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Proposed Registration Decision PRD2012-18, Fluroxypyr

Notice to the reader: The online consultation is now closed. Comments and suggestions received during the public consultation period are being considered in the finalization of this document. The final report will be made available as soon as possible.

Pest Management Regulatory Agency
20 July 2012
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2012-18E-PDF (PDF version)

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 PRD2012-18, Fluroxypyr please contact our publications office.

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

Summary

Table of Contents

Proposed Registration Decision for Fluroxypyr

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Next link will take you to another Web site Pest Control Products Act and Next link will take you to another Web site Regulations, is proposing full registration for the sale and use of Starane F Technical Herbicide and Starane II Herbicide, containing the active ingredient fluroxypyr, for postemergent suppression or control of kochia in industrial and non-cropland areas including roadsides, rights of way and industrial vegetation management areas.

Starane F Technical Herbicide (Registration Number 24814) and Starane II Herbicide (Registration Number 29463) are currently registered in Canada for use on spring and durum wheat, spring barley and oats, as well as on rangeland and permanent pasture. Industrial and non cropland areas represent a major new use of the active ingredient fluroxypyr.

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 PRD2012-18, Fluroxypyr provides detailed technical information on the human health, environmental and value assessments of Starane F Technical Herbicide and Starane II 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 (for example, those most sensitive to environmental contaminants). 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 fluroxypr, the PMRA will consider all comments received from the public in response to this consultation document. The PMRA will then publish a Registration Decision on fluroxypyr, 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 Proposed Registration Decision PRD2012-18, Fluroxypyr.

What Is Fluroxypyr?

Fluroxypyr is a systemic and selective post-emergent herbicide that offers control of hard-to-kill annual broadleaved weeds such as kochia (2-8 leaf), cleavers (1-4 whorl), and chickweed (up to 8 cm) in small grain cereals and control of kochia in rangeland, permanent pasture, industrial and other non-cropland areas. Fluroxypyr is formulated as fluroxypyr-methylheptyl ester which, after predominantly foliar uptake, hydrolyses to fluroxypyr acid, which is the herbicidally active form of fluroxypyr. Fluroxypyr induces auxin-type responses and disrupts plant cell growth in the newly forming stems and leaves of susceptible plants.

Health Considerations

Can Approved Uses of Fluroxypyr Affect Human Health?

Fluroxypyr is unlikely to affect your health when used according to label directions.

Potential exposure to fluroxypyr may occur through the diet (food and water) or when handling and applying the product. 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). 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 products are used according to label directions.

In laboratory animals, technical grade fluroxypyr (acid or methylheptyl ester) was of low acute toxicity by the oral and dermal routes and was of slight toxicity by the inhalation route of exposure. Fluroxypyr was mildly irritating to the eyes and non-irritating to the skin, and did not elicit an allergic skin reaction. Consequently, the hazard signal words "CAUTION - POISON - EYE IRRITANT" are required on the label.

The acute toxicity of the end-use product Starane II Herbicide was low via the oral, dermal and inhalation routes of exposure. It was moderately irritating to the eyes and mildly irritating to the skin. It caused an allergic skin reaction in mice. Consequently, the hazard signal words "WARNING - EYE AND SKIN IRRITANT - POTENTIAL SKIN SENSITIZER" are required on the label.

In animals given daily oral doses of fluroxypyr over long periods of time, decreases in body weight gain and changes to the kidneys and adrenals were observed. Fluroxypyr did not damage genetic material and did not cause tumours in rats or mice. There was no indication that fluroxypyr caused damage to the nervous system or immune system. Fluroxypyr did not cause birth defects in the developing young, or effects on the reproductive system. When fluroxypyr ester was given to pregnant animals, a foetal variation (retrocaval ureter) was noted in the absence of maternal toxicity, indicating that the young were more sensitive to fluroxypyr than the adult animals. The risk assessment protects against the effects of fluroxypyr by ensuring that the level of human exposure is well below the lowest dose at which these effects occurred in animal tests.

Occupational Risks From Handling Starane II Herbicide

Occupational risks are not of concern when Starane II Herbicide is used according to the proposed label directions, which include protective measures.

Workers who mix, load or apply Starane II Herbicide, as well as field workers re-entering freshly treated non-crop areas, can come in direct contact with fluroxypyr residues on the skin. Mixers, loaders and applicators may also be exposed by breathing sprays and mists. Therefore, the label specifies that anyone mixing/loading and applying Starane II Herbicide must wear coveralls over a long-sleeved shirt, long pants and chemical-resistant gloves. The label also requires that workers do not enter treated industrial and non-cropland areas until residues have dried. Taking into consideration these label statements, the number of applications and the expectation of the exposure period for handlers and workers, the risk to these individuals is not a concern.

