Assessing Environmental Exposure to Biocides
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Emission scenario document for biocides used as rodenticides Jørgen Larsen PT 8 & PT 14 Exposure Scenario Course 9-10 October 2003, Ispra European Chemicals Bureau JOINT RESEARCH CENTRE EUROPEAN COMMISSION This presentation General issues and background Basic use and exposure scenarios of the environment Exposure scenarios for primary poisoning Exposure scenarios for secondary poisoning Conclusions Life-cycle of rodenticides Production Formulation Private use Processing professional use In product In product Processing Service life Waste treatment Primary and secondary poisoning PT 14 Rodenticides Used for controlling rodents Rats Mice Voles Basic use scenarios Sewer systems Buildings (inside and around) Open fields Waste dumps Rodenticides: Application methods Scenario: Sewer Buildings Open Waste fields dumps Wax blocks ü ü ü ü Grain / pellets Bait box Contact powder Liquid Fumigation ü ü ü ü ü ü ü ü ü ü ü Rodenticides: Compartments of concern Scenario: Sewer Buildings Open Waste fields dumps STP ü ü Surface water ü Soil ü ü ü ü Air Primary ü ü ü poisoning Secondary ü ü ü ü poisoning Sewer systems: Assumptions Realistic worst-case: 21 days campaign Day 0: 300 wax blocks Day 7: 100 wax blocks replenished Day 14: 50 wax blocks replenished Maximum emission during 1st week: 100 blocks Weight of wax block: 0.3 kg Fraction of a.i. (substance) released: 0.9 Standard STP scenario (TGD) 200 L/day, 10,000 inhabitants Sewer systems: STP Elocal water Q prod Fc product Temission Variable/parameter (unit) Input: Amount of product used in control operation Freleased Symbol Unit Default Qprod kg 30 Fraction of active substance in product Fcproduct Dossier Number of emission days (control Temission Days 7 operation) Fraction of product released 0.3 + (0.6-*) Freleased Output: Local emission of active substance to Elocalwater kg.d-1 waste water during episode Sewer systems: Results Substance A: Anti-coagulant (0.005% a.i.) Substance B: Coagulant (4% a.i.) Elocalwater: 0.2 g a.i./day Cinfluent: 0.1 μg a.i./L Elocalwater: 150 g a.i./day Cinfluent: 77 μg a.i./L Sewer systems: Results Result depends on Used amount of product (Qprod) Fraction of a.i. in product (Fcproduct) Fraction of release (Freleased) Estimation of PEClocal Fate (degradation, sorption, volatilisation) in STP (presence of STP is default for local scenario) Dilution in aquatic environment PEClocalwater Disposal of sludge on farmland PEClocalsoil In and around buildings Assumptions on bait stations Realistic worst-case: 21 days campaign Bait stations: 10 No. of replenishments: 5 Weight of wax block: 0.25 kg Fraction released due to spillage: 0.01 Spillage area: 0.09 m2 (0.1 m around station) Fraction ingested: 0.99 Fraction released of ingested: 0.9 Frequented area: 550 m2 (10 m around building) Buildings: Direct emission Elocal soilcampaign Q prod Fc prod N app N refil Frelease D , soil Variable/parameter (unit) Symbol Input: Amount of product used in control operation Qprod for each bait box Fraction of active substance in product Fcprod Number of application sites Unit g 10 Napp Number of refilling times Nrefil Fraction of product released directly to soil Frelease-D, soil Output: Local direct emission rate of active substance to soil from a campain Elocalsoil-campain Default 5 0.01 g/campain Buildings: Direct soil exposure Clocal soil D Elocal soilcampain 103 AREAexp osed D DEPTH soil RHO soil N app Variable/parameter (unit) Input: Local emission to soil from a campaign Symbol Unit Area directly exposed to rodenticide