TR 081 – Human Acute Intoxication from Monochloroacetic Acid: Proposals for Therapy

Abstract

TR 081 : Human Acute Intoxication from Monochloroacetic Acid: Proposals for Therapy | November 2001

The industrial chemical monochloroacetic acid (MCAA) is used mainly in carboxylation reactions. It is readily absorbed following oral or dermal exposure and can induce severe systemic intoxication.

A number of fatalities have been reported from accidental exposure in the workplace. Symptoms are delayed and develop one to four hours after exposure. Limited clinical data in humans and experimental data in rodents indicate that lactic acidosis is the main mechanism leading to toxic effects, death generally being due to cardiovascular shock, renal failure and cerebral oedema.

Following accidental skin contact with MCAA, it is essential that the skin is decontaminated as soon as possible. There is no clear experimental evidence that sodium bicarbonate solution is more effective than water for this purpose. With regard to antidotes for MCAA intoxication, dichloroacetate (DCA), and to a lesser extent phenobarbitone (PB), have been identified as effective in reducing mortality and decreasing lactate accumulation in the blood and cerebral spinal fluid of rats and mice.

Physicians from four European national poison control centres participated in a workshop (1997) on the use of DCA and PB in the treatment of MCAA intoxication. DCA was concluded to be the preferred antidote and a protocol for the treatment of MCAA intoxication was established.

This protocol, that has now been incorporated into the IPCS-INTOX Poison Information Monograph on MCAA, proposes the early administration of DCA (50mg/kg, iv) as specific antidote therapy to prevent the development of MCAA-induced lactic acidosis. In supporting this proposal, the ECETOC TF recommends that the availability of DCA should be improved in order to provide effective treatment in the event of accidental exposure to MCAA. If no DCA is available, treatment with PB might be considered, provided that intensive care facilities were available to monitor closely the treatment.