Proposed Registration Decision PRD2018-03, Flazasulfuron and Flazasulfuron 25WG Herbicide

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Pest Management Regulatory Agency
23 February 2018
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2018-3E-PDF

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To obtain a full copy of Proposed Registration Decision PRD2018-03, Flazasulfuron and Flazasulfuron 25WG Herbicide please contact our publications office.

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Summary

Table of Contents

Proposed Registration Decision for Flazasulfuron

Health Canada’s Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act and Regulations, is proposing full registration for the sale and use of Technical Flazasulfuron Herbicide and Flazasulfuron 25WG Herbicide, containing the technical grade active ingredient flazasulfuron, for pre- and postemergent control or suppression of grasses, broadleaf weeds and sedges in grapes, conifer trees and industrial vegetation management sites.

An evaluation of available scientific information found that, under the approved conditions of use, the product has value and does not present an unacceptable risk to human health or the environment.

This summary describes the key points of the evaluation, while the Science Evaluation of Proposed Registration Decision PRD2018-03, Flazasulfuron and Flazasulfuron 25WG Herbicide provides detailed technical information on the human health, environmental and value assessments of Technical Flazasulfuron Herbicide and Flazasulfuron 25WG Herbicide.

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 flazasulfuron, the PMRA will consider any comments received from the public in response to PRD2018-03. The PMRA will then publish a Registration Decision on flazasulfuron, which will include the decision, the reasons for it, a summary of comments received on the proposed final registration decision and the PMRA’s response to these comments.

For more details on the information presented in this summary, please refer to the Science Evaluation of PRD2018-03.

What Is Flazasulfuron?

Flazasulfuron is a herbicide that inhibits production of branched-chain amino acids required for protein synthesis in plants. This results in the cessation of cell division and plant growth. Susceptible plants die shortly after exposure to sunlight. Flazasulfuron can be absorbed through both the roots and foliage of the plants.

Health Considerations

Can Approved Uses of Flazasulfuron Affect Human Health?

Flazasulfuron 25WG Herbicide, containing flazasulfuron, is unlikely to affect human health when used according to label directions.

Potential exposure to flazasulfuron may occur through the diet (food and water) or when handling and applying the end-use product Flazasulfuron 25WG Herbicide. 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 where 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-containing products are used according to label directions.

In laboratory animals, flazasulfuron and the end-use product, Flazasulfuron 25WG Herbicide, were of low acute toxicity by the oral, dermal, and inhalation routes of exposure. They were not irritating to the skin and were minimally irritating to the eye. They did not cause an allergic skin reaction.

Registrant-supplied short- and long-term (lifetime) animal toxicity tests were assessed for the potential of flazasulfuron to cause neurotoxicity, immunotoxicity, chronic toxicity, cancer, reproductive and developmental toxicity, and various other effects. There was no evidence that the young were more sensitive than the adult animal. The most sensitive endpoints for risk assessment were effects noted in the liver and kidneys. The risk assessment protects against the effects of flazasulfuron by ensuring that the level of human exposure 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 dietary intake estimates (food plus drinking water) revealed that the general population and infants less than one year old, the subpopulation which would ingest the most flazasulfuron relative to body weight, are expected to be exposed to less than 64% of the acceptable daily intake. Based on these estimates, the chronic dietary risk from flazasulfuron is not of health concern for all population subgroups.

Acute dietary (food plus drinking water) intake estimates for the general population and all population subgroups were less than 4% of the acute reference dose, and are not of health concern. The highest exposed subpopulation was all infants less than one year old.
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 the United States using flazasulfuron on grapes are acceptable. The MRL for this active ingredient can be found in the Science Evaluation of PRD2018-03.

Occupational Risks From Handling Flazasulfuron 25WG Herbicide

Occupational risks are not of concern when Flazasulfuron 25WG Herbicide is used according to the label directions, which include mitigation measures.

Workers mixing, loading, and applying Flazasulfuron 25WG Herbicide, and workers re-entering recently treated non-cropland areas can come in direct contact with Flazasulfuron 25WG Herbicide residues on the skin. Therefore, the label specifies that during mixing, loading, clean up and repair, handlers must wear a long-sleeved shirt and long pants, chemical-resistant gloves, shoes plus socks, and protective eyewear. During application, workers must wear a long-sleeved shirt, long pants, chemical-resistant gloves (not required inside closed-cab equipment), and shoes plus socks.

When using groundboom equipment and handling more than 48 kg Flazasulfuron 25WG Herbicide in a day, in addition to wearing the personal protective equipment listed above, mixers and loaders must wear chemical-resistant coveralls and chemical-resistant footwear.

