Proposed Registration Decision PRD2020-15, Trifludimoxazin, Vulcarus and Voraxor

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Pest Management Regulatory Agency
28 October 2020
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2020-15E-PDF (PDF version)

Summary

This page is a summary of the consultation document. If you would like to comment, please request the full consultation document.

To obtain a full copy of Proposed Registration Decision PRD2020-15, Trifludimoxazin, Vulcarus and Voraxor  please contact our publications office.

Should you require further information please contact the Pest Management Information Service.

Table of Contents

Proposed registration decision for trifludimoxazin

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 Tirexor Herbicide Technical, Vulcarus and Voraxor, containing the technical grade active ingredient trifludimoxazin, to control weeds in barley, field corn, field pea, soybean, wheat, lentil, and chemfallow.

One of the end-use products, Voraxor, is co-formulated with saflufenacil. Saflufenacil is registered for use in Canada.

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 PRD2020-15, Trifludimoxazin, Vulcarus and Voraxor provides detailed technical information on the human health, environmental and value assessments of trifludimoxazin, Vulcarus and Voraxor.

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:

Before making a final registration decision on trifludimoxazin, Vulcarus and Voraxor, Health Canada’s PMRA will consider any comments received from the public in response to PRD2020-15. Health Canada will then publish a Registration Decision on trifludimoxazin, Vulcarus and Voraxor, 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 PRD2020-15.

What is trifludimoxazin?

Trifludimoxazin is a herbicide that inhibits synthesis of protoporphyrinogen oxidase (PPO). The lack of PPO damages cell membranes, which leads to plant death. Under active growing conditions, susceptible emerged weeds develop injury symptoms within hours of exposure and die within 3–5 days. Susceptible emerging weed seedlings usually die as they reach the soil surface or shortly after emergence.

Health considerations

Can approved uses of trifludimoxazin affect human health?

Voraxor and Vulcarus, containing trifludimoxazin, are unlikely to affect your health when used according to label directions.

Potential exposure to trifludimoxazin may occur through the diet (food and drinking water), when handling and applying the product, or when entering an area that has been treated with the product. When assessing health risks, two key factors are considered;

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 trifludimoxazin 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 products Voraxor and Vulcarus were of low acute toxicity via the oral, dermal and inhalation routes. They were minimally irritating to the eyes and slightly irritating to the skin. They did not cause an allergic skin reaction.

Registrant-supplied short-term and long-term (lifetime) animal toxicity tests were assessed for the potential of trifludimoxazin to cause neurotoxicity, immunotoxicity, chronic toxicity, cancer, reproductive and developmental toxicity, and various other effects. The most sensitive endpoints for risk assessment were effects on the nervous system of young rats. As these effects were observed concurrently with other toxicological effects in the parents, there was no evidence of increased sensitivity of the young. 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 water and food

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

Aggregate acute dietary (food plus drinking water) intake estimates for the general population and all population subgroups are expected to be less than 2.1% of the acute reference dose, and are not of health concern.

Children 1–2 years old are the subpopulation expected to be subject to the highest exposure relative to body weight.

Aggregate dietary intake estimates (food plus drinking water) revealed that the general population and children 1–2 years old, the subpopulation which would ingest the most trifludimoxazin relative to body weight, are expected to be exposed to less 1.2%of the acceptable daily intake. Based on these estimates, the chronic dietary risk from trifludimoxazin is not of health concern for all population subgroups.

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 pose an unacceptable health risk.

Residue trials conducted throughout Canada and the United States using trifludimoxazin on legume vegetables, citrus fruits, pome fruits, tree nuts, peanuts, and cereal grains are acceptable. The MRLs for this active ingredient can be found in the Science Evaluation of PRD2020-15.

Occupational risks from handling Vulcarus and Voraxor

Occupational risks are not of concern when Vulcarus and Voraxorare used according to the label directions, which include protective measures.

Farmers and custom applicators mixing, loading or applying Vulcarus and Voraxor, and workers entering recently treated fields, can come in direct contact with trifludimoxazin or saflufenacil residues on the skin. Therefore, the label specifies that anyone mixing, loading and applying Vulcarus and Voraxor must wear a long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes. The label also requires that workers do not enter or be allowed entry into treated fields during the restricted-entry interval (REI) of 12 hours. Taking into consideration the label statements, the number of applications, and the duration of exposure for handlers and postapplication workers, the risks to these individuals are not of health concern.

