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

The Dermal Exposure (D) is 2.06 μg a.s./kg b.w./day.Re-entry by a worker for picking: inhalation exposure.Using the data from Casida et al. (1962), 20 minutes after application to the leafsurfaces of maize, cotton and peas about 50% was volatilised, while 5% remains on theleaf surfaces and 45% absorbed by the plant (in APVMA, 2008b).It is assumed therefore that only 50% of the application rate is available for possibleinhalation:Inhalation Exposure (I) = mg a.s./hr inhaled x WR / BWmg a.s./hr inhaled = kg/a.s./ha applied x Task Specific FactorWhere:indicative Task Specific Factor = 0.01 (See paragraph 5.20);WR = Work Rate (8 hours/day)AR = Application Rate (50% of 0.8 kg a.s./ha)BW = bodyweight (70 kg)I = ((0.5 x 0.8 x 0.01) x 8) / 70 = 0.032 / 70 = 0.00046 mg/kg b.w./dayInhalation Exposure (I) is 0.00046 mg a.s./kg b.w./day or 0.46 μg a.s./kg b.w./day.With RPE:The APVMA (2008b) use the following protective factors for various RPE:Half-face respirator 0.1Full-face 0.02Air-hosenil inhalation exposureWith a half-face respirator: I = 0.46 x 0.1 = 0.046 μg a.s./kg b.w./day;full-face:I = 0.46 x 0.02 = 0.0092 μg a.s./kg b.w./day;Dichlorvos reassessment – application Page 367 of 436