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REx (Version 2.1G): Page 1 of 38
RExResidential Exposure Assessment Model
TECHNICAL GUIDE
Prepared by
infoscientific.com, Inc.
Prepared for
Organo Phosphates Case Study Group
April 2000
REx (Version 2.1G): Page 2 of 38
TABLE OF CONTENTS
Page
1.0 Introduction ………. 3
2.0 Product Use Scenarios ………. 4
3.0 Exposure Pathways & Assessment Methods ………. 5
4.0 Inputs ………. 7
5.0 Algorithms ……… 10
REx (Version 2.1G): Page 3 of 38
1.0 INTRODUCTION
REx (Residential Exposure Assessment Model) is a spreadsheetEXCEL basedexposure/dose assessment model that allows aggregating product use scenarios.REx is implemented in a user-friendly environment such that both simple deterministicand complex stochastic exposure and dose assessments can be made.
The product use scenarios in REx are those based on EPA’s Residential SOPs draftdocument. One or more (up to six) scenarios can be aggregated to estimate exposureand dose to receptors of interest. Receptors included in this version of REx are adultsand three categories of children (< 1 year, 1 year < age < 6 years, and age > 6 years).
Aggregation can be done for “day 0” during and post application scenarios.
REx (Version 2.1G): Page 4 of 38
2.0 PRODUCT USE SCENARIOS
The following scenarios are currently represented in REx:- Lawn Care- Vegetable Garden Care- Ornamental Plant Care- Tree Care- Pick Own Fruits/Vegetables- Crack & Crevice Treatment- Termite Control- Rodent Control- Pet Care- Outdoor Fogger Use- Indoor Fogger Use- Indoor Treatment- Paint/Wood Treatment- Impregnated Materials- Detergent/Handsoap Use- Swimming Pool Use- Custom
REx (Version 2.1G): Page 5 of 38
3.0 EXPOSURE PATHWAYS & ASSESSMENT METHODS
The following are the receptor-specific (adult and child groups) exposure pathwaysand the associated assessment methods included in REx. The name of the algorithmrepresenting each assessment method is provided in parenthesis alongside themethod.
ADULT
During Application
DermalUnit Exposure, Area Treated (Dermal 101)Unit Exposure, Amount of Formulation Used (Dermal 102)
InhalationUnit Exposure, Area Treated (Inhalation 101)Unit Exposure, Amount of Formulation Used (Inhalation 102)
Dermal + InhalationUnit Exposure, Area Treated (Multiple 101)Unit Exposure, Amount of Formulation Used (Multiple 102)
Post Application
DermalTransfer Coefficient (Residue) (Dermal 103)Transfer Coefficient (Area Treated) (Dermal 105)Transfer Factor (Residue) (Dermal 107)Transfer Factor (Area Treated) (Dermal 109)Fraction Transferred (Dermal 111)Flux Rate (Dermal 113)Water Concentration (Dermal 115)Film Thickness (DERMAL Model) (Dermal 117)
Ingestion: WaterWater Concentration (Ingestion 106)
InhalationIndoor Air Concentration (Inhalation 103)Outdoor Air Concentration (Inhalation 105)
REx (Version 2.1G): Page 6 of 38
CHILD
Post Application
DermalTransfer Coefficient (Residue) (Dermal 104)Transfer Coefficient (Area Treated) (Dermal 106)Transfer Factor (Residue) (Dermal 108)Transfer Factor (Area Treated) (Dermal 110)Fraction Transferred (Dermal 112)Flux Rate (Dermal 114)Water Concentration (Dermal 116)Film Thickness (DERMAL Model) (Dermal 118)
Ingestion: Granules/Pellets (Formulation)Granules/Pellets (Formulation) (Ingestion 101)
Ingestion: Grass/PlantsGrass/Plants (Ingestion 102)