Health risks to bystanders

Bystander risks are not of health concern when Vulcarus and Voraxorare used according to the label directions and spray 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 trifludimoxazin is introduced into the environment?

When used according to label directions, trifludimoxazin is not expected to pose risks of concern to the environment.

Trifludimoxazin enters the environment when applied to soil to control weeds that come out before crops are planted. On land, trifludimoxazin breaks down and may move downward through the soil and reach groundwater. The breakdown-products of trifludimoxazin may also move through the soil and reach groundwater. After trifludimoxazin is sprayed, it can enter bodies of water (ponds, streams and rivers) where it will break down. Trifludimoxazin and its breakdown-products will move to sediments where they remain over time. Trifludimoxazin is not expected to be found in air or travel long distances in the atmosphere from where it was applied.

Trifludimoxazin is not expected to build up in the tissues of plants or animals.

Trifludimoxazin presents negligible risks to terrestrial organisms (earthworms, bees, beneficial arthropods, wild birds and mammals) but may pose a risk to vegetation adjacent to treated fields, which can affect native plants and habitat for wildlife. In bodies of water, trifludimoxazin presents negligible risks to aquatic invertebrates and marine algae but may pose risks to freshwater and marine fish, amphibians, freshwater algae and vascular aquatic plants. Therefore, precautionary measures and spray buffer zones are required to minimize exposure to non-target terrestrial plants and aquatic organisms. When trifludimoxazin is used in accordance with the label directions and when the required risk reduction measures are applied, the reduced environmental exposure is considered acceptable and the risks are not an environmental concern.

Value considerations

What is the value of Vulcarus and Voraxor?

Vulcarus and Voraxor provide burndown control of several broadleaf weeds with soil residual activity to suppress secondary weed flushes in barley, field corn, field pea, soybean, wheat, lentil, and in chemfallow situations.

Vulcarus is formulated as a suspension concentrate with trifludimoxazin. It provides burndown control of cleavers, kochia, lamb’s-quarters, volunteer canola, and wild buckwheat and suppression of secondary flushes of kochia, lamb’s-quarters, redroot pigweed, volunteer canola, and wild mustard in barley, field corn, field pea, soybean, and wheat (spring, durum, and winter) and in chemfallow.

Voraxor is formulated as a suspension concentrate with trifludimoxazin and the registered active ingredient saflufenacil. It provides burndown control of Canada fleabane, cleavers, kochia, lamb’s-quarters, narrow-leaved hawk’s beard, redroot pigweed, round-leaved mallow, shepherd’s purse, stinkweed, volunteer canola, wild buckwheat, and wild mustard and further suppression of secondary weed flushes in barley, field corn, lentil, field pea, soybean, and wheat (spring, durum, and winter) and in chemfallow.

Registrations of Vulcarus and Voraxor will provide farmers with options for pre-plant or pre-emergent burndown control of broadleaf weeds, including key weeds present in agricultural systems, in the early season with soil residual activity. Application of Vulcarus or Voraxor reduces early season weed competition to the emerging crop, allowing the crop to benefit from additional moisture, nutrients, and light that would otherwise be captured by weeds. Management of weeds at this time is critical, as the crop does not compete well with weeds until crop canopy closure. As Vulcarus and Voraxor have soil residual activity, the reduction in competition of weeds with the crop is extended.

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 Tirexor Herbicide Technical, Vulcarus and Voraxor 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 in direct contact with trifludimoxazin on the skin or through inhalation of sprays, workers mixing, loading and applying Vulcarus and Voraxor, and performing cleaning and repair activities must wear a long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes. In addition, standard label statements to protect against drift during application are on the labels. The labels also require that workers not enter or be allowed entry into treated fields during the restricted-entry interval (REI) of 12 hours.

Environment

Label statements and spray buffer zones to reduce the risk of spray drift to non-target terrestrial plants, freshwater fish, amphibians, aquatic vascular plants and freshwater algae are required. Label statements to reduce the risk of surface runoff entering aquatic habitats are required.

Next steps

Before making a final registration decision on trifludimoxazin, Vulcarus and Voraxor, Health Canada’s PMRA will consider any comments received from the public in response to PRD2020-15. Health Canada will accept written comments on PRD2020-15 up to 45 days from the date of publication of its publication. 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 the Health Canada makes its registration decision, it will publish a Registration Decision on trifludimoxazin, Vulcarus and Voraxor (based on the Science Evaluation of PRD2020-15). In addition, the test data referenced in PRD2020-15 will be available for public inspection, upon application, in the PMRA’s Reading Room (located in Ottawa).

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