Proposed Re-evaluation Decision PRVD2017-16, Dichlorvos and Its Associated End-use Products

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Pest Management Regulatory Agency
25 October 2017
ISSN: 1925-0967 (PDF version)
Catalogue number: H113-27/2017-16E-PDF (PDF version)

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Table of Contents

Proposed Re-evaluation Decision

Under the Pest Control Products Act, all registered pesticides must be regularly re-evaluated by Health Canada’s Pest Management Regulatory Agency (PMRA) to ensure that they continue to meet current health and environmental safety standards and continue to have value. The re-evaluation considers data and information from pesticide manufacturers, published scientific reports, and other regulatory agencies. The PMRA applies internationally accepted risk assessment methods as well as current risk management approaches and policies.

Dichlorvos is a broad spectrum, non-systemic organophosphate insecticide used to manage various insect pests on: greenhouse cucumbers, tomatoes and ornamentals, indoor and outdoor structural sites (for example, processing plants, storage facilities, livestock housing and outdoor recreational areas) and for mosquito control. Dichlorvos is applied indoors by hand sprayers, ultra-low volume applicators, and automatic foggers, as well as used in insecticide strips. It is applied outdoors by ground equipment. It is registered for both commercial and domestic uses.

This document (Proposed Re-evaluation Decision PRVD2017-16, Dichlorvos and Its Associated End-use Products) presents the proposed regulatory decision for the re-evaluation of dichlorvos including the proposed risk mitigation measures to further protect human health and the environment, as well as the science evaluation on which the proposed decision was based. All products containing dichlorvos registered in Canada are subject to this proposed re-evaluation decision. Proposed Re-evaluation Decision PRVD2017-16, Dichlorvos and Its Associated End-use Products is subject to a 90-day public consultation period, during which the public including the pesticide manufacturers and stakeholders may submit written comments and additional information to the PMRA Publications Section. The final re-evaluation decision will be published taking into consideration the comments and information received.

Outcome of Science Evaluation

Dichlorvos provides consistent and effective control of a range of economically important insect pests on greenhouse crops and indoor and outdoor structural sites. The low persistence of dichlorvos makes it a very useful tool in greenhouse tomato, cucumber and ornamental integrated pest management programs, where it is effective for end-of-season control of insect pests between crop cycles before the introduction of beneficial insects. Dichlorvos is important for controlling cigarette beetle and tobacco moth infestation in stored tobacco due to its level of efficacy against these pests. The volatility of dichlorvos adds to its effectiveness in the domestic and commercial insecticide strips. It is fast-acting and compatible with integrated pest management practices when used in conjunction with pheromones in insect traps to monitor insect pest populations in fruit and vegetable crops.

With respect to human health, risks of concern were identified for some residential and occupational exposures to dichlorvos. Therefore, cancellation of uses for greenhouse cucumbers and tomatoes, greenhouse cut flower ornamentals, outdoor mosquito control, outdoor residential living areas, and indoor pest strips (excluding areas that are unoccupied for a minimum of 4 months) is proposed. Mitigation measures are required for all remaining uses. Exposure from the remaining uses is unlikely to affect human health when used according to the proposed label directions.

Dichlorvos enters the environment when used to control insects in and around human habitation and other outdoor living spaces, or when it is present in water discharges from use in greenhouses and mushroom houses. When used according to the proposed label directions, dichlorvos is not expected to pose risks of concern to the environment.

Proposed Regulatory Decision for Dichlorvos

Under the authority of the Pest Control Products Act and based on the evaluation of currently available scientific information, Health Canada is proposing that certain products containing dichlorvos are acceptable for continued registration for sale and use in Canada, provided that the risk mitigation measures are in place.

Registered pesticide product labels include specific directions for use. Directions include risk mitigation measures to protect human health and the environment that must be followed by law. As a result of the re-evaluation of dichlorvos, further risk mitigation measures for product labels are being proposed.

Human Health

To protect homeowners and those entering treated areas, the following proposed risk mitigation measures are required.

For Domestic-class products:

  • Label statements prohibiting the use of pest strips in any area of an inhabited home, including in attics, crawl spaces, and garages.
  • Label statements prohibiting use of pest strips in commercial areas, including animal and other farm buildings, milk rooms, motels, restaurants, food processing plants, industrial and commercial locations, kennels, garbage storage areas and containers, and similar enclosed spaces.
  • Restriction of domestic pest strips to structures that are continuously unoccupied for a minimum of 4 months (for example, cottages closed for the winter).

