Atmospheric Fate of Dichlorvos:  Photolysis and OH-Initiated Oxidation Studies

Abstract

The OH-initiated oxidation of dichlorvos (a widely used insecticide) has been investigated under atmospheric conditions at the large outdoor European photoreactor (EUPHORE) in Valencia, Spain. The rate constant of OH reaction with dichlorvos, k, was measured by using a conventional relative rate technique where 1,3,5-trimethylbenzene (TMB) and cyclohexane were taken as references. With the use of the rate constants of 5.67 x 10(-11) and of 6.97 x 10(-12) cm3 molecule(-1) s(-1) for the reactions OH + TMB and OH + cyclohexane, respectively, the resulting value of the OH reaction rate constant with dichlorvos was derived to be k = (2.6 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1). The tropospheric lifetime of dichlorvos with respect to reaction with OH radical has been estimated to be around 11 h. The major carbon-containing products observed for the OH reaction with dichlorvos in air under sunlight condition were phosgene and carbon monoxide. The formation of a very stable toxic primary product such as phosgene associated with the relatively short lifetime of dichlorvos may make the use of this pesticide even more toxic for humans when released into the atmosphere.

Reactivity of Semivolatile Organic Compounds with Hydroxyl Radicals, Nitrate Radicals, and Ozone in Indoor Air

“…Second‐order rate constants for the gas‐phase OH/SVOC reactions were available for all 72 SVOCs. One hundred and thirty‐three second‐order rate constants were retrieved from the literature or calculated using the AOPWIN calculator for the gas‐phase reaction (see Table S1 in the Supporting Information). Among them, 31 were measured values from the literature, 30 were predicted values from the literature, and 72 were calculated using the AOPWIN calculator.…”

Investigating ozone-induced decomposition of surface-bound permethrin for conditions in aircraft cabins

“…Ozone could feasibly react with other unsaturated compounds on an indoor surface, form OH•, and OH• could then react with permethrin to form phosgene. The formation of phosgene from OH• radical‐oxidation of a gas‐phase dichlorovinyl compound, dichlorvos, has been detected (Feigenbrugel et al., 2006). However, phosgene was not detected in the present experiments, even with ozone‐reactive aircraft cabin materials serving as the substrate.…”

The Contribution of Molecular Modeling to the Knowledge of Pesticides

“…Knowledge of the OH-initiated DDVP oxidation mechanism and the major degradation products is limited. Feigenbrugel et al (2006) detected phosgene (Cl 2 CO) and carbon monoxide (CO) and proposed a possible reaction mechanism to explain the observed products, in which CO formation is initiated by H abstraction from the CH 3 O group of DDVP, and then the product radical may further react with O 2 /NO leading to HCO. The observed CO would be formed through the reaction of HCO with O 2 .…”