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

Appendix 6Resident Exposures to Dichlorvos, and Risk Assessment:Exposure through contact with spray drift contaminated surfaces―It is possible that spray drift fallout from applications may be deposited in privategardens adjacent to treated areas, and individuals in such locations may becomeexposed through contact with such deposits. A possible scenario that illustrates asignificant opportunity for exposure would be children playing in a garden which hasbeen subject to spray drift fallout. It is possible to estimate such exposures using spraydrift fallout values used for aquatic risk assessment purposes (Rautmann et al., 2001)and the approach used by the United States Environmental Protection Agency toestimate residential exposure from contact with treated lawns (USA EPA 1998 / 1999 /2001). The exposure assessment reported … considers the scenario of a small childplaying on a lawn …For products which may be applied to crops on more than one occasion the theoreticalworse case is to consider children‘s exposure from the maximum total dose which maybe applied, i.e. to assume that there is no dissipation in foliar residues betweensuccessive treatments. This approach may be refined where data are available to refinethe estimated residues.‖ [quoted from UK CRD 2008b]The small child playing on a lawn leads to four potential exposures: dermal (skincontact); hand-to-mouth (sucking contacted fingers and thumbs); object-to-mouth(sucking contaminated objects, toys etc.); and, soil/grass ingestion by the child.Field crop (boom) sprayersScenarios (1-4): applications at 0.8 kg a.i./ha1) Children‘s dermal exposureSystemic exposures via the dermal route were calculated using the above drift falloutvalues and the following equation for boom sprayers:SE(d) = AR x DF x TTR x TC x H x DABWSE(d) = 8 x 0.01 x (0.05 x 0.05) x 5200 x 2 x 0.30 = 0.624 / 15 = 0.0416 μg/kg b.w.15Where:SE(d) = systemic exposure via the dermal routeAR = field application rate, 0.8 kg/ha = 8 μg/cm 2DF = drift fallout value, i.e. assumed average of 1% from boom sprayerapplicationsDichlorvos reassessment – application Page 368 of 436