For bystanders, exposure is expected to be much less than that for workers and is considered negligible. Therefore, health risks to bystanders are not of concern.

Environmental Considerations

What Happen When Fluroxypyr are Introduced into the Environment?

Fluroxypyr in the form of fluroxypyr-methylheptyl ester is non-persistent in the environment and transforms readily to fluroxypyr acid. Fluroxypyr-methylheptyl ester is expected to impact terrestrial plants and aquatic organisms, therefore, spray buffer zones are required during application.

Fluroxypyr-methylheptyl ester will enter the environment through application to industrial and non-cropland areas. Fluroxypyr-methylheptyl ester is non-persistent in the environment and has low potential to leach. Fluroxypyr-methylheptyl ester biotransforms in soil and aquatic systems with hydrolysis as the predominant degradation mechanism. Fluroxypyr acid is slightly to moderately persistent in the environment and has moderate potential to leach. Phototransformation is not an important process for either of these chemicals. Two major biotransformation products of fluroxypyr-methylheptyl ester and fluroxypyr acid were identified: pyridinol, which is slightly to moderately persistent, and methoxypyridine, which is more persistent. These transformation products have mobility potential in soil but have low to moderate potential to leach to groundwater. In aquatic systems, fluroxypyr-methylheptyl ester partitions into the sediment phase after a few hours, then quickly hydrolyzes to its acid equivalent, fluroxypyr acid. Once fluroxypyr acid is released into the water phase it is expected to slowly transform under aerobic conditions. Fluroxypyr-methylheptyl ester or fluroxypyr acid will not bioconcentrate in fish.

Fluroxypyr is applied by broadcast sprayer. There is a potential that non-target terrestrial and aquatic habitats may be exposed to the chemical as a result of spray drift or runoff. Fluroxypyr-methylheptyl ester does not present a risk to earthworms, birds, small mammals, bees and beneficial arthropods. However, it poses a risk to non-target terrestrial plants and freshwater organisms including aquatic invertebrates, fish, amphibians and algae. Precautionary statements are included on the end-use product Starane II Herbicide label, and buffer zones of five metres (terrestrial habitats) and one metre (aquatic habitat) are required to mitigate risk to non-target plants and aquatic organisms from spray drift. Fluroxypyr acid does not pose a risk to terrestrial or aquatic non-target organisms.

Value Considerations

What Is the Value of Starane II Herbicide?

Starane II Herbicide is a post-emergent herbicide to control specific broadleaf weeds in small grain cereals, rangeland, permanent pasture, industrial and non-cropland areas.

Fluroxypyr formulated as Starane Herbicide (Registration Number 24815), was first registered in Canada in 1997 for control or suppression of cleavers, kochia (including Group 2 resistant biotype), round-leaved mallow, volunteer flax, chickweed, hempnettle, wild buckwheat, and stork's-bill in spring wheat, durum wheat, and spring barley.

Starane II Herbicide, with a higher product guarantee, was registered based on the registration of Starane Herbicide. Starane II Herbicide can be applied as a broadcast treatment at a rate of 0.21 0.41 L/ha in spring wheat, durum wheat, spring barley and oats. Starane II Herbicide may also be applied alone at a rate of 0.42 or 0.84 L/ha for suppression or control of kochia (including Group 2 resistant biotype), respectively, or in a tank mixture with Milestone Herbicide (Registration Number 28517; 240 g/L aminopyralid) at a rate of 0.25-0.5 L/ha for control of broad weed spectrum in industrial and other non-cropland areas.

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 Starane II Herbicide to address the potential risks identified in this assessment are as follows.

Key Risk-Reduction Measures

Human Health

To minimize direct contact with fluroxypyr residues on the skin, anyone mixing, loading and applying Starane II Herbicide must wear coveralls over a long-sleeved shirt, long pants and chemical-resistant gloves.

Workers must not enter treated industrial and non-cropland areas until residues have dried.

Environment

To mitigate risk to non-target terrestrial plants and aquatic organisms, buffer zones of five metres (terrestrial habitats) and one metre (aquatic habitats) are required during application.

Next Steps

Before making a final registration decision on fluroxypyr, the PMRA will consider all comments received from the public in response to Proposed Registration Decision PRD2012-18, Fluroxypyr. The PMRA will accept written comments on this proposal up to 45 days from the date of publication of Proposed Registration Decision PRD2012-18, Fluroxypyr.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 fluroxypyr (based on the Science Evaluation of Proposed Registration Decision PRD2012-18, Fluroxypyr). 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).