An Inhalation Exposure System for the Oil Dispersant COREXIT(R) EC9500A

An automated whole body inhalation exposure system capable of exposing 12 rats was designed to examine the potential health effects of the oil dispersant (COREXIT® EC9500A [CE]) used during the Deepwater Horizon oil spill. A computer-controlled syringe pump injected the CE into an atomizer where droplets and vapor were formed and mixed with diluent air. The aerosolized CE was passed into a customized exposure chamber where a calibrated light scattering instrument estimated the real-time particle mass concentration of the aerosol in the chamber. A custom software GUI was developed to record and control parameters during the exposures. Software feedback loops controlled the chamber aerosol concentration and pressure throughout each exposure. Particle size of the dispersant aerosol was measured and shown to have a number peak at 271 nm and a mass peak at 961 nm. The method used to determine the chamber concentration was a modification of the acidified methylene blue spectrophotometric assay for anionic surfa...