Emission scenario document for biocides used as rodenticides Jrgen Larsen

1
Emission scenario document for biocides used as
rodenticidesJørgen Larsen

• PT 8 PT 14 Exposure Scenario Course
• 9-10 October 2003, Ispra

2
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

3
Life-cycle of rodenticides
4
PT 14 Rodenticides

• Used for controlling rodents
• Rats
• Mice
• Voles
• Basic use scenarios
• Sewer systems
• Buildings (inside and around)
• Open fields
• Waste dumps

5
Rodenticides Application methods
6
Rodenticides Compartments of concern
7
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

8
Sewer systems STP
9
Sewer systems Results

• Substance A
• Anti-coagulant (0.005 a.i.)
• Elocalwater 0.2 g a.i./day
• Cinfluent 0.1 µg a.i./L

• Substance B
• Coagulant (4 a.i.)
• Elocalwater 150 g a.i./day
• Cinfluent 77 µg a.i./L

10
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

11
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)

12
Buildings Direct emission
13
Buildings Direct soil exposure
14
Buildings Indirect emission
15
Buildings Indirect soil exposure
16
Buildings Results re. bait stations

• Substance A
• Anti-coagulant (0.005 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-DID 0.047 mg/kg

• Substance B
• Coagulant (4 a.i.)
• 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-DID 37 mg/kg

17
Open areas Assumptionsre. 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

18
Open areas Emission in rat burrow
19
Open areas Concentration in rat burrow
20
Open areas Results, pellets in rat burrow

• Substance A
• Anti-coagulant (0.005 a.i.)
• Elocal-D 0.0025 g a.i.
• Clocal-D 0.17 mg a.i./kg

• Substance B
• Coagulant (4 a.i.)
• Elocal-D 2 g a.i.
• Clocal-D 138 mg a.i./kg

21
Open areas Assumptionsre. 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)

22
Open areas Release of contact powder
23
Open areas Results, contact powder

• Substance A
• Anti-coagulant (0.005 a.i.)
• Elocal-D 0.0045 g a.i.
• Clocal-D 0.3 mg a.i./kg

• Substance B
• Coagulant (4 a.i.)
• Elocal-D 3.6 g a.i.
• Clocal-D 250 mg a.i./kg

24
Primary poisoning Estimated Daily Intake

• 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)

25
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

26
Daily food intake of the indicator species
FIR Food intake rate of indicator
species (gram fresh weight per day)
DEE Daily Energy Expenditure of the indicator
species (kJ per day) FE Food Energy (kJ
per dry gram) MC Moisture Content ()
AE Assimilation Efficiency () From Crocker
et al. 2002
27
Comparison of daily food intake based on
different calculation methods
28
Comparison of daily food intake based on
different calculation methods
29
Comparison of daily food intake based on
different calculation methods
30
Estimated Daily Intake of a.i. in a small cereal
seeds eating bird (b.w. 15 g)
Estimated daily intake of a.i. 19.3 mg kg
bw/d Food intake rate 5.8 g/day Body
weight 15 g. Concentration of a.i. in fresh
diet 50 mg/kg Avoidance factor 1
Fraction of diet obtained in treated
area 1 Fraction of food type in diet 1
Realistic worst case based on calculations from
Crocker et al.2002
31
Estimated Daily Intake of a.i. in a small cereal
seeds eating mammal (b.w. 25 g)
Estimated daily intake of a.i. 11.4 mg kg
bw/d Food intake rate 5.7 g/day Body
weight 25 g. Concentration of a.i. in fresh
diet 50 mg/kg Avoidance factor 1
Fraction of diet obtained in treated
area 1 Fraction of food type in diet 1
Realistic worst case based on calculation from
Crocker et al. 2002
32
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.
33
Expected concentration of a.i. in the animal
after elimination
34
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.

35
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

36
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

37
Secondary poisoning

• For short term exposure the fraction of poisoned
  rodents in predators diet is assumed to be 1.
• For long term exposure the fraction of poisoned
  rodents in predators diet is assumed to be 0.5.

38
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

39
Secondary poisoning Estimated Concentration in
poisoned rodent
40
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

41
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

42
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