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Response to comments received on the PMRL consultation for proposed new and revised maximum residue limits for metalaxyl (PMRL2021-13)

Health Canada's Pest Management Regulatory Agency
30 April 2024

Table of contents

Background

An application was submitted by Syngenta Canada Inc. under submission number 2019-0782, to add caneberries (crop subgroup 13-07A); bushberries, except lowbush blueberries (crop subgroup 13-07B); low growing berries, except cranberries and lingonberries (crop subgroup 13-07G); and tree nuts (crop group 14-11), to the product label of ORONDIS GOLD Fungicide (PCP# 33508), for the control or suppression of phytopthora diseases on these crops. These uses will provide two modes of action to manage phytopthora diseases, which may contribute to reducing the risk of pathogen resistance development (see Value Section). Revisions to several maximum residue limits (MRLs) for metalaxyl were proposed in PMRL2021-13 as a result of these applications to support a change in the timing of application for raspberries, as well as the addition of low growing berries (crop subgroup 13-07G) to the Canadian label (see Amending MRLs Section).

Approximately 1000 comments were received from the general public, growers/users, health professionals, academia, the pesticide industry, and non-governmental organizations on the proposed maximum residue limit consultation document PMRL2021-13 for the requested metalaxyl uses.

Many comments opposed the presence and/or increase of any pesticide residues in food and questioned the definition of acceptable risk and the use of the precautionary principle. There were also questions as to why MRLs differed for the same commodity in different countries, as well as why pesticide regulatory systems differed between various countries and jurisdictions, such as that of the European Union and the United States. Comments were also received regarding the use of industry generated data and public access to these studies, transparency of the consultation process, cumulative risks, the toxic effects including the carcinogenic potential of metalaxyl and risks to vulnerable populations. Comments received on the topics discussed in this section are addressed in this document.

Comments were also received related to effects on the environment. The environmental risks of metalaxyl on various berries and tree nuts were assessed under this submission (2019-0782) and determined to be acceptable and consistent with those previously evaluated under RVD2008-03. Comments, including any scientific information, related to the environment are not addressed in this document but, as relevant, will be considered following finalization of the PMRA's new Proposed Policy on Continuous Oversight of Pesticides, PRO2024-01.

While these comments do not result in changes to the MRLs proposed in this consultation document, they do highlight the importance of providing further explanation on Canada's pesticide regulatory system, how MRLs are determined and the purpose of setting them.

Health Canada's responsibility in pesticide regulation

Health Canada's priority is to protect the health and safety of Canadians, the environment and the food supply. This includes setting the conditions for approval of each specific pesticide use in Canada, including the levels of pesticide residues that may be present in food commodities grown in Canada or that may be imported into the country. These conditions are set based on Health Canada's independent review of scientific data. The role of Health Canada's Pest Management Regulatory Agency (PMRA) is to help make sure that the amount of residues that may be present in or on food commodities grown or imported to Canada does not pose a human health concern to any segment of the Canadian population including infants and toddlers, pregnant and nursing mothers, and the elderly.

While Health Canada has the authority to register pesticides, municipalities and provinces/territories have the authority to further impose restrictions on the use of pesticides that have been approved at the federal level by the PMRA.

For more information on the activities of Health Canada's Pest Management Regulatory Agency, you are invited to refer to the Pest Management Regulatory Agency Annual Report.

Health Canada's comprehensive regulatory framework for pesticides

Because of the toxic nature of pesticides, the federal government has a comprehensive regulatory framework in place to prevent unacceptable risks to the health of Canadians and the environment from the use of pesticides. The Pest Control Products Act sets out very clear requirements for the assessment and regulation of pesticides in Canada, including the requirement that regulatory decisions about pesticides must be based on science.

There are nearly 400 scientists at Health Canada's PMRA conducting health and environmental risk assessments. These scientists are Canadians with families and children, who expect the same level of protection from harm as every person in Canada. The purpose of these risk assessments is to put in place the conditions of use for each pesticide product so that the levels at which Canadians are exposed do not cause any harmful effects and also meet protection goals for the environment. Only products that can be used safely are approved for use in Canada.

Regulatory decisions are based on the review of hundreds, sometimes thousands, of scientific studies that have been conducted according to internationally-approved study protocols and Good Laboratory Practices (GLP). The studies required to complete a registration application include those that describe possible short- and long-term effects, how a pesticide can be absorbed and broken down in the body, what happens to it in the environment, and what effect it has on non-target organisms. Health Canada scientists examine and critically review the study methodology and raw data for all available studies to assess the validity of the study conclusions. Scientists compare various studies available for each pesticide looking for consistencies and inconsistencies between results and conclusions. They also compare available information on a pesticide with others that are similar or belong to the same class of pesticides, and examine peer-reviewed academic research available in the public domain. If a study does not meet the requirements, it is not considered acceptable for risk assessment purposes. Health Canada scientists do not accept studies of poor quality claiming something is either safe or causes harm, especially when high-quality science contradicts those findings.

