<CHAP NUM="10" ID="CH.00.0010">chapter 10
<CHAP NUM="10" ID="CH.00.010"><FM><TTL>Forensic Toxicology</TTL>
<KTSET><TTL>Key Terms</TTL>
<KT>absorption</KT>
<KT>acid</KT>
<KT>alveoli</KT>
<KT>anticoagulant</KT>
<KT>artery</KT>
<KT>base</KT>
<KT>capillary</KT>
<KT>catalyst</KT>
<KT>excretion</KT>
<KT>fuel cell detector</KT>
<KT>metabolize</KT>
<KT>oxidation</KT>
<KT>pH scale</KT>
<KT>preservative</KT>
<KT>vein</KT></KTSET>
<OBJSET><TTL>Learning Objectives</TTL>
<P>After studying this chapter you should be able to:
<OBJ><P><INST>< </INST>Explain how alcohol is absorbed into the bloodstream, transported throughout the body, and eliminated by oxidation and excretion</P></OBJ>
<OBJ><P><INST>< </INST>Understand the process by which alcohol is excreted in the breath via the lungs</P></OBJ>
<OBJ><P><INST>< </INST>Understand the concepts of infrared and fuel cell breath-testing devices for alcohol testing</P></OBJ>
<OBJ><P><INST>< </INST>Describe commonly employed field sobriety tests to assess alcohol impairment</P></OBJ>
<OBJ><P><INST>< </INST>List and contrast laboratory procedures for measuring the concentration of alcohol in the blood</P></OBJ>
<OBJ><P><INST>< </INST>Relate the precautions to be taken to properly preserve blood in order to analyze its alcohol content</P></OBJ>
<OBJ><P><INST>< </INST>Understand the significance of implied-consent laws and the <ITAL>Schmerber </ITAL>v.<ITAL> California</ITAL> case to traffic enforcement</P></OBJ>
<OBJ><P><INST>< </INST>Describe techniques that forensic toxicologists use to isolate and identify drugs and poisons</P></OBJ>
<OBJ><P><INST>< </INST>Appreciate the significance of finding of a drug in human tissues and organs to assessing impairment</P></OBJ>
<OBJ><P><INST>< </INST>Understand the Drug Recognition Expert program and how to coordinate it with a forensic toxicology result</P></OBJ></P></OBJSET></FM>
<CASE NUM="1" TY="CS"><TTL>Harold Shipman, Dr. Death</TTL>
<P>Kathleen Grundy’s sudden death in 1998 was shocking news to her daughter, Angela Woodruff. Mrs. Grundy, an 81-year-old widow, was believed to be in good health when her physician, Dr. Harold Shipman, visited her a few hours before her demise. Some hours later, when friends came to her home to check on her whereabouts they found Mrs. Grundy lying on a sofa fully dressed and dead.</P>
<P>Dr. Shipman pronounced her dead and informed her daughter that an autopsy was not necessary. A few days later, Mrs. Woodruff was surprised to learn that a will had surfaced leaving all of Mrs. Grundy’s money to Dr. Shipman. The will was immediately recognized as a forgery and led to the exhumation of Mrs. Grundy’s body. A toxicological analysis of the remains revealed a lethal quantity of morphine.</P>
<P>In retrospect, there was good reason to suspect that Dr. Shipman was capable of foul play. In the 1970s, he was asked to leave a medical practice because of a drug abuse problem and charges that he obtained drugs by forgery and deception. However, Dr. Shipman was quickly back to practicing medicine. By 1998, local undertakers became suspicious at the number of his patients who were dying. What is more, they all seemed to be elderly women who were found sitting in a chair or lying fully clothed on a bed. As police investigated, the horror of Dr. Shipman’s deeds became apparent. One clinical audit estimated that Dr. Shipman killed at least 236 of his patients over a twenty-four-year period. Most of the deaths were attributed to fatal doses of heroin or morphine. Toxicological analysis on seven exhumed bodies clearly showed significant quantities of morphine. Convicted of murder, Dr. Shipman hanged himself in his jail cell in 2004.</P></CASE>
<BM><P>It is no secret that in spite of the concerted efforts of law enforcement agencies to prevent distribution and sale of illicit drugs, thousands die every year from intentional or unintentional administration of drugs, and many more innocent lives are lost as a result of the erratic and frequently uncontrollable behavior of individuals under the influence of drugs. But one should not automatically attribute these occurrences to the wide proliferation of illicit-drug markets. For example, in the United States alone, drug manufacturers produce enough barbiturates and tranquilizers each year to provide every man, woman, and child with about forty pills. All of the statistical and medical evidence shows ethyl alcohol, a legal over-the-counter drug, to be the most heavily abused drug in Western countries. In the United States, nearly 17,500 automobile deaths, 40 percent of all traffic deaths, are alcohol related, with a rate of injury requiring hospital treatment exceeding two million people per year. This highway death toll, as well as the untold damage to life, limb, and property, is testimony in itself to the dangerous consequences of alcohol abuse.</P>
<P>Because the uncontrolled use of drugs has become a worldwide problem affecting all segments of society, the role of the toxicologist has taken on new and added significance. Toxicologists detect and identify drugs and poisons in body fluids, tissues, and organs. Their services are required not only in such legal institutions as crime laboratories and medical examiners’ offices; they also reach into hospital laboratories—where the possibility of identifying a drug overdose may represent the difference between life and death—and into various health facilities responsible for monitoring the intake of drugs and other toxic substances. Primary examples include performing blood tests on children exposed to leaded paints or analyzing the urine of addicts enrolled in methadone maintenance programs.</P>
