Incidental hand-to-mouth oral exposure Dermal exposure assumptions Comparison of evaluation of MOSs

Public Health Significance of Urban Pests 521

14.8.2.4. Incidental hand-to-mouth oral exposure

For this route of exposure, the following assumptions were made. • The saliva extraction factor SEF: the percentage of the dislodged chlorpyrifos residue that is extracted from the fingers by the saliva of the child is 50. • The surface area SA of a hand put in a mouth is 20cm 2 . • The frequency Freq of hand-to-mouth events is one per day adjusted. • On surfaces, 5 of dislodgeable residues indoor surface residue, ISR are available for transfer to skin coming in contact with these treated surfaces. The daily oral dose in mgday is given by the expression: ISR x HTE x SEF x SA x Freq x EDBW, where AEL equals 1000 and HTE is the hand transfer efficiency.

14.8.2.5. Dermal exposure assumptions

For this route of exposure, the following assumptions were made. • The body surface available for transfer of residue is 16 700cm 2 for adults and 6600cm 2 for children. • On surfaces, 5 of dislodgeable residues are available for transfer to skin coming in contact with these treated surfaces. The daily dermal dose in µgkgday is given by the following expression: The Unit Exposure in µgkgAI x kgAI Handled x Dermal Absorption Factorx BW, where x is 70kg for adults and 15 kg for children, and the AEL is 1000.

14.8.2.6. Comparison of evaluation of MOSs

For the inhalation route of exposure in treated rooms kitchen and toilet, the MOSs were less than the AEL of 1000. For crack-and-crevice applications, the dermal and oral com- bined MOSs were greater than the AEL of 1000. When all exposures were combined, the MOSs for adults and children were less than the AEL of 1000 for details and the spe- cific range of values, see EPA, 2000d Therefore, residential exposures that result from consumer applications of pesticides and post-application exposure in pesticide-treated and untreated rooms were found to be unacceptable because, according to EPA calculations, the MOSs exceeded the level of concern indicated by the required AEL. Additional data were not collected to support the use pattern, and residential use of chlorpyrifos was discontinued in the United States. Pesticides: risks and hazards 520 • The daily dermal dose in µgkgday is equal to the unit exposure in µgkgAI times kgAI handled times the dermal absorption factor70 kg BW. • The inhalation dose in µgkgday is equal to: BZC x BR x EDBW, where BW is the body weight; BZC is the breathing zone concentration; BR is the brea- thing rate; and ED is the estimated duration – and is also equal to the unit exposure µgm 3 x 13.3 m 3 day x hoursday70 kg. • The total MOS is equal to: 1Inhalation MOS + Dermal MOS. • The MOSs ranged from 6 to 150, and thus were lower than the AEL of 1000. This EPA assessment concluded that when dermal and inhalation exposures were com- bined, the risk to residential applicators was low, due to an adequate margin of safety.

14.8.2.2. Residential bystander exposure assessment