Proposed Registration Decision PRD2013-11, Metconazole

Pest Management Regulatory Agency
24 May 2013
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2013-11E-PDF (PDF version)

Summary

Table of Contents

• Proposed Registration Decision for Metconazole
• What Does Health Canada Consider When Making a Registration Decision?
• What Is Metconazole?
• Environmental Considerations
• Value Considerations
• Measures to Minimize Risk
• Next Steps
• Other Information

Proposed Registration Decision for Metconazole

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 Metconazole Technical Fungicide and Tourney Fungicide, containing the technical grade active ingredient metconazole, to control several diseases on turfgrass on golf courses and sod farms.

Metconazole Technical Fungicide (Registration Number 29766) and Caramba Fungicide (Registration Number 29767) are conditionally registered in Canada. The detailed review for Metconazole Technical Fungicide and Caramba Fungicide can be found in Evaluation Report ERC2011-02, Metconazole. A portion of the data requirements identified for the conditional registration were also addressed in this application.

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 PRD2013-10, Metconazole provides detailed technical information on the human health, environmental and value assessments of Metconazole Technical Fungicide and Tourney Fungicide.

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 on how the PMRA regulates pesticides, the assessment process and risk-reduction programs, 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 metconazole, the PMRA will consider all comments received from the public in response to Proposed Registration Decision PRD2013-10, Metconazole. The PMRA will then publish a Registration Decision on metconazole, 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 PRD2013-10, Metconazole.

What Is Metconazole?

Metconazole is a triazole fungicide (demethylation-inhibiting fungicide) that inhibits sterol biosynthesis.The end-use product, Tourney Fungicide, contains 50.0% metconazole formulated as a water dispersible granule for use on turfgrass on golf courses and sod farms to control certain diseases.

Health Considerations

Can Approved Uses of Metconazole Affect Human Health?

Tourney Fungicide containing metconazole is unlikely to affect your health when used according to label directions.

Potential exposure to metconazole 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.

The technical grade active ingredient, metconazole, was moderately toxic to rats and highly toxic to mice when given as a single oral dose. It was of low acute dermal toxicity to rats and rabbits and of low inhalation toxicity to rats. It was moderately irritating to the eyes and non-irritating to the skin of rabbits. It was not a potential skin sensitizer to guinea pigs. The signal words, "DANGER - POISON" and "EYE IRRITANT" have been included on the label in light of these findings. The end-use product, Tourney Fungicide, was found to be of slight oral acute toxicity and low dermal and inhalation acute toxicity in rats. It was minimally irritating to the eyes and non-irritating to skin of rabbits and not a dermal sensitizer in guinea pigs.

Health effects in animals given repeated daily doses of metconazole over longer periods of time were decreased body weights, effects in blood (regenerative anaemia) and microscopic changes to the liver, spleen and adrenal glands. There was no evidence that metconazole damaged genetic material. Skin tumours in male mice were observed following oral administration. There was no evidence of cancer in rats.

When metconazole was orally or dermally administered to pregnant rabbits, cranio-facial malformations were observed in fetuses. Limb-flexure malformations were observed in fetuses when metconazole was administered dermally to pregnant rabbits. These effects were observed at doses that were not toxic to the mother, indicating that the fetus is more sensitive to metconazole than the adult animal. Due to the serious nature of these endpoints, extra protective factors were applied during the risk assessment to further reduce the allowable level of human exposure to metconazole.

The risk assessment protects against the above effects by ensuring that the level of human exposure is well below the lowest dose at which the above effects occurred in animal tests.

Residues in Water and Food

Dietary risks from food and water are not of concern.

Aggregate dietary intake estimates (food plus water) revealed that the general population and all infants less than one year old, the subpopulation that would ingest the most metconazole relative to body weight, are expected to be exposed to less than 56% of the acceptable daily intake. Based on these estimates, the chronic dietary risk from metconazole is not of concern for all population subgroups. The lifetime cancer risk from the use of metconazole is considered acceptable.

Acute dietary (food and water) estimate for females 13-49 years old was less than 83% of the acute reference dose, and is not of health concern. For all other subpopulations, an acute reference dose was not established, therefore an acute dietary intake estimate is not required.

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.

No residue data are required to support the registration of metconazole for use in/on turfgrass on golf courses and sod farms in Canada. For the MRLs for this active ingredient on various crop commodities, please refer to the Maximum Residue Limit Database in the Pesticides and Pest Management section of Health Canada's website.

Occupational Risks From Handling Tourney Fungicide

Occupational risks are not of concern when Tourney Fungicideis used according to the proposed label directions, which include protective measures.

