Appendix B

Computation of Average Daily Dose

The Average Daily Dose from all exposures to reclaimed water (ADDRW) can be estimated using the following equation (modified from Hutcheson et al., 1990):

ADDRW = ADDR + ADDD + ADDI

The Average Daily Dose from ingestion of the reclaimed water (ADDR) can be estimated using the following equation (modified from Hutcheson and Martin, 1992):

image

where

 
  ContaminantR = Concentration of chemical in reclaimed water (mass/volume),
  VI = Daily volume of reclaimed water ingestion (mass/volume),
  BAF = Bioavailability adjustment factor,
  D2 = Duration of the exposure period (time),
  BW = Average body weight (e.g., 70 kg),
  AP = Averaging period (time),
  C = Appropriate units conversion factor.

The Average Daily Dose from dermal contact with reclaimed water (ADDD) can be estimated using the following equation:

image

where

 
  ContaminantR = Concentration of chemical in reclaimed water (mass/volume),
  SA = Skin surface area in contact with the surface water during the period of exposure (area),
  PC = Permeability constant (volume/time × area),
  D1 = Average duration of each exposure event (time/event),
  D2 = Duration of the exposure period (time),
  BAF = Bioavailability adjustment factor,
  F = Number of exposure events during the exposure period divided by the number of days in the exposure period (events/time),
  D1 = Average duration of each exposure event (time/event),
  D2 = Duration of the exposure period (time),
  BW = Average body weight (e.g., 70 kg),
  AP = Averaging period (time),
  C = Appropriate units conversion factor.


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OCR for page 249
Appendix B Computation of Average Daily Dose The Average Daily Dose from all exposures to ADDD = Contaminant × SA × PC × BAF × F × D1 × D 2 × C D BW × AP reclaimed water (ADDRW ) can be estimated using the following equation (modified from Hutcheson et al., where 1990): ContaminantR = Concentration of chemical in ADDRW = ADDR + ADDD + ADDI reclaimed water (mass/volume), SA = Skin surface area in contact with The Average Daily Dose from ingestion of the the surface water during the reclaimed water (ADDR) can be estimated using the period of exposure (area), following equation (modified from Hutcheson and PC = Permeability constant (volume/ Martin, 1992): time × area), D1 = Average duration of each ADDR = Contaminant R × VI × BAF D 2 × C BW × AP exposure event (time/event), D2 = D uration of the exposure period (time), where BAF = Bioavailability adjustment ContaminantR = Concentration of chemical in factor, reclaimed water (mass/volume), F = Number of exposure events VI = Daily volume of reclaimed during the exposure period water ingestion (mass/volume), divided by the number of days BAF = Bioavailability adjustment in the exposure period (events/ factor, time), D2 = D uration of the exposure D1 = Average duration of each period (time), exposure event (time/event), BW = Average body weight (e.g., D2 = D uration of the exposure period 70 kg), (time), AP = Averaging period (time), BW = Average body weight (e.g., C = Appropriate units conversion 70 kg), factor. AP = Averaging period (time), C = Appropriate units conversion The Average Daily Dose from dermal contact with factor. reclaimed water (ADDD) can be estimated using the following equation: 249

OCR for page 249
250 APPENDIX B The Average Daily Dose from inhalation of con- F = Number of exposure events taminants in reclaimed water (ADDI) can be estimated during the exposure period using the following equation: divided by the number of days in the exposure period (events/ ADDI = Contaminant × VR × BAF × F × D1 × D 2 × C time), I BW × AP D1 = Average duration of each where exposure event (time/event), D2 = D uration of the exposure period ContaminantR = Concentration of chemical in (time), reclaimed water (mass/volume), BW = Average body weight (e.g., VR = Daily respiratory volume during 70 kg), the period of exposure (volume/ AP = Averaging period (time), time), C = Appropriate units conversion BAF = Bioavailability adjustment factor. factor,