KEY WORDS: forensic science, forensic chemistry, criminalistics, physical evidence, crime scene investigator, chain of custody, class characteristics, individual characteristics, presumptive test, reference samples, comparison standards, safety data sheets, control samples, background controls, positive control, negative control, accuracy, precision, replicates, standard operating procedures, quality control, quality assurance, expert witness
• To explain the difference between forensic science, criminalistics, and forensic chemistry
• To understand the historical development of forensic science
• To know the locations and identities of several forensic laboratories
• To list the units of forensic laboratories that use forensic chemistry
• To identify physical evidence in a forensic case
• To differentiate between class and individual characteristics for physical evidence types
• To identify the Scientific Working Group for the Analysis of Seized Drugs (SWGDRUG) categories of analytical techniques by category
• To understand the role of the forensic chemist in the laboratory, in the forensic community, and in court
Alcohol poisoning: Methanol and other denaturants
A man arrived at the hospital hallucinating. Although not readily apparent, the hallucinations turned out to be a symptom of methanol present in the alcohol he had consumed.
Alcohol, also known as ethanol or ethyl alcohol, is the most widely used legal drug. It is a depressant and affects the central nervous system. At low doses, it can lead to the loss of inhibitions and increased talkativeness. At higher doses, it affects reasoning, behavior, memory, speech, emotion, and abstract thinking. At very high doses, it can lead to a loss of consciousness and death.
Passed in 1919, the 18th Amendment to the US Constitution banned the manufacture, sale, and transportation of alcoholic beverages into the country. Enforcement began with the passage of the Volstead Act on January 1, 1920. Thus began prohibition. As a result, drinkers resorted to drinking wood alcohol and industrial alcohol with severe effects. Although alcohol was illegal to consume as a beverage, it was still used in industry and manufacturing in paint thinners, fuels, and medical supplies, and was also used as a solvent.
On September 7, 1919, the New York Times
reported an increase in the numbers of deaths from people drinking wood alcohol as a substitute for grain alcohol. Methanol (methyl alcohol) is found in alcohol produced by distilling wood. The National Committee for the Prevention of Blindness recorded over 1000 reported cases of blindness (across the country) resulting from the consumption of wood alcohol. Dr. Alexander Gettler, a toxicologist with
the New York Office of the Chief Medical Examiner and Chemical Laboratory of the Pathological Department, Bellevue and Allied Hospitals, also reported an increase in deaths due to wood alcohol. He reported examining over 700 human organs for alcohol in 1918–1919. As a result, states began to pass laws to regulate and control the sale of wood alcohol.
Beginning in 1906, industrial users could purchase ethanol without paying the tax levied on drinking alcohol. The US government devised a method of making the ethanol deadly to drink—by adding methanol—while leaving the bulk chemical properties unchanged. (Methanol is used today in windshield washer fluid and is poisonous and extremely toxic.) The resultant alcohol was labeled as “denatured” alcohol. Several other denaturing methods followed. Some involved the addition of poisonous metals such as mercury, cadmium, and zinc to the ethanol. Others involved the addition of less lethal but extremely bitter compounds to the ethanol, rendering it undrinkable. Bootleggers hired chemists to distill the alcohol to remove the contaminants and return the ethanol to a composition that was safe to consume. In response, by mid-1927, new denaturants were added to the alcohol including common chemicals such as gasoline, kerosene, chloroform, camphor, ether, formaldehyde, acetone, iodine, and quinine.
Eventually, prohibition was overturned with the ratification of the 21st Amendment and consumption of alcohol was again legalized on December 5, 1933.
Many Deaths Due to Wood Alcohol, New York Times, September 7, 1919.
Gettler, A.O. 1920. Critical study of methods for the detection of methyl alcohol. J. Biol. Chem. 42:311–328.
Forensic science is the application of the scientific method to legal questions. The laws themselves are enforced and upheld by the criminal justice system including federal, state, and local law enforcement agencies and the courts. The goal of the criminal justice system is the establishment of the guilt or innocence of a suspect or suspects accused of a crime.
Forensic chemistry is a subdiscipline of forensic science. Its principles guide the analyses performed in modern forensic laboratories. Forensic chemistry’s roots lie in medicolegal investigation, toxicology, and microscopy. Deaths due to tainted food products, new applications of materials in the home, drug use and abuse, and industrial pollution sped up the development of modern forensic science investigations and practices.