Value

Phytophthora species parasitize a wide range of agricultural, ornamental, and forest plants and are ubiquitous in soil and water throughout the world. Based on the value information, it can be expected that Orondis Gold Fungicide, the end-use product registered in Canada that contains the active ingredient metalaxyl-m (resolved isomer of metalaxyl), will manage these phytopthora diseases on caneberries (CSG 13-07A), bushberries (CSG 13-07B), certain low-growing berries, and certain tree nuts. Additionally, Orondis Gold Fungicide will provide two modes of action to manage these diseases, which may contribute to reducing the risk of pathogen resistance development.

Maximum residue limit

A pesticide maximum residue limit (MRL) is the highest amount of pesticide residue that may remain on or in food when a pesticide is used according to label directions. Health Canada is responsible for establishing science-based MRLs on food commodities grown domestically or imported into Canada to help ensure the food Canadians eat is safe. The MRL for each pesticide-crop combination is set at levels well below the amount that could pose a health concern. An MRL can be set on individual crops or on crop groups. For more details, refer to the Maximum residue limits, human health, and food safety page on Canada.ca.

Pesticide residues in or on food commodities

Pesticides are used on food commodities grown using conventional and organic practices to maintain food quality or prevent damage caused by pests, including insects, weeds, and fungal diseases. This helps ensure Canada has a secure supply of healthy food.

Pesticide residues are small amounts of conventional or organic pesticides that may stay in or on food. Residues are measured in parts per million (or ppm). One part per million is equal to a single granule of sugar in 273 cubes of sugar (or 1 granule in one million granules). Therefore, 1 or even 50 ppm of residue on a food commodity from a pesticide is exceedingly small.

Pesticide residues can get in or on our food when:

Pesticide residues also break down over time, so by the time the food reaches the market there can be very small amounts of pesticide residues left in or on food. Typically, the amount of pesticide residue in or on a food or crop is lower than the MRL set for that specific combination of pesticide and food or crop. The Canadian Food Inspection Agency, which is responsible for monitoring MRLs for chemical residues on food has consistently reported a high degree of overall compliance of about 97% in their annual reports (National Chemical Residue Monitoring Program and Chemistry Food Safety Oversight Program Annual Report 2020 to 2021). Nevertheless, Health Canada must be satisfied that the amount of residue that could be present in or on a food commodity, once a crop has been treated with a pesticide according to label instructions, is not a health concern.

Calculating a maximum residue limit

Health Canada calculates an MRL using the Organisation for Economic Co-operation and Development (OECD) MRL Calculator, a statistical method that is used internationally. The MRL represents the highest residue that could remain on a particular crop at harvest when the pesticide is used according to the approved label directions. An MRL is not a measure of the toxicity of a pesticide. It is a scientifically-based calculation that estimates the maximum potential amount of residue on food commodities. Studies called field trials are used for this purpose. These studies are conducted according to how a particular pesticide is proposed to be used for a specific crop or commodity. If Health Canada determines that the residue from consuming the food commodity is not a health concern, these field trial data are then used to calculate the MRL. Health Canada establishes MRLs only when there are no health risks of concern to consumers.

MRLs can be established on crop groups as well as on individual crops. A crop group includes crops that have similar features (physical characteristics of the crop), growth habits, and have the same part of the crop that is edible. Crop groupings allow for residue data on a "representative crop" to be used as a surrogate (or proxy) for other crops within the same crop group when the label directions are the same for all crops.

Often, the residues that remain are much lower under typical use conditions. If the use directions change for a given pesticide, the MRL can also change. However, before any change to an MRL is proposed, the risks must meet Health Canada's requirements for the protection of human health.

MRLs are an important aspect of food safety, but exceedances do not automatically mean a food safety concern. This is because an MRL reflects the maximum residue that may be found on a crop based on how a pesticide is applied to that crop; MRLs are not the maximum safe limit. If a pesticide is used differently, the residue may be higher and therefore the MRL may increase, but the health risk can still be acceptable.

Anyone can request a maximum residue limit

As per the Pest Control Products Act (section 10(2)), any person may submit an application to Health Canada to set an MRL. For the pesticides that will be used in Canada, the PMRA requires that the use of the pesticide product on that food commodity is supported by the manufacturer.

For example, an application can come from:

Applicants must submit a full data package including scientific studies that fulfill each of the data requirements to address health risks in support of an MRL application.

Amending maximum residue limits

Section 7(1) of the Pest Control Products Act requires that an application be made to the Minister to amend a product's registration, including changing the conditions related to its label. Section 9 of the Pest Control Products Act states that when making a decision regarding the registration of a pest control product, the Minister shall, if necessary, specify any maximum residue limits for the product or for its components or derivatives that the Minister considers appropriate in the circumstances. Accordingly, an application was received from Syngenta Canada Inc. to change the application timing for raspberries (spring application versus the registered fall application) and to add a use on lowbush blueberries as a member of crop subgroup 13-07G (low growing berries) of which strawberries is the representative crop. The established MRL on lowbush blueberries is based on field trial data for highbush blueberries.

Amending an existing, approved use of a pesticide may, at times, require amending an existing MRL for that particular use as well. MRLs are routinely amended as agricultural practices change in Canada and internationally. If an MRL increases, it does not mean that human health protection decreases. As previously noted, MRLs are a function of how a pesticide is used and not a measurement of pesticide toxicity or safety. Also, if an import MRL increases, it does not mean that a Canadian grower can use more pesticide on their crops, as the use directions and conditions of use indicated on the Canadian registered label must be adhered to at all times and is a legal requirement.

