Proposed Registration Decision PRD2023-03, 1‑Aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator, Accede SG Plant Growth Regulator

Pest Management Regulatory Agency
21 March 2023
ISSN: 1925-0886 (PDF version)
Catalogue number: H113-9/2023-3E-PDF (PDF version)

Summary

Table of contents

• Proposed registration decision for 1-Aminocyclopropanecarboxylic acid
• What does Health Canada consider when making a registration decision?
• What is 1-aminocyclopropanecarboxylic acid?
• Health considerations
• Environmental considerations
• Value considerations
• Measures to minimize risk
• Next steps
• Science evaluation

Proposed registration decision for 1-Aminocyclopropanecarboxylic acid

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 ACC Technical Powder, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, containing the technical grade active ingredient 1-aminocyclopropanecarboxylic acid, for commercial fruit tree thinning for apple trees.

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 provides detailed technical information on the human health, environmental and value assessments of 1-aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator.

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 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 on how the Health Canada regulates pesticides, the assessment process and risk-reduction programs, please visit the Pesticides portion of Canada.ca.

Before making a final registration decision on 1-aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, 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 1-aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, 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 this consultation document.

What is 1-aminocyclopropanecarboxylic acid?

1-Aminocyclopropanecarboxylic acid is a naturally occurring amino acid found in many higher plants. It is a potent plant growth regulator and is a precursor for ethylene production in plant tissues. Ethylene affects plant processes such as flower development, fruit set, fruit maturation, fruit ripening, and fruit abscission.

Health considerations

Can approved uses of 1-aminocyclopropanecarboxylic acid affect human health?

1-Aminocyclopropanecarboxylic acid is unlikely to affect your health when used according to label directions.

Potential exposure to 1-aminocyclopropanecarboxylic acid may occur through the diet (food and water) or when handling or applying the 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 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 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.

In laboratory animals, 1-aminocyclopropanecarboxylic acid was of low acute toxicity by the oral, dermal and inhalation routes, minimally irritating to the eyes, slightly irritating to the skin, and not a dermal sensitizer.

Short-term oral and dermal toxicity, prenatal developmental toxicity, reproductive toxicity, and genotoxicity/mutagenicity testing of 1-aminocyclopropanecarboxylic acid was also assessed. Animals given repeated high doses of 1-aminocyclopropanecarboxylic acid in the diet or dermally did not exhibit treatment-related adverse effects. There was no indication that the young were more sensitive than the adult animals. 1-Aminocyclopropanecarboxylic acid is not considered to be genotoxic.

In laboratory animals, the end-use product, VBC-30452 SG Plant Growth Regulator, was of low toxicity by the oral, dermal and inhalation routes, non-irritating to the eye and skin, and not a dermal sensitizer. The toxicological profile of Accede SG Plant Growth Regulator is the same as the toxicological profile of VBC-30452 SG Plant Growth Regulator. The labels for VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator also require a milk allergen warning statement.

The risk assessment protects against the findings noted above as well as any other potential effects by ensuring that the level of human exposure is well below the lowest dose at which these effects occur in animal studies.

Residues in water and food

Dietary risks from food and water are acceptable.

1-Aminocyclopropanecarboxylic acid is a plant amino acid and is the direct precursor in the biosynthesis of ethylene (a plant hormone regulating a variety of plant developmental processes) in plant tissues. Humans are exposed to 1-aminocyclopropanecarboxylic acid through fruit and vegetable consumption. Due to its low toxicity profile and the proposed use pattern (applied only twice per season and before mature fruit have formed), 1-aminocyclopropanecarboxylic acid present in VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator is not expected to pose a health risk when the end-use products are applied as directed by the label. In addition, the likelihood of residues of 1-aminocyclopropanecarboxylic acid in drinking water will be very low. 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 acceptable.

VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator are commercial products for use in apple orchards and there are no residential uses proposed. In the interest of promoting best management practices, the labels have a standard spray drift statement to protect against drift to residential areas.

Residential and non-occupational exposure to VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator is expected to be low when label directions are followed Consequently, the risk to residents and the general public is acceptable.

Occupational risks from handling VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator

Occupational risks are acceptable when VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator are used according to the label directions, which include protective measures.

Workers handling VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator can come into direct contact with 1-aminocyclopropanecarboxylic acid through inhalation and contact with skin during mixing, loading, application, clean-up and repair. Eye exposure is also possible, but expected to be minimal. To limit worker exposure to VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, the proposed labels require workers to wear a long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes during mixing, loading, application, clean-up and repair.

The labels also require that workers not enter treated areas for twelve (12) hours after application.

The occupational risks are acceptable when the label directions are followed.

Environmental considerations

What happens when 1-aminocyclopropanecarboxylic acid is introduced into the environment?

1-Aminocyclopropanecarboxylic acid can enter the environment when VBC-30452 SG Plant Growth Regulator or Accede SG Plant Growth Regulator are applied to apples for fruit thinning and enhanced return bloom. 1-Aminocyclopropanecarboxylic acid is a naturally occurring non-protein amino acid produced by many plants and microorganisms. It is non-persistent in the environment as it is rapidly transformed in higher plants and microbes. 1-Aminocyclopropanecarboxylic acid is not bound tightly to soil following application. It is not expected to accumulate in organisms.

1-Aminocyclopropanecarboxylic acid does not exhibit toxicity to most terrestrial or aquatic organisms. However, as a plant growth regulator, 1-aminocyclopropanecarboxylic acid may pose risks to algae and non-target terrestrial plants. Precautionary label statements to inform users of the toxicity to non-target aquatic and terrestrial plants and spray buffer zones to reduce exposure to aquatic and terrestrial habitats will be required to mitigate these risks. When 1-aminocyclopropanecarboxylic acid is used in accordance with the label and required precautions, the resulting environmental risk is considered to be acceptable.

Value considerations

What is the value of VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator?

VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator are proposed for use in apple orchards for the purposes of fruit thinning and enhanced return bloom.

The registration of VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator will provide apple growers with a new active ingredient and end-use products for the purposes of fruit thinning and enhanced return bloom.

VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator provide effective thinning of apple fruitlets measuring up to 18-20 mm at the time of application, which is a later stage than for currently available fruit thinners. Fruitlet thinning is important in order to increase apple size, ensure more consistent blooming in the following year (return bloom) and to help maintain harvest size from year to year.

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 ACC Technical Powder, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator to address the potential risks identified in this assessment are as follows.

Key risk-reduction measures - Human Health

• The allergen warning statement "WARNING: Contains the allergen milk" is required on the principal display panel of the label for VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator.
• To protect workers from exposure to VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, workers must wear long-sleeved shirt, long pants, chemical-resistant gloves, socks and shoes during mixing, loading, application, clean-up and repair.
• There is a restricted-entry interval of twelve (12) hours.
• A standard precautionary drift statement is present to mitigate exposure to residential areas.

Key risk-reduction measures - Environment

• Label statements to indicate toxicity to non-target terrestrial and aquatic plants
• Spray buffer zones to protect sensitive terrestrial and aquatic habitats

Next steps

Before making a final registration decision on 1-aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator, Health Canada's PMRA will consider any comments received from the public in response to PRD2023-03. Health Canada will accept written comments on this proposal up to 45 days from the date of publication of PRD2023-03. 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 1-aminocyclopropanecarboxylic acid, VBC-30452 SG Plant Growth Regulator and Accede SG Plant Growth Regulator (based on the Science Evaluation of this consultation document). 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.