Ingestion: SoilSoil (Ingestion 103)
Ingestion: Hand-To-Mouth TransferMass Balance (Ingestion 104)Fraction Transferred (Ingestion 109)EPA SOPs Method (Ingestion 110)
Ingestion: Paint ChipsPaint Chips (Ingestion 105)
Ingestion: WaterWater Concentration (Ingestion 107)
Ingestion: Flux rateFlux Rate (Ingestion 108)
InhalationIndoor Air Concentration (Inhalation 104)Outdoor Air Concentration (Inhalation 106)
REx (Version 2.1G): Page 7 of 38
4.0 INPUTS
4.1 GENERAL (scenario independent)
Exposure Clothing Penetration Fraction (Uncovered) unitlessClothing Penetration Fraction (Covered) unitlessIngestion Rate (Granules/Pellets) (Child) g/dayIngestion Rate (Grass/Plants) (Child) cm2/dayIngestion Rate (Soil) (Child) mg/dayIngestion Rate (Paint Chips) (Child) mg/dayIngestion Rate (Water) (Adult) L/hrIngestion Rate (Water) (Child) L/hrTransfer Efficiency (Hand-To-Mouth) (per Contact) (Child) unitlessFraction Transferred (Hand-To-Mouth) (Total) (Child) unitlessReference Duration day
Dose Fraction Absorbed (Dermal + Inhalation) (During Application) unitlessFraction Absorbed (Dermal) unitlessFraction Absorbed (Ingestion) unitlessFraction Absorbed (Inhalation) unitlessNOEL (Dermal) (Applied Dose) mg/kg/dayNOEL (Ingestion) (Applied Dose) mg/kg/dayNOEL (Inhalation) (Applied Dose) mg/kg/dayNOEL (Absorbed Dose) (Systemic) mg/kg/day
Human Area (Hands) (Uncovered) (Adult) cm2
Factors Area (Hands) (Covered) (Adult) cm2
Area (Upper Body) (Uncovered) (Adult) cm2
Area (Upper Body) (Covered) (Adult) cm2
Area (Lower Body) (Uncovered) (Adult) cm2
Area (Lower Body) (Covered) (Adult) cm2
Area (Feet) (Uncovered) (Adult) cm2
Area (Feet) (Covered) (Adult) cm2
Area (Hands) (Uncovered) (Child) cm2
Area (Hands) (Covered) (Child) cm2
Area (Upper Body) (Uncovered) (Child) cm2
Area (Upper Body) (Covered) (Child) cm2
Area (Lower Body) (Uncovered) (Child) cm2
Area (Lower Body) (Covered) (Child) cm2
Area (Feet) (Uncovered) (Child) cm2
Area (Feet) (Covered) (Child) cm2
Area (Total) (Adult) cm2
Area (Total) (Child) cm2
Area (Hands) (Hand-To-Mouth) (Child) cm2
Contact Frequency (Hand-To-Mouth) (Child) events/hrInhalation Rate (Adult) m3/hrInhalation Rate (Child) m3/hrBody Weight (Adult) kgBody Weight (Child) kg
REx (Version 2.1G): Page 8 of 38
4.2 SPECIFIC (scenario dependent)
Source Application (AI per Area Treated) lb ai/acreApplication (AI per Amount of Formulation Used) lb ai/galArea Treated acreAmount of Formulation as Used (By Volume) galAmount of Formulation as Used (By Weight) mgFraction AI in Formulation as Used unitlessDensity of Formulation g/cm3
Environment Air concentration (Indoor) of AI microg/m3
Dilution factor (Outdoor air) unitlessVolume of air (Outdoor, imaginary) m3
Concentration of AI in Water mg/m3
Permeability Coefficient cm/hrFlux Rate of AI through Impregnated Material mg/m2/dayFraction Transferred to Whole Body (Dermal) unitlessFraction AI available (Ingestion) unitlessTransferable Residue (Surface) (Environment/Pet) mg/cm2
Soil Density (Outdoor) g/cm3
Thickness of Effective Soil Layer cmGround Cover (Grass/Plants) g/cm2
Fraction AI Dislodgeable from Surface (Environment/Pet) unitlessFraction AI Dislodgeable from Grass/Plants unitlessFraction AI Dislodgeable from Soil unitlessFraction AI in Paint Chips unitlessFraction AI Dissipated Daily unitless
