Evaluation Report ERC2012-01, Sedaxane

Pest Management Regulatory Agency
2 October 2012
ISSN: 1911-8082 (PDF version)
Catalogue number: H113-26/2012-1E-PDF (PDF version)

Summary

Table of Contents

• Registration Decision for Sedaxane
• What Does Health Canada Consider When Making a Registration Decision?
• What Is Sedaxane?
• Health Considerations
• Environmental Considerations
• Value Considerations
• Measures to Minimize Risk
• What Additional Scientific Information Is Being Requested?
• Other Information

Registration Decision for Sedaxane

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 Sedaxane Technical and A17511B Seed Treatment, containing sedaxane, difenconazole, metalaxyl-m and thiamethoxam, A16874F Seed Treatment, containing sedaxane, difenconazole and metalaxyl-m, and Sedaxane 500FS Fungicide, containing the technical grade active ingredient sedaxane, for use on seed from various crops including certain cereals (barley, wheat, oats, rye, and triticale), canola, and soybean to control or suppress soil and seed-borne diseases of seedlings and mature plants. A17511B Seed Treatment also contains an insecticide to suppress/control wireworm activity on certain cereal crops.

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.

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 ERC2012-01, Sedaxane provides detailed technical information on the human health, environmental and value assessments of Sedaxane Technical, A17511B Seed Treatment, A16874F Seed Treatment and Sedaxane 500FS Fungicide.

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 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 Sedaxane?

Sedaxane is the active ingredient present in three new seed treatment products: Sedaxane 500FS Fungicide (containing sedaxane), A17511B Seed Treatment (containing sedaxane, difenoconazole, metalaxyl-m, thiamethoxam) and A16874F Seed Treatment (containing sedaxane, difenoconazole, metalaxyl-m). Sedaxane is a preventative seed treatment with systemic properties that inhibits the normal respiration process in target pathogenic fungi. The new sedaxane-based products are intended for use on seed from various crops including certain cereals (barley, wheat, oats, rye, and triticale), canola, and soybean to control or suppress soil and seed-borne diseases of seedlings and mature plants. A17511B Seed Treatment also contains an insecticide (thiamethoxam) to suppress/control wireworm activity on certain cereal crops.

Health Considerations

Can Approved Uses of Sedaxane Affect Human Health?

Products containing sedaxane are unlikely to affect your health when used according to label directions.

Potential exposure to sedaxane may occur through the diet (food and water), when handling and applying the product or when entering treated sites. 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, the active ingredient sedaxane and its associated end-use products, A17511B Seed Treatment, A16874F Seed Treatment and Sedaxane 500FS Fungicide, were of low acute toxicity by the oral, dermal and inhalation routes of exposure. They were minimally irritating to the eyes and non-irritating to the skin, and did not cause allergic skin reactions. Consequently, no hazard signal words are required on the labels.

Health effects in animals given repeated doses of the active ingredient sedaxane included effects on the liver, endocrine organs and circulatory system. Sedaxane did not cause birth defects in animals. When sedaxane was given to pregnant or nursing animals, effects on the developing fetus (a slight increase in abortions) and juvenile animal (decreased spleen weight) were observed at doses that were toxic to the mother, indicating that the young do not appear to be more sensitive to sedaxane than the adult animal. Sedaxane caused functional effects, possibly related to the nervous system, at high doses in rats. There was no evidence that sedaxane damaged genetic material but it did, however, cause liver tumours in mice and liver, thyroid and uterine tumours in rats. A cancer risk assessment was conducted based on the uterine tumours found in rats as this was protective of the other tumour types.

The risk assessment protects against the effects of sedaxane by ensuring that the level of human exposure is well below the lowest dose at which these effects occurred in animal tests.

Residues in Water and Food

Dietary risks from food and water are not of concern.

Aggregate dietary intake estimates (food plus water) revealed that the general population and infants, the subpopulation which would ingest the most sedaxane relative to body weight, are expected to be exposed to less than 0.9% of the acceptable daily intake. Based on these estimates, the chronic dietary risk from sedaxane is not of concern for all population sub-groups. The lifetime cancer risk from the use of sedaxane is considered acceptable (5.9 × 10-7).

The acute aggregate (food and water) dietary intake estimate for each population subgroup ranged from 0.06% to 0.37% of the reference dose, which is not a health concern.

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 in the United States and Canada using sedaxane on barley, canola, soybean and wheat were acceptable. The MRLs for this active ingredient can be found in the Science Evaluation of Evaluation Report ERC2012-01, Sedaxane and in the Evaluation Reports under Application Numbers 2010-1525, 2010-1526, 2010-1527 and 2010-1529.

