ARCHIVED - Proposed Re-evaluation Decision PRVD2011-02, Propiconazole

4 February 2011
ISSN: 1925-0959 (print version)
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2011-2E (print version)
Catalogue number: H113-27/2011-2E-PDF (PDF version)

Summary

Table of Contents

• What Is the Proposed Re-evaluation Decision?
• What Does Health Canada Consider When Making a Re-evaluation Decision?
• What Is Propiconazole?
• Health Considerations
• Environmental Considerations
• Measures to Minimize Risk
• What Additional Scientific Information Is Required?
• Next Steps

What Is the Proposed Re-evaluation Decision?

After a re-evaluation of the agricultural, turf and remedial wood preservative uses of the fungicide propiconazole, Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act and Regulations, is proposing continued registration for the sale and use of products containing propiconazole in Canada.

An evaluation of available scientific information found that products containing propiconazole do not present unacceptable risks to human health or the environment when used according to label directions. As a condition of the continued registration of propiconazole uses, new risk-reduction measures must be included on the labels of all products. No additional data are being requested at this time.

It should be noted that for end-use products containing more than one active ingredient under re-evaluation, registration status might change as a result of the re-evaluation of the remaining affected active ingredients.

This proposal affects all end-use products containing propiconazole registered for agricultural, turf and remedial wood preservative uses in Canada. Once the final re-evaluation decision is made, the registrants will be instructed on how to address any new requirements.

Proposed Re-evaluation Decision PRVD2011-02, Propiconazole is a consultation document that summarizes the science evaluation for propiconazole and presents the reasons for the proposed re-evaluation decision. It also proposes additional risk-reduction measures to further protect human health and the environment.

The information is presented in two parts. The Overview describes the regulatory process and key points of the evaluation, while the Science Evaluation provides detailed technical information on the assessment of propiconazole.

The PMRA will accept written comments on Proposed Re-evaluation Decision PRVD2011-02, Propiconazole up to 45 days from the date of publication of this document. Please forward all comments to Publications.

What Does Health Canada Consider When Making a Re-evaluation Decision?

The PMRA's pesticide re-evaluation program considers potential risks, as well as value, of pesticide products to ensure they meet modern standards established to protect human health and the environment. Regulatory Directive DIR2001-03, Pest Management Regulatory Agency Re-evaluation Program, presents the details of the re-evaluation activities and program structure.

To reach its decisions, the PMRA applies hazard and risk assessment methods as well as policies that are rigorous and modern. These methods consider the unique characteristics of sensitive subpopulations in both humans (for example, children) and 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 present 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

The current re-evaluation of propiconazole addresses all agricultural, turf and remedial wood preservative uses. Antisapstain and wood joinery uses of propiconazole are not included in this re-evaluation because they are being reviewed with other antisapstain active ingredients under a separate initiative within the PMRA. The PMRA conducted updated human health and environment assessments using all available information, including recent assessments of propiconazole from the United States Protection Agency (USEPA) Reregistration Eligibility Decision (RED) documents. Based on the use patterns and formulations of propiconazole registered in the United States, the USEPA RED was considered relevant to the Canadian situation.

For more details on the information presented in this summary, please refer to the Science Evaluation of Proposed Re-evaluation Decision PRVD2011-02, Propiconazole.

What Is Propiconazole?

Propiconazole is a triazole-based fungicide that is used to control fungi in agriculture (food/feed and non-food/non-feed crops), on turf and wood. The mode of action is by inhibition of fungal ergosterol biosynthesis that is essential for cell wall formation. Propiconazole is applied using aerial, ground boom, airblast or handheld equipment, by farm workers or professional applicators. Greenhouse uses are not specified on current propiconazole labels. Home owners can apply propiconazole using a brush for remedial wood treatment.

Health Considerations

Can Approved Uses of Propiconazole Affect Human Health?

Additional risk-reduction measures are required on propiconazole labels. Propiconazole is unlikely to affect your health when used according to the revised label directions.

