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

enclosed space applications. Head/neck, exterior of clothing and hands wereassumed to be contaminated with, respectively 0.018, 2.68 and 0.26 mg/kg activehandled, 10% of the values from the PHED high pressure handwand model [seeAppendix 2]. Without actual exposure data while using high pressure handwands,the estimates based on the modified PHED model must be seen as uncertain.4.24 For inhalation exposure from manually applied fogger solutions, the sameapproach as used for estimating applicator exposures from RTU gas is used [see §4.20 and Appendix 2] [see Table VII].4.25 In Scenarios 24 and 25 where a spray is manually applied into enclosed areas of150, 1500 and 2500 m 2 (equivalent spaces: 375, 3750 and 12,500 m 3 ) at a use rateof 0.1 and 0.3g a.i./m 2 . The APVMA considered the PHED model 35(mixer/loader/applicators mixing liquid formulations by open pour methods andapplying the spraymix with high pressure handwand) the most appropriateestimation method. The predicted dermal exposure rates on head, body and handswere respectively 1.155, 90.86 and 2.49 mg a.i./kg applied. The spaces 150, 1500and 2500 m 2 would require: 15, 150 and 250g a.i. to be handled and applied at theuse rate of 0.1g a.i./m 2 . A higher application rate of 0.30g a.i./m 2 is recommendedfor the control of cockroaches, fleas etc., and the spaces would then require: 45,450 and 750g a.i. to be handled and applied. [See Appendix 3]4.26 For inhalation exposures from using high pressure handwand equipment indoors,APVMA modified the most relevant PHED model to account for the highvolatility of dichlorvos and estimated an inhalation exposure rate of 13.2 mga.i./kg applied [50 fold increase to account for the higher volatility, but also theslower volatilisation and greater droplet precipitation of an aerosol compared to aCO 2 pressure gun efflux] [See Appendix 3 and Table VIII].4.27 In Scenarios 26 and 27 RTU gas is applied manually in a domestic enclosed spaceas a surface/crevice application for the control of cockroaches, ants, fleas,silverfish, carpet beetles etc. at a use rate of 0.25g a.i./m 2 . In New Zealand theavailable product is sold in 600mL cans with 3.1g dichlorvos/L (P03653 label,BV2 Surface Insecticide). Each can contains 1.86 g dichlorvos enough for 7.44m 2at the recommended use rate above, although the label does not provide a specificapplication rate.4.28 The UK CRD (Model, 2006; Guidance document, 2008c) have models availableto estimate exposures during amateur use of pesticides, including a data-basedAerosol Surface treatment model. The model assumes rates of dermal (hand andforearm; 0.0647 mL/min; legs, feet and face: 0.0357 mL/min) and inhalationexposure per minute taken for the task (0.0006 mL/min), with a default durationof 300 seconds (5 minutes). The models rely on 15 sets of data from twoexposure monitoring studies during tasks such as spraying a small room includingsofa, 6 metres of skirting board, 2 dining chairs, and 6 m 2 of carpet. 5 minutescould seem a long time to discharge a 600mL can, but if the total time in thetreated room(s) is considered with the time needed to spray sofa cushions andmore complex items then it would be a realistic assumption. Given that there isno application rate on the label the modelling will be very approximate.Dichlorvos reassessment – application Page 288 of 436