Proposed Registration Decision PRD2018-13, Thiamethoxam and Mainspring X Insecticide

Pest Management Regulatory Agency
15 August 2018
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2018-13E-PDF (PDF version)

Summary

Table of Contents

• Background
• Re-evaluation and Special Review of Thiamethoxam
• Proposed Registration Decision for Thiamethoxam
• What Does Health Canada Consider When Making a Registration Decision?
• What Is Thiamethoxam?
• Health Considerations
• Environmental Considerations
• Value Considerations
• Measures to Minimize Risk
• Conclusion
• Next Steps

Background

Thiamethoxam Technical (Reg. No. 26665) is fully registered in Canada for use in gel bait insecticides for ant control (USC^{Footnote 1} 20, Structures). Other uses of Thiamethoxam Technical, and its associated end-use products, are conditionally registered in Canada for use as seed treatments, foliar and soil applications^{Footnote 2}. In 2013, the major new use of greenhouse non-food crops (USC 6) was added to Thiamethoxam Technical (Reg. No. 26665), with conditions of registration required under section 12 of the the Pest Control Products Act. The end-use product associated with this use is Mainspring X Insecticide (Reg. No. 30901). The additional information for Mainspring X Insecticide has now been received and reviewed under an application to fulfil the conditions of registration, and consultation on this major new use is required, following the procedure under the former conditional registration regulations^{Footnote 3} .

List of Data Previously Required as a Condition of Registration under section 12 for Mainspring X Insecticide

DACO: 8.5
Title: Fate of thiamethoxam and the transformation product clothianidin in plants, including concentrations in nectar and pollen.
Required data: A study which determines the concentration of thiamethoxam and clothianidin in nectar and pollen of plants (plant fate study).

DACO: 9.2.4.3
Title: Hive Study (field)
Required data: The new study must follow currently accepted guidelines and address concerns regarding toxicity of thiamethoxam and the transformation.

For the outcome of the review of the information provided to fulfil the above conditions of registration, refer to Section 4.2.1 of Proposed Registration Decision PRD2018-13, Thiamethoxam and Mainspring X Insecticide.

The end-use product, Mainspring X Insecticide, contains both thiamethoxam and cyantraniliprole in equal proportions. For further information on cyantraniliprole, please consult the Proposed Registration Decision PRD2013-09, Cyantraniliprole and Regulatory Decision RD2013-25, Cyantraniliprole.

Re-evaluation and Special Review of Thiamethoxam

The re-evaluation of thiamethoxam to assess risks to pollinators was announced in 2012 (Re-evaluation Note REV2012-02, Re-evaluation of Neonicotinoid Insecticides). This re-evaluation was initiated to assess the potential risk to pollinators in light of international updates to the pollinator risk assessment framework, including information requirements. Data obtained from published literature as well as data received from the registrants, including the information (DACOs 8.5 and 9.2.4.3) that were required to fulfil the conditions of registration under section 12, were considered in the re-evaluation assessment.

In addition, the PMRA announced in 2016 the initiation of a special review to evaluate the impact of thiamethoxam on aquatic invertebrates (Re-evaluation Note REV2016-17, Initiation of Special Reviews: Potential Environmental Risk to Aquatic Invertebrates Related to the Use of Clothianidin and Thiamethoxam).

Health Canada has conducted an assessment of pollinator risk for thiamethoxam, as well as a special review to evaluate the impact of thiamethoxam on aquatic invertebrates. A Proposed Re-evaluation Decision and a Proposed Special Review Decision have been published:

• PRVD2017-24, Thiamethoxam and Its Associated End-use Products: Pollinator Re-Evaluation, summarizes the science evaluation with regards to the potential risks posed by thiamethoxam to pollinators in Canada, as well as proposes strategies to reduce the risks to these pollinators.
• PSRD2018-02, Special Review of Thiamethoxam Risk to Aquatic Invertebrates: Proposed Decision for Consultation, summarizes the science evaluation with regards to the potential risks posed by thiamethoxam to aquatic invertebrates in Canada, as well as proposes strategies to reduce the risks to these organisms.

