The role of the chemical burns caused by hydroxide ion in the toxicity of dermal exposure to tetramethylammonium ion in a rat model.
OBJECTIVE
To evaluate the role of the chemical burns caused by hydroxide ion in the fatal effects of tetramethylammonium ion (TMA) in dermal exposure to tetramethylammonium hydroxide (TMAH), we conducted a rat study consisting of two-step treatments with dermal exposure to NaOH and tetramethylammonium chloride (TMACl).


METHODS
In the first step, NaOH or saline was administered in the gauze on the shaved skin for 5 min, and in the second step, TMAH, TMACl, or saline was administered in the same way. The mean blood pressure (MBP), heart rate (HR), and survival in rats were compared among seven groups.


RESULTS
Dermal exposure to saline and then 2.75 M TMACl introduced limited and temporary non-fatal effects. Exposure to 2.75 M NaOH and then saline had almost no effects and caused no deaths. Treatments with more concentrated NaOH or TMACl resulted in suppressions of MBP and HR, and deaths were observed after the dosing of TMACl.


CONCLUSIONS
The toxicity of dermal exposure to TMA alone is limited, but fatal effects can be introduced by pre-treatment with hydroxide ion. Therefore, the chemical burn caused by hydroxide ion plays an essential role in the toxicity, implicating that effective neutralizing may help decreasing the fatality rate.
Department of Environmental and Occupational Health, College of Medicine, National Cheng Kung University, Tainan, Taiwan.
Chen-Long
CL
Wu
Shih-Bin
SB
Su
Hsiao-Yin
HY
Lien
How-Ran
HR
Guo
D000279:Administration, Cutaneous; D000818:Animals; D001337:Autonomic Agents / Q000633:toxicity*; D001794:Blood Pressure / Q000187:drug effects; D002057:Burns, Chemical / Q000209:etiology*; D006339:Heart Rate / Q000187:drug effects; D006878:Hydroxides / Q000633:toxicity*; D053208:Kaplan-Meier Estimate; D008297:Male; D016273:Occupational Exposure; D000644:Quaternary Ammonium Compounds / Q000633:toxicity*; D051381:Rats; D017208:Rats, Wistar; D012972:Sodium Hydroxide / Q000633:toxicity*
D001337:Autonomic Agents; D006878:Hydroxides; D000644:Quaternary Ammonium Compounds; D012972:Sodium Hydroxide; C031356:hydroxide ion; C027917:tetramethylammonium