UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES



## Probabilistic Analysis

**Probabilistic Analysis for the**  **Notice of Intent to Cancel Non c**  **ompliant Rodenticide**

**Products Containing Brodifacoum, Difethialone, Chlorophacinone, Diphacinone,**  **Warfarin, or Bromethalin**



### January **24 , 2013** 

**Office of Pesticides Programs**

Prepared by:

Elizabeth Riley Office of Pesticide ProgramsWhile the relative sensitivity of the standard test species used in the deterministic assessment is unknown, EPA conducted a probabilistic analysis that varied whole body residue and acute toxicity values to inform the level of confidence and explore uncertainty in the likelihood that a randomly selected secondary consumer may achieve a lethal rodenticide dose. This was accomplished using a Monte Car lo simulation with a distribution of possible outcomes that were analyzed to allow for more thorough understanding of the uncertainties associated with the available data. The modeling exercise was performed by varying selected parameters for liver or bloo d

- plasma half

- life and the LD 50 or LC 50 . The metric for comparing chemicals was based on probability density functions for percentage of species with Risk Quotients (RQs) above the acute Level of Concern (LOC) value of 0.5 (USEPA, 2004). This represents th e likelihood that an animal feeding on prey containing rodenticide could receive a dose that exceeds 1⁄2 the LD50 for a secondary consumer with the expectation that the greater proportion of outcomes resulting in an LOC exceedance, the greater the potential for adverse outcomes.

1.1.1. Methods EPA employed a Monte Carlo

- based approach in order to evaluate uncertainty regarding toxicity values for an animal encountering prey that has ingested a rodenticide . The approach also evaluated uncertainty related to the accumulation potential of each rodenticide in prey species. In this approach, distributions were developed for the exposure ( i.e., liver or blood plasma half

life) and effects variables ( i.e., LD 50 or LC 50 values) to derive a distribution of RQs. This was accomplished using CrystalBall (version 7.3.1). This distribution was then used to determine the probability that an RQ value would be above the LOC (RQ is at or above 1⁄2 the LD50) for secondary cons umers ( e.g. , predator and scavenger birds) . EPA compared the rodenticide results in this “probability to exceed” model with the expectation that the greater proportion of random outcomes resulting in a risk exceeding EPA’s level of concern, the greater th e potential for adverse outcomes.

Because the objective of the analysis was to investigate the influence of accumulation potential and toxicity on the comparative interpretation of risks among the rodenticides, EPA treated all model inputs that were not s pecific to any rodenticide as fixed values. For purposes of comparing rodenticide active ingredients, the major assumptions for fixed variables in the model

were:

• Body weights assessed for birds at risk through secondary exposure were 100g, 1000g, and 500 0g.

• 100% of secondary consumer’s diet is intoxicated primary consumers.

• 100% of primary consumer’s diet is dry, rodenticide bait.

• Rodenticide intake in the secondary consumer was calculated based on allometric equations found in the Wildlife Factors Hand book (USEPA 1993).

• For the anticoagulant rodenticides, 1

- day, 6

- day, and 14

- day accumulation periods based on consecutive feeding events in primary consumers were selected to represent the range of accumulations possible from one anticoagulant rodenticide placement. For bromethalin, the analysis focused on a 1

- day accumulation period because bromethalin’s rapid mode of action limits the accumulation potential of the chemical. A recent study by Pitt et al. (2011) found that time to death for house mice, Poly nesian rats ( Rattus exulans ) and black rats ( Rattus rattus ) offered bromethalin may occur within 1

- 3 days. Data from this study also indicates that house mice and Polynesian rats exposed to bromethalin stopfeeding on the bait after reaching a lethal dose, further reducing the potential for accumulation. These data suggest an analysis that uses 1

- day accumulation in the prey is unlikely to underestimate accumulation of for bromethalin.

• The body weights for house mouse (23g) and Norway rat (485g) were used to represent the body weights of primary consumers likely to feed on the rodenticide bait.

