PMRA Environmental Risk Assessment - Adam Oliver...

PMRA Environmental Risk Assessment

Environmental Risk Assessment

Daniel G Sauvé, MSc.

Senior Evaluation Officer, Environmental Risk Section III

Environmental Assessment Directorate

Pest Management Regulatory Agency

Scientific Evaluation and Decision-Making Process for Pest Control Products in Canada

2

Overview

o The PMRA

o Role of EAD

o Exposure assessment

o Toxicology assessment

o Risk characterization

o Risk mitigation

o Conclusion


3

PMRA History

Agriculture and Agri-Food Canada

Efficacy & phytotoxicityCoordination, assessment

and Registration

Health CanadaHuman health risk assessment

EnvironmentCanada

Terrestrial environment risk assessment

Fisheries and OceansAquatic environment

risk assessment

PMRAHealth CanadaApril 1995

Prior to April 1995:



4

PMRA Organizational Chart

Executive director

Chief registrar’s office (CRO)Registration directorate

(RD)

Value and Sustainability Assessment Directorate (VSAD)

Compliance, Laboratory Services and RegionalOperations Directorate

(CLSROD)

Policy, Communications andRegulatory Affairs Directorate (PCRAD)

Re-evaluation Management Directorate(REMD)

Environmental Assessment Directorate(EAD)

Strategic Planning, Financial and Business Operations Division (SPFBOD)

Health Evaluation Directorate (HED)


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Mandate of PMRA

• To protect human health and the environment by minimizing risks associated with pesticides while providing access to pest management tools


6

Main Activitieso Assess scientific data on the ecotoxicology and environmental

fate and behaviour of pesticides;o Conduct environmental risk assessmentso Recommend mitigation measures;o Document scientific literatureo Participate in scientific committees within PMRA, HC and other

departments and institutions (USEPA, OECD, NAFTA, etc.)

Environmental Assessment Directorate (EAD)



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Objectives of environmental risk assessment

o Evaluate the likelihood that adverse ecological effects may occur (or are occurring) following exposure to pesticides and/or their transformation products

o Determine if changes in the use pattern (or proposed use pattern) are required to better protect the environment


8

Risk assessment framework

Exposure assessment Hazards assessment

Risk characterization

Risk mitigation options

Problem formulation


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Environmental exposure assessment

o Evaluate the potential exposure (direct and indirect) to plants,insects and other animals of pesticide residues in water, food, soil and air;

o Includes information on the quantity of pesticides to which an organism can be exposed and the frequency and duration of exposure;

o Based on data on the fate and behaviour in the environment, modelling and monitoring in the field;

o Information on the active ingredient and the end-use product(s)

o For new chemicals and older already registered products



10

Fate and Behaviour in the Environment

Applied Pesticide

Foliar Interception and dissipation

Wash-off

Plant uptake

Volatilisation

Transformationmicrobial (biotic)chemical (abiotic)

Sorption /Retention

Leaching

Surface Runoff

Lateral flow

Phototransformationair, surfaces, soil, water


11

Data that may be required to assess exposure

o Physical-chemical propertieso Solubility, vapour pressure, Kow, pKa, UV absorption.

o Transformation (abiotic and biotic)o Hydrolysis, phototransformation, biotransformation (soil and water)

aerobic/anaerobic.o Mobility

o Leaching, volatilization.o Field Dissipation (DIR2006-01)

o Fate and mobility at sites representative of pesticide use in various regions in Canada

o Bioaccumulation

Ref:1. Guidelines for Determining Environmental Chemistry and Fate of Pesticides (T-1-255).2. Harmonization of environmental chemistry and fate data requirements for chemical pesticides under NAFTA(DIR2003-03).


