READ: Types of Drugs

Introduction

Introduction

 The drug unit in a forensic lab is charged with the task of identifying controlled substances that are seized by law enforcement officers by conducting a series of tests and observations. Similarly, the toxicology unit tests biological fluids and tissues to determine the presence and concentration of drugs, toxins and alcohol. Together these two units process a large portion of all of the evidence that passes through a crime lab. It is important for a Forensic Investigator to understand how the most common drugs affect the body and the significance of those drugs in an autopsy finding. Also, it is important that an investigator be familiar with the methods in which these drugs are typically used so that no pieces of evidence such as paraphernalia of drug use are missed.

Essential Questions

1. What is the role of the toxicologist in a forensic investigation?

2. How are drugs analyzed in a forensic laboratory and what do the results mean?

3. What laws govern the use and distribution of drugs?

4. How is alcohol metabolized in the body?

5. What is the legal limit of alcohol?

6. What the are classifications and names of the drugs most commonly abused?

Module Minute

Toxicology is the study of poisons and how they affect the body. A toxicologist's role is to detect and analyze chemicals found at crime scenes and within bodies to aid an investigation and provide further evidence. Often the toxins found in a body are prescription or illegal drugs and alcohol. An important part of toxicology testing is to determine the identity and amount of toxins in the body. The toxicology report includes information that is an integral part of the autopsy report and is particularly useful in cases of sudden unexplained death. Toxicology testing is also used to determine if a law has been broken as in the case with drunk driving. Finally, alcohol is metabolized by the liver which accounts for the large amounts of liver disease in people with higher average alcohol consumption. This would be an important finding in an autopsy report where an overdose is suspected.

Georgia Virtual, Forensic Toxicology, CC BY-NC-SA 3.0

Types of Drugs

Types of Drugs

A drug is a chemical that affects the processes of the body or mind. The drug unit in a forensic lab is charged with the task of identifying controlled substances that are seized by law enforcement officers by conducting a series of tests and observations. Toxicology is the study of the adverse effects of chemicals on living organisms including the symptoms, mechanisms, treatments and detection of drugs and poisons. The toxicology unit tests biological fluids and tissues to determine the presence and concentration of drugs and alcohol. The forensic toxicologist must sift through all the possible drugs and poisons to determine which, if any, may be present in any body fluids and/or organ samples submitted. Once a toxin is identified, the toxicologist must determine if the substance could have reacted with any other substances and what level of exposure would be lethal. One of the biggest challenges is the understanding that because of metabolism, a substance that enters the body in one form will likely exit in a different form. Together these two units process a good portion of all the evidence that passes through a crime lab. Some states estimate as much as 70% of the work completed in their chemistry unit is drug related. Furthermore, the number of drug related cases are increasing annually and drug offenders now make up more than half of all federal prisoners. Legal drugs can be prescription or sold over the counter. Prescription drugs can be dispensed to the public only with an order given by a properly authorized person such as a doctor. The designation of a medication as a prescription drug is made by the U.S. Food and Drug Administration. Over the Counter drugs, also known as "OTC", are medicines sold directly to a consumer without a prescription from a healthcare professional. An illicit drug is a drug that is manufactured and/or distributed illegally. Some illicit drugs do have some legal medical uses, but they are severely restricted and monitored by strict prescription guidelines.

Types of Drugs Informational Interactivity

View the interactive presentation below to learn more about the different types of drugs. Be sure to push all buttons to see the material. This material is important to your understanding of this module, so take notes and revisit the different slides as often as necessary. You will also find a printable document located in the sidebar.

Georgia Virtual, Forensic Toxicology, CC BY-NC-SA 3.0

Toxicology Tests

Techniques Used in Toxicology

As you have learned, there are many different types of drugs. The main challenge facing Forensic Toxicologists is to identify an unknown substance that could be one of a thousand or more commonly encountered drugs or substances. Toxicology testing is generally performed using blood, urine, hair or vitreous humor samples. Whereas drugs and toxins can be rapidly metabolized and absent in blood and urine samples, toxins tend to linger in both hair and vitreous humor samples for longer periods. When discussing Toxicology techniques, it is important to distinguish that there are two levels of toxicology testing used in standard toxicology investigations: Screening tests and Confirmatory tests.

Screening Tests

Screening tests are done to eliminate some drugs from consideration and narrow down the possibilities. Screening tests include a variety of spot tests, Thin Layer Chromatography, Gas Chromatography (without Mass Spectrometry), and Immunoassay. Immunoassay is a common testing procedure where the concentration of a substance in a liquid is measured using the reaction of an antibody to the antigen (the drug). It can be performed on its own without need for further confirmation for less critical needs such as to test for the presence of Strep throat in a doctor's office. In forensic investigations, however, it is used as a first step screening test and should be followed up using a confirmatory testing method in order for it to be admissible to court.