Depth of exposed soil Density of exposed soil Output: Local concentration in soil due to direct release after a campaign AREAexposed-D DEPTHsoil RHOsoil m2 m Clocalsoil-D mg/kg Default Elocalsoil-campaign g kg/m3 0.09 0.1 1700 Buildings: Indirect emission Elocal soilcampaign Q prod Fc prod N app N refil Fingested Frelease ID ,soil Input: Amount of product used in control operation Qprod for each bait box Fraction of active substance in product Fcprod g Number of application sites Napp 10 Number of refilling times Fraction of product ingested Fraction of ingested product released Nrefil Fingested Frelease-ID, soil 5 0.99 0.9 Output: Local indirect emission rate of active substance to soil from a campain Elocalsoil-campain g/campain Buildings: Indirect soil exposure Clocalsoil ID Elocalsoilcampaign 103 AREAexp osed ID DEPTH soil RHO soil Variable/parameter (unit) Symbol Unit Default Local emission rate to soil from a campaign Elocalsoil-campaign g/campaign Area indirectly exposed to rodenticide Depth of exposed soil Density of wet soil Concentration in soil due to indirect (disperse) release after a campaign AREAexposed-ID DEPTHsoil RHOsoil Clocalsoil-ID m2 m kg/m3 mg/kg 550 0.1 1700 Buildings: Results re. bait stations Substance A: Anti-coagulant (0.005% a.i.) Substance B: Coagulant (4% a.i.) Elocal-D: 0.006 g a.i. Clocal-D: 0.04 mg a.i./kg Elocal-ID: 0.56 g a.i. Clocal-ID: 0.006 mg a.i./kg Clocal-D+ID: 0.047 mg/kg Elocal-D: 5 g a.i. Clocal-D: 33 mg a.i./kg Elocal-ID: 446 g a.i. Clocal-ID: 4.8 mg a.i./kg Clocal-D+ID: 37 mg/kg Open areas: Assumptions re. pellets and impregnated grain Pellets or impregnated grain used in rat burrow Entrance holes are sealed after application Product used: 0.1 kg Soil volume: 0.0085 m3 (lower half of 0.3 m burrow, 0.1 m from the wall) Fraction released during application: 0.05 Fraction released during use: 0.2 Refills: 2 Open areas: Emission in rat burrow Elocal soilcampaign Q prod Fc prod N app N refil ( Frelease, soil,appl Frelease, soil,use ) Variable/parameter (unit) Symbol Unit Input: Amount of product used in control operation Qprod g Fraction of active substance in product Fcprod Number of application sites Napp Number of refilling times Nrefil Fraction of product released to soil during Frelease, soil, appl application Fraction of product released to soil during Frelease, soil, use use Output: Local emission of active substance to soil Elocalsoil-campaign g during a campaign Default 1 2 0.05 0.2 Open areas: Concentration in rat burrow Clocal soil Elocal soilcampaign 10 3 Vsoil exp osed RHO soil Variable/parameter (unit) Input: Local emission to soil from the episode Soil volume exposed to rodenticide Symbol Unit Elocalsoil-campaign g Vsoilexposed m3 Density of wet exposed soil RHOsoil Kg/m3 Output: Local concentration in soil after a campaign Clocalsoil-campaign mg/kg Default 0.0085 1700 Open areas: Results, pellets in rat burrow Substance A: Anti-coagulant (0.005% a.i.) Substance B: Coagulant (4% a.i.) Elocal-D: 0.0025 g a.i. Clocal-D: 0.17 mg a.i./kg Elocal-D: 2 g a.i. Clocal-D: 138 mg a.i./kg Open areas: Assumptions re. contact powder Contact powder often used when plenty of food is available Contact powder applied directly in burrow by spoon or dust-blower Soil volume: 0.0085 m3 Fraction released to soil: 0.9 Product used: 0.1 kg (example) Open areas: Release of contact powder Elocal soilcampain Q prod Fc prod N app Frelease, soil Variable/parameter (unit) Symbol Input: Amount of product used in control operation Qprod Fraction of active substance in product Number of application sites Fraction of product released to soil Output: