Residential bystander exposure assessment Inhalation exposure Residential bystander exposures Scenarios

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

As exposure data were unavailable, this assessment is based only on EPA SOPs. The general assumptions for this assessment were as follows. • The average BW of an adult is 70 kg. • The average BW of a child toddler is 15 kg. • The application of chlorpyrifos is made according to label directions. • Exposure is short-term one day to one month following application. • Only post-application exposure occurs. • The method of application was crack-and-crevice or spot treatment. • The chlorpyrifos dilution applied was 0.5. • The application rate of dilution to surfaces was 0.08 litrem 2 . • AEL is 1000.

14.8.2.3. Inhalation exposure

The general assumptions for assessing this route of exposure were as follows. • The BRs were assumed to be 1.0m 3 hour for adults and 0.7m 3 hour for children. • The exposure occurred 1–10 days after treatments. • The inhalation dose is expressed as: BZC x BR x EDBW. • The MOS is expressed as: NOAELInhalation Dose. The AEL is 1000. Public Health Significance of Urban Pests 523

14.8.3.3. Residential bystander exposures

The general assumptions made for residential bystander exposures are as follows. • The average BW of an adult is 70 kg. • The average BW of a toddler is 15 kg. • The highest label rate for each use pattern was applied. • Exposures were secondary, except for indoor foggers. For residential bystander exposure, four scenarios were assessed to take into account pos- sible exposures of adults and children after applying pyrethrins: 1. dermal transfer and incidental oral ingestion after pet treatments 2. inhalation exposure 3. incidental oral exposure during and after indoor space-spray or fogging treatments 4. dermal exposure for all use patterns.

14.8.3.4. Scenarios

14.8.3.4.1. Scenario 1: child exposure to pet treatments The assumptions made for post-application spray treatments of pets were as follows. • One half of a 473.5-ml spray container is used to treat each animal. • The transferable residue TR from a treated pet is assumed to be 20 of the maximum application rate for sprays. • The SA of a treated 15 kg dog is 6000cm 2 EPA, 1993. • The SEF is 50 50 of the dislodged residue of pyrethrins extracted from the fingers by saliva. • The SA of a hand put in a mouth is 20cm 2 . • The Freq of hand-to-mouth events is one per day. The daily incidental oral dose was given by the following expression: TR x SEF x SAhands x Freq. The MOS is given by the following expression: Short-term Oral NOAEL 20mgkgdayDaily Oral Dose mgkgday. An AEL equal to 100 was used. The MOS calculated for this route of exposure was greater than 300, which meant this route of exposure was not considered to be of concern. Pesticides: risks and hazards 522

14.8.3. Residential exposures to pyrethrins