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

“Comment: These incidents clearly illustrate the potential for dichlorvos tocause toxicity via the dermal route. Dermal absorption may have beenenhanced by the mineral spirits/organic solvents in which the dichlorvoswas diluted. Given that dichlorvos is a slight skin irritant and was present atonly 1 or 5%, the dermal reactions were probably caused by the solvents.‖(Originals not sighted; APVMA, 2008b)The APVMA (2008a) also reported:In ATSDR (1997):―Gold RE & Holcslaw (1984) Dermal and respiratory exposure ofapplicators and residents to dichlorvos-treated residences. In: Dermalexposure related to pesticide use: discussion of risk assessment (RCHoneycutt, G Zwerg & N Ragsdoleet eds). American chemical SocietySymposum Series No. 273.―Materials and Methods―Two applicators were monitored for their exposure to dichlorvos during thetreatment of twenty singlefamily residences with a 0.5% water-emulsionspray prepared from Vaponite 2EC (unspecified source and batch/lot No.;24.7%). The application rate was 0.19 g/m 2 dichlorvos (38.7 mL/m 2 spray)and the average residence size was 103±33 m 2 . Temperature and humiditywere 26.1°C and 82%, respectively. The spray was applied along thebaseboards, doorways, windows, all entrances, under the sink, stove andrefrigerator, shelves, cabinets and around plumbing and utility installations.Residents were advised not to re-enter their premise for two hours.“Conclusions: This study suggested that toxicologically-significantexposure of applicators and residents can occur during and immediatelyfollowing the application of dichlorvos. Although this study had somedeficiencies (such as the lack of reporting detail and the small sample sizes),it had qualitative value for risk assessment purposes.‖ (Originals notsighted; APVMA, 2008a)“In an intermediate-duration 21-day study in which volunteers weregiven dichlorvos orally, no signs of neurological toxicity were seen atdoses of 0.033 mg/kg [b.w.]/day (Boyer et al. 1977). Twenty-four malevolunteers had their serum cholinesterase and erythrocyteacetylcholinesterase determined twice a week for 3 weeks to establishtheir baseline levels. They were then given 0.9 mg dichlorvos 3 times aday for 21 days in either a pre-meal capsule or a 3-ounce container ofgelatin. Serum cholinesterase and erythrocyte acetylcholinesterasewere measured twice a week during the exposure period. Once a week,each volunteer had his vital signs measured, and was examined fortremor, pupillary response to light, and skin moisture. Following.theend of the study, serum cholinesterase and erythrocyteacetylcholinesterase were measured weekly for the next seven weeks.No clinical signs of neurological toxicity were observed in any of theDichlorvos reassessment – application Page 251 of 436