Local emission of active substance to soil after a campaign Unit Default g Fcprod Napp Frelease, soil, Elocalsoil-campaign g 1 0.9 Open areas: Results, contact powder Substance A: Anti-coagulant (0.005% a.i.) Substance B: Coagulant (4% a.i.) Elocal-D: 0.0045 g a.i. Clocal-D: 0.3 mg a.i./kg Elocal-D: 3.6 g a.i. Clocal-D: 250 mg a.i./kg Primary poisoning: Estimated Daily Intake FIR EDI C AV PT PD (mg / kgbw / d ) BW FIR: Food intake rate of indicator species (gram fresh weight per day) BW: Body weight (g) C: Concentration of compound in fresh diet (mg/kg) AV: Avoidance factor (0 to 1) PT: Fraction of diet obtained in treated area (0 to 1) PD: Fraction of food type in diet (0 to 1) Regression equations to predict dry weight intake for an animal (Nagy, 1987) For all birds: log DFI = 0.651 x log BW - 0.188 For songbirds: log DFI = 0.85 x log BW - 0.4 For other birds: log DFI = 0.751 x log BW - 0.521 For mammals: log DFI = 0.822 x log BW - 0.629 Daily food intake of the indicator species DEE FIR ( FE (1 ( MC / 100)) ( AE / 100) FIR: DEE: FE: MC: AE: Food intake rate of indicator species (gram fresh weight per day) Daily Energy Expenditure of the indicator species (kJ per day) Food Energy (kJ per dry gram) Moisture Content (%) Assimilation Efficiency (%) From Crocker et al. 2002 Comparison of daily food intake based on different calculation methods Bird Method Body Wt Mean food intake* Song birds: Tree sparrow; Passer montanus Tree sparrow; Passer montanus Rook; Corvus frugeligus Rook; Corvus frugeligus * Based on cereal seeds and fresh weight; Nagy 1987 Croker et al. 02 Nagy 1987 Croker et al. 02 22.0 g 22.0 g 488.0 g 488.0 g 6.3 g 7.6 g 87.0 g 67.5 g Comparison of daily food intake based on different calculation methods Bird Method Body Wt Mean food intake* Nagy 1987 Croker et al. 02 Nagy 1987 Croker et al. 02 381 g 381 g 953.0 g 953.0 g 29.5 g 50.6 g 58.9 Other birds: Grey patridge; Perdix perdix Grey patridge; Perdix perdix Pheasant; Phasianua colchicus Pheasant; Phasianua colchicus * Based on cereal seeds and fresh weight; 102.7 Comparison of daily food intake based on different calculation methods Animals Method All birds: Nagy 1987 343.5 Croker et al. 02 343.5 32.9 g 29.2 g Nagy 1987 7.0 Croker et al. 02 7.0 1.4 2.3 Mammals Harvest mouse, Micromys minutus * Based on cereal seeds (fresh weight) Body Wt Mean food intake* Estimated Daily Intake of a.i. in a small cereal seeds eating bird (b.w. 15 g)* FIR EDI C AV PT PD BW Estimated daily intake of a.i.: Food intake rate: Body weight: Concentration of a.i. in fresh diet : Avoidance factor: Fraction of diet obtained in treated area: Fraction of food type in diet: 19.3 mg kg bw/d 5.8 g/day 15 g. 50 mg/kg 1 1 1 * Realistic worst case; based on calculations from Crocker et al.2002 Estimated Daily Intake of a.i. in a small cereal seeds eating mammal (b.w. 25 g)* FIR EDI C AV PT PD BW Estimated daily intake of a.i.: Food intake rate: Body weight: Concentration of a.i. in fresh diet : Avoidance factor: Fraction of diet obtained in treated area: Fraction of food type in diet: 11.4 mg kg bw/d 5.7 g/day 25 g. 50 mg/kg 1 1 1 * Realistic worst case; based on calculation from Crocker et al. 2002 Uncertainty of the estimated food intake Preliminary probabilistic analysis indicated that the upper 95 percentile for the estimate averaged about twice the mean estimate.This result is preliminary, but indicates the potential range of uncertainty. If the user wished to be precautionary in their assessment, multiplying the estimated food intake by a factor of two might be a reasonable precaution against underestimating food intake. Expected