• Concentration of rodenticide in bait was based on the labeled concentration. The parameters allowed to vary in the model were:

• Acute toxicity endpoint of secondary consumer (i.e., LD 50 and LC 50 values);

• Half

- life of rodenticide in prey (as measured in liver for anticoagulants or blood

- plasma for bromethalin). Acute toxicity data for each of the rodenticides are de scribed in Appendix A of the SAP Background Document. The availability of species

- specific acute toxicity data varies among the rodenticides, with warfarin having the largest dataset (9 data points) and difethialone the smallest (4 data points). Similarly, the availability of acceptable half

- life data varies widely among the rodenticides. Brodifacoum, with 12 liver half

- life values and 8 blood

- plasma half

- life values, represents the greatest data availability, while chlorophacinone and bromethalin only have one half

- life value available each (measured in liver and blood

- plasma, respectively).

Because the toxicity data for each chemical may have come from different test species, LD 50 values were normalized for body weight to a 1kg animal using EPA’s standard method of calculating weight

- adjusted toxicity values. These normalized LD 50 values were then adjusted to standard body weights representative of secondary consumers of interest (100g to 5,000g for birds) in the equations used to calculate RQs. After all of the data were compiled, the range of individual data points for toxicity and metabolic half

- lives for each rodenticide were each represented as a probability distribution, fitted to log normal distributions. The result was 5 different distributions of c hemical

- specific parameters for each rodenticide (2 different distributions for the 2 toxicity endpoints and 1 for the metabolism half

- life), except in cases where there were less than two data points for a particular parameter, such that probability distr ibutions could not be created. For example, there is only 1 LC 50 value available for diphacinone, while chlorophacinone and bromethalin each have only 1 half

- life value (for liver and blood plasma, respectively). In those cases the single available toxicit y or half

- life value acted as a fixed variable in the model. Toxicity distributions were truncated at the 2.5 th and 97.5 th percentiles to reduce the potential for unreasonable extreme values in the data sets and to maintain a range of toxicity more reflect ive of the available data. Similarly, half

- life values were truncated at the lowest and highest values observed in the open literature and registrant

submitted studies. Once the data were fitted to log normal distributions, a random value was generated usi ng the parameters of the fitted distribution using the forecast function within the CrystalBall program. The randomly selected value was then used in the equations to calculate an RQ value. The Monte Carlo simulation repeated this process 10,000 times to c reate a distribution of RQs for each of the scenarios of interest.

1.1.2. Results

Although EPA performed the probabilistic assessment for predator/scavenger birds and mammals, the results and conclusions sections of this response will focus on birds at risk throughsecondary exposure, which are the subject of the SAP comment. The probab ilistic assessment for mammals at risk through secondary exposure sheds no new light on the issues in the proposed cancellations, as it simply confirms, as did the Agency’s deterministic assessment, that rodenticides designed to target mammalian species wi ll be toxic to mammals regardless of whether they are primary or secondary consumers. However, the enhanced toxicity and extended residence time in non

- target animals suggests that bioaccumulation potential and resulting secondary poisoning potential of br odifacoum and difethialone are greater relative to the other assessed rodenticides. The results of the probabilistic assessment for birds are shown in tables below ( Tables 1

- 4 ) . The percentage values, which represent the likelihood a randomly selected bir d from a particular weight class may acquire a lethal dose under the assumption in this evaluation, were visually estimated from the graphical distribution of the various distributions. As an example, Figure 1 shows the distribution of RQs for large raptor s consuming small mammals exposed to rodenticide bait for 1 day (graphs for all exposure scenarios can be found in Appendix 1 ). The RQ value, in log scale, is displayed along the horizontal axis and the likelihood of a predator or scavenger of the particular class experiencing a lethal dose, expressed

as percentages by increasing value, is displayed along the vertical axis. The vertical red line represents where the RQ value is equal to the LOC of 0.5. Po rtions of distributions that appear to the right of the vertical red line indicate species on the distribution with RQ values greater than the LOC, and thus at risk for mortality. The percentage of RQ values above the LOC are visually represented as the po int where the distribution crosses the vertical red line, to the nearest 5%, subtracted from 100%. These percentages allow for the comparison of risks among chemicals where larger percentage values suggest a higher likelihood that a randomly selected bird may achieve a lethal dose under the assumptions of this analysis.Figure 1. Distribution of Acute RQs for 5000g Birds Consuming Mice Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneAcute Dose