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Exposure Assessment

Abiotic Transformation

o Phototransformation

o Soil

o Water

o Air



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Exposure Assessment

Abiotic Transformation

o Hydrolysis

o The pH can significantly influence the rate of hydrolysis (half-life)

Chemical a

pH 4.5 = 455 d, pH 7 = 147 d, pH 9 = 17 d

Chemical b

pH 6 = 3.7 d, pH 7 = 6.5 h, pH 8 = 63 m


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Exposure Assessment

Biotransformation (20-30°C)

o Soilo Aerobic

o Anaerobic (flooded)

o Aquatic systemso Aerobic water

o Water/sediment anaerobic

o Provides information on the identity, formation and persistence of transformation products


15

Exposure Assessment

Mobility

o Adsorption/desorption

o Leaching in soil column

o Thin layer soil Chromatography

o Volatilization



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Exposure Assessment

Adsorption/desorption

o The tendency of a pesticide to be adsorbed on soil particles can be expressed as the soil water-organic carbon coefficient (Koc)

• Koc = Kd ÷ % OC

• Kd = distribution coefficient between

soil and water

• % OC= % organic carbon

A high Koc = strong affinity to soil particle;

A low Koc = highly mobile in the soil


17

Exposure Assessment

Terrestrial field Dissipation Studies

• Shows the fate and mobility of pesticides and their transformation products on sites representative of areas where the proposed product is to be used in Canada.


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Exposure Assessment

Terrestrial field Dissipation Studies

Applicants MUST

consider the

ecological regions

of Canada



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Exposure Assessment

Dissipation (aquatic environment)


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Characteristics of a chemical that has the potential to leach into the soil, Cohen et al. 1984

• Water solubility > 30 ppm• Kd < 5 and most often < 1 or 2 mL/g• Koc < 300 to 500 mL/g• Henry’s Law Constant < 10-2 atm· m3/mole• Negatively charged (either completely or partially) at

environmentally relevant pH • Hydrolysis half-life > 25 weeks• Photolysis half-life > 1 week• Soil half-life > 2 to 3 weeks


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• GUS: Groundwater Ubiquity Score

• t½ soil = time required for the chemical to decline by 50% under field conditions;

• Koc = soil water-organic carbon coefficient

Calculated GUS score classification system (Gustafson, 1989)(DIR2006-01)

Klogtlog OC1010421GUS

soil

GUS Leaching potential

> 2.8 Leacher

>1.8 and < 2.8 Borderline leacher

< 1.8 Non leacher



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Assessment of the potential for leaching

We consider:

o The Cohen et al. 1984 criteria;

o The GUS scores;

o Field dissipation studies and modelling;

o Studies conducted with lysimeters;

o And, for re-evaluations, ground water monitoring data.

o Other field studies


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Problem formulation


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Environmental Hazards Assessment

o Describes the types of effects that a pesticide may elicit on organisms and how these effects may vary according to the exposure;

o Based on internationally accepted guidelines and surrogate species;

o Determine ecotoxicological endpoints and dose-response (e.g.: LD50, NOEC, EC25)

o Identifies the most sensitive organisms and helps predict the potential adverse effects to non-target organisms



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Toxicity Tests

o Short term (acute) o e.g.: LC50, LD50, LR50

LD50= dose at which 50% of the population dies

o Long term (chronic)o e.g.: NOEC, LOEC, NOEL, LOEL

NOEL= No adverse effect level

o Lab vs. Field


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Non-Target Organisms: Terrestrial Invertebrates

Earth worms(Eisenia sp)

Honey bee(Apis mellifera)


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Non-Target Organisms: Terrestrial Invertebrates

Beneficial Predators and parasites

The Ladybird beetle predator of aphids and scale insects

Harmonia axyridis

The Crab spider, predator of aphids

Misumena vatia

Wasps:Tricogramma –(parasitic wasp)



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Non-Target Organisms: Terrestrial vertebrates

o Birds

Mallard duck (Anas platyrhynchos)

Bobwhite quail (Colinus virginianus)

Zebra finch(Taeniopygia guttata)


29

Non-Target Organisms: Terrestrial vertebrates

Mammalso Mammalian toxicity studies are assessed by the Health

Evaluation Directorate for human safety

o The typical endpoints used by EAD to

assess the risk to wild mammals are the

acute oral toxicity and 2-generation

Reproduction.