The use pattern of Mainspring X Insecticide is affected by these re-evaluation and special review proposals, and as a result, some uses are currently proposed for cancellation. The continued registration of Mainspring X Insecticide and of USC 6 of thiamethoxam technical active ingredient will be subject to the outcomes of the final decisions pertaining to the re-evaluation and special review of thiamethoxam.

Proposed Registration Decision for Thiamethoxam

With respect to greenhouse non-food crops uses of thiamethoxam, under the authority of section 8 of the Pest Control Products Act, the PMRA is proposing a three-year registration for the sale and use of the technical grade active ingredient thiamethoxam and the end-use product Mainspring X Insecticide. PRD2018-13 is carried under 28(1)(a) of the Pest Control Products Act.

An evaluation of available scientific information found that the product has value and presents an acceptable risk to human health and the environment, when used according to the proposed conditions of registration, which include amendments to the label. To address potential risks to pollinators and aquatic invertebrates, some uses are currently proposed for cancellation and amendments to the registration of the end-use product have been proposed. The continued registration of Mainspring X Insecticide will be subject to the outcomes of the final decisions pertaining to the re-evaluation and special review of thiamethoxam.

Before making a final registration decision on Thiamethoxam and Mainspring X Insecticide, Health Canada will consider any comments received from the public in response to PRD2018-13^{Footnote 4}. Health Canada will then publish a Registration Decision^{Footnote 5} on Thiamethoxam and Mainspring X Insecticide, which will include the decision, the reasons for it, a summary of comments received on the proposed registration decision and Heath Canada’s response to these comments. In addition, the confidential test data referenced in PRD2018-13 will be available for public inspection, upon application, in the PMRA’s Reading Room (located in Ottawa).

This Summary describes the key points of the evaluation of thiamethoxam on the original use pattern approved for USC 6, while the Science Evaluation of PRD2018-13 and tables in Appendix I of PRD2018-13 provide detailed technical information on the human health, environmental and value assessments of Thiamethoxam Technical and Mainspring X Insecticide. Health Canada is consulting the public under 28(1)(a) of the Pest Control Products Act for the major new use of Greenhouse non-food crops. For more details on the information presented in this Summary, please refer to the Science Evaluation of PRD2018-13.

Validity period of conditional registrations

In order to complete the consultations, the validity period of Mainspring X Insecticide has been extended until 31 December 2020. This extension is also applicable to the USC 6 of Thiamethoxam Technical (Reg. No. 26665). This extension was granted under 14(7)^{Footnote 6} of the former Pest Control Products Regulations, to carry out the consultation on the proposed registration decisions with respect to this product.

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^{Footnote 7}. The Act also requires that products have value^{Footnote 8} when used according to the label directions. Conditions of registration may include special precautionary measures on the product label to further reduce risk. When special review or re-evaluation decisions affect the registration of a product, the effective date of the amendment or cancellation may also be delayed as long as there is no suitable alternative and the risk is acceptable during that time period^{Footnote 9}.

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:

• Protecting Your Health and the Environment
• Pesticide Registration Process
• Pesticide Risk Reduction Program

What Is Thiamethoxam?

Thiamethoxam is one of the active ingredients in the commercial class product Mainspring X Insecticide. Mainspring X Insecticide is applied as a foliar spray or as a soil drench, and controls or suppresses listed insect pests of greenhouse ornamentals. Thiamethoxam moves through the leaf surface and the translocation system of the plant, affecting the insects through contact and ingestion. Mainspring X Insecticide also contains the active ingredient cyantraniliprole, which is a Mode of Action Group 28 insecticide.

Health Considerations

Can Approved Uses of Thiamethoxam Affect Human Health?

Mainspring X Insecticide, containing thiamethoxam, is unlikely to affect your health when used according to label directions.

Potential exposure to thiamethoxam may occur through the diet (food and water) or when handling and applying the products. 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 using pesticide-containing products according to label directions.

