Toxi exam 4

Ethanol: Sources of Exposures

"Grain" alcohol • "spirits"/alcoholic beverages -corn mash or other easily fermentable carbohydrate [malt], water yeast Ferment, Distill • Gasoline oxygenate ("gasohol", replace MTBE) • Medical uses (local antiseptic, solvent for many drugs) • Commercial products (solvent of flavoring extracts, aftershave, cough syrups, mouth wash, etc.) It is anticipated that use of ethanol will increase substantially in the future from winter use as an oxygenate (gasohol = E10, i.e., 10% ethanol) to use as a fuel extender/additive. Some newer vehicle models are capable of using fuels with 85% ethanol (E85).

Methanol : Sources of Exposures

"Wood alcohol" • Chemical stock (production of gasoline oxygenate MTBE production) • Commercial products (Sterno, solvent of paints, varnishes, gasline antifreeze, windsheild washer fluid, high test fuel, etc.) • "Accidental" exposure from adulterated alcoholic beverage - Sept 12, 2001 - Estonia 24 died - Nov 18, 2000 - Kenya; 100s died - 1999 - Vietnam - 1951 - Atlanta, GA; 41 died MTBE = methyl t-butyl ether

1781 Joseph Plenic

"thedetectionand identification of the poison in organs of the deceased is the only true sign of poisoning." early 1700s, one could be tried and convicted of poisoning without any proof that the poisoning had actually occurred (detection of the poison). By the end of the 1700s, however, people started to question the conviction of the accused without proof of the poison itself. The biggest problem, however, was that there weren't any true methods of analysis for these poisons. Therefore, while many believed that detection of the poison was important, the actual method of detection did not exist.

total economic cost of alcohol and drug abuse

$245.7 billion for 1992 -study prepared by the Lewin Group for the National Institute on Drug Abuse and the National Institute on Alcohol Abuse and Alcoholism -estimate includes substance abuse treatment and prevention as well as other healthcare costs, costs associated with reduced job productivity or lost earnings, and other costs to society such as crime and social welfare.

Zinc Phosphine:

(PH3)-formed following a hydrolytic reaction with water in the stomach on ingestion - Causes widespread cellular toxicity with necrosis of the GI and injury to liver and kidneys - Poisonings are a problem in children due to treated grain and a favorite chemical in suicides in Egypt

Strychnine

- Bitter alkaloid from seeds of a tree native to Sri Lanka, Australia and India - Attacks nervous system by antagonizing the action of glycine (inhibitory amino acid) - Evidence to suggest increasing brain levels of glutamic acid (amino acid transmitter for excitatory nerve impulses in muscle) - Convulsions and seizures death - Convulsions prevent respiration, a process which depends on a controlled rhythm of contraction and relaxation

Scientific Principles of Toxicology Most Relevant to Forensics

- Chemical disposition • Residue analysis in tissues - Blood, urine, stomach contents, liver, kidney disposition of a chemical determines where a chemical will disperse and reside within the body following exposure. Different chemicals have different affinities for different organs. Understanding the disposition of a chemical can help to confirm which class of chemical might be present upon detection in various organs.

"Environmental" cases/workman's compensation

- E.g., Woburn, MA - Trichloroethylene contamination of well water by and association with childhood leukemia Evidence from forensic toxicology has been key in settlement or judgment of several civil suits involving environmental contamination or occupational exposures and associated health problems. These have been portrayed in several films in recent years.

The mechanism of opioids

- they bind to opioid receptors in the brain. This leads to an increase of potassium efflux (going out of cell) and decrease in calcium influx (going into cell) in the presynaptic nerve terminals with a decrease in neurotransmitter release and excitability. Neurotransmitters that are affected include acetylcholine, norepinephrine, dopamine, and 5-hydroxytrypamine. The pharmacological effects are similar to the endogenous opioid peptides (endorphin and enkephalin) and include analgesia, mood alterations and hallucinations. IV injection leads to orgasmic feelings ("rush"), euphoria, tranquility and sedation.

Mechanism of action

-Pyrethrins are naturally occurring insecticides derived from the chrysanthemum plant. -Pyrethroids are synthetically derived - Both disrupt membrane ion transport in nerve axons - Pyrethroids prolong sodium influx and may block inhibitory pathways

Signs and symptoms

-Type I - Hyperexcitability and convulsions in insects (knockdown) and whole body tremor in mammals - Type II - Ataxia and incoordination in insects and paresthesia in humans Pyrethroid chemistry and action are classified as Type I or Type II depending on the alcohol substituent in the structure. Paresthesia is a sensation of pricking, tingling, or creeping on the skin.

distribution of a material in oil (octanol) vs. water at equilibrium

-an indication of the lipophilicity Higher values indicate greater lipophilicity, such as the value 676 for carbon tetrachloride. Simple, short chain alcohols tend to be of low lipophilicity, i.e., are water soluble. [Note: negative numbers for exponents indicate solubility in water > oil.]

