Alcoholic beverages: Proof and flammability

Correspondence ALCOHOLIC BEVERAGES:PROOFAND FLAMMABILITY To the Editor:--Gear et al 1 are to be commended for pointing out the risk of burns from flaming drinks. We were intrigued by their report and would like to offer some historical background regarding the origin of proof as a measure of the (ethyl) alcohol content of beverages. We would also like to address some measures of flammability and present data further characterizing the ability of alcohol solutions to ignite and to sustain a flame. Proof is derived from the fact that alcohol is taxable as well as flammable? In colonial America, rum was the principal liquor consumed. It was imported (from the West Indies) and became subject to taxation in 1789 when Alexander Hamilton, George Washington's Secretary of the Treasury, persuaded Congress to establish a protective tariff (on imports) to advance the economic development of the newly formed United States. Three years later, Hamilton convinced Congress to impose an excise tax (on domestic goods) to further increase treasury coffers. This included a tax (10 cents a gallon) on domestic whiskey. Whiskey producers (primarily the Scottish and Irish settlers of western Pennsylvania) considered the tax discriminatory and detrimental to their liberty and economic welfare. Their protests culminated in the Whiskey Rebellion of 1794. The federal government, eager to demonstrate its power to enforce its laws, quickly quelled this uprising, but a less visible form of protest ensued. To maintain profits, distillers and distributors began to sell whiskey in diluted form. In response, the government began testing whiskey for its alcohol content, revised the official definition of whiskey (itself the subject of much debate), and imposed additional taxes on liquor. At the time, there were few chemists available to analyze whiskey for its alcohol concentration. It was known, however, that liquors such as whiskey, which are produced by distillation, have a much higher alcohol content (95% by volume for undiluted distillate3) than beverages such as beer and wine, which are merely fermented, and that gunpowder moistened with liquor of high alcohol content remained combustible. Hence, the ability of gunpowder to burn after it was moistened with whiskey was considered "proof" that it contained sufficient alcohol to be sold as such. One hundred proof (or more accurately, 100 degrees of proof) was originally defined as tile lowest concentration of alcohol that permitted gunpowder to burn. By this definition, 100 proof reportedly occurs at an alcohol concentration of 57% (by volume). 2,4 While this remains the definition of British proof, in the US 100 proof was subsequently redefined as 50% alcohol. To stop the loss of revenue from the sale of diluted liquor, the US government also began taxing whiskey that was "below proof." It further allowed that whiskey could be diluted to 80 proof and still be sold as such. Given the above, it is tempting to conclude that solutions of ->57% alcohol are flammable. However, the fact that gunpowder moistened with such will burn does not necessarily mean that the solution itself is flammable. It is also unclear whether a spark or flame was used in the gunpowder test. In addition, the observations of Gear et aP that mixtures of equal amounts of 151 proof rum (75.5% alcohol) and amaretto (21% alcohol) or beer (3.5% alcohol), having final alcohol concentrations of 48.25% and 39.5%, respectively, are flammable appear to be at odds with the original definition of proof. To attempt to resolve some of these issues, the following experiment was performed. Measured volumes (by graduated pipette) of reagent-grade alcohol (99.5% by volume) and tap water were added to a "shot" glass and mixed by manual stirring for 15 seconds. Because tile volume of an alcohol and water mixture is

