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tetramethrin occupational and residential exposure (ORE) assessments. This review specifically 

addresses risks after consideration of a benchmark dose analysis in the November 30, 2009 

revised supplemental submission.

1.0 Executive Summary 

The most recent occupational and residential exposure and risk assessment for tetramethrin 

(D292299; June 13, 2008) identified inhalation and non-dietary ingestion risks of concern for 

children (e.g., 1-2 years old) using standard assessment EPA practices such as deterministic 

methods and conservative assumptions. As a result, the tetramethrin registrant submitted a 

probabilistic assessment in 2008 using the Cumulative and Aggregate Risk Evaluation System 

(CARES® Version 3.0), a publicly available software program that EPA has previously utilized 

and continues to recognize as useful for conducting probabilistic risk. This assessment, reviewed 

favorably by HED, showed margins of exposure (MOEs) ≥ 1000 for children’s non-dietary 

ingestion up to the 99.88th percentile of the exposure distribution. 

However, following submission of that assessment, products with a higher percentage of 

tetramethrin were subsequently identified and required inclusion in the assessment (i.e., previous 

assessments only considered aerosol space spray products up to 0.25% tetramethrin, while the 

maximum registrant-supported amount is actually 0.35%). Thus, a supplemental assessment was 

submitted by the registrant (3/23/2009; MRID 47713101) which presented MOEs ≥ 1000 up to 

the 99.5th percentile of the exposure distribution. HED’s review of this submission (M. Crowley, 

D363584; 4/10/09) included revisions to various assumptions made by the registrant and instead 

found MOEs ≥ 1000 only up to the 98.8th percentile after the registrant-based assumptions were 

modified. OPP’s Pesticide Re-registration Division (PRD) determined that these results did not 

support reregistration of 0.35% tetramethrin aerosol space sprays. 

As a result, the registrant has presented in its most recent submission (11/2009; MRID 

47921601) a benchmark dose (BMD) analysis of body weight data which was favorably 

reviewed in a separate HED review (R. Daiss, D292290; 1/6/10). This analysis presented 95% 

lower confidence limits on benchmark doses for 5% (BMDL5) and 10% (BMDL10) body weight 

changes. Using the BMDL5 (61 mg/kg/day; 611 ppm), non-dietary ingestion MOEs were shown 

to ≥ 1000 up to the 99.96th percentile. HED has confirmed these results and finds the revised 

supplemental exposure assessment acceptable for reregistration purposes. 

2.0 Summary of Revised Hazard Identification 

Previous assessments for children’s non-dietary ingestion exposure used a no observed adverse 

effect level (NOAEL) of 25 mg/kg/day from a 2-generation reproduction study in rats during 

which a decrease in both body weight and food consumption along with bile duct hyperplasia in 

F1 females was observed at a lowest observed adverse effect level (LOAEL) of 150 mg/kg/day. 

Based on HED’s favorable review of the benchmark dose analysis (R. Daiss, D292290, 1/6/10), 

MOE calculations are shown based on the BMDL5 (61.1 mg/kg/day). The selected toxicological 

endpoint was decreased offspring body weight on day 21 in the F0F1 generation. 
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3.0 Summary of Revised Residential Exposure and Risk 

As the supplemental assessment was conducted to address risks of concern for children’s nondietary ingestion exposure following use of 0.35% tetramethrin aerosol space sprays, only these 

risks are presented and summarized below. The following table is adapted from Attachment C of 

the November 30, 2009 revised supplemental and summarizes upper-end exposure percentiles 

and MOE calculations using the CARES program and the inputs HED outlined in the previous 

supplemental submitted by the registrant. HED confirms the upper-end exposure percentiles 

shown are unchanged from a previous review (reflecting appropriate use of HED-recommended 

inputs and assumptions). The exposure factor inputs used in the CARES program are also 

attached for reference. 

