Proposed Registration Decision PRD2021-02, Picarbutrazox and VAYANTIS Seed Treatment

• Pest Management Regulatory Agency
• 3 June 2021
• ISSN: 1925-0886 (PDF version)
• Catalogue number: H113-9/2021-2E-PDF (PDF version)

Summary

Table of Contents

• Proposed registration decision for picarbutrazox
• What does Health Canada consider when making a registration decision?
• What is picarbutrazox?
• Health considerations
• Environmental considerations
• Value considerations
• Measures to minimize risk
• Next steps
• Other information

Proposed registration decision for picarbutrazox

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act, is proposing registration for the sale and use of Picarbutrazox Technical and VAYANTIS Seed Treatment, containing the technical grade active ingredient picarbutrazox, to control seed rot/pre-emergence damping-off and post-emergence damping-off in corn and soybean.

An evaluation of available scientific information found that, under the approved conditions of use, the health and environmental risks and the value of the pest control products are acceptable.

This summary describes the key points of the evaluation, while the Science Evaluation of Proposed Registration Decision PRD2021-02, Picarbutrazox and VAYANTIS Seed Treatment provides detailed technical information on the human health, environmental and value assessments of picarbutrazox and VAYANTIS Seed Treatment.

What does Health Canada consider when making a registration decision?

The key objective of the Pest Control Products Act is to prevent unacceptable risks to people and the environment from the use of pest control products. Health or environmental risk is considered acceptable if there is reasonable certainty that no harm to human health, future generations or the environment will result from use or exposure to the product under its proposed conditions of registration. The Act also requires that products have value when used according to the label directions. Conditions of registration may include special precautionary measures on the product label to further reduce risk.

To reach its decisions, the PMRA applies modern, rigorous risk-assessment methods and policies. These methods consider the unique characteristics of sensitive subpopulations in humans (for example, children) as well as organisms in the environment. These methods and policies also consider the nature of the effects observed and the uncertainties when predicting the impact of pesticides. For more information please refer to the following:

• Protecting Your Health and the Environment
• Pesticide Registration Process
• Pesticide Risk Reduction Program.

Before making a final registration decision on picarbutrazox and VAYANTIS Seed Treatment, Health Canada's PMRA will consider any comments received from the public in response to PRD2021-02. Health Canada will then publish a Registration Decision on picarbutrazox and VAYANTIS Seed Treatment, which will include the decision, the reasons for it, a summary of comments received on the proposed registration decision and Health Canada's response to these comments.

For more details on the information presented in this summary, please refer to the Science Evaluation of PRD2021-02.

What is picarbutrazox?

Picarbutrazox is a new conventional fungicide active ingredient that controls particular economically important diseases of corn and soybean.

Health considerations

Can approved uses of picarbutrazox affect human health?

VAYANTIS Seed Treatment, containing picarbutrazox, is unlikely to affect your health when used according to label directions.

Potential exposure to picarbutrazox may occur through the diet (food and drinking water), when handling and applying the end-use product, or when handling and planting treated seeds. When assessing health risks, two key factors are considered:

• the levels where no health effects occur and
• the levels to which people may be exposed.

The dose levels used to assess risks are established to protect the most sensitive human population (for example, children and nursing mothers). As such, sex and gender are taken into account in the risk assessment. Only uses for which the exposure is well below levels that cause no effects in animal testing are considered acceptable for registration.

Toxicology studies in laboratory animals describe potential health effects from varying levels of exposure to a chemical and identify the dose level at which no effects are observed. The health effects noted in animals occur at doses more than 100-times higher (and often much higher) than levels to which humans are normally exposed when pesticide products are used according to label directions.

In laboratory animals, the technical grade active ingredient picarbutrazox was of low acute toxicity via the oral, dermal and inhalation routes. It was minimally irritating to the eyes and non-irritating to the skin. It did not cause an allergic skin reaction.

The end-use product VAYANTIS Seed Treatment, containing picarbutrazox, was of low acute toxicity via the oral, dermal, and inhalation routes. It was minimally irritating to the eyes and non-irritating to the skin. It did not cause an allergic skin reaction.

Registrant-supplied short-term and long-term (lifetime) animal toxicity tests were assessed for the potential of picarbutrazox to cause neurotoxicity, chronic toxicity, cancer, reproductive and developmental toxicity, and various other effects. The most sensitive endpoints for risk assessment were effects on the liver and thyroid in rats. There was no evidence of increased sensitivity of the young. Thyroid tumours were noted in male and female rats at the highest dose tested, however, there was no evidence to suggest that picarbutrazox damaged genetic material. The risk assessment protects against the effects noted above and other potential effects by ensuring that the level of exposure to humans is well below the lowest dose at which these effects occurred in animal tests.

Residues in food and drinking water

Dietary risks from food and drinking water are not of health concern.

Animal studies revealed no acute health effects. Consequently, a single dose of picarbutrazox is not likely to cause acute health effects in the general population (including infants and children).

On the strength of the overall information, a threshold approach was considered appropriate for the cancer risk assessment based on the observed thyroid follicular cell adenomas in rats. Overall the endpoints selected for the non-cancer dietary risk assessment are considered protective of these findings.

Aggregate chronic (non-cancer and cancer) dietary intake estimates (food plus drinking water) for the general population and all population subgroups are expected to be less than or equal to 3% of the acceptable daily intake, and are not of health concern.

