Proposed Registration Decision PRD2022-06, Potassium chloride and Potash Molluscicide

• Pest Management Regulatory Agency
• 13 April 2022
• ISSN: 1925-0886 (PDF version)
• Catalogue number: H113-9/2022-6E-PDF (PDF version)

Summary

Table of contents

• Proposed registration decision for potassium chloride
• What does Health Canada consider when making a registration decision?
• What is potassium chloride?
• Health considerations
• Environmental considerations
• Value considerations
• Measures to minimize risk
• Next steps
• Other information

Proposed registration decision for potassium chloride

Health Canada's Pest Management Regulatory Agency (PMRA), under the authority of the Pest Control Products Act, is proposing registration for the sale and use of Potassium Chloride Technical and Potash Molluscicide, containing the technical grade active ingredient potassium chloride, for control of zebra and quagga mussels in water reservoirs and other water bodies as well as in water pipelines and closed systems, including fire suppression systems in hydroelectric plants.

An evaluation of available scientific information found that, under the approved conditions of use, the health and environmental risks and the value of the pest control products are acceptable.

This Overview describes the key points of the evaluation, while the Science Evaluation of Proposed Registration Decision PRD2022-06, Potassium chloride and Potash Molluscicide provides detailed technical information on the human health, environmental and value assessments of potassium chloride and Potash Molluscicide.

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^{Footnote 1} 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^{Footnote 2} 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:

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

Before making a final registration decision on potassium chloride and Potash Molluscicide, Health Canada's PMRA will consider any comments received from the public in response to this consultation document.^{Footnote 3} Health Canada will then publish a Registration Decision^{Footnote 4} on potassium chloride and Potash Molluscicide, which will include the decision, the reasons for it, a summary of comments received on the proposed registration decision and Health Canada's response to these comments.

For more details on the information presented in this Overview, please refer to the Science Evaluation of PRD2022-06.

What is potassium chloride?

Potassium chloride is a new active ingredient for the control of invasive zebra and quagga mussels in certain bodies of water and certain closed systems, including agricultural irrigation pipelines and hydroelectric plants. It releases potassium ions into the water, which interferes with valve closure and respiration and reduces filtration rate, resulting in the mortality of the target mussel species.

Health considerations

Can approved uses of potassium chloride affect human health?

Potassium Chloride is unlikely to affect human health when it is used according to label directions.

Potential exposure to potassium chloride may occur when handling and applying the product Potash Molluscicide, as well as during typical occupational activities following application. 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 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 at which no effects are observed.

Potassium Chloride Technical is considered to be of low acute toxicity by the oral route. No data are available on the acute dermal or inhalation toxicity, but based on the low octanol/water partition coefficient and low vapour pressure of potassium chloride, it can be assumed that the salt will be poorly absorbed across the skin and be non-volatile. Based on the information from the material safety data sheet (MSDS), potassium chloride may cause eye, skin, and respiratory tract irritation by mechanical means, and it is not likely a dermal sensitizer.

Based on the weight-of-evidence of the available data for potassium chloride, which is a common salt form of potassium, and taking into consideration the history of use of potassium chloride in the human diet and in pharmaceuticals, the low toxicity profile of potassium chloride, and the anticipated limited human exposure based on the proposed use patterns, no short-term toxicity, developmental toxicity, genotoxicity, or other adverse effects are anticipated for potassium chloride.

Potash Molluscicide is a repack of Potassium Chloride Technical; therefore, the toxicological profile of Potash Molluscicide is identical to that of Potassium Chloride Technical.

Residues in water and food

Dietary risks from food and water are not of concern.

Potash Molluscicide is not proposed for food or feed use, and its application to water bodies, water reservoirs, pipelines or closed systems populated by zebra and quagga mussels is not expected to exceed the natural background levels of potassium and chloride following treatment. Dietary risk from food and drinking water is therefore expected to be negligible and not of concern. Consequently, health risks are acceptable for all segments of the population, including infants, children, adults and seniors.

Risks in residential and other non-occupational environments

Estimated risk for residential and other non-occupational exposure is not of concern.

There are no residential uses for Potash Molluscicide. Non-occupational exposure to individuals coming into contact with Potash Molluscicide during handling and application is not expected to result in unacceptable risk when Potash Molluscicide is used according to label directions.

