Intentional self-poisoning with the chlorophenoxy herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA).
OBJECTIVE
Data on poisoning with MCPA (4-chloro-2-methyl-phenoxyacetic acid) are limited to 6 case reports. Our objective is to describe outcomes from intentional self-poisoning with MCPA in a prospective case series of 181 patients presenting to hospitals in Sri Lanka.


METHODS
Patient information was collected by on-site study physicians as part of an ongoing prospective cohort study of poisoned patients. Medical history, clinical details, and blood samples were obtained prospectively.


RESULTS
Overall clinical toxicity was minimal in 85% of patients, including mild gastrointestinal symptoms in 44% of patients. More severe clinical signs of chlorophenoxy poisoning reported previously, such as rhabdomyolysis, renal dysfunction, and coma, also occurred but were uncommon. Eight patients died (4.4%). Most deaths occurred suddenly from cardiorespiratory arrest within 48 hours of poisoning; the pathophysiological mechanism of death was not apparent. The correlation between admission plasma MCPA concentration and clinical markers of severity of toxicity (physical signs, symptoms, and increased creatine kinase level) was poor.


CONCLUSIONS
Intentional self-poisoning with MCPA generally causes mild toxicity, but cardiorespiratory arrest and death may occur. All patients should receive routine resuscitation and supportive care. It seems reasonable to correct acidosis and maintain an adequate urine output, but there is insufficient evidence to support other specific interventions. Our data do not support a clinical role for measurement of plasma MCPA in the acute management of poisoning, and insufficient data were available to fully examine the utility of measured electrolytes and creatine kinase levels.
Roberts
Darren M
DM
South Asian Clinical Toxicology Research Collaboration, Medical School, Australian National University, Acton, Australian Capital Territory, Australia. dmroberts@iprimus.com.au
Seneviratne
Ruwan
R
Mohammed
Fahim
F
Patel
Renu
R
Senarathna
Lalith
L
Hittarage
Ariyasena
A
Buckley
Nick A
NA
Dawson
Andrew H
AH
Eddleston
Michael
M
D008456:2-Methyl-4-chlorophenoxyacetic Acid / Q000097:blood / Q000506:poisoning*; D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood; D015331:Cohort Studies; D003402:Creatine Kinase / Q000097:blood; D004635:Emergency Medicine / Q000379:methods; D005260:Female; D006540:Herbicides / Q000097:blood / Q000506:poisoning*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010043:Outcome and Process Assessment, Health Care; D011041:Poisoning / Q000097:blood / Q000628:therapy; D011446:Prospective Studies; D013188:Sri Lanka; D013406:Suicide, Attempted; D016019:Survival Analysis
D015415:Biomarkers; D006540:Herbicides; D008456:2-Methyl-4-chlorophenoxyacetic Acid; D003402:Creatine Kinase