Before understanding the mechanism of action of OPs, we first need to understand normal nerve conductance.

1. The action potential arrives at the presynaptic terminal causing calcium channels to open by increasing calcium permeability. 2. Calcium ions enter the presynaptic terminal and initiate release of acetylcholine (neurotransmitter) from vesicles. 3. The acetylcholine diffuses across the synaptic cleft and binds to receptors in the postsynaptic muscle fiber membrane causing an increase in sodium channel p ermeabilit y . 4. The postsynaptic membrane depolarizes and once a threshold is reached, another action potential results. Background: nerves communicate with muscles by actions potentials (momentary reversal in electrical potential across a plasma membrane, as of a nerve cell or muscle fiber, that occurs when a cell has been activated by a stimulus) and by neurotransmitters (chemical messengers). 1. Once acetylcholine is released into the synaptic cleft, it binds to receptors. 2. ACH is rapidly broken down in the synaptic cleft by an enzyme, acetylcholinesterase, to acetic acid and choline. 3. The choline is reabsorbed by the presynaptic terminal and combined with acetic acid to form more ACH, which enters the synaptic vesicle.

Alcohol

According to the National Institute on Alcohol Abuse and Alcoholism, 13,760,000 U.S. adults were categorized for alcohol abuse or dependence in 1992. That's 7.41% of people aged 18 or older. About 40% of adult Americans have direct family experience with alcohol or alcoholism. On college campuses across the country, approximately 44% of all students (50% of males and 40% of females) are binge drinkers.

Two alcohols and a diol

All have relatively high LD50s, yet human poisonings - often self-imposed - occur. Note that humans and cats more sensitive than rats to ethylene glycol acute toxicity. Of the chronic effects, fetal alcohol syndrome is the most important.

Pyrethrins and Pyrethroids

Another class of pesticides are pyrethroids. The pyrethroid insecticides are typically esters of chrysanthemic acid (from the chrysanthemum plant). Natural pyrethrins are toxic to a wide range of insects but are short-lived and not persistent enough for insect control. Synthetic pyrethroids are more persistent and more effective even at lower doses. Acute human poisonings can cause skin and upper airway irritation. They are not as toxic as OPs.

Specimen Collection

Blood - most important specimen collected Vitreous Humor - eye fluid; good stability from chemical breakdown during body decomposition Urine - shows the presence of metabolites from biotransformation Bile - collect in the absence of urine Liver - for drug metabolism Other - Lung tissue (inhalation); Spleen (CO analysis from RBCs); Stomach (overdose); Hair (drug abuse - arsenic)

Chemicals involved in criminal/civil cases

Classes of Forensic Chemicals: o Common homicidal poisons, suicide agents - Arsenic - Carbon monoxide o Drugs of abuse - methamphetamine - marijuana (THC) - heroin o Chemicals affecting performance - Erythropoietin (EPO) - Androgenic steroids o DUI - Ethanol (impaired motor function) In the 1800s, Arsenic became known as the "inheritance powder" as it was commonly used by women to dispose of their wealthy husbands. Carbon monoxide is a popular agent used in suicidal attempts. Both are detectable through analytical laboratory techniques.

Crime Scene Investigation

Collection of information and specimens - Historical information (age, sex, weight, medical history, i.d. of medications or other drugs taken before death, time interval between taking these and death) - Many different body fluids and organs should be collected • Chemicals have different affinities for different tissues - Collect specimens prior to processes that may destroy evidence • Embalming masks ethanol poisoning since ethanol is a component of embalming fluid - Burn or buried victims - bone marrow, skeletal muscle, vitreous humor, hair and maggots Burn or buried victims my have little to no (deteriorated) tissue to perform normal analytical techniques. In these cases, alternative methods are used.

The 10 Fields of Forensic Science

Criminalistics - collection and analysis of physical evidence; Engineering Science - accident reconstruction General - forensic photography, facial reconstruction, accounting, computers Jurisprudence - lawyers/judges with forensic background; Odontology - dental/bite mark analysis Pathology/Biology - medical examiner/autopsy; Physical Anthropology - skeletal/bone identification Psychiatry/Behavioral - criminal profiling; Questioned Documents - fake signatures/document identification Toxicology

Chlorinated hydrocarbons

DDT Chlordane Aldrin Dieldrin DDT (dichlorodiphenyltrichloroethane) is a pesticide once widely used to control insects in agriculture and insects that carry diseases such as malaria. DDT is a white, crystalline solid with no odor or taste. Its use in the U.S. was banned in 1972 because of damage to wildlife, but is still used in some countries to combat malaria. The insecticidal properties of DDT were first discovered in 1939 in Germany by Paul Mueller. DDT has relatively low acute toxicity to humans, but is very persistent and fat soluble. Chlordane, aldrin and dieldrin are cyclodienes. The organochlorines are mostly of historic interest because only a few are still used today.

