhanced oversight of the safety of imported fresh green onions sold at retail in Canada. While fresh green onions are popular among CanadiansFootnote 2, they have unfortunately been associated with foodborne illness outbreaksFootnote 3Footnote 4.
Fresh produce, including green onions can be contaminated with parasites through contact with human and animal waste at any step in the food supply chain such as during production, harvest, post-harvest handling, packaging, distribution, and/or at retail. Unlike bacteria, parasites are unable to grow on foods, however they can remain viable for extended periods of time and may cause illness when ingested. Therefore the presence of parasites on fresh green onions is of concern as they are a commonly consumed by Canadians and are generally consumed raw.
When was the survey conducted
The survey was conducted over a 1-year period from April 1, 2019 to March 31, 2020.
Where were the samples collected from
Samples were collected from national retail chains and local/regional grocery stores located in the following 11 major cities across Canada:
- Halifax
- Moncton
- Quebec City
- Montreal
- Toronto
- Ottawa
- Vancouver
- Victoria
- Calgary
- Saskatoon
- Winnipeg
The planned number of samples to be collected from each city was based on the population of the province in which the city was located relative to the total population of Canada.
How many and what kind of samples were collected
A total of 197 imported fresh green onions were collected. Wherever possible, pre-packaged samples were collected. Samples were collected throughout the year, however a higher proportion was planned for the months of April to October to reflect the seasonality of foodborne parasitic infections in endemic countriesFootnote 4Footnote 5Footnote 6 imports into Canada, and reported cases of cyclosporiasis in Canada. A sample consisted of a single or multiple consumer sized packages of the same lot weighing at least 100g.
What were the samples tested for
All 197 samples were tested for C. cayetanensis, Cryptosporidum spp., and T. gondii.
What methods were used to test the samples
Samples were analyzed using methods that detect the presence of deoxyribonucleic acid (DNA) of C. cayentanensis, Cryptosporidum spp., and T. gondii.
How were the samples assessed
There are currently no Canadian standards regarding the presence of parasites in fresh produce. As the analytical methods used in this survey can only determine the presence or absence of parasite DNA, they cannot discriminate between living (infectious) and dead (non-infectious) parasites. Therefore, the detection of parasite DNA was assessed (table 1) as "investigative" and required further consideration to determine appropriate follow-up actions.
| Parasite | Satisfactory | Investigative |
|---|---|---|
| C. cayetanensis | Not detected | Detected |
| Cryptosporidium spp. | Not detected | Detected |
| T. gondii | Not detected | Detected |
What were the survey results
C. cayentanensis, Cryptosporidium spp., and T. gondii DNA were not found in any samples.
| Parasite | Number of samples tested | Satisfactory (%) | Investigative (%) |
|---|---|---|---|
| C. cayetanensis | 197 | 197 | 0 |
| Cryptosporidium spp | 0 | ||
| T. gondii | 0 | ||
| Total | 197 | 197 (100) | 0 (0) |
Survey results are also presented by production practice (table 3), and origin (table 4).
| Production practice | Number of samples tested (%) | Satisfactory |
|---|---|---|
| Conventional | 152 (77.2) | 152 |
| Organic | 45 (22.8) | 45 |
| Total | 197 | 197 |
| Production origin | Number of samples tested (%) | Satisfactory |
|---|---|---|
| Mexico | 159 (80.7) | 159 |
| United States | 36 (18.3) | 36 |
| United States and Mexico | 1 (0.5) | 1 |
| Spain | 1 (0.5) | 1 |
| Total | 197 (100) | 197 |
What do the survey results mean
Previous CanadianFootnote 7Footnote 8 and internationalFootnote 9 studies on the microbial safety of retail fresh green onions have shown similarFootnote 8 and higherFootnote 7Footnote 9 prevalence rates as compared those found in this study. Differing prevalence rates between studies may be attributable to differences in product type tested, methodology, study design, etc.
Overall, our survey results indicate that imported fresh green onions sold in Canada are generally safe for consumption. However, as with all foods, and especially with those that are consumed raw, good hygienic practices are recommended for producers, retailers and consumers.
What is done with the survey results
All results are used to:
- inform risk management decisions
- support program design and re-design
Can I access the survey data
Yes. The data will be accessible on the Open Government Portal.