Occupational Risks From Handling Sedaxane 500FS Fungicide, A17511B Seed Treatment and A16874F Seed Treatment

Occupational risks are not of concern when Sedaxane 500FS Fungicide, A17511B Seed Treatment and A16874F Seed Treatment are used according to the proposed label directions, which include protective measures.

Workers treating seed with Sedaxane 500FS Fungicide, A17511B Seed Treatment or A16874F Seed Treatment in commercial seed treatment facilities, workers treating seed on-farm and workers planting treated seed can come into direct contact with sedaxane residues on the skin. Therefore, the label specifies that workers treating and handling treated seed must wear the following personal protective equipment (PPE). In commercial seed treatment facilities, workers treating, bagging, sewing, stacking, and forklifting treated seed must wear cotton coveralls over a long-sleeved shirt and long pants and chemical-resistant gloves. In addition, workers cleaning treatment equipment in commercial seed treatment facilities must wear chemical-resistant coveralls over a long-sleeved shirt and long pants and chemical-resistant gloves. Workers treating on-farm and/or planting treated seed must wear a long-sleeved shirt, long pants and chemical-resistant gloves. For good hygiene purposes, it is also recommended for workers to wear a NIOSH approved dust mask during all job activities. Closed transfer is required for treating cereal seeds in commercial seed treatment facilities. Taking into consideration these label statements, the number of applications and the expectation of the exposure period for handlers and workers, the risk to these individuals is 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 Sedaxane Is Introduced Into the Environment?

When sedaxane is introduced into the environment as a seed treatment for canola and cereal grains it will adsorb to soil or be taken up into growing plants.

Based on the physical, chemical properties of sedaxane and environmental fate data, limited movement in soil is expected and leaching into groundwater or runoff into surface water is not predicted. Although birds and mammals may be exposed to sedaxane if they feed on treated seed, a risk assessment has shown that sedaxane poses practically no risk to birds or mammals even if a high amount of treated seed is ingested. Although Sedaxane is moderately to highly toxic to aquatic organisms, when sedaxane is used as a seed treatment limited exposure to the aquatic environment is expected.

Value Considerations

What Is the Value of Sedaxane 500FS Fungicide, A17511B Seed Treatment, and A16874F Seed Treatment?

Sedaxane 500FS Fungicide, A17511B Seed Treatment, and A16874F Seed Treatment are preventative seed treatments effective in the control or suppression of seed and soil-borne diseases in crops.

Sedaxane 500FS Fungicide, A17511B Seed Treatment, and A16874F Seed Treatment provide effective solutions to manage commercially important diseases such as rots (seed, root, crown, and foot), seedling blights, damping-off, seed-borne septoria, smuts, bunts and take-all. The multiple modes of fungicidal action found in A17511B Seed Treatment, and A16874F Seed Treatment provide benefits in terms of disease resistance management along with increased spectrum of disease protection. Moreover, because of recommended tank-mixes on all of the three products' labels and the insecticidal active ingredient in A17511B Seed Treatment, these three products provide options for simultaneous management of certain insect pests and fungal diseases.

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 on the labels of A17511B Seed Treatment, A16874F Seed Treatment and Sedaxane 500FS Fungicide to address the potential risks identified in this assessment are as follows.

Key Risk-Reduction Measures

Human Health

Because there is a concern with users coming into direct contact with Sedaxane 500FS Fungicide, A17511B Seed Treatment and A16874F Seed Treatment on the skin or through inhalation of spray mists and dust, the label specifies that workers treating seed and handling treated seed must wear the following PPE. In commercial seed treatment facilities, workers treating, bagging, sewing, stacking, and forklifting treated seed must wear cotton coveralls over a long-sleeved shirt and long pants and chemical-resistant gloves. In addition, workers cleaning treatment equipment in commercial seed treatment facilities must wear chemical-resistant coveralls over a long-sleeved shirt and long pants and chemical-resistant gloves. Workers treating on-farm and/or planting treated seed must wear a long-sleeved shirt, long pants and chemical-resistant gloves. For good hygiene purposes, it is also recommended for workers to wear a NIOSH approved dust mask during all job activities. Closed transfer is required for treating cereal seeds in commercial seed treatment facilities.

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 Evaluation Report ERC2012-01, Sedaxane or in the Section 12 Notice associated with these conditional registrations. The applicant must submit the following information within the time frames indicated.

Human Health

• DACO 4.3.6 - Short-term inhalation toxicity study in rats.
• DACO 4.5.1, 4.8 - Low and mid-dose assessments of ovarian follicle counts in the 2-generation reproductive toxicity study in rats.
• The final freezer storage stability study reports for sedaxane metabolites in crop commodities up to 24 months (Report T014683-05-REG), and for sedaxane residues in processed commodities up to 12 months (Report KP-2009-02) are required to support the maximum storage intervals of samples from the magnitude of the residues studies.

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 Evaluation Report ERC2012-01, Sedaxane (for example, 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.