544

appreciably less than the sum of the volumes of the components,5 the volumes of alcohol and water were calculated so that their sum was equal to 10 mL. This yielded solutions with alcohol concentrations of known volume per volume percent, the standard unit for describing the alcohol content of beverages. Solutions were prepared in incremental alcohol concentrations (of 1%) and subjected to the flame of a gun-style butane lighter designed for igniting fireplace and grill fuels. At room temperature, the brief (1-second) application of flame resulted in ignition and continued burning when the alcohol concentration was -->55%. The brief application of flame resulted in a momentary flash when the alcohol concentration was between 46% and 55%. Ignition was not observed at concentrations of <46%. With the prolonged application of flame, ignition with sustained combustion occurred at alcohol concentrations as low as 20%. The duration of flame application necessary for both ignition and sustained combustion was noted to be inversely proportional to the alcohol concentration and suggested that the ability of an alcohol solution to ignite and support a steady flame was dependent on its temperature as well as its alcohol concentration. To test this, the 20% solution was heated (in a microwave oven) to a brief boil, allowed to cool for 15 seconds, and then subjected to flame. The result was immediate ignition with continued burning. We also repeated the experiment described by Gear et al. 1 In contrast to their findings, we noted that mixtures of equal parts rum and amaretto or beer (and also amaretto alone) simply flashed momentarily when a brief flame was applied. Sustained combustion occurred only after prolonged exposure to flame or prior heating. These observations suggest that Gear et al subjected their mixtures to prolonged flame or that there was incomplete mixing of the components. With respect to the latter, alcohol is less dense than water and incomplete mixing could have resulted in the component with the higher alcohol concentration (ie, the rum) layering on top. Since the rum had an alcohol concentration of >55%, such a "mixture" would ignite and continue to burn after the brief application of flame even though its "mean" alcohol concentration is lower. Gear et all noted that the flash point of (anhydrous) alcohol is 13°C. It is the burning or fire point of a substance, however, that more accurately reflects its flammability (ie, ability to burn after removing the ignition source). The flash point is the lowest temperature at which a volatile liquid or solid gives off sufficient vapor that, when mixed with air, will ignite momentarily (as demonstrated by a flash) upon application of a flame, whereas the burning or fire point is the lowest temperature at which the production of combustible vapors occurs at a rate fast enough to support continued burning after ignition.6 Experimentally, the flash point is determined in either a closedcup or an open-cup apparatus. It is lower when the closed-cup method is used. An open-cup apparatus is used for burning point determinations. The burning point always occurs at a higher temperature than the flash point. The flash point may reflect the explosion hazard of a combustible liquid but the burning point, which characterizes the ability of a substance to burn independently, is more important in determining its fire risk. 7 By convention, liquids that have a closed-cup flash point below 61°C or an open-cup flash point below 66°C are considered highly flammable.6 Anhydrous ethanol obviously is in this category. We could find no published data pertaining to the burning point of pure alcohol or to the temperatures at which solutions of lower concentrations will flash or burn when subjected to flame. Our results, however, support the following conclusions. The flash and burning points of alcohol solutions are inversely related to their alcohol concentrations. Liquors with alcohol

CORRESPONDENCE

545

concentrations of ->55% (110 proof) have a burning point of room temperature (about 23°C) or below. Unless chilled or diluted, they pose a risk for fire when briefly exposed to flame. Beverages such as fortified wine, liqueurs, and mixed drinks that have alcohol concentrations of ->20% (40 proof) but <55% have a burning point between room temperature and the boiling point of alcohol (about 78°C). If heated (eg, when used for cooking) before flame exposure or subjected to prolonged flame exposure, they are also flammable and represent a fire hazard. Even with prolonged flame exposure or prior heating, beverages such as beer and wine, which have an alcohol concentration of less than 20%, cannot be ignited by the flame of a butane lighter. Although it is theoretically possible for tktem to ignite at temperatures between boiling point of alcohol and that of water, under most conditions of use they are not likely to be flammable or to pose a risk of fire. CHRISTOPHERH. LINDEN, MD JEFFREYR. TUCKER,MD

Division of Toxicology Department of Emergency Medicine University of Massachusetts Medical Center Worcester, MA

References 1. GearAJL, Nguyen WD, Himell HN, et al: "Flaming Dr. Pepper"Another cause of recreational burn injury. Am J Emerg Med 1997;15: 108-111 2. Henderson Y: The high proof of liquor as a factor in the production of alcoholism. Q J Stud Alcohol 1940;1:1-12 3. Windholz M, Budavari S, Blumetti RE et at (eds): The Merck Index: An Encyclopedia of Chemicals, Drugs, and Biologicals. Rahway, NJ, Merck and Company, 1983 4. Ferner RE: Forensic Pharmacology: Medicines, Mayhem, and Malpractice. Oxford, Oxford University Press, 1996 5. Saunders L: Principles of Physical Chemistry for Biology and Pharmacy (ed 2). London, Oxford University Press, 1971 6. Panov GE, Polozkov VT: Flammable substances. In Parmeggiani L (ed): Encyclopedia of Occupational Health and Safety (ed 3). Geneva, International Labour Organization, 1983, pp 881-883 7. Van Nostrand's Scientific Encyclopedia (ed 4). Princeton, NJ, D. Van Nostrand Company, 1968

