Evaluation Report ERC2011-05, Veridian 0.33G and Veridian 25WG containing Thiamethoxam

This content was archived on June 24, 2013.

Pest Management Regulatory Agency
11 July 2011
ISSN: 1911-8082 (PDF version)
Catalogue number: H113-26/2011-5E-PDF (PDF version)

Summary

Table of Contents

• 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
• What Additional Scientific Information Is Being Requested?
• Other Information

Registration Decision for Thiamethoxam

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the  Pest Control Products Act and  Regulations, has granted conditional registration for the sale and use of Thiamethoxam Technical, Veridian 0.33G and Veridian 25WG, containing the technical grade active ingredient thiamethoxam, to control European chafer, Japanese beetle, black turfgrass ataenius and masked chafer on turf.

An evaluation of available scientific information found that, under the approved conditions of use, the products have value and do not present an unacceptable risk to human health or the environment.

Although the risks and value have been found acceptable when all risk reduction measures are followed, the applicant must submit additional scientific information as a condition of registration.

This summary describes the key points of the evaluation, while the Science Evaluation of Evaluation Report ERC2011-05, Veridian 0.33G and Veridian 25WG containing Thiamethoxam provides detailed technical information on the human health, environmental and value assessments of Thiamethoxam Technical, Veridian 0.33G and Veridian 25WG.

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

What Is Thiamethoxam?

Thiamethoxam is a systemic insecticide belonging to the neonicotinoid class of compounds. Thiamethoxam moves through the translocation system of the plant, and affects insects by both contact and ingestion exposure. It interferes with the insect's central nervous system causing tremors, loss of coordination, irreversible cessation of feeding and eventual death. It is effective against all insect life stages except eggs. Veridian 0.33G and Veridian 25WG are applied as foliar broadcast sprays to turf, for control of larvae of European chafer, Japanese beetle, black turfgrass ataenius and masked chafer.

Health Considerations

Can Approved Uses of Thiamethoxam Affect Human Health?

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

When assessing health risks, two key factors are considered:

• 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 those uses for which exposure is well below levels that cause no effects in animal testing are considered acceptable for registration.

Thiamethoxam was of moderate toxicity following oral ingestion. Thiamethoxam was not found to be genotoxic. Thiamethoxam did not cause cancer in rats, but did produce tumours in mice. However, the process of tumour formation in the mouse is not expected to occur in humans under typical exposure conditions. Other health effects in animals included effects in the liver, kidneys and nervous system. The risk assessment protects against these effects by ensuring that the level of human exposure is well below the lowest dose at which these effects occurred in test animals.

When thiamethoxam was given to pregnant animals, effects on the offspring were observed at doses that did not have health effects in the mother, indicating that the young were more sensitive to thiamethoxam than the adult animal. Consequently, extra protective measures were applied in the risk assessment to further reduce the allowable level of human exposure to thiamethoxam.

Veridian 0.33G is considered to be of low toxicity to rats via the oral and inhalation routes, and is of low toxicity to rabbits via the dermal route. It is minimally irritating to the eyes and non-irritating to the skin of rabbits. It is considered to be a dermal sensitizer in guinea pigs.

Veridian 25WG is considered to be of low toxicity to rats via the oral and inhalation routes, and is of low toxicity to rabbits via the dermal route. It is mildly irritating to the eyes and slightly irritating to the skin of rabbits. It is not considered to be a dermal sensitizer to guinea pigs.

Risks in Residential and Other Non-Occupational Environments

Bystander risks are not of concern if label directions and precautionary measures are followed.

Adults, youth and children may come in contact with thiamethoxam residues on skin or through non-dietary (incidental) oral ingestion by entering freshly treated commercial, recreational or residential lawns (up to one month). Potential exposure and risks to these individuals are not of concern if label directions and precautionary measures are followed.

Occupational Risks From Handling Veridian 0.33G and Veridian 25WG

Occupational risks are not of concern when the productsare used according to the label directions, which include precautionary measures.

Commercial applicators and lawn care operators who mix, load and/or apply Veridian 25WG or Veridian 0.33G,as well as workers re-entering freshly treated lawns may come in direct contact with thiamethoxamresidues on the skin and by inhalation, intermittently for up to six months. Because there is a concern with users coming into direct contact with thiamethoxam residues on the skin or through inhalation, risk reduction measures such as specifying personal protective equipment and interval for re-entering treated areas are required on the Veridian 25WG and Veridian 0.33G labels. Taking into consideration these precautionary measures, a single application per year and the expected exposure period for workers, the risks to these individuals are not a concern.