Exposure Unit Exposure (Dermal + Inhalation) (During Application) mg/lb aiUnit Exposure (Dermal) (During Application) mg/lb aiUnit Exposure (Inhalation) (During Application) mg/lb aiFilm Thickness of Formulation on Dermal Area cmTransfer Coefficient (Dermal) (Adult) cm2/hrTransfer Coefficient (Dermal) (Child: age > 6) cm2/hrTransfer Coefficient (Dermal) (Child: 16) cm2
Area Contacted with Imp Material (Child: 1
REx (Version 2.1G): Page 9 of 38
Area Mouthed with Imp Mat (Child: 16) hrExposure Duration (Impregnated Material) (Child: 1
REx (Version 2.1G): Page 10 of 38
5.0 ALGORITHMS
5.1 Exposure Pathway: Dermal
Methods:
Dermal 101Unit Exposure, Area Treated
Dermal 102Unit Exposure, Amount of Formulation Used
Dermal 103/104Transfer Coefficient (Residue)
Dermal 105/106Transfer Coefficient (Area Treated)
Dermal 107/108Transfer Factor (Residue)
Dermal 109/110Transfer Factor (Area Treated)
Dermal 111/112Fraction Transferred
Dermal 113/114Flux Rate
Dermal 115/116Water Concentration
Dermal 117/118Film Thickness (DERMAL Model)
REx (Version 2.1G): Page 11 of 38
Dermal 101
Method: Unit exposure, Area treated
Application: DuringReceptor: Adult
Inputs
Source Application (AI per Area Treated) kg ai/m2
Area Treated m2
Exposure Unit Exposure (Dermal) (During application) mg/kg aiReference Duration day
Human Factor Body Weight (Adult) kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
TreatedAreaDermalAdult
WeightBodyDurationferenceRe
TreatedAreanApplicatioExposureUnitExposure
×
××=
REx (Version 2.1G): Page 12 of 38
Dermal 102
Method: Unit exposure, Amount of Formulation Used
Application: DuringReceptor: Adult
Inputs
Source Application (Amount of AI Used) kg ai/m3
Amount of Formulation Used m3
Exposure Unit Exposure (Dermal) (During Application mg/kg aiReference Duration day
Human Factor Body Weight (Adult) kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
UsedFormAmtDermalAdult
WeightBodyDurationferenceRe
UsedFormofAmountnApplicatioExposureUnitExposure
×
××=
REx (Version 2.1G): Page 13 of 38
Dermal 103/104
Method: Transfer Coefficient (Residue)
Application: PostReceptor: Adult / Child
Inputs
Environment Transferable Residue (Surface) (Environment/Pet) mg/cm2
Fraction Dissipated Daily unitlessExposure Transfer Coefficient (Adult/Child) cm2/hr
Fraction Transferred to Hand (Dermal) (Child) unitlesst (= Post Application Day) dayExposure Duration (Adult/Child) hr/day
Human Factor Body Weight (Adult/Child) kg
Calculation (Transferable Residue: mg/cm2; ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( )ttt DailyDissipatedFractionsidueReleTransferabsidueReleTransferab −×= = 10
( ) ( ) ( )( )
Child/Adult
Child/AdultChild/AdulttChild/Adult WeightBody
DurationExptCoefficienferTranssidueReTransExposure
××=
( ) ( ) ( ) ( )ChildChild,HandChildtChild,Hand DurExpTransFracCoeffTranssReTransExposure ×××=
REx (Version 2.1G): Page 14 of 38
Dermal 105/106
Method: Transfer Coefficient (Area Treated)
Application: PostReceptor: Adult / Child
Inputs
Source Application (AI per Area Treated) kg ai/m2
Environment Fraction AI Dislodgeable in Surface unitlessFraction AI Dissipated Daily unitless
Exposure Transfer Coefficient (Adult/Child) cm2/hrt (= Post Application Day) dayFraction Transferred to Hand (Dermal) (Child) unitlessExposure Duration (Adult/Child) hr/day
Human Factor Body Weight (Adult/Child) kg