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Non-Target Organisms: Terrestrial Vascular plants

o Seedling emergence

o Vegetative vigour



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Non-Target Organisms: Freshwater

o InvertebratesCrustaceans: Daphnia

(Acute toxicity and reproduction)

o Fisho Warm water (Blue-gill sunfish)

o Cold water (Rainbow trout)

(Acute toxicity, Early life stage (ELS) and

full life cycle)

o Amphibiano Often, fish study is used as a surrogate

Bluegill Sunfish(Lepomis macrochirus)

Rainbow Trout(Oncorhynchus mykiss)

Water flea(Daphnia magna)


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Non-Target Organisms: Freshwater Algae

Green alga (Selenastrum capricornutum)

Cyanobacteria (Anabaena sp.)


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Non-Target Organisms: Freshwater vascular plants

o Duckweed

(Lemna gibba)



34

Non-Target Organisms:Estuarine / marine

o Crustaceans: Acute toxicity and Chronic

o Mollusc embryo Larvae or shell deposition

o Fish

o Acute toxicity

o Salinity challenge test

o Algae (1 species)o Marine diatom

Sheepshead minnow

Cyprinodon variegatus


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Problem formulation


36

Risk Characterization

o Compare the exposure (Estimated Environmental Concentration – EEC) in the environment, according to the existing or proposed use pattern to the level at which adverse effects are observed in laboratory or field studies.

o If the EEC exceeds the level at which adverse effects are likely to occur (Level of concern – LOC), mitigative measures can be proposed to reduce the expected risk.



37

Risk Characterization : Screening level or refined assessment?

o Screening level risk assessment (triage)o Is to identify :

o Pesticides and/or specific uses that do not pose a risk to non-target organisms ;

o Groups of organisms that are not expected to be at risk;o Pesticides and groups of organisms where there may be a

potential for concern and for which further characterization of the risk is required

o Based on conservative scenarios and simple methods.

o Further risk characterizationo Objective : Refine the risk characterization with more detailed exposure

scenarios.o Refinement steps to further characterize and understand the risks


38

Expected Environmental Concentrations(EEC) – Terrestrial species

o Screening assessment

o Soil : g ai/kg soil (Earthworms)

o Application rate : g ai/ha (honey bees, beneficial arthropods, plants)

o Food source : g ai/kg food (birds and small mammals)

o Consumption of contaminated food items estimated according to the Hoerger and Kenaga (1972) nomogram and modified by Fletcher et al. (1994)


39

Risk Characterization– Terrestrial species (Toxicity endpoints used)

o Earthwormso LC50 (Acute) or NOEC (Reproduction)

o Beneficial Arthropodso LR50

o Birds/mammalso LD50 (Acute oral toxicity) o LC50 (Dietary) o NOEC (Reproduction)

o Vascular Plantso EC25 for the most sensitive species (Seedling emergence or vegetative

vigour)o Application of uncertainty factor

o Inter- and intra-species variationo Protection of population and community



40

Risk Characterization – Screening assessment for terrestrial species

o Integrates exposure and effects to determine risk using a Risk Quotient (RQ) for the most sensitive group of organisms.

o RQ = [EEC / Toxicity Endpoint]

o RQ ≥ 1 environmental concerns may exist

o RQ < 1 indicates margin of safety


41

Risk Characterization – Refinement options for terrestrial species

o More realistic exposure scenarioo Use patterno Information on fate and persistence

o Consideration of spray drift depositiono Deposition attenuates with distance from spray equipment

o Specific scenarioo Crop specific scenario, pertinent species, species-specific feed

guild, species behaviour

o Supplemental optionso Other ecotoxicity endpoints; o Monitoring data and incident reports;o Probabilistic risk assessment (SSD vs. exposure distribution).


