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Subject:
Re: [DCHAS-L] TMAH Incident
Date:
Jan 16, 2021 21:25 UTC
Author:
NEAL LANGERMAN <neal**At_Symbol_Here**CHEMICAL-SAFETY.COM>
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Subject:
Re: [DCHAS-L] TMAH Incident
Date:
Jan 17, 2021 07:22 UTC
Author:
Eugene Ngai <eugene_ngai**At_Symbol_Here**COMCAST.NET>
From:
Alan Hall <oldeddoc**At_Symbol_Here**GMAIL.COM>
Subject:
Re: [DCHAS-L] TMAH Incident
Date:
Jan 17, 2021 00:37 UTC
Reply-To:
ACS Division of Chemical Health and Safety
In-Reply-To:
Re: [DCHAS-L] TMAH Incident
Et al,
You might consider our recent article regarding TMAH exposures in a retrospective observational study (data also from Taiwan):
Huang C-K, Hall AH, Wu M-L et al. Presentation of tyetramethylammonium hydroxide dermal exposure and the valuable potential of diphoterine solution in decontamination: a retrospective observational study. BMC Pharmacol Toxicol 2020; 21:83; doi: 101186/s40360-020-00465-8.
It appears that the TMAH causes both base corrosive skin/eye injuries and that the compound readily dissociates into the TMA+ cation and the OH- anion. The anion causes skin injury which allows the TMA+ ion to more easily penetrate the skin, be absorbed, and cause systemic cholinergic agonist toxicity, sometimes fatal. It seems that this is analogous to the effects of HF, where the H- anion causes dermal injury and allows deeper penetration and absorption of the F+ ion which causes severe and often fatal systemic toxicity.
In both cases, early skin decontamination must be done, (potable water does not seem to be efficacious) and as the TMAH cholinergic toxicity mainly manifests as respiratory and cardiac failure, supplemental oxygen (by endotracheal tube if needed) and mechanical ventilation are required in severe cases. Atropine does not seem to be efficacious. So far to my knowledge, no one has tried acetylcholinesterase reactivators such as 2-PAM chloride, Toxigonin, or HI-6. Tetramethylammonium chloride has little systemic toxicity in experimental animals, unless the skin first been injured by exposure to a significant skin corrosive substance, which strongly suggests that TMA+ is not well absorbed through uninjured skin.
Our group has recently performed 2 studies of the skin penetration of TMAH in a human skin explants model, one of which I am currently writing up for publication. We will later submit the second study for publication.
I would be happy to discuss this issue with anyone interested off-line.
Disclaimer: I am a paid consultant to Laboratoire Prevor, Vallmondois, France, manufacturer of Diphoterine(R) solution.
Alan
Alan H. Hall, M.D.
Phone: (817) 818-3298
Eugene
Thank you for this update on TMAH. Has a metabolic mechanism for this very high toxicity been proposed? A related compound, tetramethyl ammonium chloride, has a surprisingly low aquatic toxicity.
NL