- Based Assessment

Ten thousand RQs were calculate d for 100

- g birds consuming mice or rats that are primary consumers of rodenticides based on the 10,000 randomly sampled LD 50 and half

- life values. For each rodenticide, the values in Table 1 provide the percentage of calculated RQs that were above the LOC for 100

- g birds when toxicity and exposure parameters were randomly sampled. These percentages allow for the comparison of risks among chemicals where larger percentage values suggest a higher likelihood that a randomly selected b ird may achieve a lethal dose under the assumptions of this analysis. Based on this analysis, birds have a high likelihood of receiving a dose that exceeds 1⁄2 the LD50 (RQ exceeds the LOC) when consuming prey species intoxicated with brodifacoum, difethialo ne and bromethalin, even where the prey have only consumed the equivalent of one day’s feeding. However, the likelihood of bird RQs exceeding the LOC from secondary exposure to difethialone is less than the likelihood resulting from secondary exposure to b rodifacoum or bromethalin, even under the 1

- day accumulation scenario. Relative to the risks of brodifacoum, difethialone and bromethalin, there is a lower likelihood that birds consuming prey contaminated with warfarin would receive a dose sufficient to result in LOC exceedances in all scenarios. Chlorophacinone and diphacinone have still lower likelihoods of exceeding the level of concern, relative to the other assessed rodenticides, though it should be noted that sensitive 100

- g birds feeding on small m ammals exposed to diphacinone bait for extended period of time may exceed concern levels.

Table 1 . Percentage of Acute Dose

- Based RQs for 100 g Birds that are Greater than the LOC.

Duration of accumulation in

prey (days) Brodifacoum Difethialone Warfarin Chlorophacinone Diphacinone Bromethalin

House Mouse as prey 1 99% 60% 5% ~0% ~0% 95% 6 100% 80% 50% ~0% ~0% NA 14 100% 85% 75% ~0% 1% NA Norway Rat as prey 1 70% 40% ~0% ~0% ~0% 10% 6 100% 65% 10% ~0% ~0% NA 14 100% 75% 30% ~0% ~0% NA NA

- not applicable. Animals consuming bromethalin are not expected to continue feeding on bromethalin bait for six or fourteen days.

For each rodenticide, the values in Table 2 provide the percentage of calculated RQs that exceeded the LOC for 1000

- g birds when toxicity and exposure parameters were randomly sampled. Based on this analysis, 1000g birds have a high likelihood of receiving a dose sufficient to exceed the LOC when consuming prey species intoxicated with b rodifacoum and difethialone. However, there is a higher likelihood of risk from exposure to prey contaminated with brodifacoum than difethialone. For warfarin there is little chance of predator/scavenger birds receiving a dose that may exceed the LOC, exc ept under high accumulation scenarios. Bromethalin, chlorophacinone and diphacinone have lower likelihoods of triggering concern relative to the other rodenticides evaluated.Table 2 . Percentage of Acute Dose

- Based RQs for 1000 g Birds that are Greater th an the LOC. Exposure Type Brodifacoum Difethialone Warfarin Chlorophacinone Diphacinone Bromethalin House Mouse as prey 1 95% 40% ~0% ~0% ~0% 10% 6 100% 65% 15% ~0% ~0% NA 14 100% 75% 40% ~0% ~0% NA Norway Rat as prey 1 60% 25% ~0% ~0% ~0% ~0% 6 100% 50% ~0% ~0% ~0% NA 14 100% 60% 40% ~0% ~0% NA NA

- not applicable. Animals consuming bromethalin are not expected to continue feeding on bromethalin bait for six or fourteen days.