Situations that could lead to an application to amend the established MRL include:

Maximum residue limit differences between countries

To the extent possible, and only when there are no health concerns, Health Canada will align MRLs with those of other countries as part of Canada's international treaty obligations to facilitate trade. However, MRLs may vary from one country to another for a number of reasons, including differences in how the pesticide is used on a particular crop in various countries and the geographical locations of the crop field trials that are used to analyze and measure residue data on these crops.

With respect to metalaxyl, a difference in the residue definition (in other words, components of a pesticide that are analyzed by the Canadian Food Inspection Agency to enforce MRLs) between different regulatory bodies resulted in differences in MRLs between Canada and the United States. In Canada, the residue definition for metalaxyl in food commodities is metalaxyl including metabolites that can be converted to the 2,6-dimethylaniline moiety (expressed as metalaxyl equivalents) while in the United States, the residue definition is metalaxyl only. There are currently no Codex MRLs established for residues of metalaxyl in or on caneberries, bushberries, or tree nuts.

Health Canada's mandate is to determine if risks are acceptable with the proposed MRLs, and if Health Canada's standards are met, MRLs may be specified. Mechanisms are also in place to help minimise potential trade impacts when differences in MRLs between countries occur.

Enforcing maximum residue limits

MRLs are legal limits that are specified under the Pest Control Products Act and enforced by the Canadian Food Inspection Agency (CFIA). The latest National Chemical Residue Monitoring Program and Chemistry Food Safety report that uses MRLs to determine compliance rates can be requested on the Food safety testing reports and journal articles page on Canada.ca.

Every year, the CFIA tests over 15 000 domestically-produced and imported food samples for pesticide residues. Each sample can include monitoring for more than 450 different pesticides, including metalaxyl, generating more than 6 million pesticide residue monitoring results.

The most recent testing (2020-21 CFIA annual report) shows that 93.8% of imported foods and 99.2% of domestically-produced foods meet the established MRL. If the CFIA finds a food with residues greater than the MRL (or the default level of 0.1 ppm when no specific MRL is established), appropriate regulatory action is taken (see the Maximum residue limit exceedance does not mean there is a human health risk Section).

Maximum residue limit exceedance does not mean there is a human health risk

MRLs are used for monitoring purposes to help ensure the safety of Canada's food supply. When Good Agricultural Practices are followed, including the use of pesticides according to the approved label directions/conditions, residues in foods should comply with MRLs. However, an exceedance of an MRL, does not automatically mean there is a health risk of concern. That said, when a pesticide residue level exceeds the MRL, follow-up actions for non-compliant products are initiated by CFIA in a manner that reflects the magnitude of the potential health concern. Actions may include further analysis, notification to the producer or importer, follow-up inspections, additional directed sampling, a health risk assessment of MRL exceedances by Health Canada, and recall of products.

Understanding acceptable risk

Before approving the registration of a pesticide for a specific use or allowing the importation of a pesticide-treated food, Health Canada thoroughly assesses the risks to human health to make sure that the level of human exposure, when used according to the label directions, is well below the level that would be of health concern. Only pesticides for which health risks are shown to be acceptable are approved.

To do this assessment, Health Canada combines scientific information on pesticide toxicity with information on the degree and duration of dietary exposure to the pesticide residue from food. The risk assessment process involves four distinct steps:

  1. Identifying the toxicology hazards of a pesticide
  2. Determining the "acceptable dietary level" for Canadians (including all vulnerable populations), that is protective of adverse health effects, by setting the acceptable level at least 100-fold below the level where no effects are observed in animal studies;
  3. Estimating how much of a pesticide people may be exposed to in their diet from all possible sources (domestic and imported commodities), based on how much residue remains in or on the food and the amount of treated food an individual may consume; and
  4. Characterizing human risk by comparing the estimated dietary exposure to the acceptable dietary level set in Step 2.

If estimated human exposure from Step 3 is less than, or equal to the acceptable level (developed in Step 2), Health Canada concludes that consuming residues resulting from use according to approved label directions is not a health concern. This quantity of residue is then subject to consultation to legally specify it as an MRL. If risks to human health from the consumption of treated food are not shown to be acceptable, the pesticide product will not be permitted for sale or use in Canada, and an MRL (or import MRL) will not be established.

An MRL applies to the identified raw agricultural food commodity as well as to any processed food product that contains that commodity. On occasion, and depending on the characteristics of a given pesticide, a different MRL may be specified for a processed product made from that raw agricultural commodity (for example, corn versus corn oil).

As previously noted under the Calculating a maximum residue limit section, Health Canada establishes MRLs only when there are no health risks of concern to consumers; in other words, the risks are shown to be acceptable. This approach is consistent with the international approach to health risk assessment and is considered protective, as exposure to pesticide residues in the diet must be below levels that could pose a health concern.

