New substances: risk assessment summary, new substances notification 21573

Official title: New substances: risk assessment summary, New Substances Notification 21573 – Schedule 1 of the New Substances Notification Regulations (Organisms)

Notified organism: Saccharomyces cerevisiae expressing lactate dehydrogenase (LDH) from Rhizopus oryzae

Schedule of the NSNR(O): Schedule 1 - Information Required in Respect of Micro-organisms

Organism type: Yeast

Use: Import for use in the production of sour-flavoured beer

Anticipated quantity: confidential and not for disclosure

Assessment level of concern:

• Human health hazard: Medium
• Human exposure: Low
• Environmental hazard: Low
• Environmental exposure: Low

Assessment conclusion under section 64 of the Canadian Environmental Protection Act, 1999 (CEPA): Low risk, not suspected to be toxic

Category: Added to the Domestic Substances List on April 24, 2024

Recommended action: None

Waiver: None

Synopsis

The notified organism is a genetically modified strain of S. cerevisiae that was notified to the New Substances program for use in beer production (fermentation and flavouring). It could also be used in similar types of fermentation where sour flavouring is desired.

There is no evidence to suggest a potential risk of adverse environmental and indirect human health effects at the exposure levels predicted to the environment and general population in Canada from the import and use of the notified organism.

It is determined that the notified strain is not toxic or capable of becoming toxic according to the criteria under section 64 of the Canadian Environmental Protection Act, 1999 (CEPA) as there is no evidence to suggest that the notified organism may enter the environment in a quantity or concentration or under conditions that:

• have or may have an immediate or long-term harmful effect on the environment or its biological diversity
• constitute or may constitute a danger to the environment on which life depends
• constitute or may constitute a danger in Canada to human life or health

No risk management is recommended.

Background information

The notified organism is a genetic modification, of S. cerevisiae (baker’s yeast), which resulted in the introduction of a synthetic lactate dehydrogenase (LDH) gene from a filamentous saprophytic fungus Rhizopus oryzae.

The genetic modifications allow the notified organism to give the beer a sour flavour through production of lactic acid. No other potential uses have been identified by the notifier for the notified organism and would not be used likely beyond brewing or fermentation.

Hazard

The environmental hazard potential of the notified organism is determined to be low because:

1. S. cerevisiae has a wide distribution in nature and a long history of use especially in baking and alcohol production. The notified organism is genetically modified to include a synthetic LDH gene from R. oryzae that has no documented history of environmental adverse effects.
2. The genetic modifications in the notified organism are well-defined and the introduced genetic material is stably integrated. Methods are available to distinguish the notified strain from its parental strain and other S. cerevisiae strains. No adverse environment effects are associated with these modifications.
3. No pathogenicity and toxicity testing were performed on the notified organism. However, surrogate information provided by the same notifier on another genetically modified strain and information obtained from the public domain has not shown involvement of the notified organism or other closely related strains in causing any adverse effects to plants, vertebrates or invertebrates. The notified organism and the species S. cerevisiae are classified as Risk Group (RG) 1^{Footnote 1} animal pathogens by the Public Health Agency of Canada (PHAC).

The human hazard potential of the notified organism is determined to be medium because:

1. The genetic modifications are well-characterized and stably integrated into the genome. As such, the probability of any mobilization of the inserted genetic material in the notified organism is limited.
2. The genetic material inserted into the notified organism is well-defined and there are no pathogenic, toxic, or antibiotic resistance effects associated with these genes.
3. S. cerevisiae has been associated with human activities for centuries (that is, bread and alcoholic beverage production). Most infections in humans related to S. cerevisiae have been reported in vulnerable individuals with compromised immunity, underlying diseases, or medical conditions. Furthermore, the notified organism and the species S. cerevisiae are classified as RG 1 human pathogens by the PHAC.
4. The notified organism’s parental strain (M14629) is capable of growing at temperatures above 35°C (that is, close to human body temperature). The genetic modifications are not anticipated to alter the growth conditions of the parental strain and therefore, it is likely to grow at normal human body temperatures.
5. Allergic reactions caused by prolonged and repeated occupational exposures to S. cerevisiae have been reported. However, such reactions are rare in the general population. Although the sequence of LDH is similar to known allergens, LDH is widely distributed in nature. While there is potential for the notified organism to cause allergic reactions in sensitized individuals, it is not expected to occur in the general population that are otherwise non-sensitized to that enzyme.
6. No pathogenicity and toxicity testing were performed on the notified organism. However, information available on another genetically modified strain of S. cerevisiae (notified previously by the same notifier) as well as information found in the published literature noted that other closely related strains of S. cerevisiae have not been implicated in causing any mortality in animal test models and did not show signs of toxicity similar to unmodified strains. Therefore, the notified organism is expected to perform similarly.
7. In an unlikely event of infections caused by the notified organism, clinically relevant antifungal drugs are available for treatment of such infections. The notified organism is susceptibile to fluconazole and amphotericin B.

Exposure

The environmental and indirect^{Footnote 2} human exposure potential of the notified organism is determined to be low because:

1. The notified organism will be imported and shipped directly to end-users in Canada (that is, commercial scale breweries or homebrewers) in sachets for use in beer production.
2. Under commercial brewery settings, the standard operating procedures for inactivation (pasteurization and filtration) and subsequent disposal (landfill or wastewater) would limit the likelihood of large-scale environmental release. Under home brewery situations, very limited quantities would be used by consumers, therefore the potential environmental release and subsequent potential exposure would be limited.
3. In the event of an accidental spill, the potential for exposure would be localized to the immediate area. Procedures on spill management to inactivate and clean up the spilled yeast were provided by the notifier and deemed to be acceptable.
4. S. cerevisiae can survive in a variety of conditions. Should release occur, the genetic modifications made to the notified organism are not expected to provide any competitive advantage to persist or proliferate in the environment. Its potential for dispersal in the urban environment is low, and therefore, it is not expected to be dispersed a great distance from its point of release.
5. The notified organism is eligible for addition to the Domestic Substances List^{Footnote 3} and therefore could be used in other applications. However, given its mode of action and known uses of similar strains, the applications are likely to be limited to fermentation where sour flavouring is desired.
6. The notifier does not intend to manufacture this organism in Canada. Should manufacture occur in Canada in the future, the likelihood of release to the environment is not expected to increase significantly.
7. Environmental concentrations of the notified organism to which humans may be exposed were calculated using New Substances program’s Computational Tool for several potential release scenarios (for example, disposal, accidental spill). In all release scenarios, the concentration at which humans would be exposed to the notified organism from environmental media is lower than the concentration at the point of introduction (potential releases from disposal or accidental spills).

Risk characterization

Owing to the low potential hazard and the low potential exposure, the environmental risk associated with the import of the notified organism for use in beer production and other potential uses is assessed to be low.

Owing to the medium potential hazard due to potential for allergenicity and the low potential exposure, the human health risk associated with the import of the notified organism for use in beer production and other potential uses is assessed to be low.

Risk assessment conclusion

There is no evidence to suggest a potential a risk of adverse environmental and human health effects at the exposure levels predicted to the environment and general population from the import and use of the notified organism in beer production or other types of fermentation used in food processing. The risk to the environment and human health associated with the notified organism is not suspected to meet the criteria in paragraphs 64(a), (b), or (c) of CEPA. No further action is recommended.