Calculation (Transferable Residue: mg/cm2, ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( ) ( ) 1001 ×−××= tTreatedAreat DailyDissFracDislodgeAIFracnApplicatiosidueReTrans
( ) ( ) ( )( )
Child/Adult
Child/AdultChild/AdulttChild/Adult WeightBody
DurationExptCoefficienferTranssidueReTransExposure
××=
( ) ( ) ( ) ( )ChildChild,HandChildtChild,Hand DurExpTransFracCoeffTranssReTransExposure ×××=
REx (Version 2.1G): Page 15 of 38
Dermal 107/108
Method: Transfer Factor (Residue)
Application: PostReceptor: Adult / Child
Inputs
Environment Transferable Residue (Surface) (Environment/Pet) mg/cm2
Fraction Dissipated Daily unitlessExposure Transfer Factor – Hands (Uncovered) (Adult/Child) unitless
Transfer Factor – Hands (Covered) (Adult/Child) unitlessTransfer Factor – Upper Body (Uncovered) (Adult/Child) unitlessTransfer Factor – Upper Body (Covered) (Adult/Child) unitlessTransfer Factor – Lower Body (Uncovered) (Adult/Child) unitlessTransfer Factor – Lower Body (Covered) (Adult/Child) unitlessTransfer Factor – Feet (Uncovered) (Adult/Child) unitlessTransfer Factor – Feet (Covered) (Adult/Child) unitlessClothing Penetration Fraction (Uncovered) (Adult/Child) unitlessClothing Penetration Fraction (Covered) (Adult/Child) unitlessReference Duration day
Human Factor Surface Area (Hands) (Uncovered) (Adult/Child) cm2
Surface Area (Hands) (Covered) (Adult/Child) cm2
Surface Area (Upper Body) (Uncovered) (Adult/Child) cm2
Surface Area (Upper Body) (Covered) (Adult/Child) cm2
Surface Area (Lower Body) (Uncovered) (Adult/Child) cm2
Surface Area (Lower Body) (Covered) (Adult/Child) cm2
Surface Area (Feet) (Uncovered) (Adult/Child) cm2
Surface Area (Feet) (Covered) (Adult/Child) cm2
Body Weight (Adult/Child) kg
Calculation (Transferable Residue: mg/cm2; ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( )ttt DailyDissipatedFractionsidueReleTransferabsidueReleTransferab −×= = 10
( ) ( ) ( ){ } ( )( ) ( )
Child/Adult
tChild/AdultChild/Adult
WeightBodyDurationferenceRe
sReTransFactorPenClothAreaSurfFactorTransExposure
××××
= ∑
- summation across all body parts (uncovered and covered)
( ) ( ) ( ){ } ( )( )DurationferenceRe
sReTransFactorPenClothAreaSurfFactTransExposure tChildChild,Hand
∑ ×××=- summation across hands (uncovered and covered)
REx (Version 2.1G): Page 16 of 38
Dermal 109/110
Method: Transfer Factor (Area Treated)
Application: PostReceptor: Adult / Child
Inputs
Source Application (AI per Area Treated) kg ai/m2
Environment Fraction AI Dislodgeable in Surface unitlessFraction AI Dissipated Daily unitless
Exposure Transfer Factor – Hands (Uncovered) (Adult/Child) unitlessTransfer Factor – Hands (Covered) (Adult/Child) unitlessTransfer Factor – Upper Body (Uncovered) (Adult/Child) unitlessTransfer Factor – Upper Body (Covered) (Adult/Child) unitlessTransfer Factor – Lower Body (Uncovered) (Adult/Child) unitlessTransfer Factor – Lower Body (Covered) (Adult/Child) unitlessTransfer Factor – Feet (Uncovered) (Adult/Child) unitlessTransfer Factor – Feet (Covered) (Adult/Child) unitlessClothing Penetration Fraction (Uncovered) unitlessClothing Penetration Fraction (Covered) unitlesst (= Post Application Day) dayReference Duration day
Human Factor Surface Area (Hands) (Uncovered) (Adult/Child) cm2
Surface Area (Hands) (Covered) (Adult/Child) cm2
