Chemical Reaction between Boric Acid and Phosphine Indicates Boric Acid as an Antidote for Aluminium Phosphide Poisoning.
OBJECTIVE
Aluminium phosphide (AlP) is a fumigant pesticide which protects stored grains from insects and rodents. When it comes into contact with moisture, AlP releases phosphine (PH3), a highly toxic gas. No efficient antidote has been found for AlP poisoning so far and most people who are poisoned do not survive. Boric acid is a Lewis acid with an empty p orbital which accepts electrons. This study aimed to investigate the neutralisation of PH3 gas with boric acid.


METHODS
This study was carried out at the Baharlou Hospital, Tehran University of Medical Sciences, Tehran, Iran, between December 2013 and February 2014. The volume of released gas, rate of gas evolution and changes in pH were measured during reactions of AlP tablets with water, acidified water, saturated boric acid solution, acidified saturated boric acid solution, activated charcoal and acidified activated charcoal. Infrared spectroscopy was used to study the resulting probable adduct between PH3 and boric acid.


RESULTS
Activated charcoal significantly reduced the volume of released gas (P <0.01). Although boric acid did not significantly reduce the volume of released gas, it significantly reduced the rate of gas evolution (P <0.01). A gaseous adduct was formed in the reaction between pure AlP and boric acid.


CONCLUSIONS
These findings indicate that boric acid may be an efficient and non-toxic antidote for PH3 poisoning.
Pistachio Safety Research Center, Rafsanjan University of Medical Sciences, Rafsanjan, Iran;
Motahareh
M
Soltani
Ameretat Shimi Pharmaceutical Co., Tehran, Iran;
Seyed F
SF
Shetab-Boushehri
Department of Toxicology & Pharmacology, School of Pharmacy and; Razi Drug Research Center, Iran University of Medical Sciences, Tehran, Iran.
Seyed V
SV
Shetab-Boushehri
Activated Charcoal; Aluminum Phosphide; Antidotes; Boric Acid; Phosphine; Poisoning