Proposed Registration Decision PRD2016-02, Sulfoxaflor
Pest Management Regulatory Agency
January 26, 2016
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2016-2E-PDF (PDF version)
This page is a summary of the consultation document. If you would like to comment, please request the full consultation document.
To obtain a full copy of Proposed Registration Decision PRD2016-02, Sulfoxaflor please contact our publications office.
Should you require further information please contact the Pest Management Information Service.
Table of Contents
Proposed Registration Decision for Sulfoxaflor
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 Isoclast Active and Rascendo, containing the technical grade active ingredient sulfoxaflor, as seed treatment to control flea beetles on oilseeds (canola, rapeseed and oilseed mustard).
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.
Isoclast Active (Registration Number 30824) is currently registered in Canada for use in other foliar applied end-use products to control or suppress aphids, leafhoppers, San Jose scale and Lygus bug on field vegetable, cereal grain, oilseed, fruit and nut crops. The detailed review for the foliar use can be found in the Proposed Registration Decision PRD2015-08, Sulfoxaflor and Registration Decision RD2015-09, Sulfoxaflor.
This summary describes the key points of the evaluation, while the Science Evaluation of Proposed Registration Decision PRD2016-02, Sulfoxaflor provides detailed technical information on the human health, environmental and value assessments of Isoclast Active and Rascendo.
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. 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:
Before making a final registration decision on sulfoxaflor, the PMRA will consider any comments received from the public in response to Proposed Registration Decision PRD2016-02, Sulfoxaflor. The PMRA will then publish a Registration Decision on sulfoxaflor, 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 PRD2016-02, Sulfoxaflor.
What Is Sulfoxaflor?
Sulfoxaflor is an insecticide that causes excitation of insect nerves. This active ingredient can be formulated into products that provide control or suppression of a variety of sucking insects on field vegetables, cereal grains, oilseeds and fruit and nut crops when sprayed on the foliage, or applied as a seed treatment in combination with thiamethoxam or clothianidin to provide control of flea beetles on canola, rapeseed and oilseed mustard.
Can Approved Uses of Sulfoxaflor Affect Human Health?
Rascendo, containing sulfoxaflor, is unlikely to affect your health when used according to label directions.
Potential exposure to sulfoxaflor may occur through the diet or when handling and applying the end-use 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.
In laboratory animals, sulfoxaflor was demonstrated to be of slight to moderate toxicity via the oral route; therefore, the signal word and hazard statement “WARNING – POISON” are required on the label. Sulfoxaflor was demonstrated to be of low toxicity via the dermal and inhalation routes. It was minimally irritating to eyes and skin, and did not cause an allergic skin reaction.
The end-use product, Rascendo, containing sulfoxaflor, was of low acute toxicity by the oral, dermal and inhalation routes of exposure, was minimally irritating to the eyes and non-irritating to the skin, and did not cause an allergic skin reaction. Based on these findings, no acute hazard labelling is required.
Registrant-supplied short-term and long-term (lifetime) animal toxicity tests, as well as information from the published scientific literature were assessed for the potential of sulfoxaflor to cause neurotoxicity, immunotoxicity, chronic toxicity, cancer, reproductive and developmental toxicity, and various other effects. The most sensitive endpoints used for risk assessment included reduced survival in the developing young, as well as reduced activity and effects on the testes in adult animals. There was an indication that the young animal was more sensitive than the adult animal. The risk assessment protects against these and any other potential effects by ensuring that the level of exposure to humans is well below the lowest dose at which these effects occurred in animal tests.
Residues in Drinking Water and Food
Dietary risks from food and drinking water are not of health concern.
Aggregate chronic dietary intake estimates (food plus drinking water) for the general population and all population subgroups (except for the females 13-49 years old) revealed that infants, the subpopulation which would ingest the most sulfoxaflor relative to body weight, is expected to be exposed to less than 86% of the acceptable daily intake (ADI). Based on these estimates, the chronic dietary risk from sulfoxaflor is not of health concern for all subpopulations. There are no lifetime cancer risks of concern from the use of sulfoxaflor.
Aggregate acute dietary intake estimates (food plus drinking water) for the general population and all population subgroups (except for the females 13-49 years old) were less than 24% of the acute reference dose (ARfD), and are not of health concern. The highest exposed subpopulation was infants less than one year old.
For females 13-49 years old, the ARfD and the ADI for sulfoxaflor from exposure to metabolite X11719474 residues in drinking water (no sulfoxaflor present in drinking water sources) is different from the ARfD/ADI from exposure to sulfoxaflor residues in food, hence aggregate dietary intake estimates (food plus drinking water) were not conducted. For females 13-49 years old, the chronic dietary risks from food are less than 9% of the ADI and, the chronic dietary risks from drinking water are less than 20% of the ADI. For this subgroup, the acute dietary risks from food and drinking water are 117% and 6.6% of the ARfD, respectively.
A single dose of sulfoxaflor is not likely to cause acute health effects to any population subgroup (including infants and children) in light of the conservatisms inherent in the risk assessment (for example, assumed maximum rates, maximum number of applications, and shortest preharvest interval).