Insect repellants

DEET is not an insecticide (does not kill the insect) but is a repellant. There is concern that too much DEET exposure in mosquito repellants is hazardous. However, DEET containing products have been used for over 40 years by millions of people and has an excellent safety record when applied properly.

Paraquat Induced Lung Damage

Destructive phase - Type I and II damage - Damage to pulmonary capillaries - Early necrosis of terminal bronchioles - Alveolar and interstitial edema Proliferative phase - Fibroblasts and collagen synthesis - Intraalveolar fibrosis type I and II damage refers to epithelial cells in the deep lung region (alveolar region). This is where gas exchange happens. The destructive phase does not always precede the proliferative phase. Fibrosis is the synthesis of collagen fibers in the lungs that impair the ability for gas exchange. It is extensive scaring of the lungs. This is often fatal.

To DEET or not to DEET?

Developed by the US Agriculture Dept Approved for public use since 1957 EPA estimates over 38% of US population uses DEET-based repellents Acts by blocking receptors on insect's antenna normally attracted to carbon dioxide and odor from humans Use products containing 10% or less on children Adverse reactions rare—seizures Benefits outweigh risks

Ethanol

EtOH

ALCOHOLS of Toxicological Significance Methanol, Ethanol, Ethylene Glycol

H Ethanol CH3C OH H Acute Tox, LD50 400 mg/kg (oral, mouse) 6 - 14 gm/kg (oral, rat/rabbit) Irritation Chronic Tox TBD - carc. NEG. - mutag. POS/? - repro (male rat) - terato (rat; high-dose) NEG. - carc., mutag. POS - terato.(HUMAN Fetal Alcohol Syndrome) NEG. - carc., mutag., repro. POS. - terato. Prepared by Sharon A. Meyer, 10/25/04 Methanol H3C OH ~16 gm (20 ml)/kg (dermal, rabbit) ~ 7 gm (9 ml)/kg (oral, rat/mouse) [~ 500-600 ml/human] ~1 pint ~5 gm/kg (oral, rat) < 5 gm/kg (oral, cat & human) (rabbit: 500mg/24hr) ~10 gm/kg (dermal, rabbit) skin -- 400 mg; mild (rabbit, non-occluded) eye -- mild (rabbit: 500mg/24hr) skin -- 555 mg; mild (rabbit, non-occluded) Ethylene H HO C-C OH H Glycol eye -- mild H H

recommendations for DEET:

If you are taking your children into the woods or in grassy areas where ticks and mosquitoes are prevalent, applying a DEET- containing insect repellent is the only effective way of protecting them from potentially serious bites. Here are a few guidelines: The U.S. EPA has determined that when label instructions are followed, all concentrations of DEET repellents can be used by people of all ages. Only apply insect repellents to exposed skin taking care to avoid the eyes and mouth. Read the entire product label before using the repellent. Do not apply on wounds or scratches. Apply to clothing (natural fibers only) for added protection as directed on the product label. Avoid over-saturation -- it's not necessary for adequate protection. Do not apply to the hands of small children, since they frequently put their hands into their mouths. Do not allow children to apply the product themselves. Cleanse the skin with soap and water after returning indoors. Keep out of the reach of children, because like many chemicals, DEET can be toxic if ingest ed. A very small percentage of children and adults may be sensitive to chemicals such as DEET. If there is a suspected reaction to an insect repellent, wash the area and seek medical attention.

Microsomal Ethanol Oxidation

In addition to acute toxicity of ethanol mediated through ADH metabolism to acetaldehyde, excess alcohol consumption has adverse effects on liver. Liver cirrhosis is commonly observed in alcoholics. When liver alcohol exceeds that that can be metabolized by ADH, metabolism through another pathway occurs. This pathway, catalyzed by cytochrome P450 isozyme 2E1, occurs in 2 x 1 electron steps and thus, can leak small amounts of free radicals from the enzyme. Free radicals are very damaging to cells.

FORENSIC TOXICOLOGY = APPLICATION OF SCIENTIFIC PRINCIPLES OF TOXICOLOGY & ANALYTICAL CHEMISTRY TO LEGAL MATTERS.

Includes, but not limited to: • Identification of causative agents causing death or injury in humans and animals • Urine testing to detect drug use • Courtroom testimony and consultation concerning toxicology

Inhalant Abuse

Inhalants can be breathed in through the nose or the mouth in a variety of ways such as: "Sniffing" or "snorting" fumes from containers; Spraying aerosols directly into the nose or mouth "Bagging" - sniffing or inhaling fumes from substances sprayed or deposited inside a plastic or paper bag "Huffing" from an inhalant-soaked rag stuffed into the mouth; Inhaling from balloons filled with nitrous oxide. Inhaled chemicals are rapidly absorbed through the lungs into the bloodstream and quickly distributed to the brain and other organs. Within minutes of inhalation, the user experiences intoxication along with other effects similar to those produced by alcohol (slurred speech, an inability to coordinate movements, euphoria, and dizziness). In addition, users may experience lightheadedness, hallucinations, and delusions, such as thinking they can fly. Because intoxication lasts only a few minutes, abusers frequently seek to prolong the high by repeated inhalation. This can result in loss of consciousness and death.