ACUTE GASTRIC PERFORATIONIN A CHLORALHYDRATE OVERDOSE To the Editor:--Chloral hydrate (CH) overdoses have been reported to cause various toxicities. These include central nervous system depression, respiratory depression, cardiac dysrhythmias, and gastrointestinal irritation. 1 We report a case of CH overdose with all of the aforementioned findings, as well as an acute gastric perforation. Acute gastric perforation secondary to CH ingestion has not been reported before. A 68-year-old woman with a history of depression ingested 10 grams of CH in a suicide attempt. Her initial vital signs were a heart rate of 68 beats/min, blood pressure of 64/48 mm hg, respiratory rate of 8 breaths/min, and a normal temperature. The cardiac monitor showed a normal sinus rhythm. The patient had a Glasgow Coma Scale score of 3. An increasing abdominal girth and signs of peritoneal irritation were noted on initial examination. A pneumoperitoneum was noted on X-rays. No opaque foreign bodies were seen. The patient responded well to fluid resuscitation and supportive care. She underwent emergency surgery during which a perforated anterior gastric ulcer was repaired. Cardiac monitoring later reported multiple runs of supraventricular tachycardia that resolved spontaneously. The patient's trichloroethanol level peaked 48 hours after presentation at 103 mg/L (toxic levels, >40 rag/L). The patient was discharged in good condition 13 days after presentation.

CH has been intermittently popular as a sedative-hypnotic agent since its reported medicinal use in 1869. 2 Soon afterward, its cardiovascular, central nervous system, and respiratory toxicities became well known. Although the use of CH has decreased dramatically with the introduction of safer sedative-hypnotic agents such as barbiturates and benzodiazepines, CH is still prescribed to certain subgroups of patients. CH is still popular as a short-term sedation for children undergoing minor procedures and as a sleeping agent for elderly patients who might suffer from paradoxical excitement and confusion as seen with other agents. 3 In overdose settings, cardiovascular compromise, central nervous system depression, respiratory depression, and gastric irritation are the most common effects. However, the documented cause of death is usually resistant cardiac dysrhythmia.l,3 Cardiac irritability causing various dysrhythmias, including torsades de pointes, has been well documented. 4-7 Several authors have reported that CH and its breakdown product, trichloroethanol, behave like halogenated hydrocarbons, inducing myocardial depression and sensitization to catecholamines. 6-s In our patient, an acute surgical abdomen with circulatory and respiratory collapse were the initial life-threatening presentations. Cardiac dysrhythmia, which occurred 24 hours after ingestion, consisted of episodes of transient supraventricular tachycardia that resolved without intervention. CH is well known to have irritant gastrointestinal effects. Epigastric discomfort, nausea, and vomiting are well reported side effects from therapeutic use of CH2 Although acute gastric perforation has never been reported in the English medical literature, delayed gastric perforation secondary to an acute CH overdose has been reported. Vellar et aP ° reported a patient who developed signs of peritoneal irritation 4 days after a 20-gram ingestion of CH elixir. Gastric perforation and necrosis were diagnosed on laparotomy. Esophageal stricture has also been reported as a sequela of CH overdose. Gleich et a111 reported a patient who developed gastrointestinal bleeding 11 days after an 18-gram ingestion of CH elixir. Although a barium swallow result was reported as normal, a distal esophageal stricture was documented 4 months later. The authors attributed these findings to CH irritation of the esophageal mucosa. The mechanism of CH-induced gastric mucosal injury is unclear. CH has been shown to cause ulcers in animals into which CH was intraperitoneally or subcutaneously injected. 12,~3 Intraperitoneal injection of CH has also been reported to cause adynamic ileus in rats and guinea pigs.14 In summary, we reported a patient with a CH overdose who presented with an acute surgical abdomen. Toxicologic cases of acute surgical abdomen requiring immediate surgery are relatively rare. CH toxicity should be considered when a pattern of cardiac dysrhythmias, central nervous system and respiratory depression, and peritonitis are present. DAVID C. LEE, MD

Department of Emergency Medicine North Shore University Hospital Manhasset, NY CHRISTOPHERVASSALLUZZO,DO Department of Emergency Medicine St. Mary's Hospital Allegheny University of the Health Sciences Medical College of Pennsylvania Philadelphia, PA

References 1. Ellenhorn MJ, Schonwald S, Ordog G, eta]: Ellenhorn's Medical Toxicology (ed 2). Baltimore, MD, Williams and Wilkins, 1997