Spot Tests

Spot tests are sometimes performed by law enforcement officers in the field, but this can be dangerous due to the volatile chemicals used in drug production and is only advised in certain situations. In a forensic lab, spot tests are often done on a spot plate or in a test tube. Spot tests do not confirm on their own the presence of a particular drug but they are a good indicator for the absence of a drug and a starting point for further investigation in a certain direction. It is important to note that spot tests typically destroy the sample so if only a small quantity of evidence is available they may not be indicated.

There are 5 Primary color spot tests:

1. Marquis - Turns purple in presence of an Opium derivative and orange-brown in presence of Amphetamines/Methamphetamines.

2. Dillie-Koppanyi - Turns violet-blue in the presence of most Barbiturates.

3. Duquenois-Levine - A purple color appears if Marijuana is present.

4. Van Urk - Turns purple in the presence of LSD.

5. Scott Test - A blue color appears if Cocaine is present.

See sample images of some color spot tests below:

Confirmation Tests

Confirmation tests identify a specific substance and include spectroscopic tests. The most accurate and commonly used confirmatory test is Gas Chromatography with Mass Spectrometry. Depending on the type of substance and quantity available, forensic scientists need to select a method that will provide insight without completely eliminating the evidence.

Drugs can also be examined microscopically. There are two types of microscopic observations that can be conducted; Morphology and Microcrystalline. Morphology examinations involve observing the structure of substances such as botanical features to potentially identify certain substances such as Marijuana. Microcrystalline examinations involve the observation of crystalline structures which can be highly characteristic of certain drugs such as Cocaine.

Collection & Preservation of Drug Evidence

Drug evidence is relatively simple to collect for analysis. Urine and blood samples are typically collected in clean containers designated for these specific purposes. If the evidence involves plant materials, investigators will photograph the plant evidence and allow it to dry before packaging to avoid mold growth. Items of drug paraphernalia are packaged according to their type of material. Drug samples are generally placed in a clean, airtight containers to avoid contamination and loss of evidence. Investigators should be especially aware of the risks associated with handling used needles and clandestine drug lab evidence when involved in those cases and heed all safety guidelines. Clandestine drug labs are typically thought of as "Meth Labs" or "Crack houses" and typically contain many volatile substances that present numerous hazardous conditions. Evidence collection at these places takes place after the site has been deemed safe for personnel to enter by hazardous materials experts. Each item of evidence is collected and packaged as indicated by the type of material it is.

Georgia Virtual, Forensic Toxicology, CC BY-NC-SA 3.0

Toxicology Results

Significance of Toxicology Results

When discussing toxicology, it is important to understand the significance of drugs and toxicology in an investigation. Drugs, both legal and illegal, are widespread and are often a part of daily life for many people. By extension of their widespread use, they also are quite common items of evidence and significance in Forensic investigations. In addition to people who legally use pharmaceuticals within their prescribed limits, some individuals become addicted or use drugs in ways that they are not intended. In this case, Forensic investigators may be faced with an investigation involving an overdose.

Interesting Statistics

View the interesting statistics about drug use below.

Also, in 2012, the DEA seized the following amounts of illegal drugs:

Cocaine: 36,001 Kilograms

Heroin: 934 Kilograms

Marijuana: 354,023 Kilograms

Methamphetamine: 3,898 Kilograms

Hallucinogens: 784,213 dosage units

Drug dependence is an addiction to drugs, or the inability to stop using harmful substances despite the problems they cause. There are two types of drug dependence: psychological dependence and physical dependence. Psychological dependence is the conditioned use of a drug caused by underlying emotional needs. Physical dependence is the physiological need for a drug that has been brought about by its regular use.

 Dependence is characterized by withdrawal sickness when administration of the drug is abruptly stopped. Different drugs can cause different withdrawal symptoms but there are some common symptoms associated with substance abuse withdrawal including nausea, vomiting, sweating, shaking, anxiety, paranoia, and weight loss.

In addition to harming themselves, those who abuse drugs also may harm others. Whether it is someone driving under the influence of alcohol who crashes into another motorist, or a Methamphetamine user who steals an item to obtain drug money; drug abuse can be a huge social problem. View the graphic to the right to see the ranking of various drugs on a scale of their tendency to harm based on damage to health, drug dependency, economic costs and crime. Note that alcohol, a legal drug, is ranked as the drug with the most potential to harm on this scale! How can this be? While alcohol is the 4th most harmful drug on the graph to the individual user, it is the most harmful drug listed for others of society outside of the user. This is most likely due to its widespread availability and use, as well as the potential for harmful events such as drunk driving. Note that Heroin, Crack Cocaine, and Methamphetamine appear to be the most harmful to the individual user.

Drug Schedules Interactivity