1832

John Bodle was brought to trial being accused of poisoning his grandfather by placing arsenic in his coffee. James Marsh was the chemist assigned to the trial and he was able, through simple techniques, produce a yellow precipitate indicating the presence of arsenic. However, the precipitate did not keep well and by the time of the trial, it had deteriorated and the jury, with lack of evidence, found Bodle not guilty. Marsh was so frustrated that Bodle had been acquitted, particularly when Bodle later confessed to the crime, that he became determined to devise a better technique to determine the presence of arsenic. He soon developed a method in which arsenic could be detected in tissue through the production of arsine gas which leaves a silvery black deposit on a cold ceramic bowl held over the jet of the flame used to oxidize the arsenic. The method was used in 1839 in which Marie Lafarge became the first accused to be convicted of poisoning based on actual analytical detection of the poison, itself. The method is still used today

methanol and ethanol are volatile and flammable.

Kow, the distribution of a material in oil (octanol) vs. water at equilibrium, is an indication of the lipophilicity. Higher values indicate greater lipophilicity, such as the value 676 for carbon tetrachloride. Simple, short chain alcohols tend to be of low lipophilicity, i.e., are water soluble. [Note: negative numbers for exponents indicate solubility in water > oil.]

Chronic Ethanol Toxicity

Liver - Cirrhosis damage - Hepatitis • Risk of cardiovascular disease (stroke & hypertension) • Fetal Alcohol Syndrome (FAS)/Fetal Alcohol Effects (FAE) Large vacuoles result from fat accumulation, while infiltration by white blood cells (hepatitis) are indicated by chains of blue dots. This is one type of pathology observed with chronic consumption of ethanol. Cirrhosis is characterized by bands of tough connective tissue that surround groups of liver cells to form nodules as shown in the gross pathology of the liver to the right.

Club drug

MDMA (Ecstasy) GHB Rohypnol Ketamine Methamphetamine LSD a vague term that refers to a wide variety of drugs. Uncertainties about the sources, chemicals, and possible contaminants used to manufacture many club drugs, make it extremely difficult to determine toxicity and resulting medical consequences.

Mechanism of action

MOA of DDT has never been clearly established but in some complex manner it apparently acts on the sodium channel to cause "leakage" of sodium ions. - "DDT jitters"-neurons fire impulses spontaneously causing muscles to twitch followed by convulsions and death Cyclodienes-MOA not clearly understood. Acts on the GABA (gamma-aminobutyric acid) receptor. - Prevents chloride ions from entering the neurons (inhibits the inhibitory mechanism of GABA)-results in tremors, convulsions

Signs and symptoms

MOA-inhibition of acetylcholinesterase - Accumulation of free, unbound Ach at the nerve terminal—continual stimulation of all cholinergic nerves Stimulation of muscarinic receptors of the parasympathetic (increased secretions, bronchioconstriction, diarrhea, urination, etc) Stimulation and subsequent blockade of nicotinic receptors of para and sympathetic (tachycardia, tremors, muscle weakness and flaccid paralysis) CNS (ataxia, lethargy, mental confusion, generalized weakness, convulsion, coma) Death results from two factors that compromise respiration: interference with oxygen exchange caused by excessive bronchial secretions and muscular paralysis.

Methanol

MeOH

1918

Medical Examiner's Office and Toxicology Laboratory established in New York City. Alexander O. Gettler - 1st Chief Forensic Toxicologist - Considered Father of American Toxicology

effects of cocaine in the brain

One neural system that appears to be most affected is located in the ventral tegmental area (VTA). Nerve cells originating in the VTA extend to the region of the brain known as the nucleus accumbens, one of the brain's key pleasure centers. In the normal communication process, dopamine is released by a neuron into the synapse (the point at which a nervous impulse passes from one neuron to another), where it can bind with dopamine receptors on neighboring neurons. Normally dopamine is then recycled back into the transmitting neuron by a specialized protein called the dopamine transporter. If cocaine is present, it attaches to the dopamine transporter and blocks the normal recycling process, resulting in a buildup of dopamine in the synapse which contributes to the pleasurable effects of cocaine.

Anabolic Steroid Abuse

One of the main reasons people give for abusing steroids is to improve their performance in sports. Among competitive bodybuilders, steroid abuse has been estimated to be very high. Among other athletes, the incidence of abuse probably varies depending on the specific sport.

