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

Conclusions on bystander and residential exposure estimates from spray drift:6.21 No reliable exposure models were available to assess bystander exposures tospray drift at time of application or inhalation of volatilised pesticides followingapplication.6.22 Residential exposure estimates from outdoor uses of dichlorvos were estimated byconsidering risks to young children from surfaces contaminated by spray drift.The risks were calculated to be acceptable after boom sprayer use at 0.8 kg a.i./ha(Scenarios 1-4), and from air assisted sprayers at 2.052 or 1.026 kg dichlorvos/ha(Scenarios 5-6 and 7-8) (see Table XX).6.23 Applications into structures (glass- and mushroom houses, Scenarios 13-16; andindustrial buildings, Scenarios 17-25) should not result in bystander exposureunless an accident occurred or the structure was not properly sealed beforetreatment.6.24 Intentional or inadvertent venting from the treated structure could result indichlorvos escaping as a point source plume carried by the wind until degradationor deposition, but modelling was not attempted. The amounts of dichlorvos fromeach individually treated facility would be relatively small in relation to theoutside airspace.6.25 Estimated exposures to children after domestic uses indoors (Scenarios 26 & 27)and outdoors (Scenarios 28 & 29) indicate very high risks (RQs of >>1,) couldresult from contact with contaminated surfaces (i.e. from carpets, soft furnishings,floors etc.). While the calculated exposures will have been over-estimated inthese models, because no dissipation of dichlorvos has been factored in [see TableXXI], the risk levels are unacceptably high.6.26 Estimated exposures to children after public space applications (Scenario 30)indicate very high risk (RQs of >>1) could result from contact with contaminatedsurfaces (i.e. from playing on sprayed turf). While, the calculated exposures willhave been over-estimated in these models, because no dissipation of dichlorvoshas been factored in [see Table XXII], the risk levels are unacceptably high.Dichlorvos reassessment – application Page 341 of 436