In laboratory animals, the technical grade active ingredient thiamethoxam was moderately acutely toxic via the oral route and of low toxicity via the dermal and inhalation routes of exposure. It was minimally irritating to eyes, non-irritating to skin, and it did not cause an allergic skin reaction. Based on these findings, the signal word and hazard statement “WARNING POISON” are required on the label.

Mainspring X Insecticide was of low acute toxicity via the oral, dermal, and inhalation routes of exposure. It was minimally irritating to the eyes, non-irritating to the skin, and did not cause an allergic skin reaction.

Health effects in animals given repeat doses of thiamethoxam over long periods of time included effects on the liver, kidneys, testes and nervous system. There was no evidence to suggest that thiamethoxam damaged genetic material, and it did not cause cancer in rats. Thiamethoxam did produce liver tumours in mice; however, the process of tumour formation is not expected to occur in humans due to differences in metabolism. In animal reproductive toxicity tests, adverse effects on the sperm and testes of offspring were observed at dose levels that did not have health effects in the mother, indicating that the young were more sensitive to thiamethoxam than the adult animal. In additional studies in which pregnant animals were given thiamethoxam, reduced brain weight and changes in brain measurements were observed in offspring at dose levels which produced minimal effects on the mother, again suggesting sensitivity of the young. The risk assessment protects against the effects of thiamethoxam 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 Mainspring X Insecticide

Occupational risks are not of concern when Mainspring X Insecticide is used according to the proposed label directions, which include protective measures.

Workers who mix and load Mainspring X Insecticide and apply as a foliar or soil treatment and workers re-entering treated greenhouses and nurseries can come in direct contact with thiamethoxam residues on the skin and/or through inhalation. Therefore, the label specifies that anyone mixing and loading thiamethoxam must wear a long-sleeved shirt, long pants, chemical-resistant gloves, socks and boots and safety glasses or goggles, and when applying, workers must wear a long-sleeved shirt, long pants, socks and boots. Chemical-resistant gloves must also be worn when applying this product using hand-held equipment. Taking into consideration these label statements, precautionary measures, and the exposure duration for handlers, it was determined that the risks to these individuals are 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 Happens When Thiamethoxam Is Introduced into the Environment?

The risks to pollinators from greenhouse uses of thiamethoxam have not been shown to be acceptable for bee attractive plants that will be planted outside. As such, mitigation, including cancellation of some uses, has been proposed. The risk to aquatic invertebrates from greenhouse uses of thiamethoxam have been shown to be acceptable, with appropriate mitigation measures restricting the discharge of wastewater into aquatic habitats.

Information for fate and ecotoxicity of thiamethoxam can be found under PRVD2017-24 (Thiamethoxam and Its Associated End-use Products: Pollinator Re-evaluation), PSRD2018-02, (Special Review of Thiamethoxam Risk to Aquatic Invertebrates: Proposed Decision for Consultation) and ERC2007-01 (Thiamethoxam), which include relevant tables.

The end-use product, Mainspring X Insecticide, containing thiamethoxam was conditionally registered for greenhouse non-food crops (such as ornamentals). Although most non-target outdoor terrestrial organisms are not expected to be exposed to thiamethoxam from a greenhouse use, there is potential exposure for pollinators and other beneficial arthropods. For pollinators, there is potential exposure when plants are treated in the greenhouse, and bees are used in greenhouse production. There is also potential for oral exposure to bees if bee attractive plants are treated with thiamethoxam in the greenhouse and then planted outside, since residues may remain in pollen and/or nectar. For other beneficial arthropods, the main route of exposure would be for insects that are used in greenhouse production. Thus, potential risk from Mainspring X Insecticide for these exposure scenarios was assessed.

The PMRA recently completed a re-evaluation of the potential risks posed by thiamethoxam to pollinators (PRVD2017-24). That re-evaluation was conducted considering the current use pattern for thiamethoxam (including Mainspring X insecticide) and current risk assessment methods. Therefore, throughout this consultation document, the potential effects and proposed mitigation for pollinators will reference PRVD2017-24. In addition, information related to the toxicity of thiamethoxam to other beneficial arthropods will reference ERC2007-01.