42

Risk Characterization– Aquatic species (Toxicity endpoints used)

o Aquatic plants and invertebrates (pelagic and benthic)o Acute toxicity : EC50

o Chronic toxicity : NOECo Fish

o Acute toxicity : LC50

o Chronic toxicity and early life stages : NOECo Amphibians (aquatic stages) : Fish endpoint used as surrogate

when amphibian data is not available.o Acute toxicity : LC50

o Chronic toxicity : NOECo Application of uncertainty factor

o Inter- intra-species variationo Protection of population and community



43

Aquatic Risk Characterization – Screening assessment

o Water : g ai/Lo 15 cm deep: forest and/or seasonal water body

o 80 cm deep: permanent water body

o Conservative hypotheses : Maximum yearly application rate, shortest application interval, Adjusting for transformation for multiple applications, direct application

o RQ ≥ 1 environmental concerns may exist

o RQ < 1 indicates margin of safety


44

Aquatic Risk CharacterizationRefined risk assessement

o Spray drift

o If RQ ≤ 1 – Default 1 m buffer zones are required

o If RQ > 1 – Appropriate bufferzones are determined

o Aerial spray – AgDISP v.8.15 (2005);

o Ground boom application (Wolf et Caldwell, 2001);

o Ground Airblast application – (Ganzelmeier et coll., 1995).o Run-off

o EEC obtained by the models PRZM-EXAMS :

o If RQ < 1 – Risk by run-off is acceptable

o If RQ ≥ 1 – potential risk identified by run-off; May characterize further – risk mitigation measures may be required


45

Aquatic Risk Characterization– Other options for risk refinement

o Further characterize input to the modelling to more realistic scenarios.

o Other ecotoxicity endpoints;

o Monitoring data and incident reports;

o Probabilistic risk assessment (SSD vs. exposure distribution).



46

Water modelling

o EAD runs the drinking water modelling. These values are used by HED for the human health risk assessment

o PRZM and EXAMS Models : EEC in drinking water from surface run-off

o Leaching Estimation and Chemistry Model (LEACHM) : EEC in drinking water from ground water (contamination from leaching)

o Ground water monitoring data may also be used for drinking water assessment if available

SPN2004-01, Estimating the Water Component of a Dietary Exposure Assessment


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Problem formulation


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Risk mitigation measures – examples

o Reduce the number of applications per season;o Establish buffer zones to reduce adverse effects caused by

spray drift to sensitive habitats;o Only allow ground applications (no aerial applications);o Limit application for consecutive years;o Use lower application rate (Supported by VSAD);o Modify application timing (time of day or season);o Use only some types of product formulations;o Require immediate soil incorporation;o Limit certain uses or active ingredient (ai);o Adding hazard statements on the label



4949

Buffer Zones

• Distance between the point of direct application and the closest downwind edge of a sensitive terrestrial and/or aquatic habitat

• Calculated by spray drift models

• Risk based (i.e., RQ → buffer zone)

• Pesticide specific


5050

Maximum Drift Deposition Table

Maximum Spray Drift Deposition % Drift at 1 m downwindMode of Application Spray Quality (ASAE) Drift (% of applied)

Ground Boom Sprayer Coarse 3%Ground Boom Sprayer Medium 6%Ground Boom Sprayer Fine 11%Airblast - Early Season Fine 74%Airblast - Late Season Fine 59%Aerial - Agricultural Crops Coarse 17%Aerial - Agricultural Crops Medium 23%Aerial - Agricultural Crops Fine 26%Aerial - Non-Crops Coarse 60%Aerial - Non-Crops Medium 60%Aerial - Non-Crops Fine 44%Aerial - Forestry Coarse 77%Aerial - Forestry Medium 85%Aerial - Forestry Fine 90%Note: RQs should be calculated for all uses on the label in order to characterize the risk.. For field and aerial applications use a Fine and Medium droplet sizes for insecticides and herbicides, respectively, unless otherwise stated on the label


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Habitats to be protected



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Protect the environment


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