Understanding toxicity testing of pesticides

Health Canada scientists use the four-step scientific risk assessment process (described in the Understanding acceptable risk section) to protect human health. The process is accepted by scientists and organizations across the world. The first step is referred to as hazard identification and is described on the Pesticide assessments in Canada: Human health risk page, as well as in more detail below. The goal of this process is to understand the toxicity of a pesticide, and the extent of human exposure based on how the product will be used, so that Health Canada can specify the conditions for safe use for the product label so that human exposure is well below the level that could cause harm.

The registration of a new pesticide is a multi-year process that involves evaluation of the results from a robust dataset of studies that include in vitro and in vivo toxicology studies. These studies assess the potential of the pesticide to cause effects following exposure to various doses, via multiple routes (in other words, oral, dermal and inhalation, where relevant) and for different periods of time. The suite of toxicology studies that are provided to Health Canada for evaluation includes studies that are designed to assess the potential for a pesticide to cause specific health effects, such as effects on reproduction and development over one or more generations, cancer, and effects on the nervous and endocrine systems, among other effects. Studies on how pesticides are broken down or act in the body are also examined. The results of all of these studies are taken into consideration when determining the safe use of a pesticide.

The dose levels used in laboratory studies are much higher than the levels to which humans would be exposed when pesticide products are used according to label directions. These higher dose levels help scientists understand when and how effects may occur, and also identify levels when no effects occur, in order to set acceptable levels for pesticide exposure, called reference values. In addition, when setting these reference values, a 100-fold uncertainty factor is applied to a dose that has no effects, to account for observations in laboratory animals being extended to humans as well as variability between humans. An additional margin is included through retention of another factor (called the Pest Control Products Act factor) if there are any concerns for potential sensitivity of the young. The application of these uncertainty factors in setting reference values helps ensure there is a protective margin between the dose levels that elicit toxicity in laboratory animal studies and the anticipated human exposure. For more information, please refer to SPN2008-01, The Application of Uncertainty Factors and the Pest Control Products Act Factor in the Human Health Risk Assessment of Pesticides.

In animal studies assessing the long-term effects of a pesticide, including the potential to cause cancer, the animals are exposed to the pesticide at high dose levels over their entire lifetime and potential effects on all tissues and organ systems are investigated. Endpoints evaluated in these studies include clinical signs of toxicity, effects on body weight, organ weights and pathology, effects on hematology and clinical chemistry parameters, and the potential to cause gene mutations and tumour formation. Human epidemiology studies are also taken into consideration, when available and relevant. When there is evidence from these studies that a pesticide has the potential to cause cancer, consideration is given to whether or not the type of cancer would be relevant to humans and all the ways that humans may be exposed to the pesticide over a lifetime (for example, through the ingestion of food and water, exposure to pesticides in the workplace, and in and around the home). The probability that an individual will develop cancer if exposed to the pesticide for a lifetime is calculated mathematically, and only pesticides that are predicted not to increase the lifetime risk for developing cancer by one in one million are registered for use in Canada.

The studies provided to Health Canada also include those that are specifically designed to assess the potential neurological effects of a pesticide. These studies pay particular attention on potential effects of the pesticide on nervous system tissues, such as pathology of the brain and nerves, and also include a battery of tests conducted on the animals, called a Functional Observational Battery, which is designed to detect gross functional deficits in the animals. Endpoints examined in these tests include things such as (but not limited to) any unusual behaviours, the presence of convulsions and tremors, unusual respiration, pupil dilation or constriction, increased levels of salivation, vocalization, sensory function (vision, auditory capability, pain perception), and grip strength in the animals. In addition, these studies are designed to evaluate effects on motor activity (for example, increases or decreases in activity) and learning and memory in the animals. These endpoints are assessed through observation of the animals' behaviour under various situations, such as in an open area and using tests involving specialized chambers and mazes.

The potential of a pesticide to cause effects on the endocrine system is also assessed in various scientific studies with laboratory animals that are provided to Health Canada. Gross and microscopic examinations of endocrine tissues such as the ovaries, testes, adrenals, thyroid, pituitary and thymus, are conducted in these studies, as well as measurement of hormone levels (for example, thyroid hormones) in relevant studies. In addition, the potential for the pesticide to have an effect on growth, reproduction and development is evaluated in studies specifically designed for this purpose.

In studies that assess effects on reproduction, both male and female parental animals (usually rodents) are given high levels of the pesticide via an appropriate route (usually orally in the diet) before and during mating, and then the females continue to receive the pesticide throughout gestation, and then throughout birth, lactation, and weaning of their young. Once they are weaned, the young animals also begin receiving the pesticide at the same dose levels as the maternal animals, and this continues until they themselves are considered adults and are able to be mated to produce a second generation of offspring, if required. In this way, the effect of the pesticide on the ability of the animals to successfully mate, become pregnant, and produce viable offspring is examined throughout the lifecycle, and in some cases, over multiple generations.

Other specialized studies, called developmental toxicity studies, are designed to examine the effect of the pesticide on developing young (in other words, in utero) when their mothers are given high doses of the pesticide throughout the critical time in pregnancy. Studies in two different species are required (usually rats and rabbits). In these studies, fetuses are subjected to detailed external and internal examinations for any effects on development. Assessment of the fetuses includes examination of the morphology of internal organs as well examination of the skeletal system for any observed alterations in bone growth and development.

