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

The modelling is based upon discharge over a period of 5 minutes of a 600mLRTU can containing 3.1 g a.i/L (P03653 label, BV2 Surface Insecticide); dermalabsorption, 30%; inhalation absorption, 100%. Predicted exposures (75 thpercentile values) from Scenarios 26 and 27 with the RQ values are shown inTable IX.4.29 Scenarios 28 & 29 envisage amateur users loading a ready to use (RTU)dichlorvos spray solution into a knapsack sprayer for applications to larger areas,such as patios and decks. The registered product (P03915, BV2 SurfaceInsecticide Bulk) contains 4.4g dichlorvos/L, and is sold in 4L packs (containing17.6g a.i. in total). No application rate is recommended beyond the labelstatement that treated surfaces should be damp. This is essentially the same asScenarios 24 and 25 [§ 4.25], except for amateur instead of professional users, andwhere no PPE or RPE can be expected but smaller areas would be treated. Formodelling it is assumed that the complete 4L pack is used in one session, but theavailable models require an application rate for calculations. The professionalproducts (Scenarios 24 & 25, § 4.25) recommended application rates of 0.30ga.i./m 2 for the control of similar pests, cockroaches, fleas etc. At 0.30g a.i./m 2 , 4Lof product containing 4.4 g/L would cover approximately 60m 2 (17.6 / 0.3).Given that there is no application rate on the label the modelling will be veryapproximate.4.30 The UK CRD‘s POEM_07 (UK CRD, 2007) has models available to estimateexposures during amateur use of pesticides through knapsack sprayers (5L),which the BBA model does not, so this model was used for this application. Themodel accepts that hand contamination may be higher than for professional users.The model also requires inputs for mixing/loading. The worst-case for handcontamination during mixing / loading is posed by containers with separatemeasuring caps, and the least exposure using an "integral squeeze-to-fillmeasure". Since, the RTU product involves no measuring only loading the lowestexposure option was used. The default assumptions are that the operator uses nogloves, wears a T-shirt and shorts, and exposure lasts for 30 minutes. However,since only 4L of the RTU product is to be applied 15 minutes has been used as anupper limit for the time needed to spray 4L in place of this default setting.4.31 The exposures (75 th percentile values) from Scenarios 28 and 29 with the RQvalue are shown in Table IX.4.32 For Scenario 30, fogging of public spaces, the Nuvos label (P001132) describesthe use as covering parks, beaches, sports areas and other fly breeding sites for thecontrol of fly larvae and mosquitoes by applying a cold fog to wet the top 5-8cmof litter. The use rate is taken to be 10ml product/ 2L spraymix/ 100m 2 , based onthe area coverage advised for other applications, and as Nuvos contains 1000gdichlorvos/L this is 0.1g a.i./m 2 . For similar uses, APVMA (2008b) estimatedexposures and risks from spraying 1 or 5 ha/day.4.33 The APVMA considered the PHED model 3 (mixer/loader mixing liquidformulations by open pour methods) the most appropriate estimation method forpredicting dermal and inhalation exposures. The predicted dermal exposure rateson head, body and hands were respectively 0.0116, 0.6622 and 6.248 mg a.i./kgDichlorvos reassessment – application Page 289 of 436