The Food and Drugs Act prohibits the sale of adulterated food, that is, food containing a pesticide residue that exceeds the established maximum residue limit (MRL). Pesticide MRLs are established for Food and Drugs Act purposes through the evaluation of scientific data under the Pest Control Products Act. Food containing a pesticide residue that does not exceed the established MRL does not constitute a health risk of concern.

Residue trials conducted throughout Canada and the United States using picarbutrazox as a seed treatment on soybean and on field corn, sweet corn and popcorn are acceptable. The MRLs for this active ingredient can be found in the Science Evaluation of PRD2021-02.

Occupational risks from handling VAYANTIS Seed Treatment

Occupational risks are not of health concern when VAYANTIS Seed Treatment is used according to the proposed label directions, which include protective measures.

Workers treating seeds with VAYANTIS Seed Treatment in commercial facilities or with commercial mobile treaters as well as workers planting treated seeds, may come into direct contact with picarbutrazox residues on the skin and through inhalation. Therefore, the label of VAYANTIS Seed Treatment specifies that treatment must be conducted with a closed-transfer system only. In addition, workers must wear long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes during mixing, loading, application, cleaning, bagging, sewing, stacking, as well as during handling and planting of treated seeds. Taking into consideration these label statements, the rate of application and the duration of exposure for handlers and workers, health risks to these individuals are not of concern.

Health risks to bystanders

Bystander risks are not of health concern when VAYANTIS Seed Treatment is used according to the proposed label directions and drift restrictions are observed.

A standard label statement to protect against drift during application is on the label. Therefore, health risks to bystanders are not of concern.

Environmental considerations

What happens when picarbutrazox is introduced into the environment?

When used according to label directions, the risks associated with the use of picarbutrazox are acceptable from the viewpoint of environmental protection.

Picarbutrazox will remain in the soil for up to 2 to 3 months depending on the soil type and conditions; however, when considering the breakdown-products of picarbutrazox, the combination of picarbutrazox and its breakdown products can remain in the soil for up to a year depending on the soil type and conditions. It will not move from the treatment area into the air and, therefore, will not move to another area by movement through the air. Picarbutrazox is not expected to move downward in the soil, and, therefore, is unlikely to reach groundwater; however, many of its breakdown-products can move downward in the soil and reach groundwater. Picarbutrazox has low potential to move off the treatment area to reach surface waters such as ponds, streams and rivers. If it does enter water, picarbutrazox will move to the sediment where it will not remain for a long period of time. Picarbutrazox is not expected to accumulate in plant or animal tissue.

When picarbutrazox is used in accordance with the label directions and the required precautions, the risk to terrestrial invertebrates, birds, wild mammals, bees, beneficial arthropods, terrestrial plants, aquatic invertebrates (including sediment-dwelling invertebrates), amphibians, fish, algae and vascular aquatic plants from the use of picarbutrazox were determined to be acceptable without the requirement of additional risk mitigation measures.

Value considerations

What is the value of VAYANTIS Seed Treatment?

Picarbutrazox is the active ingredient in VAYANTIS Seed Treatment. The registration of this product will provide Canadian growers with a unique mode of action to manage important fungal diseases in corn and soybean while mitigating the risk of resistance development by causal pathogens to other fungicides that are registered to control the same diseases.

VAYANTIS Seed Treatment is applied to seed of corn and soybean to control seed rot/pre-emergence damping-off and post-emergence damping off that can reduce crop stands.

Measures to minimize risk

Labels of registered pesticide products include specific instructions for use. Directions include risk-reduction measures to protect human and environmental health. These directions must be followed by law.

The key risk-reduction measures being proposed on the label of Picarbutrazox Technical and VAYANTIS Seed Treatment to address the potential risks identified in this assessment are as follows.

Key risk-reduction measures

Human health

To reduce the potential of workers coming into direct contact with picarbutrazoxon the skin or through inhalation, workers must wear long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes during mixing, loading, applying, cleaning, bagging, sewing, stacking, as well as during handling and planting of treated seeds. The label also specifies that commercial seed treatment must be conducted with closed-transfer system only. Furthermore, a standard label statement to protect against drift during application is present on the label.

Environment

• Precautionary statements are required to inform users of the toxicity of picarbutrazox to aquatic organisms.
• Precautionary statements are required for the labeling of treated seed.
• Precautionary statements are required to inform users of the potential for leaching.

Next steps

Before making a final registration decision on picarbutrazox and VAYANTIS Seed Treatment, Health Canada's PMRA will consider any comments received from the public in response to PRD2021-02. Health Canada will accept written comments on PRD2021-02 up to 45 days from the date of publication of PRD2021-02. Please note that, to comply with Canada's international trade obligations, consultation on the proposed MRLs will also be conducted internationally via a notification to the World Trade Organization. Please forward all comments to Publications. Health Canada will then publish a Registration Decision, which will include its decision, the reasons for it, a summary of comments received on the proposed decision and Health Canada's response to these comments.

Other information

When Health Canada makes its registration decision, it will publish a Registration Decision on picarbutrazox and VAYANTIS Seed Treatment (based on the Science Evaluation of PRD2021-02). In addition, the test data referenced in this consultation document will be available for public inspection, upon application, in the PMRA's Reading Room (located in Ottawa).