In summary, toxicology studies are designed to identify a variety of potential health effects from varying levels of exposure to a pesticide and also identify the dose level at which no effects are observed.

When assessing health risks from exposure to pesticides, only uses for which the exposure is well below levels that cause no effects in laboratory testing are considered acceptable for registration. In fact, the health effects noted in laboratory tests occur at dose levels 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, which is protective.

Understanding the toxic effects of metalaxyl, including if there is potential for neurodevelopmental and neurotoxic effects, developmental effects and cancer

A summary of Health Canada's assessment of metalaxyl can be found in the Proposed Re-evaluation Decision PRVD2007-10. As noted in this document, the re-evaluation was based on the United States Environmental Protection Agency (USEPA) Reregistration Eligibility Decision (RED) (Metalaxyl: Reregistration Eligibility Decision (RED) | USEPA archive document).

There was no evidence of neurotoxicity, genotoxicity or reproductive toxicity related to metalaxyl. Developmental delay (unossified sternebrae) was noted at doses that were toxic to maternal animals, with the main effects on liver. Metalaxyl did not demonstrate cancer potential and was classified as a Group E carcinogen (evidence of non-carcinogenicity for humans). This information is consistent with the pesticide fact sheet prepared by Le Centre de référence en agriculture et agroalimentaire du Québec (CRAAQ) (Fiche Matière active - SAgE pesticides (available in French only), which was also based on the 1994 USEPA RED and cited by some commenters.

While one comment cited a textbook reference to delayed ossification of cranial bones, Health Canada determined that the comment was made in error, as further examination of the original 2002 Joint Meeting of Pesticide Residues (JMPR) report, on which the textbook reference was made, did not note any delayed ossification of cranial bones related to metalaxyl exposure. A detailed monograph produced by JMPR Pesticide residues in food - 2002: toxicological evaluations (who.int), likewise did not indicate any significant effect on cranial bone ossification.

The reference values for human health risk assessment were selected to ensure that levels of metalaxyl to which humans may be exposed when metalaxyl-containing products are used according to label directions are at least 100-times lower than dose levels causing any toxic effect, including developmental delay, in animals.

Metalaxyl on its own (referred to as the technical grade active ingredient) is a moderate eye irritant. Acute hazards, such as eye irritancy, are identified on the label of each formulated product containing metalaxyl, if warranted. Formulated products can contain a range of concentrations of the active ingredient along with other ingredients and therefore, can have different acute hazard profiles than the technical grade active ingredient on its own. Separate toxicity testing is conducted for the formulated products, and the results inform the hazard statements that are found on individual product labels.

Protecting sensitive sub-populations/vulnerable populations

Health Canada conducts a rigorous assessment of scientific data when determining the conditions for safe use of a pesticide product prior to registration. The human health risk assessment characterizes both the hazard profile of the pesticide as well as the potential for exposure. The potential hazards are investigated through evaluation of a large number of in vitro and in vivo toxicology studies as outlined in the Understanding toxicity testing of pesticides section. Variability in the human population is addressed in the risk assessments performed by Health Canada by setting reference values based on these toxicity studies that incorporate additional uncertainty factors. A 10-fold uncertainty factor for intraspecies variability is applied in addition to a 10-fold uncertainty factor to account for differences between humans and animals (interspecies variability), as observations in laboratory animals are extended to humans. An additional margin is included through retention of another factor (the Pest Control Products Act factor) if there are any residual concerns for potential sensitivity of the young. The application of these uncertainty factors in setting reference values helps to ensure that there is a protective margin between the dose levels that elicit toxicity in laboratory studies and the anticipated human exposure. For more information, please refer to SPN2008-01, The Application of Uncertainty Factors and the Pest Control Products Act Factor in the Human Health Risk Assessment of Pesticides.

Health Canada also receives studies that assess potential dietary and non-dietary exposure to the pesticide product when it is used according to label directions. Using this information, Health Canada conducts specific risk assessments for sensitive groups, including children and pregnant people, taking their unique physiological characteristics into account. The behaviours and play-habits of children, such as their body weight and hand-to-mouth contact while playing near treated areas are considered when determining their potential exposure, and the highest potential exposure scenarios are taken into account when determining acceptable application rates for a product, in order to be protective.

The health of workers exposed to pesticides is also considered by Health Canada. Label directions provide workers with information for safe use, including proper handling information and directions on required personal protective equipment. In addition, provinces and territories are responsible for training and licensing professional pesticide users.

Thus, Health Canada's risk assessments are designed to protect all population subgroups including the most vulnerable.

Concerns over food allergies and intolerances to foods due to pesticides

The hazard assessment of pesticides includes evaluations of studies that assess the potential for pesticides to cause allergic skin reactions and effects on the immune system. Allergenic potential is also assessed for each pesticide formulation, which informs hazard statements on the product label. There are many potential causes of food allergies and intolerance to food in general, including genetic predisposition. Additional information related to food allergies and food intolerances can be found at the following resources: Food allergies - Canada.ca; Food Allergies and Intolerances - Canada.ca; Food Allergy Canada. Currently, there is no compelling evidence demonstrating a link between pesticide exposure and food allergies or food intolerances. However, Health Canada will take into consideration any emerging science that may indicate such a concern to help further ensure that the risk assessment is protective of these potential effects.