Surface Area (Upper Body) (Uncovered) (Adult/Child) cm2
Surface Area (Upper Body) (Covered) (Adult/Child) cm2
Surface Area (Lower Body) (Uncovered) (Adult/Child) cm2
Surface Area (Lower Body) (Covered) (Adult/Child) cm2
Surface Area (Feet) (Uncovered) (Adult/Child) cm2
Surface Area (Feet) (Covered) (Adult/Child) cm2
Body Weight (Adult/Child) kg
Calculation (Transferable Residue: mg/cm2, ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( ) ( ) 1001 ×−××= tTreatedAreat DailyDissFracDislodgeAIFracnApplicatiosidueReTrans
( ) ( ) ( ){ } ( )( ) ( )
Child/Adult
tChild/AdultChild/Adult
WeightBodyDurationferenceRe
sReTransFactorPenClothAreaSurfFactorTransExposure
××××
= ∑
- summation across all body parts (uncovered and covered)
( ) ( ) ( ){ } ( )( )DurationferenceRe
sReTransFactorPenClothAreaSurfFactTransExposure tChildChild,Hand
∑ ×××=- summation across hands (uncovered and covered)
REx (Version 2.1G): Page 17 of 38
Dermal 111/112
Method: Fraction Transferred
Application: PostReceptor: Adult / Child
Inputs
Source Amount of Formulation as Used (By Weight) mgFraction AI in Formulation unitless
Environment Fraction AI Dislodgeable on Surface (Environment/Pet) unitlessFraction AI Dissipated Daily unitless
Exposure Fraction Transferred to Whole Body (Dermal) cm2/hrFraction Transferred to Hand (Dermal) (Child) unitlesst (= Post Application Day) dayReference Duration day
Human Factor Body Weight (Adult/Child) kg
Calculations (Transferable Residue: mg; ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( ) ( ) ( )tt DailyDissFracDislodgeAIFracFormAIFracUsedFormAmtsidueReTrans −×××= 1
( ) ( )( )
Child/Adult
Child/Adult,BodyWholet
Child/AdultWeightBody
dTransferreFractionsidueReleTransferabExposure
×=
( ) ( ) Child,HandtChild,Hand dTransferreFractionsidueReleTransferabExposure ×=
REx (Version 2.1G): Page 18 of 38
Dermal 113/114
Method: Flux Rate
Application: PostReceptor: Adult / Child
Inputs
Environment Flux Rate of AI through Impregnated Material mg/m2/dayFraction Dissipated Daily unitless
Exposure Exposure Duration (To Impregnated Material) (Adult/Child) hrFraction Transferred to Hand (Dermal) unitlesst (= Post Application Day) dayReference Duration day
Human Factor Surface Area Contact with Impregnated Material (Ad/ Ch) cm2
Body Weight (Adult/Child) kg
Calculations (ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( )tChild/Adult DailyDissFracAIRateFluxExposure −×= 1( ) ( )
( ) ( ) ( )2410000××××
×Child/Adult
Child/AdultChild/Adult,Contact
WeightBodyDurationferenceRe
DurationExposureAreaSurface
( ) ( )tChild,Hand DailyDissipatedFractionAIRateFluxExposure −×= 1( ) ( ) ( )
( ) ( )2410000××××
×DurationferenceRe
DurationExposuredTransferreFractionAreaSurfaceChildChild,HandChild,Contact
REx (Version 2.1G): Page 19 of 38
Dermal 115/116
Method: Water Concentration
Application: PostReceptor: Adult / Child
Inputs
Environment Concentration of AI Pool Water mg/m3
Fraction Dissipated Daily unitlessPermeability Coefficient cm/hr
Exposure Exposure Duration (Adult/Child) hrt (= Post Application Day) dayReference Duration day
Human Factor Surface Area (Whole Body) (Adult/Child) cm2
Body Weight (Adult/Child) kg
Calculations (ExposureAdult/Child: mg/kg/day)
( ) ( ) ( )CoefftyPermeabiliDailyDissipatedFractionWaterAIConcExposure tChild/Adult ×−×= 1( ) ( )( ) ( ) ( )1000000××
