Risco ambiental da aplicação de éteres de difenilas polibromadas como retardantes de chama / Environmental risks involved with the application of polybrominated diphenyl ethers as flame retardants

Flame retardants are additives of combustible materials, such as plastics, textile, electronic circuitry, wood and paper providing resistance to the combustion process when exposed to fire and high temperature. The main flame retardants used are inorganic chemicals (such as antimony oxides), organic phosphate esters with or without halogens, and chlorinated and brominated organic compounds. The brominated flame retardants (BFRs) are largely used due to its efficiency and low cost. The most used flame retardants are the polybrominated diphenyl ethers (PBDEs), produced inlarge-scale whose degradation is very difficult. Thus, they have been found in many different environmental samples. These observations suggest the current destination of these substances is still devoid of recycling or specific treatment. Despite the increased application in oil polymers, little is known about its impact upon the ecosystem. In this review, we provide an overview about the use and risks related to PBDEs as a recognized toxicants found in industries.

Os retardantes de chama, dentre os quais se destacam os éteres de difenilas polibromadas, são aditivos de materiais destinados a torná-los resistentes ao fogo ou a altas temperaturas, inibindo ou suprimindo o processo de combustão, dentre os quais se destacam os éteres de difenilas polibromadas (PBDEs, do inglês, polibromated diphenyl ethers). Devido a sua produção em grande escala e sua difícil degradação, os PBDEs têm sido um contaminante emergente frequentemente encontrados em diferentes amostras ambientais, demonstrando que o processo produtivo, em especial o destino desse material, requer medidas estratégicas que racionalize seu uso. Apesar da ampla utilização desses aditivos em polímeros (na maioria derivados de petróleo) e tecidos inflamáveis comumente utilizados, pouco se sabe a respeito do impacto dessas substâncias sobre o ecossistema. Nessa revisão, uma relação consistente a respeito do risco ambiental resultante do uso indiscriminado desses aditivos, ainda carentes de regulamentação específica, foi estabelecida com base na ação desses compostos bem como a prevalência de algumas classes, reconhecidamente tóxicas em alguns ambientes.

Efficacy of nitrous oxide, halothane, ether and spinal anaesthesia on hearing acuity and middle ear pressure

A prospective study was executed on 80 patients with 160 healthy ears to detect the efficacy of different anaesthetic agents and techniques on middle ear pressure and hearing acuity. The patients were randomly divided into 4 equal groups according to the received anaesthetic; nitrous oxide, halothane or ether general anesthesia and spinal anaesthesia respectively. Tympanograms and audiograms were done prior to, during and after the operation for every case. Significant middle ear pressure changes were recorded during the operation and 30 minutes subsequent to cessation of nitrous oxide anaesthesia. Moreover, significant hearing impairment especially at low frequencies were detected in all patients of group I who received nitrous oxide anaesthesia, and in 50% of cases of group IV who were anaesthetized spinally. On the other hand, halothane and ether anaesthesia had no effect on neither the hearing acuity, nor the middle ear pressure