Abstract: On February 7, 2011, Employee #1, a tank wash lead man, was cleaning the interior and exterior of a tank truck (Brenner Tank, Model SS Transport, VIN 10BFV7212NF0A3251) in wash bay 1 at Enterprise Products Transportation Company, LLC. He opened the manway and connected a compressed air hose to the rear washout coupling to ventilate the tank. At approximately 6:30 p.m., Employee #1 was found unresponsive inside the tanker truck immediately beneath the main manway hatch by an assistant tank washer working in wash bay 2. An alarm was sounded, and a coworker entered the tank and removed Employee #1. He was transported by ambulance to a nearby community hospital and later airlifted to a Houston hospital. Employee #1 died the next day. The product reported to have last been in the tanker truck was Dow Styrofoam(TM) RS 2030 Polyol. This chemical was a urethane-based product that was a mixture of 9 or more chemicals, including a number of oxirane, amine, oxide, formaldehyde and phthalate molecular compounds. MSDS information indicated Dow and ACGIH exposure limits as low as TWA of 0.05 ppm (skin) and STEL 0.15 ppm (skin). The MSDS information also indicated that in confined areas, the vapor can easily accumulate and cause unconsciousness and death due to displacement of oxygen (vapor pressure 27.2 psi & 32 deg C). The chemical was off-loaded from the tank trailer at a customer site using nitrogen. Residual nitrogen in the tank, combined with the chemical's oxygen displacing characteristics, could produce an oxygen-deficient atmosphere at the manway opening. The employees who rescued Employee #1 stated that a water hose used to test the product inside the tankers - to see if old water washing would remove the product - was found running and dangling on the side of the tanker, and the Employee #1's flashlight was found inside the tanker. Apparently, Employee #1 positioned himself over the open manway to peer inside the tanker, was overcome, and fell into the tank.