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

Table XVII: Re-entry into glasshouses treated at 72 mg dichlorvos/m 3 – total exposure and risksat venting: 30 minutes exposure (240 minutes after application)Dose (mg/kg b.w.) aRespiratory protection bNone Half-face Full-face Air-hoseInhalation 0.025 0.003 0.0005 NilDermal (with PPE) 0.0005 0.0005 0.0005 0.0005Total 0.0255 0.0035 0.0010 0.0005Risk Quotient (RQ) c 18 d 2.5 d 0.7 0.4abBody weight, 70kg;Protection factors from APVMA, 2008b: factor of 0.1 for a half face mask and a factor of 0.02 for afull face mask respectively, and no exposure for air-hose (supplied air system) [results rounded];cRQ = Total Estimated Occupational Exposure / AOEL where AOEL = 0.0014 mg/kg b.w./day;dRQ > 1 indicates the likelihood of an unacceptable risk to those exposed.REI for workers re-entering and working in a glasshouse for Cymbidium production:5.45 The second Brouwer et al. study (see 5.25) where the glasshouse was ventilatedafter 360 minutes indicated a faster rate of dissipation of air concentrations onceventilation had started. No further data are available on the reduction in DFR,other than the information of Casida et al. (1962), so it is assumed that beyond 20minutes after treatment, no further dissipation from plant surfaces occurs. Bycalculating a systemic dose from dermal exposure, the residual portion of theAOEL may be used to find a REI when the workplace atmospheric concentrationof dichlorvos has dropped low enough to allow an 8-hour work-day.The UK CRD equation for dermal exposure with TC for Ornamentals - Cut / Sort/ Bundle / Carry - 5000 and PPE, (hood/visor + overalls over long-sleeved shirtand long-legged trousers + boots + gloves) indicates:At 52 mg dichlorvos/m 3 :D = DFR x TC x DA x WR x AR x P / BWD = 0.5 x 5000 x 0.3 x 8 x 1.3 x 0.05 / 70 = 390 / 70 = 5.57 μg a.s./kg b.w./dayAt 72 mg dichlorvos/m 3 :D = 0.5 x 5000 x 0.3 x 8 x 1.8 x 0.05 / 70 = 540 / 70 = 7.71 μg a.s./kg b.w./day[Equation parameters are as discussed in 5.43, with appropriate modifications:WR = Work Rate [8 hours/day].]Dichlorvos reassessment – application Page 321 of 436