1839

OrfilasuccessfullyusedMarsh'stest to identify arsenic in human organs; used to convict Marie Lafarge

Systemic Lung Toxins

Paraquat - Bipyridyl derivative - methyl viologen - Herbicide - 1959 - Oral - irritating nausea vomiting diarrhea kidney damage first use as an oxidation/reduction indicator for chemical reactions. The herbicidal properties were discovered in 1959. It is a very effective herbicide and quickly kills weeds and binds tightly to soil and is rendered nontoxic. However, it is odorless and tasteless with a brown color (similar to coke). Decanting the liquid into an unmarked container or bottle has resulted in accidental ingestion. It is called the "hit-and-run" poison because if an individual survives the acute exposure (nausea, vomiting, kidney damage, etc.), there is some recovery. However, it is just a matter of time before the lungs are affected (10-14 days later). This compound is toxic by dermal, inhalation, and oral ingestion and causes a highly fatal pulmonary fibrosis.

fibrotic lung

Paraquat causes intraalveolar fibrosis.

paraquat in the lungs

Paraquat is selectively taken up into the alveolar cells by an active transport system. In the cells, the oxidized paraquat is reduced by NADPH (an enzyme cofactor). The reduced paraquat reacts with oxygen to form several highly reactive compounds that are capable of damaging the cells through lipid peroxidation (damage to membranes). Another mechanism is a depletion of NADPH that is critical for cellular function. Both mechanisms will damage cells. Fibroblasts are recruited to the area and collagen fibers are synthesized. This is fibrosis and is very deadly. Notice that one molecule of paraquat goes in a cycle of oxidation and reduction. The lungs obviously contain ample amounts of oxygen to continue the cycle until cell death occurs.

Childhood Effects of Maternal Alcohol Exposure

Psychoeducational Profiles of Children with FAS/FAE • INFANCY: Irritability / Irregular sleep & Sleep disturbances / Poor muscle tone • CHILDHOOD: A.D.D. / Hyperactivity / Weak grip strength • DEVELOPMENTAL: Delayed speech and articulation problems / Fine motor delay / Tremors / Gross motor delay / Disordered Behavior / Poor eye contact / Inappropriate reactions / Hyperactive FAE (borderline > dull): Weak verbal skills (Memory) / Poor visual-perceptual skills / Poor handwriting / Immature social behavior / clumsiness Several clinical conditions have been associated with maternal alcohol consumption. The most obvious are the characteristic facial features caused by the developmental toxicity of ethanol during organ development.

Ethylene Glycol

SOURCES - Radiator fluid SYMPTOMS of ACUTE POISONING - Metabolic acidosis (glycolic acid) -- critical effect - Renal damage: Glycolic acid - - B1 - - Glyoxylic acid - - Oxalic acid (Ca2+oxalate HO O crystals in urine) THERAPIES - B Vitamins; Thiamine (B1), Pyridoxine (B6) - ADH block with ethanol, 4-MP - Dialysis

Methanol Poisoning

SYMPTOMS of ACUTE POISONING • Mild inebriation • Headache, dizziness • Metabolic acidosis (formic acid) -- critical effect • Visual impairment -Irreversible damage to retina and optic disks THERAPIES Folic acid • Folic acid: Formic acid CO2 + H2O • Ethanol infusion (EtOH is better ADH substrate) • 4-Methylpyrazole (4-MP; better ADH substrate than MeOH or EtOH) • Dialysis

Forensic Toxicology

Scientific Principles - Cont'd - Pharmacokinetics • Residence time of chemical ∝ time crime committed - "Reverse" Hazard ID • Clinical symptoms ∝ chemical toxicity

Aging

T he OP has attached to the acetylcholinesterase active site. The enzyme is no longer capable ofbreaking down ACH, so ACH accumulates in the synaptic cleft and stimulates cholinergic processes (signs and symptoms of poisoning occur). T he nerves go into cholinergic crisis, become exhausted due to overstimulation and no longer function. This results in respiratory paralysis and death. The difference in toxicity between OP compounds is due to the potential for " aging" on the enzyme site. T his process is essentially irreversible.

to be determined

TBD

normal lung section

The alveolar region is a single cell thickness with air spaces for gas exchange.

Forensic Scientist

The forensic scientist is first, a scientist. When he applies his scientific knowledge to assist juries, attorneys and judges in understanding science, he is a forensic scientist.

Organophosphates and carbamates

The insecticidal properties of OPs were first discovered in Germany during WWII as a result of nerve gas research. They became popular in agriculture in the 1960s and are still used today. The chemicals comprising this type of insecticide have a common mechanism of action (acetylcholinesterase inhibition) but arise from two distinctly different chemical classes, the esters of phosphoric or phosphorothioic acid and those of carbamic acid. There are a vast array of structures - over 200 different OPs and 25 carbamates. OPs are used locally to control pests on cotton and other crops. The big concern is pesticide residues on food and greater susceptibility of children to pesticide exposure. The scientific community is divided on this issue.

