A persistência de um pesticida no solo depende de processos de dissipação, como a degradação, que pode estar relacionada com o metabolismo microbiano. Com o objetivo de se avaliar os mecanismos de dissipação do herbicida atrazina no solo e a importância dos microrganismos neste processo, avaliou-se sua mineralização, degradação intermediária e formação de resíduos não-extraíveis ou ligados ao solo após aplicação de 14C-atrazina em solo Glei Húmico. Os processos foram quantificados através de técnicas radiométricas e cromatográficas em solo natural, solo esterilizado e solo esterilizado e infectado com Pseudomonas putida. Observou-se a importância dos microrganismos através dos estudos de biomineralização nos quais detectou-se mineralização de 14C-atrazina somente em solo natural (cerca de 15%). Entretanto, houve formação de metabólitos extraíveis de atrazina, tanto em solo esterilizado (67%) como em solo natural (75%), o que indica que este processo não dependeu apenas da presença de microrganismos. Já os resíduos não-extraíveis foram formados em maior quantidade (cerca de 56%) no solo esterilizado.

Microwave-assisted solvent extraction (MASE) was investigated as an alternative for extraction of parathion (O,O-diethyl O-4-nitrophenyl phosphorothioate), methyl parathion (O,O-dimethyl O-4-nitrophenyl phosphorothioate), p,p'-DDE [1,1'-dichloro-2,2-bis(4-chlorophenyl)ethane], hexachlorobenzene (HCB), simazine (6-chloro-N2,N4-diethyl- 1 ,3,5-triazine-2,4-diamine) and paraquat dichoride (1,1'-dimethyl-4,4'-bipyridinium) from two different soils and from an earthworm-growing substrate. The matrices were fortified with 14C-radiolabeled pesticides and extracted with various solvent systems under different microwave conditions. Recoveries of more than 80% could be obtained depending on the used microwave conditions and solvent, except for paraquat whose recovery was generally less efficient. Thus, MASE can be successfully used to extract pesticides from environmental and biological samples and could be a viable alternative to conventional extraction methods. The technique uses smaller amounts of organic solvents, thereby minimizing the costs of the analysis and the disposal of waste solvent.

Residential indoor environments are potential sources of exposure to pyrethroids, which have low acute toxicity to humans but are allergenic and suspected endocrine disruptors. The present study evaluated the persistence of the pyrethroids cypermethrin and beta-cyfluthrin on indoor surfaces and in house dust. Cypermethrin and beta-cyfluthrin were applied and maintained on aluminum foils and in dust samples for 112 d under controlled conditions and for 12 mo in a test house; periodically, they were quantified by high-performance liquid chromatography. Cypermethrin and beta-cyfluthrin concentrations showed decreases of 10.1% and 7.7% on aluminum foils, and 12.7% and 16.4% in dust, respectively, at 112 d under controlled conditions. In the test house, cypermethrin and beta-cyfluthrin concentrations decreased by 40.3% and 60.2% on aluminum foils, and 29.6% and 56.2% in dust at the end of the study. The results show the considerable persistence of cypermethrin and beta-cyfluthrin indoors and indicate the risk of exposure to these products. Environ Toxicol Chem 2017;36:2895-2898. © 2017 SETAC.

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