For each rodenticide, the values in Table 3 provide the percentage of calculated RQs that exceeded the LOC for 5000

- g birds when toxicity and exposure parameters were randomly sampled. Based on this analysis, 5000g birds have a high likelihood of receiving a dose sufficient to exceed the LOC when consuming prey species intoxicated with brodifacoum and difethialone. However, there is a higher likelihood of risk from secondary exposure to brodifacoum than difethialone. For warfarin, there is little chance of predator/scavenger birds receiving a dose that results in an LOC exceedance, except under high accumulation scenarios. Bromethalin, chlorophacinone and diphacinone have a lower likelihood of exceeding the LOC relative to the other rodenticides evaluated.

Table 3 . Percentage of Acute Dose

- Based RQs for 5000 g Birds that are Greater than the LOC. Exposure Type Brodifacoum Difethialone Warfarin Chlorophacinone Diphacinone Bromethalin House Mouse as prey 1 95% 30% ~0% ~0% ~0% ~0% 6 100% 55% 5% ~0% ~0% NA 14 100% 65% 15% ~0% ~0% NA Norway Rat as prey 1 50% 15% ~0% ~0% ~0% ~0% 6 99% 35% ~0% ~0% ~0% NA 14 100% 50% ~0% ~0% ~0% NA NA

- not applicable. Animals consuming bromethalin are not expected to continue feeding on bromethalin bait for six or fourteen days.

Acute Dietary

- Based Assessment

For each rodenticide, the values in Table 4 provide the percentage of calculated dietary

- based RQs that exceeded the LOC for birds when toxicity and exposure parameters were randomly sampled. Based on this analysis, birds have a high likelihood of receiving a dose sufficient to exceed the LOC when consuming prey species intoxicated with brodifacoum and difethialone on a dietary basis. For warfarin and chlorophacinone there is little chance of predator/scavenger birds receiving a dose sufficient to exceed the LOC, except under high accumulation scenarios. Again, birds feeding on diphacinone and bromethal in contaminated animals have lower likelihood of exceeding concern levels relative to the other rodenticides evaluated.Table 4 . Percentage of Acute Dietary

- Based RQs for Birds that are Greater than the LOC. Exposure Type Brodifacoum Difethialone Warfarin Chlorophacinone Diphacinone Bromethalin
House Mouse as prey 1 100% 100% ~0% ~0% ~0% ~0% 6 100% 100% 1% 15% ~0% NA 14 100% 100% 15% 60% ~0% NA Norway Rat as prey 1 95% 50% ~0% 0% ~0% ~0% 6 100% 100% ~0% 0% ~0% NA 14 100% 100% ~0% 5% ~0% NA NA

- not applicable. Animals consuming bromethalin are not expected to continue feeding on bromethalin bait for six or fourteen days.

1.1.3. Conclusions For each chemical, results from the probabilistic assessment support the overall conclusions the EPA has draw n from the other lines of evidence ( i.e., RQ estimates, quantity of contaminated mice or rats in diet required to consume the equivalent of an LD 50 , and results of the secondary feeding studies). Results of the probabilistic assessment indicate:

• Brodifacou m and difethialone pose greater secondary exposure risk to birds relative to the other chemicals assessed regardless of exposure scenario.

• Bromethalin may pose secondary exposure risk to certain sensitive species ( i.e., small birds consuming small prey a nimals); however, potential for secondary risk is somewhat limited due to the lower likelihood of continuous feeding of prey after reaching a lethal threshold and rapid mortality observed in primary feeding studies with bromethalin. Risks to small birds co nsuming large prey animals and risks to medium and large birds consuming small or large prey animals are substantially lower than for brodifacoum and difethialone.

• Warfarin may pose risk to certain sensitive species, especially under high accumulation

scen arios; however, the likelihood of secondary exposure to exceed the LOC for warfarin is substantially lower than for brodifacoum and difethialone.

• Diphacinone does not have a high likelihood of triggering secondary risk concerns regardless of accumulation scenario assessed. However, results of the probabilistic analysis indicate that there is a possibility that the most sensitive smaller secondary avian consumers modeled may be at risk from diphacinone poisoning under the highest accumulation scenario. EPA recognized potential for risks to this class of birds in the SAP background document. Secondary exposure risks for diphacinone are substantially lower than for brodifacoum and difethialone.