COCAINE

The principal routes of cocaine administration are oral, intranasal, intravenous, and inhalation. The slang terms for these routes are, respectively, "chewing", "snorting", "mainlining", and "smoking" (including freebase and crack cocaine). The pure powder form is cocaine hydrochloride salt. This will easily dissolve in water and is usually taken IV or through the nose. The freebase form has not been neutralized by acid to make the salt. This can be smoked. Crack is the freebase form that has been processed by removing the hydrochloride salt. The small rocks of crack get its name from the crackling sound when smoked. Some users combine cocaine powder or crack with heroin in a "speedball". • Powerfully addictive stimulant • Extracted from Erythroxylon coca leaf • Effects the ventral tegmental area of brain - one of the brain's key pleasure centers Cocaine use ranges from occasional use to repeated or compulsive use, with a variety of patterns between these extremes. There is no safe way to use cocaine. Any route of administration can lead to absorption of toxic amounts, leading to cardiovascular ore cerebrovascular emergencies that could result in sudden death. Repeated cocaine use by any route can produce addiction and other adverse health consequences. Dopamine is normally transported back into the transmitting neuron •Cocaine blocks the normal recycling process resulting in a buildup of dopamine in the nerve synapse and contributes to the pleasurable effects - euphoric effects

Interaction and aging:

The reaction between an OP ester and the active site in the enzyme (serine hydroxyl group) results in the formation of a transient intermediate complex that partially hydrolyzes with the loss of the X substitute leaving group, leaving a stable, phosphorylated and largely unreactive inhibited enzyme that is only reactivated at a very slow rate. With many OP ester insecticides, an irreversibly inhibited enzyme is formed and the signs and symptoms of toxicity are prolonged and persistent requiring medical intervention. Without intervention the toxicity will persist until new enzyme is synthesized in 20 to 30 days. The victim has cannot wait for new enzyme to be synthesized. T he nature of the substitute leaving group (X) plays an important role in 1) the specificity for the enzyme, 2) the tenacity of binding to the active site, and 3) the rate at which the phosphorylated enzyme dissociates. With carbamates, the rate of dissociation is sufficiently rapid that these esters are considered to be reversible inhibitors. VX and sarin are very deadly because they are essentially irreversible. These bind tenaciously to the active site to produce an irreversibly inhibited enzyme through the process of " aging". T he aging process is generally accepted as being caused by the dealkylation of the intermediate dialkylphosphorylated enzymes.

Alcohol , Aldehyde , Carboxylic Acid

Toxicity of all three compound depend upon oxidative metabolism The reactive metabolite of methanol and ethylene glycol are the organic acid products of aldehyde dehydrogenase (AlDH), while the intermediate aldehyde is the reactive metabolite of ethanol produced by alcohol dehydrogenase (ADH). Oxidizing equivalents come from cellular nicotinamide dinucleotide (NAD), which is reduced as the compounds are oxidized. "Antabuse", i.e., disulfiram, is a AlDH inhibitor that works to deter craving for alcohol be causing build-up of toxic acetaldehyde.

Anticoagulants

Warfarin--brodifacoum - Anticoagulant by antagonizing the actions of vitamin K in the synthesis of clotting factors (factors II, VII, IX and X) - Onset of action delayed 8 to 12 h - Multiple doses required before toxicity develops (safety factor for children) - Human poisonings rare except in suicide attempts and attempted murders

Folic acid

a cellular requirement for further metabolism of the reactive metabolite of methanol, formic acid to non-toxic products.

Marijuana

a green or gray mixture of dried, shredded flowers and leaves of the hemp Cannabis sativa. The main active chemical in marijuana is THC (delta-9tetrahydrocannabinol). • THC (delta-9-tetrahydrocannabinol) • THC changes the way sensory information is processed by the hippocampus (component of brain's limbic system; learning, memory, emotional motivations). THC suppresses activity of nerve fibers • Stimulates the dopamine pathway in the ventral tegmental area (reward system) • Effects on lungs: similar to tobacco smokers (bronchitis and emphysema • Severe increases in heart rate and blood pressure when used with cocaine • Decreases in attention, memory and learning

Paraquat

a very dangerous herbicide that has been associated with thousands of accidental, suicidal, and homicidal events.

Parathion

an OP insecticide, is metabolically activated to the oxon. Oxidative desulfuration involves the production of an intermediate that rearranges to paraoxon; catalyzed by cytochrome P450. This is the active compound that inhibits acetylcholinesterase. Other OPs do not have to be bioactivated to cause toxicity.

PCP (angel dust)

an animal tranquilizer. In humans, it has anesthetic properties. However, abusers often become agitated, delusional, irrational, and violent when down from this drug. This compound may increase dopamine activity and antagonize (to act in opposition to) glutamate action.