concentration of a.i. in the animal after elimination EC ETE (1 El ) Variable/parameter (unit) Symbol Unit Input: Estimated daily uptake of a compound ETE mg./kg/d Fraction of daily uptake eliminated (number El between 0 and 1) (number between 0 and 1) Output: Expected concentration of active EC substance in the animal in the animal mg./kg Default Refinement steps in the evaluation of the potential for primary poisoning As rodenticides inevitably are toxic to non-target species an exposure assessment that is based on exclusive feeding on the bait will always come to the conclusion of potential risk. Two refinement steps are obvious: Consider accessibility of baits: Accessibility might be reduced by requiring appropriate use instructions to be put on the label Consider attractivity: The bait could be unattractive to e.g. birds to a certain degree due to colour, consistency and other factors. Secondary poisoning Calculation of rodenticide in target animal on Day 1 immediately after first meal The food intake rate divided with body weight is as default set to 10% i.e. FIR/BW = 0.1 illustrating realistic worst case (AV, PT, and PD = 1) The concentration of a.i. in the bait C = 50 mg/kg ETE 0.1 50 111 5mg / kg Secondary poisoning The estimated residue concentration in target rodent on Day 2 before meal: EC2 = 5 x (1- 0.3) = 3.5 mg/kg Day 5 after the last meal = 13.9 mg/kg Day 6 * = 9.7 mg/kg Day 7 (mean time to death) = 6.8 mg/kg * The feeding period has been set to a default value of 5 days until the onset of symptoms after which it eats nothing until its death Secondary poisoning For short term exposure the fraction of poisoned rodents in predator´s diet is assumed to be 1. For long term exposure the fraction of poisoned rodents in predator´s diet is assumed to be 0.5. Secondary poisoning Predators (mammals or birds) feeding on poisoned rodents Oral exposure (PECoral,predator) depends on ECn: Estimated Concentration in rodent on day n ETE: Estimated daily uptake on day n Frodent: Fraction of poisoned rodent in diet of predator ECn depends on fraction bait consumption PECoral, predator ( EC n ETE ) Frodent Secondary poisoning: Estimated Concentration in poisoned rodent 18 16 14 Residues, mg/kg 12 20% before 20% after 50% before 50% after 100% before 100% after 10 8 6 4 2 0 1 3 5 7 9 Day 11 13 Refinement steps in the evaluation of the potential for secondary poisoning If a risk is indicated the following options for refinement are promising: Evaluate secondary poisoning studies which are already available for current rodenticides Improve estimate of proportion of target rodent in the diet of predators; suitable information might already be available from literature on feeding ecology; otherwise data could be generated using a marker in the bait Field studies, monitoring Conclusions PT 14 Rodenticides Emission Scenario Document has been prepared (Danish EPA, EUBEES 2) ESD covers use scenarios and environmental compartments of (presumed) highest concern ESD based on empirical data & default values ESD has not been validated in practice ESD can be used when no other data are available Applicants should, whenever possible, use specific data on use pattern and emission rate Conclusions PT 14 Rodenticides Emission Scenario Document has been prepared (Danish EPA, EUBEES 2) ESD covers use scenarios and environmental compartments of (presumed) highest concern ESD based on empirical data & default values ESD has not been validated in practice ESD can be used when no other data are available Applicants should, whenever possible, use specific data on use pattern and emission rate