• For chlorophacinone, results of the probabilistic analysis for th e acute dose

- based exposure scenarios demonstrate a low likelihood of secondary exposure risk. However, results of the probabilistic assessment conducted for dietary

- based exposure indicate that chlorophacinone may have a greater likelihood of posing risk to predator/scavenger birds under the higher accumulation scenarios than the one

- day accumulation scenario. While these results represent a departure from the other analyses, the likelihood of secondary exposure risk for chlorophacinone is still substantia lly lower than for brodifacoum and difethialone.1.1.4. Uncertainties

Uncertainties associated with the available data are discussed in the SAP Background Document. Uncertainties associated with this type of probabilistic assessment have been discussed in previous SAP meetings (USEPA, 2001). A few of the important limitations are discussed below.

As discussed above, the availability of acute toxicity data varies widely among the rodenticides. Distributions created from few data points can result in signific antly different estimates of risk depending on where the individual species lies on the sensitivity distribution, particularly at the extremes, i.e., opposite tails. Given that the avian toxicity datasets for each of the chemicals are relatively small (2 t o 4 LD 50 definitive values and 1 to 5 definitive LC 50 values), EPA believes that this uncertainty is common across the chemicals and exerts a similar influence on the confidence of each chemical’s separate analysis. The availability of acceptable half

- life data also varies widely among the rodenticides. Brodifacoum, with 12 liver half

- life values and 8 blood

plasma half

- life values, has the most data available, while chlorophacinone and bromethalin only have one half

- life value available each (measured in l iver and blood

- plasma, respectively). As discussed above, when only one toxicity or half

- life value was available, the data point was treated as a fixed variable in the model. For chlorophacinone and bromethalin, the single half

- life values available resul ted in steeper distributions, which reflect the potential uncertainty associated with a single data point..

EPA has used the available toxicity data to construct distributions of possible species sensitivity. The variance of each of these distributions i s different and owes much to the number and breadth of the species randomly selected for testing in addition to the actual inherent variability of sensitivity. As discussed in the SAP Background Document, there is uncertainty associated with using the stan dard test species (bobwhite quail and mallard duck) to represent toxicity for secondarily exposed bird species. For example, Rattner et al. (2011) reported an LD 50 value of 96.8 mg a.i./kg

- bwt for American kestrels ( Falco sparverius ) consuming diphacinone, which is approximately 20 times more sensitive than the LD 50 values reported for the bobwhite quail. The probabilistic assessment addresses this uncertainty for diphacinone by including the more sensitive LD 50 value in the estimation of the parameters of the log normal distribution for LD 50 values. Results of the assessment indicate that approximately 1% of 100

- g predator/scavenger birds could receive a dose of diphacinone that would result in risk concerns. However, none of the other evaluated rodenticide s have data for which an LD 50 for raptors or, more generally, predatory/scavenging birds is available, so it is uncertain if this increased sensitivity would be the same across the different rodenticides or different predatory/scavenging bird species.

Alt hough this assessment modeled multiple exposure scenarios, including multiple prey types, accumulation scenarios, and predator body weights, it does not encompass the entirety of possible scenarios. For example, probabilities associated with food intake fo r the primary and secondary consumers were not evaluated in this assessment due to the limited nature of the data set. Also, exposure scenarios where contaminated animals were consumed occasionally or where target species fed on less than a single day of food for multiple days were not quantified. However, if these scenarios were included in the probabilistic model, they would accentuate, rather than diminish, the conclusions that chemicals with longer retention times pose greater secondary exposure risks relative to chemicals with shorter retention times, and that chemicalsthat can cause LOC exceedances after a single feeding pose greater secondary exposure risks relative to those where multiple feeding events on contaminated animals are needed to result in LOC exceedances.

References

Pitt, W. C., Driscoll, L.C., and Sugihara, R.T. 2011. Efficacy of rodenticide baits for the control of three invasive rodent species in Hawaii. Arch. Environ. Contam. Toxicol. 60 , 533

- 542.