Forensic toxicology

an applied field; a subspecialty of forensic science. The fundamental principles of toxicology most relevant here are those useful as evidence that exposure to a poison or drug of abuse has occurred and those that predict time of exposure.

GABA

an inhibitory neurotransmitter. It triggers an increase in chloride permeability, allowing chloride ions to enter the neuron and makes the membrane potential more negative (raising the threshold for an action potential).

Forensic Science

any science used in public, court or justice system - Any science used for the purposes of the law -based on sound scientific principles including the scientific method. The scientific method is made up of hypotheses, data and theories. When scientists apply these principles and methods towards the legal arena, they are known as "forensic" scientist.

Hallucinogens

are drugs that cause hallucinations - profound distortions in a person's perception of reality.

carcinogenesis

carc

Abbreviations

carc = carcinogenesis mutag = mutagenesis repro = reproductive toxicity terato = teratogenesis i.e., causes birth defects; TBD = to be determined

Hallucinogens

cause profound distortions in a person's perception of reality. Users see images, hear sounds and feel sensations that do not exist These drugs disrupt the interaction of nerve cells and the neurotransmitter serotonin -involved in control of behavior, perception, mood, hunger,muscle control

Pesticides

chemicals intended to kill or suppress populations of several types of pest organisms. Insecticides - insects fungicides - fungi herbicides - weeds rodenticides - rodents Over 700 million kilograms of pesticides are produced annually in the U.S. Insecticides comprise 35% of total pesticides used in the agriculture industry and 50% of total pesticides used in the home.

The active center of the enzyme, acetylcholinesterase

consists of a negative subsite, which attracts the quaternary group of choline (by hydrophobic forces) and an esteratic subsite where nucleophilic attack occurs on the acyl carbon of the substrate (ACH). [A nucleophile is an ion or molecule which is strongly attracted to a region of positive charge. Nucleophiles are either fully negative ions or have a slightly negative charge] During enzymatic attack on the ester, a tetrahedral intermediate is formed that collapses to an acetyl enzyme conjugate with the release of choline. The acetyl enzyme is easily hydrolyzed, which results in the formation of acetate and the regeneration of the active enzyme. This process is critical for normal neuronal functioning. If acetylcholinesterase is inhibited and no longer able to break down ACH, then toxicity occurs.

Aliphatic alcohols

contain the -OH group

Aliphatic alcohol

contain the -OH group. Two alcohols and a diol are the focus of this lecture. All have relatively high LD50s, yet human poisonings - often self-imposed - occur. Note that humans and cats more sensitive than rats to ethylene glycol acute toxicity. Of the chronic effects, fetal alcohol syndrome is the most important.

1700s

convictions of homicidal poisoning based on circumstantial evidence rather than ID of toxicant within victim

Hazard Identification

deals with giving a chemical and observing its clinical symptoms. In reverse hazard identification, the symptoms are observed first. It is then up to the forensic scientist to deterimine the chemical that caused these symptoms. Clinical symptoms are directly proportional to the chemical's toxicity.

Pharmacokinetics

describes the residence time of a chemical within the body, i.e., biotransformation. Some chemicals metabolize more rapidly than others. Knowing the half-life of a chemical in the body can help determine how much of the chemical was there initially and give an idea of when the crime was actually committed. Residence time of chemical is directly proportional to the time the crime was committed.

PCP and ketamine

developed as anesthetics, distort perceptions of sight and sound and produce feelings of detachment Alter the distribution of the neurotransmitter glutamate in the brain. Glutatmate is involved in the perception of pain, responses to the environment and memory.

1836 James M. Marsh

developed test for presence of arsenic in tissue

Acute Ethanol Toxicity

effects of alcohol vary with amount consumed, as evident from the blood alcohol concentration (BAC). Most states outlaw driving a motor vehicle at BAC>80 mg/dl (ie., .08%). Experimental animals will not consume alcohol at toxic levels. Instead, it must be force fed through a feeding tube to achieve lethal concentration. In contrast, lethal concentrations have been consumed by human beings during "binge drinking".

Performance-enhancing drugs

have also become a priority of forensic drug testing labs, as well as drugs that impair operation of a motor vehicle.

"Psychedelic" drugs

have been used by many cultures for "mind-revealing" rituals. Users say that these drugs give them new ways of looking at the world and new insights into personal problems.

Dissociative drugs

initially developed as general anesthetics for surgery, distort perceptions of sigh and sound and produce feelings of detachment - dissociation- from the environment and self. cause their effect by disrupting the interaction of nerve cells and the neurotransmitter serotonin. This chemical is found throughout the brain and spinal cord, and is involved in the control of behavior, perception, and regulatory systems, including mood, hunger, body temperature, sexual behavior, muscle control, and sensory perception.