<P>The role of the forensic toxicologist is limited to matters that pertain to violations of criminal law. However, the responsibility for performing toxicological services in a criminal justice system varies considerably throughout the United States. In systems with a crime laboratory independent of the medical examiner, this responsibility may reside with one or the other or may be shared by both. Some systems, however, take advantage of the expertise residing in governmental health department laboratories and assign this role to them. Nevertheless, whatever facility handles this work, its caseload will reflect the prevailing popularity of the drugs that are abused in the community. In most cases, this means that the forensic toxicologist handles numerous requests relating to the determination of the presence of alcohol in the body.</P>
<H1>Toxicology of Alcohol</H1>
<H2>The Fate of Alcohol in the Body</H2>
<P>The subject of the analysis of alcohol immediately confronts us with the primary objective of forensic toxicology—the detection and isolation of drugs in the body to determine their influence on human behavior. In the case of alcohol, however, the problem is further complicated by practical considerations. The predominant role of the automobile in our society has mandated the imposition of laws to protect the public from the drinking driver. This has meant that toxicologists have had to devise rapid and specific procedures for measuring the degree of alcohol intoxication. The methods used must be suitably designed to test hundreds of thousands of motorists annually without causing them undue physical harm or unreasonable inconvenience, while at the same time providing a reliable diagnosis that can be supported and defended within the framework of the legal system.</P>
<P>Alcohol, or ethyl alcohol, is a colorless liquid normally diluted with water and consumed as a beverage. Logically, the most obvious measure of intoxication would be the amount of liquor a person has consumed. Unfortunately, most arrests are made after the fact, when such information is not available to legal authorities; furthermore, even if these data could be collected, numerous related factors, such as body weight and the rate of alcohol’s <KT>absorption</KT> into the body, are so variable that it would be impossible to prescribe uniform standards that would yield reliable alcohol intoxication levels.<SIDEIND NUM="1" ID="MN2.09.001"/></P>
<P>Like any other depressant, alcohol primarily affects the central nervous system, particularly the brain. The extent of the depression is proportional to the concentration of alcohol within the nerve cells. The nerve functions most susceptible to alcohol are found in the surface areas of the forebrain. Later, as the person absorbs alcohol to a greater extent, the functions of the central and rear portions of the brain are affected. The nerve functions that are most resistant, and the last to fail, are centered in the brain’s medulla, which regulates such vital functions as respiration and heart activity.</P>
<P>Theoretically, for a true determination of the quantity of alcohol impairing an individual’s normal body functions, it would be best to remove a portion of brain tissue and analyze it for alcohol content. For obvious reasons, this cannot be done on living subjects. Consequently toxicologists concentrate on the blood, which provides the medium for circulating alcohol throughout the body, carrying it to all tissues, including the brain. Fortunately, experimental evidence supports this approach and shows blood-alcohol concentration to be directly proportional to the concentration of alcohol in the brain. From the medicolegal point of view, blood-alcohol levels have become the accepted standard for relating alcohol intake to its effect on the body.</P>
<P>Alcohol appears in the blood within minutes after it has been consumed and slowly increases in concentration while it is being absorbed from the stomach and the small intestine into the bloodstream. When all the alcohol has been absorbed, a maximum alcohol level is reached in the blood, and the postabsorption period begins. Then the alcohol concentration slowly decreases until a zero level is again reached.</P>
<P>Many factors determine the rate at which alcohol is absorbed into the bloodstream, including the total time taken to consume the drink, the alcohol content of the beverage, the amount consumed, and the quantity and type of food present in the stomach at the time of drinking. With so many variables, it is difficult to predict just how long the absorption process will require. For example, beer is absorbed more slowly than an equivalent concentration of alcohol in water, apparently because of the carbohydrates present in beer. Also, alcohol consumed on an empty stomach is absorbed faster than an equivalent amount of alcohol taken when there is food in the stomach. The longer the total time required for complete absorption to occur, the lower the peak alcohol concentration in the blood (see <LINK LINKEND="FG.10.001">Figure <FIGIND NUM="1" ID="FG.10.001"/>10–1</LINK>). Depending on a combination of factors, maximum blood-alcohol concentration may not be reached until two or three hours have elapsed from the time of consumption. However, under normal social drinking conditions, it takes anywhere from thirty to ninety minutes from the time of the final drink until the absorption process is completed.</P>
