On May 27, 1927, in Argentina, a deadly poisoning event unfolded when alcohol used in the preparation of diphtheria antitoxin became contaminated with methanol (wood alcohol). The incident is frequently cited in public-health histories as among the earliest clearly recorded cases in which adulterated alcohol administered for medical purposes caused mass morbidity and mortality. Background Diphtheria antitoxin in the early 20th century was an essential therapeutic agent derived from horse serum; its preparation sometimes required alcohol for cleaning, sterilization, or extraction steps. Methanol, a cheaper industrial alcohol, was known to be toxic, but distinguishing it from ethanol (drinking alcohol) was more difficult before modern analytical methods and strict regulatory controls were widespread. Accidental or deliberate substitution of methanol for ethanol in medicinal or beverage supplies occurred in multiple countries during this era. The 1927 incident Contemporary reports and later public-health reviews identify a 1927 outbreak in Argentina in which contaminated alcohol used in producing diphtheria antitoxin led to acute poisoning. Victims developed symptoms consistent with methanol toxicity — visual impairment or blindness, central nervous system depression, and death in severe cases. Estimates of casualties vary in different accounts; historical sources indicate dozens of fatalities and numerous survivors left with permanent vision loss. Investigation and response Investigations at the time sought to determine how methanol entered the supply chain for the antitoxin production. Possible explanations included substitution of industrial alcohol for ethanol by suppliers, inadequate testing of medicinal-grade alcohol, or contamination during storage and transport. The tragedy highlighted gaps in quality control for medical supplies and spurred calls for stricter regulation, testing standards, and oversight of alcohol intended for therapeutic use. Legacy and significance The 1927 Argentina case is significant for public-health history because it underscored the lethal risks of methanol contamination in medicinal and beverage alcohol and helped catalyze improvements in regulatory practices. Subsequent decades saw stronger controls over production and labeling of ethanol and industrial methanol, the development of better chemical assays to detect methanol, and heightened awareness within medical and pharmaceutical communities about sourcing and testing alcohol used in treatments. Caveats and sources Precise casualty figures and some procedural details from 1927 vary between contemporary newspaper reports, medical journals, and later historical summaries. Where exact numbers differ in the record, accounts consistently report multiple deaths and numerous cases of blindness or severe neurological injury. Key primary and secondary sources include contemporaneous Argentine press coverage, public-health bulletins of the period, and retrospective analyses in medical and regulatory histories. For rigorous research, consult original 1927 medical reports and archives from Argentine public-health authorities and published reviews in medical history literature. While earlier and later mass poisonings involving contaminated beverage alcohol are documented in other countries and eras, the 1927 Argentina antitoxin contamination stands out in the medical-record literature as an early, well-documented instance of methanol poisoning tied directly to medicinal use rather than recreational consumption.