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

(Casida et al., 1962). Dichlorvos was effectively absorbed in 6 male and6 female rats following the oral administration of 3.6 mg/kg [b.w.][methyl- 14 C]dichlorvos in arachis oil as indicated by the recovery of64.6% of the dose in urine (Hutson and Hoadley 1972a). Identicalrecovery was obtained in 6 male and 6 female mice given 22 mg/kg[b.w.] [methyl-14C]dichlorvos (Hutson and Hoadley 1972a). When[vinyl- 14 C]dichlorvos was administered orally to 2 male Syrianhamsters at a dose of 3.7 mg/kg [b.w.] and to a female at a dose of 1.5mg/kg [b.w.], it was rapidly absorbed and 11.9-21.8% of the dose wasrecovered in the urine.“Evidence for rapid absorption of dichlorvos by the oral route includesdeath of Swiss mice within 9 minutes after a single gavage dose of 150mg/kg [b.w.] (Mohammad et al. 1989) and in crossbred swine within15-30 minutes receiving 100-560 mg/kg [b.w.] in an LD50 study(Stanton et al., 1979). Signs of cholinergic toxicity (vomiting, diarrhea)were observed in greyhound dogs within 7-15 minutes of receiving 11mg/kg [b.w.] dichlorvos by gelatin capsule (Snow and Watson 1973).(Originals not sighted; ATSDR, 1997)InhalationCalDRP (1996) reported:―In a comparison study with the oral route of exposure, rats (male, strain notgiven) were exposed to DDVP (0.71-1.07 mg in vapor) for 1 hour by noseonlyinhalation (Hutson et al., 1971). Urine, feces, exhaled air, and tissueswere collected following the same protocol as the oral route. The actualadministered dose was unknown since DDVP adsorbed to the apparatus.Therefore, results were expressed as the percentage of the total recoveredyield of carbon dioxide, the major metabolite. The amount of radioactivityretained in the tissues was similar to those for the oral route with the highestradioactivity level in the liver. The rates and routes of excretion, and urinarymetabolites by the inhalation route were considered similar to those afteroral administration.‖ (Originals not sighted; CalDPR, 1996)The ATSDR (1997) reported:“Indirect evidence for absorption of dichlorvos following inhalation inhumans was obtained by measuring dichloroethanol, a specificdichlorvos metabolite, in the urine of a male volunteer (Hutson andHoadley 1972b). This individual was exposed at the extremely highlevel of 38 mg/m3 (4.2 ppm) for 105 minutes. The first urine sampleobtained after exposure ended was analyzed by gas-liquidchromatography and 0.42 μg dichloroethanol/mL urine was detected(Hutson and Hoadley 1972b). The dichlorvos metabolite dimethylphosphate was found in the urine of 3 of 13 male volunteer pesticideapplicators who applied dichlorvos during an 8-hour workday (Das etal., 1983). During the application, they wore goggles, caps, respirators,coats, gloves, and shoes. Each applicator sprayed 4 homes using 10-14Dichlorvos reassessment – application Page 164 of 436