Dietary risks are calculated using consumption data from the Dietary Exposure Evaluation Model - Food Commodity Intake Database™

Health Canada's dietary exposures assessments for new active ingredients, re-evaluations, and new uses to registered active ingredients, such as for metalaxyl, rely upon the "Dietary Exposure Evaluation Model - Food Commodity Intake Database™ (DEEM-FCID™), and uses the most recent version available at the time of the assessment.

In support of the proposed MRLs in PMRL2021-13, DEEM-FCID™ Version 4.02, 05-10-c, was used to update the dietary risk assessment. This version of the software incorporates food consumption data from the United States' National Health and Nutritional Examination Survey, What We Eat in America (NHANES/ WWEIA) from 2005 to 2010. The update to the dietary risk assessment included the proposed new and revised MRLs.

While Canadian dietary consumption data is available from the Canadian Community Health Survey (CCHS) a comparison of the Canadian data and American consumption data from NHANES/WWEIA showed no significant differences between the two surveys. In addition, the NHANES/WWEIA data is a larger sample size relative to the Canadian data, and it collects data for infants less than 1 year of age (often the most sensitive age subgroup for dietary risk assessment) while the CCHS does not. NHANES/WWEIA is also a continuous survey that covers multiple years and captures consumption patterns over a longer period of time than CCHS, thus providing robust data that is regularly updated (SPN2014-01, General Exposure Factor Inputs for Dietary, Occupational, and Residential Exposure Assessments).

It is also important to note that the residue input in DEEM obtained from field trial studies on crops treated with metalaxyl according to Good Agricultural Practice (GAP) is determined based on the analysis of the entire unwashed sample of each crop (for example, whole berries are harvested in the field and the entire sample is analyzed so that the results represent residues both on the surface and interior of the fruit). So even though metalaxyl is a systemic pesticide, residues both on and inside the crop are taken into account in the dietary exposure assessment. In addition, the use of samples from unwashed produce is an additional protective measure when considering potential residues present, which is not necessarily the case for data from the CCHS survey, given it is a nutrition survey of foods as eaten.

Dietary risk assessment results for metalaxyl

Studies in laboratory animals showed no acute health effects relevant to dietary risk assessment. Consequently, a single dose of metalaxyl is not likely to cause acute health effects in the general population (including infants and children). As such, an acute dietary risk assessment was not required.

A cancer dietary exposure assessment was not required as metalaxyl did not show any cancer potential in toxicity studies.

Chronic dietary intake estimates for food and drinking water indicated that the general population and all population subgroups are exposed to less than 13% of the acceptable daily intake and therefore there are no health concerns. The dietary risk for each subpopulation is reported in the Summary of chronic dietary risk for metalaxyl table.

Table Summary of chronic dietary risk for metalaxyl
Population subgroup Acceptable daily intake (ADI)
(mg/kg bw/day)		 % ADI
General Population 0.075 5.2
All Infants 4.5
Children 1–2 years old 12.7
Children 3–5 years old 10.9
Children 6–12 years old 6.7
Youth 13–19 years old 4.1
Adults 20–49 years old 4.4
Adults 50+ years old 4.6
Females 13–49 years old 4.4

Health Canada considers chronic risk may be of concern when exposure is greater than 100% of the ADI. When the chronic dietary risk is lower than 100% of the ADI, it means that there are no long-term human health concerns from eating foods treated with metalaxyl every day over a person's life.

For more information on how Health Canada assesses and manages risk from pesticides, refer to this guidance document:

For more information on the MRL process, refer to Section 19 Maximum Residue Limits found within this guideline:

Cumulative risk

The Pest Control Products Act requires Health Canada's PMRA to consider the cumulative effects of pest control products as per the Science Policy Note SPN2018-02, Cumulative Health Risk Assessment Framework. A cumulative risk assessment (CRA) evaluates the potential adverse health effects from being exposed to more than one pesticide at a time from the same pesticide "group". These groups are created based on a common toxic effect that occurs by the same or similar mechanism of action.

CRAs may consist of a qualitative or quantitative assessment, or result in a determination that a cumulative risk assessment is not required. For example, situations in which no common mechanism of toxicity exists or that do not involve co-exposures, would not require a cumulative risk assessment.

In addition to identifying a common mechanism of toxicity, other important considerations must be explored as part of the process to determine the need to conduct a CRA. These considerations include defining and comparing the use patterns of the different chemicals belonging to a class of pesticides with a common mechanism of toxicity to determine if the same uses are registered, whether the uses are wide-ranging, if there are residential uses, the potential routes of exposure and the potential for co-occurrence of exposure to the different chemicals. In addition, monitoring data from the Canadian Food Inspection Agency (CFIA) and/or the United States Department of Agriculture (USDA) Pesticide Data Program (PDP), as well as drinking water monitoring information, are important sources of real-world data for dietary exposure assessment, and are key in order to conduct realistic CRAs.

Metalaxyl is part of the acylalanine chemical class of fungicides along with benalaxyl and furalaxyl. While metalaxyl, benalaxyl and furalaxyl are known to share a common pesticidal mode of action for the control of target pests, based on currently available information, it is unclear if they have the same mechanism of action for mammalian toxicity. Nonetheless, as a conservative approach, they are considered to form a cumulative assessment group at this time.