××
Child/Adult
Child/AdultChild/Adult,Contact
WeightBodyDurationferenceRe
DurationExposureAreaSurface
REx (Version 2.1G): Page 20 of 38
Dermal 117/118
Method: Film Thickness (DERMAL Model)
Application: PostReceptor: Adult / Child
Inputs
Environment Density of Formulation mg/cm3
Fraction of AI in Formulation unitlessExposure Film thickness of Formulation on Dermal Area cm
Fraction Transferred to Hand (Dermal) (Child) unitlessReference Duration day
Human Factor Surface Area (Exposed to Formulation) (Adult/Child) cm2
Body Weight (Adult/Child) kg
Calculations (ExposureAdult/Child: mg/kg/day; ExposureHand,Child: mg/day)
( ) ( ) ( ) ( )( ) ( )
Child/Adult
Child/Adult,Exposed
Child/AdultWeightBodyDurationferenceRe
AreaSurfThickFilmFormAIFracFormDensityExposure
×
×××=
( ) ( ) ( )ThicknessFilmnFormulatioAIFractionnFormulatioDensityExposure Child,Hand ××=( ) ( )
( )DurationferenceRedTransferreFractionAreaSurface
Child,HandChild,Exposed×
×
REx (Version 2.1G): Page 21 of 38
5.2 Exposure Pathway: Ingestion
Methods:
Ingestion 101Granules/Pellets (Formulation)
Ingestion 102Grass/Plants
Ingestion 103Soil
Ingestion 104Hand-To-Mouth Transfer: Mass Balance
Ingestion 105Paint Chips
Ingestion 106/107Water Concentration (Swimming Pool)
Ingestion 108Flux Rate
Ingestion 109Hand-To-Mouth Transfer: Fraction Transferred
Ingestion 110Hand-To-Mouth Transfer: EPA SOP
REx (Version 2.1G): Page 22 of 38
Ingestion 101
Method: Granules/Pellets (Formulation)
Application: PostReceptor: Child
Inputs
Source Fraction AI in Formulation as Used unitlessExposure Ingestion Rate (Granules/Pellets) (Child) mg/dayHuman Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( )( )
Child
Child,Pellets/GranulesChild
WeightBody
Pellets/GranulesinAIFractionRateIngestionExposure
×=
REx (Version 2.1G): Page 23 of 38
Ingestion 102
Method: Grass/Plants
Application: PostReceptor: Child
Inputs
Source Application (AI per Area treated) kg ai/m2
Environment Ground Cover (Grass/Plants) g/cm2
Fraction AI Dislodgeable from Grass/Plants unitlessFraction AI Dissipated Daily unitless
Exposure Ingestion Rate (Grass/Plants) (Child) mg/dayt (= Post Application Day) day
Human Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( ) ( )( )CoverGround
DailyDissFracPlants/GrassAIFracnApplicatiosidueRe
tTreatedArea
Plants/Grass
−××=
1
( ) ( )( )
Child
Child,Plants/GrassPlants/GrassChild
WeightBody
RateIngestionsidueReExposure
×=
REx (Version 2.1G): Page 24 of 38
Ingestion 103
Method: Direct: Soil
Application: PostReceptor: Child
Inputs
Source Application (Area Treated) kg ai/m2
Environment Soil Density (Outdoor) g/cm3
Thickness of Effective Soil Layer cmFraction AI Dislodgeable from Soil unitlessFraction AI Dissipated Daily unitless
Exposure Ingestion Rate (Soil) (Child) mg/dayt (= Post Application Day) day
Human Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( ) ( )( ) ( )LayerSoilThicknessDensitySoil
DailyDissipatedFractionSoilAIFractionnApplicatiosidueRe
tTreatedArea
Soil ×
−××=
1
( ) ( )( )
Child
Child,SoilSoilChild
WeightBody
RateIngestionsidueReExposure
×=
REx (Version 2.1G): Page 25 of 38
Ingestion 104
Method: Hand-To-Mouth Transfer (Mass Balance)
Application: PostReceptor: Child
Inputs
Exposure Hand Dermal Exposure (Child) mg/dayContact Frequency (Hand-To-Mouth) (Child) events/hrTransfer Efficiency (Hand-To-Mouth) (per Contact) (Child) unitlessExposure Duration (Hand-To-Mouth) (Child) hr