USEPA. 1993. Wildlife Exposur e Factors Handbook. Volume 1. EPA/600/R

- 93/187a. Office of Research and Development, Washington, D.C.Appendix 1 : Distribution Graphs

Graphs in the appendix show the distribution of RQ values derived from the Agency’s limited probabilistic risk assessments for each of the six rodenticides considered in the SAP Background Document. The RQ value, in log scale, is displayed along the horizontal axis and the likelihood of a predator of the particul ar class experiencing a lethal dose, expressed as percentages by increasing value, is displayed along the vertical axis. The vertical red line represents where the RQ value is equal to the LOC of 0.5. Portions of distributions that appear to the right of t he vertical red line indicate species on the distribution with RQ values greater than the LOC, and thus at risk for mortality. The percentage of RQ values above the LOC are visually represented as the point where the distribution crosses the vertical red l ine, to the nearest 5%, subtracted from 100%. These percentages allow for the comparison of risks among chemicals where larger percentage values suggest a higher likelihood that a randomly selected bird may achieve a lethal dose under the assumptions of th is analysis.100 g Birds Dose

- Based Exposure

Figure 1. Di stribution of Acute RQs for 100 g Birds Consuming Mice Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 2. Di stribution of Acute RQs for 100 g Birds Consuming Mice Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 3. Distribution of Acute RQs for 100 g Birds Consuming Mice Exposed to Bait for 14 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 4. Di stribution of Acute RQs for 100 g Birds Consuming Rats Exposed to Bait for 1 DayFigure 5. Di stribution of Acute RQs for 100 g Birds Consuming Rats Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 6. Distribution of Acute RQs for 100 g Birds Consuming Rats Exposed to Bait for 14 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

Diphacinone1 000 g Birds Dose

- Based Exposure

Figure 7. Distribution of Acute RQs for 1 000 g Birds Consuming Mice Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 8. Distribution of Acute RQs for 1 0 00g Birds Consuming Mice Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 9. Distribution of Acute RQs for 1 000 g Birds Consuming Mice Exposed to Ba it for 1 4 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 10. Di stribution of Acute RQs for 1000 g Birds Consuming Rats Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 11. Di stribution of Acute RQs for 1000 g Birds Consuming Rats Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 12. Distribution of Acute RQs for 1000 g Birds Consuming Rats Exposed to Bait for 14 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

Diphacinone5000 g Birds Dose

- Based Exposure

Figure 13. Distribution of Acute RQs for 5000 g Birds Consuming Mice Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 14. Distribution of Acute RQs for 5000 g Birds Consuming Mice Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

Diphacinone

Figure 15. Distribution of Acute RQs for 5000 g Birds Consuming Mice Exposed to Bait for 1 4 Day s0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 16. Di stribution of Acute RQs for 5000 g Birds Consuming Rats Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 17. Di stribution of Acute RQs for 5000 g Birds Consuming Rats Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 18. Distribution of Acute RQs for 5000 g Birds Consuming Rats Exposed to Bait for 14 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00001 0.0001 0.001 0.01 0.1 1 10 100 1000Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneDietary

- Based Exposure

Figure 19. Distribution of Dietary RQs for Birds Consuming Mice Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00 0.00 0.01 0.10 1.00 10.00 100.00Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 20. Distribution of Dietary RQs for Birds Consuming Mice Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00 0.00 0.01 0.10 1.00 10.00 100.00Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 21. Distribution of Dietary RQs for Birds Consuming Mice Exposed to Bait for 1 4 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.0001 0.001 0.01 0.1 1 10 100Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 22. Di stribution of Dietary RQs for Birds Consuming Rats Exposed to Bait for 1 Day

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.00 0.00 0.01 0.10 1.00 10.00 100.00Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Bromethalin

Chlorophacinone

DiphacinoneFigure 23. Di stribution of Dietary RQs for Birds Consuming Rats Exposed to Bait for 6 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.0001 0.001 0.01 0.1 1 10 100Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

DiphacinoneFigure 24. Distribution of Dietary RQs for Birds Consuming Rats Exposed to Bait for 14 Day s

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0.0001 0.001 0.01 0.1 1 10 100Percentile

RQ value (log scale) Brodifacoum

Difethialone

Warfarin

Chlorophacinone

Diphacinone