Thiamethoxam presents a potential risk to bees and other beneficial insects. Please refer to the most recent assessment (in PRVD2017-24) of the potential risk to pollinators from use of Mainspring X Insecticide, and proposed mitigation. Mitigation for greenhouse use, including cancellation of some uses where bee-attractive crops will be planted outdoors, has been proposed in PRVD2017-24. For other beneficial arthropods, in order to inform users of the potential risk, label statements are required on the label.

Although there is some potential for exposure to aquatic organisms from greenhouse effluent, appropriate mitigation measures restricting the discharge of wastewater into aquatic habitats would mitigate the potential risk (PSRD2018-02).

Value Considerations

What Is the Value of Mainspring X Insecticide?

Mainspring X Insecticide controls or suppresses a variety of insect pests of greenhouse ornamentals.

Mainspring X Insecticide controls or suppresses aphids, mealybugs, soft scales and whiteflies when applied to the foliage of greenhouse ornamentals. When applied as a soil drench to greenhouse ornamentals, it targets these pests, as well as dipteran leafminers and thrips. These insects are widespread pests in the greenhouse ornamental industry. Thiamethoxam represents a new mode of action for use against dipteran leafminers, mealybugs and thrips on greenhouse ornamentals. Therefore, Mainspring X Insecticide aids in resistance management of these crop-pest combinations and is a new management tool for use on greenhouse ornamentals.

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.

Key Risk-Reduction Measures

Human Health

As workers could come into direct contact with thiamethoxam on the skin or through inhalation of spray mists, anyone mixing and loading thiamethoxam and performing cleaning and repair activities must wear a long-sleeved shirt, long pants, chemical-resistant gloves, socks, boots and safety glasses or goggles. During application, workers must wear long-sleeved shirt, long pants, socks and boots. Chemical-resistant gloves must also be worn when applying this product using hand-held equipment. Foliar application of Mainspring X Insecticide to greenhouse cut flowers is not permitted.

Environment

As a result of the pollinator re-evaluation of thiamethoxam and the special review on aquatic invertebrates, further risk mitigation measures for product labels are being proposed. See the documents below for more information^{Footnote 10}.

• Measures to Protect Pollinators, as found in PRVD2017-24, Thiamethoxam and Its Associated End-Use Products: Pollinator Re-Evaluation.
• Measures to Protect Aquatic Invertebrates, as found in PSRD2018-02, Special Review of Thiamethoxam Risk to Aquatic Invertebrates: Proposed Decision for Consultation.

The risk-reduction measures and other conditions of registration being proposed as a result of the re-evaluation review of the risk to pollinators and of the special review will apply to the end-use product Mainspring X Insecticide. For other beneficial arthropods used in greenhouse production, in order to inform users of the potential risk, label statements are required on the label.

Conclusion

The conditions of registration relating to the submission of additional information required under section 12 of the Pest Control Products Act for thiamethoxam and Mainspring X Insecticide have been met. To address potential risks to pollinators and aquatic invertebrates, amendments to the registrations of the end-use products have been proposed, including cancellation of some uses.

Health Canada’s PMRA, under the authority of section 8 of the Pest Control Products Act, is proposing a three-year registration for the sale and use of Thiamethoxam Technical (Reg. No. 27445) and the end-use product Mainspring X Insecticide (Reg. No. 30901). The continued registration of USC 6 of thiamethoxam is subject to the final outcome of the special review on aquatic invertebrates, and of the final decision on the pollinator re-evaluation.

Next Steps

Before making a final registration decision on Thiamethoxam and Mainspring X Insecticide, Health Canada will consider any comments received from the public in response to PRD2018-13. Health Canada will accept written comments on PRD2018-13 up to 90 days from the date of its publication. Please forward all comments to Publications. Health Canada will then publish a Registration Decision on Thiamethoxam and Mainspring X Insecticide, which will include its decision, the reasons for it, a summary of comments received on the proposed decision and Heath Canada’s response to these comments.

In addition, the confidential test data referenced in PRD2018-13 will be available for public inspection, upon application, in the PMRA’s Reading Room (located in Ottawa).