MOE Table from Attachment C of MRID 

47921601 

Percentile 

TedU (Toxic 

Equivalent 

Dose - User 

Only) 

(mg/kg/day) 

MOE - UserOnly (Using 

BMDL05 value 

of 61.1 

mg/kg/day) 

100 0.081 754 

99.99 0.07 873 

99.98 0.067 912 

99.97 0.063 970 

99.96 0.061 1002 

99.95 0.059 1036 

99.94 0.058 1053 

99.93 0.055 1111 

99.92 0.055 1111 

99.91 0.055 1111 

99.9 0.054 1131 

99.89 0.053 1153 

99.88 0.049 1247 

99.87 0.047 1300 

99.86 0.046 1328 

99.85 0.046 1328 

99.84 0.046 1328 

99.83 0.045 1358 

99.82 0.042 1455 

99.81 0.042 1455 

99.8 0.042 1455 

4.0 Conclusion 

HED has confirmed that for the exposure modeling results submitted by the tetramethrin 

registrant using CARES, MOEs are > 1000 (using the BMDL5) at the 99.9th percentile exposure 

and can be referenced for the purposes of tetramethrin reregistration. Also, as HED outlined in 

previous assessments, these results should be viewed in context of other assumptions 

incorporated into standard residential exposure assessments. That is, estimated risks reflect the 

population of “exposed only” (i.e., the assessment was not for all children, only those who are 
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exposed to tetramethrin) and the exposure calculated as “day 0” (i.e., individuals continuously 

experience exposure on the “day of application” without consideration of dissipation and retreatment). Both of these aspects are considered to add additional conservatism to the 

assessment. 

It is important to note that this assessment is limited to tetramethrin indoor space sprays, and 

does not incorporate other registered uses such as outdoor uses (e.g., lawn treatment, yard 

foggers, perimeter treatments) or other indoor uses (e.g., pet sprays, crack-and-crevice 

treatments). Consideration of these exposure scenarios was included in previous tetramethrin 

assessments. As such, this assessment does not aggregate multiple uses of this active ingredient 

(e.g, a household in which spraying a lawn, treating a pet, and using both indoor space as well as 

crack and crevice sprays occurs on the same day). Current HED policy on aggregating such uses 

is on a case-by-case basis and the present registrant submission did not attempt to perform such 

aggregation. To appropriately perform such aggregation using a fully probabilistic approach 

would require additional data on use rates, percent of households applying the product, 

concurrent use practices, and timing of use and retreatment intervals. HED does not yet have 

policies or procedures for single chemical assessments that address these data inputs. 
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Attachment: CARES Inputs
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Residential Wizard SettingsScenarios & Methods Scenario During/Post Route Method Pet Care - 1 Post Ingestion (H-To-M) Ingestion 109: EPA SOP Outdoor Fogger Use - 1 Post Ingestion (H-To-M) Ingestion 109: EPA SOP Outdoor Fogger Use - 1 Post Inhalation Inhalation 104: Air Concentration, Calculated Indoor Fogger Use - 1 Post Ingestion (H-To-M) Ingestion 109: EPA SOP Indoor Treatment - 1 Post Ingestion (H-To-M) Ingestion 109: EPA SOP Indoor Treatment - 1 During Inhalation Inhalation 102: Unit Exposure, Amount of Formulation 

Used 

Indoor Treatment - 1 Post Inhalation Inhalation 103: Air Concentration, Specified Custom - 1 Post Ingestion (H-To-M) Ingestion 109: EPA SOP Custom - 1 Post Inhalation Inhalation 104: Air Concentration, CalculatedScenarios & Products Scenario Product CAS Product Probability Outdoor Fogger Use P101;Outdoor Total 

Release Fogger 

Tetramethrin 1 

Indoor Treatment P102;Indoor Spray - 

Aerosol Can 

Tetramethrin 1 

Pet Care P103;Pets - Aerosol 

Can 

Tetramethrin 1 

Indoor Fogger Use P104;Indoor Total 

Release Fogger 

Tetramethrin 1 

Indoor Treatment P105;Indoor Spray - 

RTU 

Tetramethrin 0 

Custom P106;Outdoor Spray - 

Handheld Fogger 

Tetramethrin 0.5 

Custom P107;Outdoor Spray - 

Aerosol Can 

Tetramethrin 0.5

Scenario Probabilities Scenario Scenario 

Probability 

Market Share (Chemical Probability) 