The end-use product label will include measures to minimize bystander exposure, such as a spray drift statement and a statement to notify the public that certain bodies of water are closed for recreation, fishing, and commercial activities for ten days after the last treatment of Potash Molluscicide by using signs and other markers.

Occupational risks from handling Potash Molluscicide

Occupational risks are acceptable when Potash Molluscicide is used according to the label directions, which include protective measures.

Potash Molluscicide is to be used only by a certified applicator for control of mussels. Occupational exposure to Potash Molluscicide is expected to be short-term and predominantly by the inhalation, dermal, and ocular routes when workers are exposed to the dust from handling the end-use product for pre-mixing. Exposure to mixed solution is also possible by the dermal and ocular routes during storage, transportation, and preparatory work for the treatment.

Potential exposure to Potash Molluscicide can be reduced by following precautionary statements on the label, the use of appropriate personal protective equipment (PPE), and by following general occupational hygiene practices.

The occupational risks are acceptable when the precautionary statements on the label are observed.

Environmental considerations

What happens when potassium chloride is introduced into the environment?

When used according to label directions, environmental risks associated with potassium chloride and its end-use product, Potash Molluscicide, are acceptable.

Potassium chloride can enter the environment when Potash Molluscicide is used to control invasive zebra and quagga mussels in water related infrastructure (including irrigation systems), closed loop fire suppression systems, reservoirs and water bodies. Potassium chloride is a naturally occurring salt that is highly soluble in water. It is commonly found in the environment and is widely used as a fertilizer.

The use of potassium chloride and its end-use product, Potash Molluscicide, is restricted and is only permitted where zebra and/or quagga mussels have been confirmed to occur. The establishment of invasive mussels presents a high threat to aquatic ecosystems. While there is a risk to non-target aquatic organisms from the use of potassium chloride to control invasive mussels, the PMRA recognizes that control of invasive species is necessary in order to help protect habitats for native species. When used according to label directions, Potash Molluscicide will have the desired effect of controlling zebra and quagga mussels that pose a risk to aquatic habitats.

Value considerations

What is the value of Potash Molluscicide?

Potash Molluscicide can be used to control zebra and quagga mussels, which are damaging invasive species and biofouling agents that are spreading across Canada.

The registration of Potash Molluscicide is intended to provide a means to manage or control invasive zebra and quagga mussels throughout Canada.

Potash Molluscicide can provide effective control of invasive zebra and quagga mussels.

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 labels of Potassium Chloride Technical and Potash Molluscicide to address the potential risks identified in this assessment are as follows.

Key risk-reduction measures

Human health

The applicant-proposed hazard signal words "CAUTION – EYE IRRITANT" are present on the technical grade active ingredient label and the end-use product label. In addition, standard hazard and precautionary statements are required on both the labels to inform workers of the potential for irritation to eye, skin, and respiratory tract.

The PPE requirements on the end-use product label instruct personnel to wear goggles or a face shield, chemical-resistant gloves, long-sleeved shirt, long pants, shoes, and socks during handling, mixing/loading, clean-up or repair of equipment, and additionally, a NIOSH-approved N95 (minimum) filtering facepiece respirator (dust mask) while handling Potash Molluscicide in its solid form.

The end-use product label instructs that the public be notified that certain bodies of water are closed for recreation, fishing, and commercial activities for ten days after the last treatment of Potash Molluscicide by using signs and other markers.

Standard precautionary drift statements are required to mitigate bystander exposure.

Environment

• This product will be classified as restricted. The product can be used only by licensed pesticide applicators under appropriate federal or provincial authorizations.
• Precautionary label statement to inform users of the toxicity of potassium chloride to aquatic organisms.
• A label requirement to confirm the presence of zebra and/or quagga mussels prior to use.

Next steps

Before making a final registration decision on potassium chloride and Potash Molluscicide, Health Canada's PMRA will consider any comments received from the public in response to PRD2022-06. Health Canada will accept written comments on PRD2022-06 up to 45 days from the date of publication of this document. Please forward all comments to Publications. Health Canada will then publish a Registration Decision, which will include its decision, the reasons for it, a summary of comments received on the proposed decision and Health Canada's response to these comments.

Other information

When the Health Canada makes its registration decision, it will publish a Registration Decision on potassium chloride and Potash Molluscicide (based on the Science Evaluation of PRD2022-06). In addition, the test data referenced in this consultation document will be available for public inspection, upon application, in the PMRA's Reading Room. For more information, please contact the PMRA's Pest Management Information Service.