Of the three pesticides, only metalaxyl is registered in Canada and the United States. The other two active ingredients, benalaxyl and furalaxyl, are registered in other foreign countries; however, for furalaxyl, there are no Codex MRLs and no US tolerances, and for benalaxyl, there are Codex MRLs and only two US tolerances for imported crops. In addition, based on the last five years of monitoring data from the CFIA and the USDA PDP for benalaxyl and furalaxyl, no significant residue levels have been detected in food commodities that could be imported into Canada. Therefore, dietary exposure to benalaxyl and furalaxyl is not expected and no co-exposure scenarios could be established. Hence, a cumulative risk assessment is not required at this time.

Worker and bystander exposure and risk

Worker and bystander assessments were conducted as part of the application requesting new and revised MRLs under submission number 2019-0782. The use of the product Orondis Gold Fungicide, which contains metalaxyl, on Crop Subgroups 13-07A and 13-07B, tree nuts and low-growing berries, as listed in the PMRL consultation document, is not expected to result in health risks of concern for chemical handlers, postapplication workers, and bystanders, provided that the product is used according to the label directions. The label specifies the conditions for safe use for the product label so that human exposure is well below the level that could cause harm.

Precautionary principle

The concept of exercising precaution is applied by Health Canada's PMRA in its regulatory decision-making. The Act and Regulations specify that a scientifically-based approach is required as a basis for regulatory decisions. Therefore, a detailed rigorous risk assessment of scientific data is necessary before a pesticide can be registered in Canada. Uncertainty factors and the Pest Control Products Act factor, as discussed in previous sections, are applied in the risk assessment, where appropriate. Conservative considerations are also applied to the assessment to be protective. A product will be registered or continue to be registered as a result of periodic re-evaluation, only if there is sufficient scientific evidence to show that health and environmental risks posed by a product under the approved conditions of use are acceptable, and that it serves a useful purpose. Conditions of registration are specified for every product, including detailed use instructions, and a product can only be used according to label directions. If the proposed use could pose an unacceptable risk, additional conditions or restrictions can be imposed so that the remaining risk becomes acceptable. If the risks remain unacceptable, a registration is denied or cancelled, and the product cannot be used. When uncertainty remains in risk assessment, for example, insufficient data to assure safety, a use will not be approved.

As indicated in the Pest Control Products Act, the Precautionary Principle may be applied where there are threats of serious or irreversible damage. In the case of metalaxyl, sufficient data were available to conduct a robust science based risk assessment. Health Canada determined that the pesticide can be used safely when used as directed for bearberries, bilberries, cloudberries, muntries, partridgeberries, Caneberries (crop subgroup 13-07A, except raspberries), and Tree Nuts (crop group 14-11, except almond nuts, black walnuts, and English walnuts).

Organic farming

Health Canada recognizes that to be healthy, we need to eat a variety of foods, especially fresh fruits and vegetables. Pesticides play an important role in making sure there is enough food for everyone, by protecting crops from pests like insects, weeds, and fungal diseases. Food safety is a priority of the Government of Canada, and while pesticides help protect our food supply, some people have concerns about small amounts of pesticide residue that may be on the food they eat.

Eating organic or conventionally grown produce is a personal choice. Health Canada regulates all products that make pesticidal claims, including products intended to repel pests and protect organic produce. To date, there is no evidence to show that there is a health risk from eating conventionally-grown produce that contain small amounts pesticide residues, or that organic foods are safer to consume than conventionally produced food.

Food safety in Canada is a shared responsibility and priority between growers, industry, provinces and federal organizations. Health Canada, the Canadian Food Inspection Agency and Agriculture and Agri-Food Canada work together on a number of programs that help provide safe food for Canadians and encourage environmental protection. Food producers help keep food safe by using and improving upon good agricultural and pest management practices. One key practice, which is required by law, is to follow pesticide label directions, because labels give instructions for the safe and proper use of pesticides. This helps keep residues within the limits, thus helping to ensure a safe food supply. Food producers also participate in a variety of on-farm programs to help implement effective food safety procedures in their day-to-day operations.

Health Canada works in collaboration with Agriculture and Agri-Food Canada to register pesticides that meet the criteria for certified organic food production. To this end, Health Canada registers many biopesticides as part of reduced risk and sustainable pest management, which is in line with the goals of the Pest Control Products Act. The PMRA annual report shows increasing numbers of biopesticide registrations over the years, relative to conventional pesticides. All growers use pesticides, whether from synthetic or natural sources, and both sources of pesticides present various levels of toxicity and risk. When growing food, it is always recommended to do so in a sustainable way and pesticides play a role in this practice. Furthermore, by adopting a sustainable approach, growers can produce more with less on the same area of land, in addition to using natural resources wisely. Pesticide use can reduce food losses, help with better harvesting and are one tool used by growers to produce safe, quality foods at affordable prices. Responsible use of pesticides as part of an integrated pest management (IPM) program, that may include cultural production practices such as reduced or conservation tillage, contributing to reduced soil erosion and improved soil health, also supports sustainable agricultural production systems.

