Mass Casualty Event in Texas

7-28-21

I have had a couple of long-time readers ask me to comment on this, so here goes. Last night there was an incident at a plant outside of Houston, TX that killed at least two people. Early news reports (here, here and here) would seem to indicate that there was a release (one report says 100,000 lbs) of acetic acid, perhaps glacial acetic acid. A number of people were taken to local hospitals, and more were treated on site.

Dilute acetic acid is most familiar to people as vinegar. The concentrations typically found at industrial production facilities would be much higher than that found in food grade vinegar. Glacial acetic acid, the most concentrated, nearly pure, version of acetic acid, is very corrosive and quickly produces chemical burns upon contact. Inhaled fumes of glacial acetic acid could produce chemical burns in the airways and lungs, resulting in death if inhaled in large enough quantities. More dilute acetic acid products would produce comparatively reduced injuries. Glacial acetic acid is flammable (flashpoint of about 104˚F), more diluted versions may vary from combustible to non-flammable depending on the concentration of water.

Early reports mentioned an explosion, but other reports said that there was no explosion. With the large amount of material reportedly released I would suspect that there was a storage tank failure. A catastrophic failure could create a large sound that could be mistaken for an explosion. If personnel had been in the vicinity of the tank during the release process, they could have sustained physical injuries in addition to chemical burns.

News reports have also mentioned methyl iodide, hydrogen iodide and methyl acetate as potentially being involved in the incident. These chemicals would be present in much smaller quantities and are unlikely to be a substantial cause of significant damage at the facility.

We are a long way from knowing what actually happened at the facility. There has not yet been an announcement about the Chemical Safety Board sending a team to investigate, but with two deaths, that is an almost forgone conclusion.