Workers who mix, load or apply Tourney Fungicide, as well as workers re-entering freshly treated golf courses and sod farms, can come in direct contact with metconazole residues on the skin. Taking into consideration the approved personal protective equipment and engineered controls outlined in the Key Risk-Reduction Measures section below, the label statements, the number of applications and the expectation of the exposure period for handlers and workers, the non-cancer and cancer risks to these individuals are not of 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.

Risks in Residential and Other Non-Occupational Environments

Non-occupational risks are not of concern when Tourney Fungicide is used according to label directions.

Adults and youth may be exposed to metconazole while golfing on treated courses. Based on the expected short-term duration of this activity, risk to golfers is not a concern. There were no cancer risks of concern.

Environmental Considerations

What Happens When Metconazole Is Introduced Into the Environment?

Metconazole is toxic to non-target terrestrial plants, birds, small wild mammals and aquatic organisms. It is persistent in soil and aquatic sediment; however, it is not persistent in water. Metconazole is a potential leacher and may reach groundwater. Label instructions, including spray buffer zones, are required.

Metconazole enters the environment when used as a fungicide on agricultural crops and on turfgrass. Metconazole is moderately persistent to persistent in the terrestrial environment. It is relatively stable to hydrolysis and phototransformation, undergoing minor biotransformation in both soil and water. Despite its high soil adsorption, metconazole has the potential to leach into groundwater due to its solubility in water and persistence in soil. Based on its low volatility (low vapour pressure and Henry's law constant), metconazole residues are not expected in the air, nor is long-range aerial transport expected. Specific instructions to mitigate carryover, groundwater contamination and runoff into aquatic habitats are provided on the end-use product label.

Metconazole presents a negligible risk to terrestrial invertebrates including earthworms and honeybees, freshwater invertebrates including daphnids, juvenile stages of freshwater fish, freshwater algae, marine fish and marine algae. However, it may adversely affect non-target terrestrial plants, birds, small wild mammals, amphibians, early life stages of freshwater fish, freshwater aquatic vascular plants and marine invertebrates, including mysid shrimps. Therefore, toxicity statements for non-target terrestrial plants, birds, mammals, and aquatic organisms are specified on the product label. Spray buffer zones are also required to protect terrestrial, freshwater and estuarine/marine habitats adjacent to areas treated with metconazole fungicide.

Value Considerations

What Is the Value of Tourney Fungicide?

As a new fungicide active ingredient for use on turfgrass, Tourney Fungicide contributes to integrated pest management on golf courses and sod farms.

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 Tourney Fungicide to address the potential risks identified in this assessment are as follows.

Key Risk-Reduction Measures

Human Health

Because there is a concern with users coming into direct contact with Tourney Fungicide on the skin or through inhalation of spray mists, anyone mixing, loading and applying must wear a long-sleeved shirt, long pants, shoes, socks and chemical-resistant gloves when handling up to 18.5 kg of Tourney Fungicide during groundboom application or when handling up to 2.1 kg of Tourney Fungicide during low pressure turf gun application. When handling more than 18.5 kg of Tourney Fungicide during groundboom application, mixer/loader/applicators must wear cotton coveralls over a long-sleeved shirt, long pants, shoes, socks and chemical-resistant gloves and must apply using a closed cab tractor. When handling more than 2.1 kg of Tourney Fungicide during low pressure turf gun application, workers must wear cotton coveralls over a long-sleeved shirt, long pants, shoes, socks and chemical-resistant gloves. The label also requires that workers do not enter treated golf courses and sod farms for 24 hours after application for transplanting, planting and slab harvesting activities. For other activities, the label requires that workers do not enter treated areas until sprays have dried.

Environment

For field sprayer application on turfgrass, spray buffer zones up to 5 metres in width are required to protect sensitive aquatic and terrestrial habitats from spray drift of Tourney Fungicide.

Next Steps

Before making a final registration decision on metconazole, the PMRA will consider all comments received from the public in response to Proposed Registration Decision PRD2013-10, Metconazole. The PMRA will accept written comments on Proposed Registration Decision PRD2013-10, Metconazole up to 45 days from the date of publication of Proposed Registration Decision PRD2013-10, Metconazole. 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 metconazole (based on the Science Evaluation of Proposed Registration Decision PRD2013-10, Metconazole). In addition, the test data referenced in Proposed Registration Decision PRD2013-10, Metconazole will be available for public inspection, upon application, in the PMRA's Reading Room (located in Ottawa).