Absorption through the skin
In a laboratory accident, a worker was splashed with a 25% solution of ammonium hydroxide in water, wetting 29% of the surface area of his skin. He immediately tried to decontaminate himself under an emergency shower, but was found unconscious 15 minutes later. He suffered a cardiac arrest before he could be transported to hospital, was resuscitated, but then fell into a coma and died eight days later.
In another case, a person was splashed with an 8.75% tetramethylammonium hydroxide solution, wetting 12% of his body surface area. The staff member did not take this seriously and continued to work. After 25 minutes, he went to the locker rooms to take a shower. One hour later, he was found lying dead in front of the shower with severe skin burns.
Other cases similar to these and animal studies have shown that the toxic effect of tetramethylammonium hydroxide is even more dangerous than its corrosive effect. It is assumed that the activity of tetramethylammonium hydroxide is analogous to that of hydrofluoric acid: both the tetramethylammonium cation and the fluoride anion quite readily penetrate the skin and cause toxicity. Like the proton, the hydroxide anion is responsible for the corrosive effect.
Absorption through the skin is unusually rapid. As expected, the size of the contaminated area of skin and the concentration play a major role in the severity of the effect: the substance can lead to fatal poisoning even if only a small per cent of the body surface area is exposed.
In addition to instruction in safety procedures, key protective measures include an efficient chain of emergency response, especially protective clothing that effectively protects the skin from splashes, and a full-body emergency shower that is quickly reached (ideally within 5 seconds). Even minor skin contact requires medical treatment. It is advisable to exercise the same degree of caution in handling tetramethylammonium hydroxide as for hydrofluoric acid.