Mortality from dermal exposure to tetramethylammonium hydroxide

Tetramethylammonium hydroxide (TMAH; (CH₃)₄NOH, CAS No. 75-59-2) was used mainly in research and development laboratories in the past, but recently has become widely used in the micro-electromechanical industries, e.g. in the manufacture of semiconductors and liquid crystal displays (LCDs)¹⁾. It is considered to have a relatively low level of toxicity²⁾ although little toxicological information is available. In the literature, there are only a few reports of intoxication caused by the tetramethylammonium ion (TMA; (CH₃)₄N^-), a simple quaternary ammonium compound and cholinergic agonist resulting from the breakdown of TMAH, but not TMAH itself. Most of the intoxication cases were caused by eating food containing TMA, mainly gastropods, and the reported symptoms and signs were usually mild and self-limited³⁾. However, industrial TMAH is in the form of a concentrated strong alkaline and thus might have severe hazardous effects. We here present a mortality case caused by dermal exposure to industrial TMAH at work.