Pet Care - 1 0 0 Outdoor Fogger Use - 1 0 0 Indoor Fogger Use - 1 0 0 Indoor Treatment - 1 1 1 Custom - 1 0 0
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Event Allocation Monthly Probabilities (Jan-Jun) Scenario Jan Feb Mar Apr May Jun Pet Care - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Outdoor Fogger Use - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Indoor Fogger Use - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Indoor Treatment - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Custom - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833Monthly Probabilities (Jul-Dec) Scenario Jul Aug Sep Oct Nov Dec Pet Care - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Outdoor Fogger Use - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Indoor Fogger Use - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Indoor Treatment - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833 Custom - 1 0.0833 0.0833 0.0833 0.0833 0.0833 0.0833Day of Week Probabilities Scenario Sun Mon Tue Wed Thr Fri Sat Pet Care - 1 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 Outdoor Fogger Use - 1 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 Indoor Fogger Use - 1 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 Indoor Treatment - 1 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 Custom - 1 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429 0.1429Annual Use & Treatment Interval Scenario # Uses Treatment Interval (Days) Pet Care - 1 Single (10) Single (10) Outdoor Fogger Use - 1 Single (10) Single (10) Indoor Fogger Use - 1 Single (10) Single (10) Indoor Treatment - 1 Single (10) Single (10) Custom - 1 Single (10) Single (10)Co-Occurrence Scenario 1 Scenario 2 Co-Occurence Pet Care - 1 Pet Care - 1 0 Pet Care - 1 Outdoor Fogger Use - 1 0 Pet Care - 1 Indoor Fogger Use - 1 0 Pet Care - 1 Indoor Treatment - 1 0 
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Pet Care - 1 Custom - 1 0 Outdoor Fogger Use - 1 Pet Care - 1 0 Outdoor Fogger Use - 1 Outdoor Fogger Use - 1 0 Outdoor Fogger Use - 1 Indoor Fogger Use - 1 0 Outdoor Fogger Use - 1 Indoor Treatment - 1 0 Outdoor Fogger Use - 1 Custom - 1 0 Indoor Fogger Use - 1 Pet Care - 1 0 Indoor Fogger Use - 1 Outdoor Fogger Use - 1 0 Indoor Fogger Use - 1 Indoor Fogger Use - 1 0 Indoor Fogger Use - 1 Indoor Treatment - 1 0 Indoor Fogger Use - 1 Custom - 1 0 Indoor Treatment - 1 Pet Care - 1 0 Indoor Treatment - 1 Outdoor Fogger Use - 1 0 Indoor Treatment - 1 Indoor Fogger Use - 1 0 Indoor Treatment - 1 Indoor Treatment - 1 0 Indoor Treatment - 1 Custom - 1 0 Custom - 1 Pet Care - 1 0 Custom - 1 Outdoor Fogger Use - 1 0 Custom - 1 Indoor Fogger Use - 1 0 Custom - 1 Indoor Treatment - 1 0 Custom - 1 Custom - 1 0INPUTS Scenario-Specific Group Variable Name Unit Value Outdoor Fogger Use - 1 Exposure Duration (Adult) hr/day Uniform (1,2) Outdoor Fogger Use - 1 Exposure Duration (Child) hr/day Percentile2 (interpolated) 

(0 0 5 0.083 25 0.75 50 0.9 75 2.4 90 3.5 100 3.5) 

Indoor Treatment - 1 Exposure Duration (Adult) hr/day Uniform (1,8) Indoor Treatment - 1 Exposure Duration (Child) hr/day Uniform (1,8) Custom - 1 Exposure Duration (Adult) hr/day Uniform (1,2) Custom - 1 Exposure Duration (Child) hr/day Percentile2 (interpolated) 

