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

can reduce dermal exposures to mixer/loaders by 2.7 fold (a factor of 0.37)(Franklin & Worgan, 2005) [see Appendix 1].4.7 Enclosed cabs on motorised ground equipment can reduce the dermal, and if fittedwith appropriate filtered ventilation systems, inhalation exposures to applicatorsduring spraying. The US EPA considers that a correctly used and maintainedenclosed cab/filtration system can reduce exposures to applicators by 3 fold (afactor of 0.33) when using ground-booms and by 13.4 fold (0.075) with air-blastequipment (Franklin & Worgan, 2005) [see Appendix 1].4.8 Tables II, III, and IV show the modelled operator exposures and risks for theoutdoor activities with dichlorvos based on the BBA model, with and without PPEand RPE, and with and without engineering controls (for Scenarios 1-4, 5 & 6).For Scenarios (7 & 8), that use hand-held sprayers, no enclosed cab is possibleand it has been assumed that no closed mixing and loading system would beavailable for such small quantities.4.9 Scenarios 9-14 where applications are indoors (greenhouses, mushroom houses) itis assumed that the application equipment is automatic or remote (i.e. applicatorsare not in the space being treated), so that occupational exposure is confined tomixer/loader, or in the case of gas products, connecting/disconnecting cylinders.4.10 The APVMA re-assessment (APVMA, 2008b) considered that operators might beexposed via the hands to dichlorvos when changing cylinders during gas foggingof glasshouse or mushroom houses (Scenarios 9 & 10). The APVMA estimateddermal exposure to 0.001 mL/cylinder (equivalent to 0.0014g dichlorvos, and with30% dermal absorption, a systemic dose of 0.00042g; glove penetration, 10%).Inhalation exposure could also result if some of the dichlorvos evaporated into the1m 3 personal air space around the operator‘s breathing zone. If 0.005ml ofdichlorvos (wt. 7.1mg) was available for inhalation for 1 minute, then they wouldinhale 0.12mg or 0.0017 mg/kg b.w. (70kg) [see Appendix 2].4.11 In New Zealand, RTU gases are sold in 7 & 35L cylinders, containing 50g a.i./L;and are applied at use rates of 0.05g a.i./m 3 for volume fogging. The maximumcoverage per day is stated at 1.25ha (Scenarios 9 & 10), and assuming a 2.5mbuilding height, this would require approximately 1.6kg (31.25L of product) orfive 7L cylinders or one 35L.4.12 The fogging of glasshouses with EC dichlorvos solutions for crops or mushroomhouses (Scenarios 11 & 12) is modelled on use rates of 0.05g a.i./m 3 with amaximum coverage of 1.25ha (rate 1.25kg a.i./ha, assuming a 2.5m buildingheight) [Note: the product label also recommends use as a light spray, but Plant &Food Research reports that this is not done, and has not been modelled]. Thefogging of glasshouses for Cymbidium production (Scenarios 13 & 14) is stated tobe confined to 0.1ha per day, at a use rate of 1300 g/ha.4.13 Table V shows the modelled mixer/loader exposures and risks for the indooractivities with dichlorvos using remotely operated application equipment, withPPE and RPE (for Scenarios 9-14). The mixing loading exposure estimates forScenarios 9 & 10 were based on the APVMA approach above. For Scenarios 11-Dichlorvos reassessment – application Page 285 of 436