People could be exposed to propiconazole by consuming food and water, working as a mixer/loader/applicator, by entering treated sites or through non-occupational exposure at golf courses and pick your own (PYO) operations (such as commercial farms or orchards that allow public access for harvesting fruits or vegetables).

The PMRA considers two key factors when assessing health risks: the levels at which 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 exposure is well below levels that cause no effects in animal testing are considered acceptable for continued registration.

Residues in Water and Food

Dietary risks from food and water are not of concern.

Reference doses define levels to which an individual can be exposed over a single day (acute) or lifetime (chronic) and expect no adverse health effects. Generally, dietary exposure from food and water is acceptable if it is less than 100% of the acute reference dose or chronic reference dose (acceptable daily intake). An acceptable daily intake is an estimate of the level of daily exposure to a pesticide residue that, over a lifetime, is believed to have no significant harmful effects.

Dietary exposure to propiconazole was estimated for the most highly exposed subpopulations (for example, children 1-2 years old and females 13-49 years old). The aggregate acute and chronic exposure estimates represented between 11% and 46% of the reference doses; thus, are below the PMRA's level of concern.

Maximum Residue Limits

The Food and Drugs Act prohibits the sale of 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. Each MRL value defines the maximum concentration in parts per million (ppm) of a pesticide allowed in/on certain foods. Food containing a pesticide residue at the established MRL does not pose an unacceptable health risk.

Propiconazole is currently registered in Canada for use on a variety of food/feed crops and could be used in other countries on crops that are imported into Canada. MRLs are currently established on registered domestic and import agricultural uses and published in Health Canada's List of MRLs Regulated under the Pest Control Products Act on the Maximum Residue Limits for Pesticides webpage. Where no specific MRL has been established, a default MRL of 0.1 ppm applies, which means that pesticide residues in a food commodity must not exceed 0.1 ppm. However, changes to this general MRL will be implemented in the future, as indicated in the December 2009 Information Note, Progress on Minimizing Reliance on the 0.1 Parts per Million as a General Maximum Residue Limit for Food Pesticide Residue. No modification of the MRLs was proposed during the course of this re-evaluation.

Triazole metabolites

Dietary exposure to triazolyl-1-alanine (TA) and triazolyl-1-acetic acid (TAA) may occur from the use of propiconazole on food commodities. Residues of TA in plant commodities are regulated in Canada not to exceed 2.0 ppm. These metabolites are common to all triazole fungicides, including propiconazole. The cumulative risks from TA and TAA will be addressed in a separate document.

Risks in Residential and other Non-Occupational Environments

The two registered products for residential use are being proposed for discontinuation due to risk concerns. Other non-occupational scenarios were not of concern.

There is currently one registered residential use of propiconazole for remedial wood treatment. A quantitative assessment of the potential risk to residential handlers applying the ready-to-use domestic product by brush was conducted. The resulting dermal margins of exposure (MOEs) were below the target MOE, and therefore represented a risk of concern for the PMRA. It is proposed that registration of the domestic end-use products be discontinued.

A quantitative assessment of the potential risk of exposure incurred by the public at "Pick-Your-Own (PYO)" operations or at public golf courses was conducted to ensure that there was no risk of concern for the public from acute exposure to propiconazole.

Aggregate exposure estimates were calculated to determine the risk of exposure for the public from all known potential sources: diet, drinking water and non-occupational exposure events. The combined exposures of diet, drinking water and golfing or PYO activities resulted in MOEs greater than the target MOE and are not of concern.

Occupational Risks from Handling Propiconazole

Occupational mixer/loader/applicator risks are not of concern provided proposed mitigation measures are followed.

Quantitative assessments for workers handling propiconazole for agricultural, turf or remedial wood treatment in mushroom houses were conducted. Dermal and inhalation MOEs for all scenarios were above the target MOE, with the implementation of mitigation measures, except for use of a high pressure sprayer in mushroom houses. Overall, it is proposed that additional personal protective equipment (PPE) be required for workers handling more than 78 kg propiconazole per day for turf uses, and that the use of high pressure sprayers for remedial wood treatment in mushroom houses be prohibited.