Human Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( )[ ]( ) ( )[ ]
∑×
=
−−− −×=
DurationExpFreqContact
n
nMouthToHand EffTransferEffTransferFactorTransfer
1
11
( ) ( )( )
Child
MouthToHandChild),Dermal(Hand
ChildWeightBody
FactorTransferExposureExposure −−
×=
REx (Version 2.1G): Page 26 of 38
Ingestion 105
Method: Paint Chips
Application: PostReceptor: Child
Inputs
Source Fraction AI in Paint Chips unitlessFraction AI (in Paint Chips) available for ingestion unitless
Exposure Ingestion Rate (Paint Chips) (Child) mg/dayHuman Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( ) ( )( )
Child
Child,ChipsintPa
ChildWeightBody
AvailableAIFracChipsintPainAIFracRateIngestionExposure
××=
REx (Version 2.1G): Page 27 of 38
Ingestion 106/107
Method: Water Concentration (Swimming Pool)
Application: PostReceptor: Adult / Child
Inputs
Source Water Concentration (Swimming Pool) mg ai/m3
Exposure Ingestion Rate (Pool Water) (Adult/Child) m3/hrExposure Duration (in Pool) (Adult/Child) hrReference Duration day
Human Factor Body Weight (Adult/Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( ) ( )( ) ( )
Child/Adult
Child/AdultChild/Adult,WaterPoolPoolgminSwimChild/Adult
WeightBodyDurationferenceRe
DurExpRateIngConcWaterExposure
×
××=
REx (Version 2.1G): Page 28 of 38
Ingestion 108
Method: Flux Rate
Application: PostReceptor: Child
Inputs
Source Flux Rate of AI mg/cm2/dayExposure Surface Area (Impregnated Material) Mouthed (Child) cm2
Human Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( )( )
Child
MouthedChild WeightBody
MaterialpregnatedImAreaSurfaceAIRateFluxExposure
×=
REx (Version 2.1G): Page 29 of 38
Ingestion 109
Method: Hand-To-Mouth Transfer (Fraction Transferred)
Application: PostReceptor: Child
Inputs
Exposure Hand Exposure (Dermal) (Child) mg/dayFraction Transferred (Hand-To-Mouth) (Based on TotalContacts Per Day) (Child)
unitless
Human Factor Body Weight (Child) kg
Calculation (ExposureChild: mg/kg/day)
( ) ( )( )
Child
MouthToHandChild),Dermal(Hand
ChildWeightBody
dTransferreFractionExposureExposure −−
×=
REx (Version 2.1G): Page 30 of 38
Ingestion 110
Method: Hand-To-Mouth Transfer (EPA SOP)
Application: PostReceptor: Child
Inputs
Source Application (Area Treated) kg ai/m2
Environment Fraction AI Dislodgeable in Surface unitlessFraction AI Dissipated Daily unitless
Exposure t (= Post Application Day) dayHand-To-Mouth Contact Frequency (Child) events/hrExposure Duration (Child) hrSurface Area of Hands Mouthed (Child) cm2
Human Factor Body Weight (Child) kg
Calculation (Transferable Residue: mg/cm2, ExposureChild: mg/kg/day)
( ) ( ) ( ) 1001 ×−××= tTreatedAreat DailyDissFracDislodgeAIFracnApplicatiosidueReTrans
( ) ( ) ( ) ( )( )
Child
ChildChild,HandsChildtChild
WeightBody
DurExpMouthedAreaSurfFreqContHtoMsReTransExposure
×××=
REx (Version 2.1G): Page 31 of 38
5.3 Exposure Pathway: Inhalation
Methods:
Inhalation 101Unit Exposure, Area Treated
Inhalation 102Unit Exposure, Amount of Formulation Used
Inhalation 103/104Indoor Air Concentration
Inhalation 105/106Outdoor Air Concentration
REx (Version 2.1G): Page 32 of 38
Inhalation 101
Method: Unit exposure, Area treated
Application: DuringReceptor: Adult
Inputs
Source Application (AI per Area Treated) kg ai/m2