<P>During the absorption phase, alcohol slowly enters the body’s bloodstream and is carried to all parts of the body. When the absorption period is completed, the alcohol becomes distributed uniformly throughout the watery portions of the body—that is, throughout about two-thirds of the body volume. Fat, bones, and hair are low in water content and therefore contain little alcohol, whereas alcohol concentration in the rest of the body is fairly uniform. Hence, if blood is not available, as in some postmortem situations, a medical examiner can select a water-rich organ or fluid—for example, the brain, cerebrospinal fluid, or vitreous humor—for determining the body’s alcohol content to a reasonable degree of accuracy.</P>
<P>As the alcohol is circulated by the bloodstream, the body begins to eliminate it. Alcohol is eliminated through two mechanisms—<KT>oxidation</KT> and <KT>excretion</KT>. Nearly all of the alcohol (95–98 percent) consumed is eventually oxidized to carbon dioxide and water. Oxidation takes place almost entirely in the liver. Here, in the presence of the enzyme alcohol dehydrogenase, the alcohol is converted into acetaldehyde and then to acetic acid. The acetic acid is subsequently oxidized in practically all parts of the body to carbon dioxide and water.<SIDEIND NUM="2" ID="MN2.09.002"/><SIDEIND NUM="3" ID="MN2.09.003"/></P>
<P>The remaining alcohol is excreted unchanged in the breath, urine, and perspiration. Most significantly, the amount of alcohol exhaled in the breath is in direct proportion to the concentration of alcohol in the blood. This observation has had a tremendous impact on the technology and procedures used for blood-alcohol testing. The development of instruments to reliably measure breath for its alcohol content has made possible the testing of millions of people in a rapid, safe, and convenient manner.</P>
<P><BOLD>The fate of alcohol in the body is therefore relatively simple</BOLD><BOLD>—</BOLD><BOLD>namely, absorption into the bloodstream, distribution throughout the body</BOLD><BOLD>’</BOLD><BOLD>s water, and finally, elimination by oxidation and excretion.</BOLD> The elimination or “burn-off” rate of alcohol varies in different individuals; 0.015 percent w/v (weight per volume) per hour seems to be average once the absorption process is complete.<FNIND NUMBER="1"/>1 However, this figure is an average that varies by as much as 30 percent among individuals.</P>
<H2>Alcohol in the Circulatory System</H2>
<P>The extent to which an individual may be under the influence of alcohol is usually determined by measuring the quantity of alcohol present in the blood system. Normally, this is accomplished in one of two ways: (1) by direct chemical analysis of the blood for its alcohol content and (2) by measurement of the alcohol content of the breath. In either case, the significance and meaning of the results can better be understood when the movement of alcohol through the circulatory system is studied.</P>
<P>Humans, like all vertebrates, have a closed circulatory system, which consists basically of a heart and numerous arteries, capillaries, and veins. An <KT>artery</KT> is a blood vessel carrying blood away from the heart, and a <KT>vein</KT> is a vessel carrying blood back toward the heart. <KT>Capillaries</KT> are tiny blood vessels that interconnect the arteries with the veins. The exchange of materials between the blood and the other tissues takes place across the thin walls of the capillaries. A schematic diagram of the circulatory system is shown in <LINK LINKEND="FG.10.002">Figure <FIGIND NUM="2" ID="FG.10.002"/>10–2</LINK>.<SIDEIND NUM="4" ID="MN2.09.004"/><SIDEIND NUM="5" ID="MN2.09.005"/><SIDEIND NUM="6" ID="MN2.09.006"/></P>
<P>Let us now trace the movement of alcohol through the human circulatory system. After alcohol is ingested, it moves down the esophagus into the stomach. About 20 percent of the alcohol is absorbed through the stomach walls into the portal vein of the blood system. The remaining alcohol passes into the blood through the walls of the small intestine. Once in the blood, the alcohol is carried to the liver, where its destruction starts as the blood (carrying the alcohol) moves up to the heart. The blood enters the upper right chamber of the heart, called the right atrium (or auricle), and is forced into the lower right chamber of the heart, known as the right ventricle. Having returned to the heart from its circulation through the tissues, the blood at this time contains very little oxygen and much carbon dioxide. Consequently, the blood must be pumped up to the lungs, through the pulmonary artery, to be replenished with oxygen.<SIDEIND NUM="7" ID="MN2.09.007"/></P>
<P>The respiratory system bridges with the circulatory system in the lungs, so that oxygen can e...
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