Environmental Considerations

What Happens When Thiamethoxam Is Introduced Into the Environment?

Environmental risk from thiamethoxam can be minimized when used according to label directions.

Thiamethoxam enters the environment when used on turf for control of insect pests as either a granule or foliar spray. Thiamethoxam is persistent in the environment with the main route of transformation in the terrestrial environment being in soil. Thiamethoxam is not expected to volatilize, however, it is expected to leach.

The only major transformation product identified in the terrestrial field dissipation studies was clothianidin. Clothianidin is a registered insecticide in its own right. Clothianidin is persistent in the environment with the main route of transformation in the terrestrial environment being in soil. Clothianidin is not expected to volatilize; however, it is expected to leach.

Although the use pattern of this product does not include direct application to water, the possibility that aquatic systems will be exposed to thiamethoxam and its major transformation products, directly or indirectly, cannot be ruled out. Thiamethoxam can enter the aquatic environment through spray drift and runoff from treated turf. In aquatic systems, thiamethoxam transforms quickly via aerobic biotransformation to two transformation products. Further discussion regarding these transformation products occurs in the Science Evaluation of this document. The transformation product clothianidin is slightly persistent in the aquatic environment.

The risk to the environment was assessed for thiamethoxam and the thiamethoxam end-use products Veridian 0.33G and Veridian 25WG. The screening level risk assessment identified the potential risks to bees, terrestrial plants and aquatic invertebrates. Exposure to bees from turf application is expected to be lower than currently registered products containing thiamethoxam. Additional characterization of exposure to bees from drift to adjacent habitats resulted in negligible risk from contact exposure and less risk from oral ingestion. To help mitigate for potential toxicity, precautionary label statements are required. Further characterization of the risk to terrestrial plants and aquatic invertebrates from off field spray deposition indicated that no-spray buffer zones of one metre are required to protect sensitive habitats downwind of the site of application.

Value Considerations

What Is the Value of Veridian 0.33G and Veridian 25WG?

Veridian 0.33G and Veridian 25WG control larvae of four insect species that infest turf in Canada.

A single application of Veridian 0.33G and Veridian 25WG can control larvae of European chafer, Japanese beetle, black turfgrass ataenius and masked chafer on turf. Use of this insecticide is compatible with current management practices, especially if users monitor pest populations and make applications during the period of peak egg-laying.

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 Veridian 0.33G and Veridian 25WG to address the potential risks identified in this assessment are as follows.

Key Risk-Reduction Measures

Human Health

Mixers and loaders must wear a long-sleeved shirt, long pants, chemical resistant gloves, socks and boots. Applicators must wear a long-sleeved shirt, long pants, socks and boots. Workers must not enter treated areas within the first 12 hours after application.

Mixers, loaders, and applicators of Veridian 0.33G must also wear a suitable dust mask approved by NIOSH/MSHA. Veridian 0.33G must not be applied by hand.

Environment

Hazard statements are required for aquatic organisms and bees. Appropriate precautionary measures are also required to address risk to bees.

A no-spray buffer zone of one metre is required for aquatic habitats to mitigate risk of spray drift of Veridian 25WG to aquatic organisms. A no-spray buffer zone of 1 metre is also required to mitigate the potential risk of spray drift of Veridian 25WG to terrestrial plants.

What Additional Scientific Information Is Being Requested?

Although the risks and value have been found acceptable when all risk-reduction measures are followed, the applicant must submit additional scientific information as a condition of registration. More details are presented in the Science Evaluation of of Evaluation Report ERC2011-05, Veridian 0.33G and Veridian 25WG containing Thiamethoxam or in the section 12 Notice associated with these conditional registrations. The applicant must submit the following information by September 1, 2013.

Environment

• A field dissipation study with thiamethoxam applied to turf.
• A new hive study with thiamethoxam.

Other Information

As these conditional registrations relate to a decision on which the public must be consulted, the PMRA will publish a consultation document when there is a proposed decision on applications to convert the conditional registrations to full registrations or on applications to renew the conditional registrations, whichever occurs first.

The test data cited in of Evaluation Report ERC2011-05, Veridian 0.33G and Veridian 25WG containing Thiamethoxam (i.e. the test data relevant in supporting the registration decision) will be made available for public inspection when the decision is made to convert the conditional registrations to full registrations or to renew the conditional registrations (following public consultation). If more information is required, please contact the PMRA's Pest Management Information Service.