Pesticides offer benefits other than controlling and destroying pests in agricultural crops. They help reduce labour, fuel and machinery required for crop protection activities, thus reducing impacts of these activities on the environment.

Finally, by controlling toxin-producing microorganisms in food and feed crops, pesticides also contribute to reduced exposure to harmful food contaminants.

Access to scientific data

Scientific data and information considered during Health Canada's pre- and post-market scientific evaluations may come from a variety of sources, such as from applicants/registrants, federal and provincial governments, academia and the research community, other internationally recognized regulatory agencies, as well as a large body of published independent scientific studies.

The notice of intent for the proposed amendments to the Pest Control Products Regulations to facilitate access to confidential test data (CTD) was published for consultation in June 2023. Currently, members of the public may inspect confidential test data either in-person in the Reading Room, located at the Health Canada PMRA National Head Office in Ottawa, Ontario, or remotely (virtual Reading Room pilot project), and initiatives are underway to allow for greater accessibility of this information. Refer to NOI2023-01, Strengthening the regulation of pest control products in Canada (20 June 2023) for further details.

Increased transparency

It is noted that since PMRL2021-13 was published for consultation in May 2021, Health Canada's PMRA made substantial improvements to the transparency and clarity of its published proposals and decisions, with more initiatives underway.

As of 1 April 2023, the names of applicants and registrants have been released in the Pesticide Product Information Database (PPID). This new measure, as noted in the Consultation Summary: Notice of Intent Enhanced Transparency of the Pesticide Regulatory Process, NOI2022-01, supports the Government of Canada's initiatives towards Open Government as well as its commitment to enhanced transparency of the pesticide review process.

As noted in previous sections, the MRLs proposed under PMRL2021-13 for the pesticide metalaxyl were submitted by Syngenta Canada Inc. under submission number 2019-0782 (Category B.3.12).

The addition of the applicant's or registrant's name will provide additional information about the application that has been filed to further support meaningful public participation in the regulatory process. Health Canada's PMRA recognizes that the transparency and openness of its work is critical in strengthening trust in the regulatory decisions. Disclosing the applicant's or registrant's name in the public registry is one step in revisiting the types of information and data that are made available.

As noted under the Increased transparency section, Health Canada's PMRA has also developed and consulted on a Notice of Intent (NOI2023-01) on the proposed amendments to the Pest Control Products Regulations. This includes the intent to publish notifications to increase transparency of MRL applications for pesticide residues on imported food products.

To further increase transparency as well as to further promote science literacy and help people in Canada better understand the complicated aspects of pesticide science, including about MRLs, the PMRA has published an Infographic on MRLs in Canada to explain what MRLs are and how they are set, it has posted a blog (Collaborating for safer food and stronger agriculture) written in collaboration with the CFIA that explains the roles of CFIA and Health Canada's PMRA in pesticide regulation and cooperation in keeping Canada's food safe, and has also issued a podcast on MRLs in conjunction with Agriculture and Agri-Food Canada.

Health Canada's consultations

Health Canada's Pest Management Regulatory Agency consults with the public on all proposed major registration decisions, including new registrations, major new uses of a pesticide, re-evaluations and special reviews. Consultations can be found on our Pesticides and pest management consultations page.

For each open consultation, you can learn more about the proposed decision, access a consultation statement that outlines the major findings of the evaluation and the proposed decision, and leave a comment that will be considered before the final decision is made. Final decisions are available on our decisions and updates page.

Health Canada's PMRA is undergoing a transformation process that will strengthen its oversight and its protection of human health and the environment. The Minister of Health's Mandate letter (2021) as well as the information regarding the Pest Management Regulatory Agency's transformation resulted in 4 pillars of action: improved transparency, increased use of real-world data and independent advice, strengthened human health and environmental protection through modernized pesticide business processes and a targeted review of the Pest Control Products Act.

The PMRA has engaged and received positive feedback from non-governmental organizations (NGOs) and academic organizations on these proposed initiatives. In addition, the Science Advisory Committee on Pest Control Products (SAC-PCP), established in 2022, provides Health Canada with independent scientific advice on various evidence-based decisions for pesticides.

The transformation process is helping to make Health Canada's pesticide program more transparent to people in Canada. Over the course of 2022 and 2023, Health Canada's PMRA engaged in comprehensive stakeholder consultations on its transformation agenda, including on ways it could continue to improve transparency. To help improve overall transparency and science communication, we have established a Science Communication Team. This unit of trained science communicators develops communication products that describe how science is conducted at the PMRA and how it informs decision-making. They work to communicate decisions clearly with the right information for the audience. Their improvements have included re-designed webpages with more plain language and easier navigation for users to find what they are looking for and documents written using language suited to an engaged public audience along with clearer explanations of the basis for proposed decisions. If you would like to learn more about the science on pest management, you can reach them at: scicomm.pmra-commsci.arla@hc-sc.gc.ca.

Dietary risks from the consumption of metalaxyl residues in or on the food commodities noted in the PMRL consultation document (PMRL2021-13) were shown to be acceptable when metalaxyl is used according to the approved label directions. Therefore, the foods containing these residues are safe to eat, and the MRLs will be specified in the MRL Database as proposed (PMRL2021-13).

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