Postapplication risks are not of concern provided proposed mitigation measures are followed.

Postapplication occupational risk assessments were conducted to estimate exposures to workers entering treated sites based on the current product label directions for use. Occupational postapplication dermal MOEs were above the target MOE for all scenarios, and are not of concern when proposed protective measures are followed. It is proposed that restricted-entry intervals (REIs) be required for detasseling and hand harvesting corn, and for hand pruning highbush blueberries. The minimum 12-hour REI is proposed for the remaining scenarios and uses. Postapplication exposure is not of concern for golf course workers, and a standard label statement is proposed for workers to wait until the area is dry before re-entry.

Environmental Considerations

What Happens When Propiconazole Is Introduced Into the Environment?

Additional risk-reduction measures are required on propiconazole labels. Propiconazole is unlikely to affect non-target organisms when used according to the revised label directions.

Propiconazole enters the terresterial environment when it is used as a fungicide on a variety of crops and on golf courses. In the terresterial environment, propiconazole is expected to be slightly persistent to persistent. Biotransformation is an important route of transformation for propiconazole with major transformation products being 1,2,4-triazole and compounds hydoxylated at the dioxolane moiety. Phototransformation on soil or in air is not expected to be an important route of transformation for propiconazole. Propiconazole appears to have medium to low mobility in soil. An assessment of leaching potential based on a variety of criteria indicates that propiconazole has the potential to reach ground water through leaching, especially in soils with low organic matter contents. Available field studies indicate that propiconazole is typically detected in the upper soil layers, but the transformation products were detected deeper in the soil profile.

Propiconazole can enter the aquatic environment through spray drift and run-off. Propiconazole is very soluble in water, and appears to phototransform slowly and to be stable to hydrolysis. In the aquatic environment, propiconazole is expected to be moderately persistent to persistent. Biotransformation is an important route of transformation with major transformation products being two compounds hydroxylated at the dioxolane moiety. Propiconazole partitions from water to soil or sediment quickly, where it is expected to be persistent under anaerobic conditions. Therefore, propiconazole may contaminate aquatic ecosystems through off-site runoff under heavy rainfall when soil erosion occurs. Limited water monitoring information indicates that propiconazole is detected but with a low detection frequency. Propiconazole depurates rapidly, thus bioaccumulation is not expected to be a major concern for propiconazole.

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. As a result of the re-evaluation of propiconazole, the PMRA is proposing further risk-reduction measures for product labels.

Human Health

• Additional protective equipment to protect mixers/loaders/applicators.
• Restricted-entry intervals to protect workers re-entering treated sites.
• Prohibition of the use of high pressure sprayers for remedial wood preservative uses in mushroom houses.
• Discontinuation of the domestic ready-to-use remedial wood preservative products.
• Additional label statements regarding the use of propiconazole in greenhouses and around residential areas.

Environment

• Risks of propiconazole to non-target terrestrial plants and aquatic organisms are identified. The risks to non-target beneficial insects vary depending on the end-use product being tested. Appropriate hazard/precautionary statements are required on the product label.
• Spray buffer zones are required to mitigate the risks identified for non-target terrestrial plants and aquatic organisms resulting from spray drift.
• Runoff or discharge of propiconazole to aquatic environments should be avoided and hazard/precautionary statements are required on the product label.
• Propiconazole poses a potential risk of groundwater contamination in certain soils. A precautionary groundwater leaching statement is required on the product label.
• The label statement for cranberry uses is required on the product label to minimize the surface water contamination.

A submission to implement label revisions will be required within 90 days of finalization of the re-evaluation decision.

What Additional Scientific Information Is Required?

No additional scientific information related to human health or the environment is required.

Next Steps

Before making a final re-evaluation decision on propiconazole, the PMRA will consider all comments received from the public in response to this consultation document. The PMRA will then publish a Re-evaluation Decision that will include the decision, the reasons for it, a summary of comments received on the proposed decision and the PMRA's response to these comments.