For Commercial-class products:

  • For use with automatic application equipment only and a 4-day restricted-entry interval with full ventilation for greenhouse potted ornamentals, tobacco storage, animal buildings, food processing plants, industrial plants, warehouses, and theaters.
  • Restriction on amount handled per day for tobacco storage, food processing plants, industrial plants, warehouses, and theaters (limited to 1.14 kg a.i./day).
  • Additional required label statements (see Appendix X of PRVD2017-16, Dichlorvos and Its Associated End-use Products for Proposed Label Amendments for Products Containing Dichlorvos)

The following uses pose risks of concern to human health and do not meet Health Canada’s current standards for human health protection. As a result, these uses are proposed to be cancelled:

  • greenhouse tomato and cucumber, and greenhouse ornamentals (excluding greenhouse potted ornamentals),
  • outdoor mosquito control,
  • outdoor residential living areas, and
  • indoor pest strips (excluding areas that are unoccupied for a minimum of 4 months).

The use in mushroom houses was not supported by dichlorvos registrants, and was not included in PRVD2017-16. Therefore, this use is proposed to be removed from the product labels.

Residue Definition for Enforcement:

  • The current residue definition for dichlorvos is dichlorvos per se for enforcement purposes. No change to the residue definition for enforcement purposes is being proposed. Dichlorvos is a metabolite and degradation product of naled, a registered pesticide. For risk assessment purposes, dichlorvos from all sources, including dichlorvos resulting from the use of naled were considered. In addition, since dietary exposures from naled and dichlorvos can co-occur and since they have a common toxic effect (cholinesterase inhibition), a risk assessment from combined exposures to both dichlorvos and naled was conducted.


To protect the environment, the following proposed risk mitigation measures are required:

  • Hazard statements on the label to inform the user that dichlorvos is toxic to pollinators, beneficial arthropods, birds, mammals, and aquatic organisms. For uses where pollinator and beneficial arthropod species could be exposed, label statements must advise to avoid application during periods of bloom, and when bees and other beneficial insects are used in greenhouses. In addition, during the phase-out of the use of mosquito fogging, or should this use remain registered after public consultation, statements indicating that applying during cooler hours of the night and early morning reduces exposure to foraging bees and beneficial insects are required.
  • A label statement to inform the user to not discharge dichlorvos-contaminated effluent from greenhouses into aquatic environments.
  • Label statements informing users of ways to reduce the potential for runoff will be required.

International Context

Dichlorvos is currently acceptable for use in other Organisation for Economic Co-operation and Development (OECD) member countries, including the United States. Dichlorvos is under registration review by the United States’ Environmental Protection Agency.

Due to health and environmental concerns, dichlorvos is no longer approved for sale or use in plant protection products in the European Union as per European Commission regulation 1100/2009.

Next Steps

The public including the registrants and stakeholders are encouraged to submit additional information that could be used to refine risk assessments during the 90-day public consultation period upon publication of PRVD2017-16.

All comments received during the 90-day public consultation period will be taken into consideration in preparation of re-evaluation decision document, which could result in revised risk mitigation measures. The re-evaluation decision document will include the final re-evaluation decision, the reasons for it and a summary of comments received on the proposed re-evaluation decision with the PMRA’s responses.

Additional Scientific Information

The science evaluation of dichlorvos considered chemical/scenario specific information for many uses provided by the registrants and stakeholders through consultations. Therefore, no additional data are required at this time. However, certain areas of the occupational and/or residential exposure and risk assessment relied on the current label information only. Therefore, additional information in these areas may further refine the occupational and/or residential exposure and risk assessment, which in turn, could potentially result in maintaining certain uses that are proposed for cancellation.

For greenhouse cucumber, tomato, and/or greenhouse cut flower ornamentals:

  • Additional use information on how and when dichlorvos is used in greenhouses
  • Depending on how this information impacts the risk assessment, chemical-specific dislodgeable foliar residue data in greenhouses and air monitoring data in greenhouses may also be useful for further refinement.

For outdoor mosquito control and outdoor residential living areas:

  • To refine the handler assessment, use pattern information (that is, amount treated per day to potentially refine area treated per day in the handler assessment)
  • Depending on how this information impacts the risk assessment, chemical-specific passive dosimetry study or biological monitoring with acceptable human pharmacokinetic data for applicators may also be useful for further refinement.
  • To refine the postapplication exposure assessment, chemical-specific air monitoring data and transferable residue data.
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