Propanil: Toxicological Characteristics, Metabolism, and Biodegradation Potential in Soil

Abstract

Propanil [3′,4′‐dichloropropionanilide (DCPA)] is a biologically active pollutant. Propanil is extensively used around the world for control of weeds in rice (Oryza sativa L.) production. Although propunil by itself is of low toxicity, the highly toxic impurities 3,3′,4,4′‐tetrachloroazobenzene (TCAB) and 3,3′,4,4′‐tetrachloroazoxybenzene (TCAOB) from the manufacture of 3,4‐dichloroaniline (DCA) often contaminate the 3,4‐DCA‐derived herbicide propanil. These componnds are approximately isosteric to 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin (TCDD), and acting at the Ah receptor, are toxic by mechanisms similar to those of TCDD. Both TCAB and TCAOB are cytotoxic, embryolethal, and teratogenic, and hence are classified as possible human genotoxins. In soil, biodegradation of propanil liberates DCA, which is converted by microbial peroxidases to TCAB and other azo products. The TCAB and TCAOB may accumulate in rice‐growing soils, and leach into groundwater. The toxicity and fate of these compounds in the environment and the ability of microorganisms to detoxify them are discussed.

Irrigation with Treated Wastewater: Potential Impacts on Microbial Function and Diversity in Agricultural Soils

“…Hence, due to biodegradation activity, soil microorganisms contribute to avoid the dissemination of micropollutants to the surrounding environment through surface run-off and leaching into aquifers. However, soil microbial communities may have a limited capacity to regenerate soils submitted to frequent discharges of xenobiotics (not naturally produced) or natural exogenous substances that will act as pollutants [84][85][86][87]. In general, it can be hypothesised that the longterm wastewater reuse, mainly if the minimal quality standards are not met, will have implications either on the turnover of some chemical components or on the adequate balance of microbial populations in soils.…”

Oxidation of Dichloroanilines and Related Anilides Catalyzed by Iron(III) Tetrasulfonatophthalocyanine

“…3,4-DCA is formed Dichloroanilines (DCAs) are used as precursors on a during the biodegradation of the herbicide Propanil (3,4-large scale in the industrial synthesis of pesticides, plastics dichloropropionanilide). [2] From 1970 to 1987, on average, and dyes. [1] The contamination of aquatic environments by 3Ϫ7 kg of Propanil/ha were applied each year to about 70 DCAs can occur directly through their accidental release to 100% of rice culture in the United States.…”

“…cide Propanil (3,4-dichloropropionanilide, 3,4-DCPA) is used extensively around the world for control of weeds in rice cultures. [2] Although Propanil itself has a low toxicity, Results its conversion into 3,4-DCA by microorganisms in soil is a problem, since the acute exposure to this DCA isomer reWe first investigated the oxidative degradation of the two sults in renal and hepatic toxicity in vivo. [3] In order to different dichloroanilines 3,5-DCA and 3,4-DCA using solve this problem several investigations have been carried FePcS as the catalyst and potassium monopersulfate or hyout to find efficient systems for DCA degradation by re-drogen peroxide as the oxidant.…”

“…The formation of ring cleavage products probably occurred via the dechlorination values of these reactions corresponded to 0.5 released chloride ions per converted substrate molecule. In intermediates 2,6-dichloro-1,4-quinoneimine (1) and 2,6-dichloro-1,4-benzoquinone (2). Their respective reduced other words, one covalent chlorine atom of 50% of DCA molecules was transformed into a chloride ion.…”

“…[5c] Therefore, we proal., [2] compound B can react with another substrate molpose the oxidation of the acyl methylene group, since sececule to form the 3,5,3Ј,5Ј-tetrachlorohydrazobenzene C, ondary CϪH bonds of a methylene group in the α-position which is then oxidized to the 3,5,3Ј,5Ј-tetrachloroazobenwith respect to a carbonyl group should be weaker than zene (7) and to the 3,5,3Ј,5Ј-tetrachloroazoxybenzene (8). tertiary CϪH bonds of a methyl group.…”