Area Treated m2
Exposure Unit Exposure (Inhalation) (During Application mg/kg aiReference Duration day
Human Factor Body Weight (Adult) kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
TreatedAreaInhalationAdult
WeightBodyDurationferenceRe
TreatedAreanApplicatioExposureUnitExposure
×
××=
REx (Version 2.1G): Page 33 of 38
Inhalation 102
Method: Unit exposure, Amount of Formulation Used
Application: DuringReceptor: Adult
Inputs
Source Application (Amount of AI in Formulation) kg ai/m3
Amount of Formulation Used m3
Exposure Unit Exposure (Inhalation) (During Application) mg/kg aiReference Duration day
Human Factor Body Weight kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
UsedFormAmtInhalationAdult
WeightBodyDurationferenceRe
UsedFormofAmountnApplicatioExposureUnitExposure
×
××=
REx (Version 2.1G): Page 34 of 38
Inhalation 103/104
Method: Indoor Air Concentration
Application: PostReceptor: Adult / Child
Inputs
Environment Air concentration of AI (Indoor) µg/m3
Exposure Exposure Duration (Adult/Child) hr/dayHuman Factor Inhalation Rate (Adult/Child) m3/hr
Body Weight (Adult/Child) kg
Calculation (ExposureAdult/Child: mg/kg/day)
( ) ( ) ( )( )
Child/Adult
Child/AdultChild/AdultChild/Adult WeightBody
DurationExposureRateInhalationAIConcAirExposure
××=
REx (Version 2.1G): Page 35 of 38
Inhalation 105/106
Method: Outdoor Air Concentration
Application: PostReceptor: Adult / Child
Inputs
Source Amount of Formulation (As Used) (By Volume) m3
Fraction of AI in Formulation (As Used) unitlessDensity of Formulation mg/m3
Environment Dilution Factor (Outdoor Air) unitlessVolume (Outdoor, Imaginary) m3
Exposure Exposure Duration (Adult/Child) hr/dayHuman Factor Inhalation Rate (Adult/Child) m3/hr
Body Weight (Adult/Child) kg
Calculation (ExposureAdult/Child: mg/kg/day)
( ) ( ) ( ) ( )( )Outdoor
OutdoorOutdoor
Volume
FactorDilutionFormDensityFormAIFracFormAmtionConcentratAir
×××=
( ) ( ) ( )( )
Child/Adult
Child/AdultChild/AdultOutdoorChild/Adult WeightBody
DurationExposureRateInhalationConcAirExposure
××=
REx (Version 2.1G): Page 36 of 38
5.4 Exposure Pathway: Multiple (Dermal + Inhalation)
Methods:
Multiple (Dermal+Inhalation) 101Unit Exposure, Area Treated
Multiple (Dermal+Inhalation) 102Unit Exposure, Amount of Formulation Used
REx (Version 2.1G): Page 37 of 38
Multiple 101
Method: Unit exposure, Area treated
Application: DuringReceptor: Adult
Inputs
Source Application (AI per Area Treated) kg ai/m2
Area Treated m2
Exposure Unit Exposure (Dermal + Inhalation) (During Application) mg/kg aiReference Duration day
Human Factor Body Weight (Adult) kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
TreatedAreaInhalationDermalAdult
WeightBodyDurationferenceRe
TreatedAreanApplicatioExposureUnitExposure
×
××= +
REx (Version 2.1G): Page 38 of 38
Multiple 102
Method: Unit exposure, Amount of Formulation Used
Application: DuringReceptor: Adult
Inputs
Source Application (Amount of AI in Formulation) kg ai/m3
Amount of Formulation Used m3
Exposure Unit Exposure (Dermal + Inhalation) (During Application) mg/kg aiReference Duration day
Human Factor Body Weight (Adult) kg
Calculation (ExposureAdult: mg/kg/day)
( ) ( ) ( )( ) ( )
Adult
UsedFormAmtInhalationDermalAdult
WeightBodyDurationferenceRe
UsedFormofAmountnApplicatioExposureUnitExposure
×
××= +