The label also requires that workers do not enter or be allowed entry into treated vineyards, conifer trees (field- and container-grown), and conifer release (forestry) areas, during the restricted-entry interval (REI) of 12 hours; and do not enter or allow others to enter treated non-cropland or industrial vegetation areas until sprays have dried. Taking into consideration these label statements and the expectation of the exposure durations for handlers and postapplication workers, the risks to these individuals are not of concern.

Bystanders are not expected to be in a treatment area during application. A standard label statement to protect against drift during application is on the label. Health risks are not of concern for bystanders entering treated industrial vegetation and conifers on the day of application.

Environmental Considerations

What Happens When Flazasulfuron Is Introduced Into the Environment?

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

Flazasulfuron can enter the environment when applied to control weeds in grapes, in conifer trees, forests, and in industrial sites. It does not, however, remain in the environment for a long time. It breaks down by reacting with water to form several breakdown products. Flazasulfuron is not expected to move into the air from water or moist soils. It is not expected to accumulate in the tissues of organisms. It is not expected to carry over into the next growing season. Flazasulfuron and its breakdown products have the potential to move through soil to reach groundwater and run-off into surface water. A precautionary label statement is required to inform users that flazasulfuron can reach groundwater. Specific instructions are required to minimize risk of runoff from treated areas into aquatic habitats.

Flazasulfuron and its breakdown products do not present a risk of concern to birds, small wild mammals, bees, fish, amphibians, beneficial arthropods (such as beetle and spider), and invertebrates (such as earthworms and water fleas). Flazasulfuron and its breakdown products may affect non-target plants on land and in the water from spray drift and run-off. To minimize exposure and reduce risks to non-target plants, spray buffer zones and precautionary label statements are required.

Value Considerations

What Is the Value of Flazasulfuron 25WG Herbicide?

Flazasulfuron 25WG Herbicide provides pre- and postemergent control or suppression of grasses, broadleaf weeds, and sedges in grapes and conifer trees and for industrial vegetation management.

Flazasulfuron 25WG Herbicide provides pre- and postemergent control of grasses, broadleaf weeds, and sedges, with residual activity and tank-mix flexibility. It controls key weeds which are present in agricultural and forestry systems, including ragweed, pigweed, nightshade, and lamb’s-quarters. Control of broadleaf weeds with flazasulfuron in Christmas trees has been identified as a priority by Canadian growers.

The registration of Flazasulfuron 25WG Herbicide would provide Canadian growers not only with access to a product that is currently available in the United States for the same uses, but also a new mode of action for managing weeds in grapes and conifer trees. Flazasulfuron 25WG Herbicide may be particularly useful in managing weeds that have developed resistance to other modes of action.

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 Flazasulfuron 25WG Herbicide 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 Flazasulfuron 25WG Herbicide on the skin or through inhalation of sprays, workers must wear a long-sleeved shirt and long pants, chemical-resistant gloves, shoes plus socks, and goggles or face shield during mixing, loading, clean-up and repair. During application, workers must wear a long-sleeved shirt, long pants, chemical-resistant gloves (not required inside closed-cab equipment), and shoes plus socks.

When using groundboom equipment and handling more than 48 kg Flazasulfuron 25WG Herbicide in a day, in addition to wearing the personal protective equipment listed above, mixers and loaders must wear chemical-resistant coveralls and chemical-resistant footwear.

The label also requires that workers do not enter or be allowed entry into treated vineyards and conifer trees (field- and container-grown), and conifer release (forestry) areas, during the REI of 12 hours; and do not enter or allow others to enter treated non-cropland or industrial and vegetation areas until sprays have dried.

Environment

Precautionary label statements are required to inform users of the potential risks of flazasulfuron to groundwater. Specific instructions are required to minimize risk of runoff from treated areas into aquatic habitats. To minimize exposure and reduce risks to plants in water and land, spray buffer zones and precautionary label statements are required.

Next Steps

Before making a final registration decision on flazasulfuron, the PMRA will consider any comments received from the public in response to PRD2018-03. The PMRA will accept written comments on PRD2018-03 up to 45 days from the date of 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. The PMRA will then publish a Registration Decision, which will include its decision, the reasons for it, a summary of comments received on the proposed final decision and the Agency’s response to these comments.

Other Information

When the PMRA makes its registration decision, it will publish a Registration Decision on flazasulfuron (based on the Science Evaluation of PRD2018-03). In addition, the test data referenced in PRD2018-03 will be available for public inspection, upon application, in the PMRA’s Reading Room (located in Ottawa).

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