(0 0 5 0.083 25 0.75 50 0.9 75 2.4 90 3.5 100 3.5)

Method-Specific Group Variable Name Unit Value Pet Care - 1 ; Ingestion 109: EPA SOP Contact Frequency (Hand-to-Mouth) event/hr Triangular 

(1,13,26) 

Pet Care - 1 ; Ingestion 109: EPA SOP Transfer Efficiency per Contact (Hand-toMouth) unitless Uniform (0.2,0.5) 
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Pet Care - 1 ; Ingestion 109: EPA SOP Exposure Duration hr/day Triangular 

(0.03,0.108,1.03) 

Pet Care - 1 ; Ingestion 109: EPA SOP Surface Area - Hands (Mouthed) cm2 Triangular 

(1,7,20) 

Outdoor Fogger Use - 1 ; Ingestion 109: EPA SOP Contact Frequency (Hand-to-Mouth) event/hr Triangular 

(1,6,26) 

Outdoor Fogger Use - 1 ; Ingestion 109: EPA SOP Transfer Efficiency per Contact (Hand-toMouth) unitless Uniform (0.2,0.5) Outdoor Fogger Use - 1 ; Ingestion 109: EPA SOP Exposure Duration hr/day Uniform (1,2) Outdoor Fogger Use - 1 ; Ingestion 109: EPA SOP Surface Area - Hands (Mouthed) cm2 Triangular 

(1,7,20) 

Outdoor Fogger Use - 1 ; Inhalation 104: Air Concentration, Calculated 

Dilution Factor (Indoor or Outdoor Air) unitless Single (0.01) 

Outdoor Fogger Use - 1 ; Inhalation 104: Air Concentration, Calculated 

Volume (Indoor or Outdoor) m3 Single (130.2) 

Indoor Fogger Use - 1 ; Ingestion 109: EPA SOP Contact Frequency (Hand-to-Mouth) event/hr Triangular 

(1,13,26) 

Indoor Fogger Use - 1 ; Ingestion 109: EPA SOP Transfer Efficiency per Contact (Hand-toMouth) unitless Uniform (0.2,0.5) Indoor Fogger Use - 1 ; Ingestion 109: EPA SOP Exposure Duration hr/day Uniform (1,5) Indoor Fogger Use - 1 ; Ingestion 109: EPA SOP Surface Area - Hands (Mouthed) cm2 Triangular 

(1,7,20) 

Indoor Treatment - 1 ; Ingestion 109: EPA SOP Contact Frequency (Hand-to-Mouth) event/hr Triangular 

(1,13,26) 

Indoor Treatment - 1 ; Ingestion 109: EPA SOP Transfer Efficiency per Contact (Hand-toMouth) unitless Uniform (0.2,0.5) Indoor Treatment - 1 ; Ingestion 109: EPA SOP Exposure Duration hr/day Uniform (1,5) Indoor Treatment - 1 ; Ingestion 109: EPA SOP Surface Area - Hands (Mouthed) cm2 Triangular 

(1,7,20) 

Custom - 1 ; Ingestion 109: EPA SOP Contact Frequency (Hand-to-Mouth) event/hr Triangular 

(1,6,26) 

Custom - 1 ; Ingestion 109: EPA SOP Transfer Efficiency per Contact (Hand-toMouth) unitless Uniform (0.2,0.5) Custom - 1 ; Ingestion 109: EPA SOP Exposure Duration hr/day Uniform (1,2) Custom - 1 ; Ingestion 109: EPA SOP Surface Area - Hands (Mouthed) cm2 Triangular 

(1,7,20) 