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.
Residue trials conducted throughout Canada and the United States using sulfoxaflor on treated canola seeds are acceptable. The MRL for this active ingredient has been established for Rapeseed Crop Subgroup 20A (CSG 20A) based on data generated following foliar application of canola. The seed treatment use of sulfoxaflor on canola, rapeseed, and oilseed mustard is not expected to result in residues exceeding the established MRL.
Occupational Risks From Handling Rascendo
Occupational risks are not of concern when Rascendo is used according to the label directions, which include protective measures.
Commercial facility seed treaters who mix, load, treat, or bag, sew, or stack bags of treated seeds, as well as farmers planting seeds treated with Rascendo can come in direct contact with sulfoxaflor residues on the skin. Therefore, the label specifies that anyone mixing, loading, and treating seeds with Rascendo must wear chemical-resistant coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, work boots and socks. Baggers, sewers, stackers, forklift operators and others handling treated seed, including planters, must wear cotton coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, work boots and socks. Cleaners must wear chemical-resistant coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, chemical-resistant footwear and socks.Taking into consideration these label statements, the risks to seed treatment workers and farmers are not a concern.
For bystanders, exposure is expected to be much less than that for workers. Therefore, health risks to bystanders are not of concern.
What Happens When Sulfoxaflor Is Introduced Into the Environment?
When used according to label directions, sulfoxaflor is not expected to pose an unacceptable risk to the environment.
Sulfoxaflor enters the environment when used as Rascendo for use on canola, rapeseed and oilseed mustard (Brassica spp.) seeds. A risk assessment was conducted considering all seed treatment exposure routes. A risk assessment of potential exposure pathways through foliar application was conducted previously (PRD2015-08).
Sulfoxaflor is rapidly broken down by microbes in the soil. Sulfoxaflor transformation products that are formed in soil are persistent and have the potential to leach through the soil profile and enter groundwater. When sulfoxaflor enters surface water, it also breaks down in the presence of microbes, albeit more slowly than in soil. Sulfoxaflor and its transformation products are not expected to be found in air. Sulfoxaflor is a systemic insecticide and can move from the seed through the plant. Residues in or on canola flowers, pollen and nectar were not detected in plants when seeds were treated with sulfoxaflor.
Sulfoxaflor is toxic to bees; however, based on residue studies in canola flowers, exposure to bees through treated seed is not a concern. Transformation products of sulfoxaflor are persistent in the environment but are not toxic to bees. Therefore, when used according to label directions as a seed treatment, risk to bees is not a concern. Risks to birds and wild mammals were identified and are expected to be mitigated through label statements which instruct users to cover seeds exposed on the surface of the soil following planting.
What Is the Value of Rascendo?
Rascendo, when applied as a seed treatment in combination with thiamethoxam or clothianidin, controls flea beetles in canola, rapeseed and oilseed mustard in regions where species composition of the flea beetle population has changed.
Flea beetles are early season pests of canola, rapeseed and oilseed mustard and are predominately controlled using seed treatments, though foliar insecticides are also available. In Western Canada, the crucifer flea beetle has historically been the dominant species; however, the flea beetle species composition has been shifting to include more striped flea beetles, which are less susceptible to thiamethoxam and clothianidin seed treatments. Sulfoxaflor cannot be used as a stand-alone seed treatment to control flea beetles; however when used on canola, rapeseed, or oilseed mustard, the combination of sulfoxaflor and thiamethoxam or clothianidin as a seed treatment is expected to improve control of flea beetles where species composition has been shifting.
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 Rascendo to address the potential risks identified in this assessment are as follows.
Key Risk-Reduction Measures
As there is a concern with users coming in direct contact with Rascendo on the skin or through inhalation of dust, anyone mixing, loading, and treating seeds with Rascendo must wear chemical-resistant coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, work boots and socks. Baggers, sewers, stackers, forklift operators and others handling treated seed, including planters, must wear cotton coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, work boots and socks. Cleaners must wear chemical-resistant coveralls over a long-sleeved shirt and long pants, chemical-resistant gloves, chemical-resistant footwear and socks. In addition, standard label statements to protect against drift during planting are on the label.
Sulfoxaflor product labels inform the user of the leaching potential of sulfoxaflor transformation products. Label instructions will direct the user to cover seeds that have been left exposed following planting to mitigate the potential for exposure to birds and mammals.
Before making a final registration decision on sulfoxaflor, the PMRA will consider any comments received from the public in response to Proposed Registration Decision PRD2016-02, Sulfoxaflor. The PMRA will accept written comments on PRD2016-02, Sulfoxaflor up to 45 days from the date of publication of PRD2016-02. 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.
When the PMRA makes its registration decision, it will publish a Registration Decision on sulfoxaflor (based on the Science Evaluation of Proposed Registration Decision PRD2016-02, Sulfoxaflor). In addition, the test data referenced in PRD2016-02 will be available for public inspection, upon application, in the PMRA’s Reading Room (located in Ottawa).
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