Application for the Reassessment of a Hazardous Substance under ...

in the EPA Exposure Factors HandbookDA = percent dermal absorption (30%)BW = body weight - 15kg which is the average of UK 1995-7 Health Surveys forEngland values for males and females of 2 and 3 yrsChildren’s hand-to-mouth exposure (UK CRD, 2008b)6.6 Hand-to-mouth exposures were calculated using turf transferable residue levelsusing the following equation:SE(h) = AR x DF x TTR x SE x SA x Freq x H / BWWhere:SE(h) = systemic exposure via the hand-to-mouth routeAR = field application rate (μg/cm 2 )DF = drift fallout valueTTR = turf transferable residuesSE = saliva extraction factor – the default value of 50% was usedSA = surface area of the hands – the assumption used here is that 20 cm 2 of skinarea is contacted each time a child puts a hand in his or her mouth (this isequivalent to the palmar surface of three figures; UK CRD default value).Freq = frequency of hand to mouth events/hour – for short term exposures thevalue of 20 events/hours is used, this is the 90th percentile of observations thatranges from 0 to 70 events/hourH = exposure duration (hours) – this has been assumed to be 2 hours whichmatches the 75th percentile for toddlers playing on grass in the EPA ExposureFactors HandbookBW = body weight - 15kg which is the average of UK 1995-7 Health Surveys forEngland values for males and females of 2 and 3 yrsChildren’s object-to-mouth exposure (UK CRD, 2008b)6.7 Object to mouth exposures were calculated using turf transferable residue levelsusing the following equation:SE(o) = AR x DF x TTR x IgR / BWWhere:SE(o) = systemic exposure via mouthing activityAR = field application rate (μg/cm 2 )DF = drift fallout valueTTR = turf transferable residuesIgR = ingestion rate for mouthing grass/day – this was assumed to be equivalentto 25cm 2 of grass/dayBW = body weight – 15kg which is the average of UK 1995–7 Health Surveys forEngland values for males and females of 2 and 3 yrs.Dichlorvos reassessment – application Page 334 of 436