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

Exposure through contactwithcontaminatedsurfaces(cumulative)(mg/kg b.w./day)acChild‘s hand-to-mouthexposure a 0.0333Child‘s object-to-mouthexposure a 0.0083Child‘s soil ingestion b 0.0011Child‘s total exposure 1.2428 888UK CRD Bystander Exposure Guidance Document (2008b); b US EPA (2006b);Where: Dermal absorption = 30%; Inhalation absorption = 100%;RQ = Estimated Residential Exposure / AOEL where AOEL = 0.0014 mg/kg b.w./day; RQ > 1indicates the likelihood of an unacceptable risk to those exposed.6.17 The calculated exposures will have been over-estimated in these models, becauseno dissipation of dichlorvos has been factored in due to lack of relevantinformation on the behaviour of dichlorvos after the treatment of residentialhouses with furniture, soft furnishings etc. (Scenarios 26 & 27). In the outdooruses (Scenarios 28 & 29) the treated surfaces could be anything from concrete(reported to cause rapid degradation) to wooden decks which may act as areservoir (Hussey & Hughes, 1963 in APVMA, 2008b).6.18 For public space application, children with their potential for high contact,exploratory nature and low body weight appear to be the most at risk, andavailable models will offer worst-case exposure estimates.6.19 The models used previously (§ 6.5-6.8) to estimate children‘s exposure throughcontact with spray drift contaminated surfaces are used, assuming that the averagedrift value is 100% (i.e. the surface is directly sprayed and the spray remainswhere applied) and no dissipation occurs before and during the 2 hours of contact.[See Appendix 6 and Table XXII].Scenario (30) Indoor:Table XXII: Dichlorvos – Public Space Uses (1 hectare)Bystander Internal Exposure Estimates and Risk Assessment aExposure through contactwithcontaminatedsurfaces(cumulative)(mg/kg b.w./day)acExposure(mg/kg b.w./day)Child‘s dermalexposure a 0.104Child‘s hand-to-mouthexposure a 0.0133Child‘s object-to-mouthexposure a 0.0033Child‘s soil ingestion b 0.0001Risk Quotient(RQ) cChild‘s total exposure 0.1207 86UK CRD Bystander Exposure Guidance Document (2008b); b US EPA (2006b);Where: Dermal absorption = 30%; Inhalation absorption = 100%;RQ = Estimated Residential Exposure / AOEL where AOEL = 0.0014 mg/kg b.w./day; RQ > 1Dichlorvos reassessment – application Page 339 of 436