RESUMO
Fake news?? The contact insecticide DDT has been reappraised as a safe, life-saving compound by special interest groups committed to repealing environmental regulations. It is shown in this essay how some specific toxicological data has been misused by those aiming to disingenuously influence public policy. Graphic: Pestroy, a DDT-laced coating marketed in 1946 by Sherwin-Williams Research Laboratories.
Assuntos
Conservação dos Recursos Naturais , DDT/toxicidade , Política Ambiental , Inseticidas/toxicidade , Animais , Conservação dos Recursos Naturais/história , Conservação dos Recursos Naturais/legislação & jurisprudência , DDT/síntese química , DDT/química , DDT/história , Política Ambiental/história , Política Ambiental/legislação & jurisprudência , História do Século XIX , História do Século XX , Inseticidas/síntese química , Inseticidas/química , Inseticidas/históriaRESUMO
Pseudomonas aeruginosa RW41 is the first bacterial strain, which could be isolated by virtue of its capability to mineralize 4-chlorobenzenesulfonic acid (4CBSA), the major polar by-product of the chemical synthesis of 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)ethane (DDT). This capability makes the isolate a promising candidate for the development of bioremediation technologies. The bacterial mineralization of 4CBSA proceeds under oxygenolytic desulfonation and transient accumulation of sulfite which then is oxidized to sulfate. High enzyme activities for the turnover of 4-chlorocatechol were measured. The further catabolism proceeded through 3-chloromuconate and, probably, the instable 4-chloromuconolactone, which is directly hydrolyzed to maleylacetate. Detectable levels of maleylacetate reductase were only present when cells were grown with 4CBSA. When the ordinary catechol pathway was induced during growth on benzenesulfonate, catechol was ortho-cleaved to cis,cis-muconate and a partially purified muconate cycloisomerase transformed it to muconolactone in vitro. The same enzyme transformed 3-chloro-cis,cis-muconate into cis-dienelactone (76%) and the antibiotically active protoanemonin (24%). These observations are indicative for a not yet highly evolved catabolism for halogenated substrates by bacterial isolates from environmental samples which, on the other hand, are able to productively recycle sulfur and chloride ions from synthetic haloorganosulfonates.
Assuntos
Benzenossulfonatos/metabolismo , Hidrocarbonetos Halogenados/metabolismo , Pseudomonas aeruginosa/metabolismo , Catecóis/metabolismo , Cromatografia por Troca Iônica , DDT/síntese química , Furanos/metabolismo , Liases Intramoleculares/metabolismo , Lactonas/metabolismo , Maleatos/metabolismo , Redes e Vias Metabólicas , Oxirredução , Pseudomonas aeruginosa/crescimento & desenvolvimento , Ácido Sórbico/análogos & derivados , Ácido Sórbico/metabolismo , Sulfatos/metabolismo , Sulfitos/metabolismoAssuntos
DDT/toxicidade , Animais , Testes de Carcinogenicidade , Carcinógenos/síntese química , Carcinógenos/química , Carcinógenos/farmacologia , Carcinógenos/toxicidade , Cricetinae , DDT/síntese química , DDT/química , DDT/farmacologia , Exposição Ambiental/efeitos adversos , Exposição Ambiental/legislação & jurisprudência , Feminino , Guias como Assunto , Humanos , Inseticidas/síntese química , Inseticidas/química , Inseticidas/farmacologia , Inseticidas/toxicidade , Masculino , Camundongos , Modelos Biológicos , RatosRESUMO
Using a novel in vitro technique, whereby microsomal enzymes were embedded in an agar layer to prolong their viability, 1,1-bis(p-chlorophenyl) ethylene(DDNU), a mammalian metabolite of 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethane (DDT), was converted by microsomal mono-oxygenases of mouse liver into 1,1-bis(p-chlorophenyl)-1,2-ethanediol (DDNU-diol). The putative epoxide intermediate, 1,1-bis(p-chlorophenyl)ethylene oxide (DDNU-oxide), a new compound, was synthesized; it showed weak alkylating activity with 4-(4-nitrobenzyl)pyridine but was not mutagenic in Salmonella typhimurium strains TA100 and TA98. DDT and 13 of its metabolites or putative synthetic derivatives, including 1,1-bis(p-chlorophenyl)-2,2-dichloroethylene (DDE), 1 1,1-bis(p-chlorophenyl)-2-chloroethylene (DDMU), 1,1-bis(p-chlorophenyl)-2-chloroethane (DDMS)-DDNU, 2,2-bis(p-chlorophenyl)ethanol (DDOH), bis(p-chlorophenyl)acetic acid (DDA) and 1,1-bis(p-chlorophenyl)-2,2,2-trichloroethanol (Kethane), caused no mutagenic effects in S. typhimurium strains TA100 or TA98, either in the presence or absence of a mouse-liver microsomal fraction. 1,1-Bis(p-chlorophenyl)-2,2,2-trichloroethyl acetate (Kelthane acetate) was a direct-acting mutagen in strain TA100, whereas 1,1-bis(p-chlorophenyl)-2,2-dichloroethane (DDD) was mutagenic in TA98, only in the presence of a mouse-liver microsomal system. The results are discussed in relation to possible pathways whereby DDT is activated to mutagenic and/or carcinogenic metabolites.