Custom - 1 ; Inhalation 104: Air Concentration, Calculated Dilution Factor (Indoor or Outdoor Air) unitless Single (0.01) Custom - 1 ; Inhalation 104: Air Concentration, Calculated Volume (Indoor or Outdoor) m3 Single (130.2)Product-specific Group Variable Name Unit Value P101; Outdoor Total Release Fogger Application (AI per Area Treated) kg/m2 Single (0.0001) P101; Outdoor Total Release Fogger Fraction AI Dislodgeable in Surface unitless Single (0.05) 
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P101; Outdoor Total Release Fogger HalfLife day Single (0.00001) P101; Outdoor Total Release Fogger Amount of Formulation Used (Volume) cm3 Single (170) P101; Outdoor Total Release Fogger Fraction AI in Formulation unitless Single (0.0054) P101; Outdoor Total Release Fogger Density of Formulation g/cm3 Single (1) P102; Indoor Spray - Aerosol Can Application (AI per Area Treated) mg/cm2 Uniform 

(0.0085,0.017) 

P102; Indoor Spray - Aerosol Can Fraction AI Dislodgeable in Surface unitless LogNormal 

(0.032,0.018,0.01,0.19) 

P102; Indoor Spray - Aerosol Can HalfLife day Single (7) P102; Indoor Spray - Aerosol Can Application (Amount of AI Used) kg/m3 Single (2.5) P102; Indoor Spray - Aerosol Can Amount of Formulation Used (Volume) m3 Single 

(0.000454) 

P102; Indoor Spray - Aerosol Can Unit Exposure (Inhalation) mg/lb Single (1.3) P102; Indoor Spray - Aerosol Can Concentration of AI in Air mg/m3 Uniform 

(0.00022,0.011) 

P103; Pets - Aerosol Can Application (AI per Area Treated) mg/cm2 Single (0.024) P103; Pets - Aerosol Can Fraction AI Dislodgeable in Surface unitless Single (0.02) P103; Pets - Aerosol Can HalfLife day Single (0.00001) P104; Indoor Total Release Fogger Application (AI per Area Treated) mg/cm2 Single (0.00129) P104; Indoor Total Release Fogger Fraction AI Dislodgeable in Surface unitless LogNormal 

(0.032,0.018,0.01,0.19) 

P104; Indoor Total Release Fogger HalfLife day Single (0.00001) P105; Indoor Spray - RTU Application (AI per Area Treated) mg/cm2 Single (0.0051) P105; Indoor Spray - RTU Fraction AI Dislodgeable in Surface unitless LogNormal 

(0.032,0.018,0.01,0.19) 

P105; Indoor Spray - RTU HalfLife day Single (0.00001) P105; Indoor Spray - RTU Application (Amount of AI Used) lb/gal Single (0.02) P105; Indoor Spray - RTU Amount of Formulation Used (Volume) gal Single (1) P105; Indoor Spray - RTU Unit Exposure (Inhalation) mg/lb Single (0.123) P105; Indoor Spray - RTU Concentration of AI in Air mg/m3 Uniform 

(0.00022,0.011) 

P106; Outdoor Spray - Handheld Fogger Application (AI per Area Treated) mg/cm2 Single 

(0.000053) 

P106; Outdoor Spray - Handheld Fogger Fraction AI Dislodgeable in Surface unitless Single (0.05) P106; Outdoor Spray - Handheld Fogger HalfLife day Single (0.00001) P106; Outdoor Spray - Handheld Fogger Amount of Formulation Used (Volume) oz Single (1) P106; Outdoor Spray - Handheld Fogger Fraction AI in Formulation unitless Single (0.001) P106; Outdoor Spray - Handheld Fogger Density of Formulation g/cm3 Single (1) P107; Outdoor Spray - Aerosol Can Application (AI per Area Treated) mg/cm2 Single (0.01) 
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P107; Outdoor Spray - Aerosol Can Fraction AI Dislodgeable in Surface unitless Single (0.05) P107; Outdoor Spray - Aerosol Can HalfLife day Single (0.00001) P107; Outdoor Spray - Aerosol Can Amount of Formulation Used (Volume) cm3 Single (170) P107; Outdoor Spray - Aerosol Can Fraction AI in Formulation unitless Single (0.0054) P107; Outdoor Spray - Aerosol Can Density of Formulation g/cm3 Single (1)