Opium

is the boiled sap of the opium poppy (Papaver somniferum). The main opioid drugs that are most commonly abused are heroin, morphine, and oxycodone.

mutagenesis

mutag

Rodenticides

often are anticoagulants and will cause the rodent to bleed to death. The following slides present rodenticides with different mechanisms of action.

reproductive toxicity

repro

Pyrethroid toxicity

results from the potent effects on nerve impulse generation within both the central and peripheral nervous systems. Under normal conditions, neurons possess a transmembrane voltage of about -60 mV on the inside. The nerve impulse or action potential consists of depolarization driven by an influx of sodium ions followed by downstroke from the efflux of potassium ions. Ion fluxes occur due to the opening and closing of specific ion channel proteins embedded within the nerve terminal. Type I induce multiple spike discharges in peripheral sensory and motor nerves, as well as interneurons within the CNS. Type II depolarize the axon membrane potential and eventually lead to a loss of electrical excitability. These effects occur because pyrethroids prolong the current flowing through sodium channels by slowing or preventing the shutting of the channels. Differences between I and II are due to the degree of physiological effect: the duration of modified sodium currents by I last tens or hundreds of milliseconds, while II lasts for minutes or longer. These effects on the sodium current cause a profound release of neurotransmitters from nerve terminals.

Urinary metabolites of drugs of abuse

such as methamphetamine and marijuana, are used to monitor illegal drug use. The presence of the metabolite is an indicator that the parent material was present.

teratogenesis

terato causes birth defects

Glycolic acid

the product of ethylene glycol oxidation by ADH and AlDH, is further oxidized to glyoxylic acid, then oxalic acid. Renal damage results from formation of calcium oxalate kidney stones. Vitamins B1 and B6 are co-factors of metabolism that leads away from formation of oxalate and, hence, are therapies used for detoxification.

Acute ethanol poisoning

treated with supportive care while the drug clears, while alcohol dependency is treated with the AlDH inhibitor, disulfiram. An important interaction of prior ethanol consumption on increasing the toxicity of acetaminophen (Tylenol) has been described.

methanol and ethanol

volatile and flammable

Health consequences with steroids

• Acne and breast development in men • Masculinization of women; excessive body hair, decrease in breast size, voice deepens • Heart attacks • Liver cancer

Forensic Toxicology Analysis

• Analytical methods chosen depend on: - Amount of specimen available • Tissue,blood,hair,organs - Nature of the toxicant • Parent,Metaboliteorboth(Biotransformation) • A low concentration of the parent compound may reflect biotransformation to a toxic metabolite as opposed to a low level of exposure • Toxicity may be from parent, metabolite or both

Ketamine: Special K, K, Vitamin K, Cat Valiums

• Animal anesthetic • Produces dream-like states and hallucinations • High doses: delirium, amnesia, impaired motor function, high blood pressure, depression and potentially fatal respiratory problems • Low doses: impaired attention, learning ability and memory Ketamine is an injectable anesthetic that has been approved for both human and animal use in medical settings since 1970. Ketamine gained popularity for abuse in the 1980s, when it was realized that large doses cause reactions similar to those associated with use of PCP, such as dream-like states and hallucinations.

Rohypnol: Roofies, Forget me Pill

• Benzodiazepines (valium): sedative • Tasteless and odorless and dissolves easily in carbonated beverages • "Anterograde amnesia"- no memory while under drug • Used in sexual assaults • Decreased blood pressure, drowsiness, confusion Rohypnol is tasteless and odorless, and it dissolves easily in carbonated beverages. The sedative and toxic effects of Rohypnol are aggravated by concurrent use of alcohol. Even without alcohol, a dose as small as 1 mg can impair a victim for 8 to 12 hours.

Laboratory Analyses

• Colorimetric Screening Tests • Thermal Desorption - Analysis of stains and residuals • Gas Chromatography (GC) • High-Performance Liquid Chromatography (HPLC)

Heroin

• Converted to morphine and binds to opioid receptors • "Rush"-surge of pleasurable sensation In the brain, heroin is converted to morphine and binds rapidly to opioid receptors. Short-Term Effects •"Rush" •Depressed respiration •Clouded mental functioning •Nausea and vomiting •Suppression of pain •Spontaneous abortion Long-Term Effects •Addiction •Infectious diseases, for example, HIV/AIDS •Bacterial infections •Abscesses •Infection of heart lining and valves •Arthritis and other rheumatologic problems

Forensic Toxicologist

• Deals primarily with Laboratory Analysis and Courtroom Testimony • Answers the question: "Did prescription or illegal drugs and/or alcohol lead or contribute to the person's death or intoxication?" • Most Crime scenes are handled Crime Scene Technicians who work for Forensic Toxicologist differ from criminal investigators in many ways.

Cost to society

• Economic cost: $245.7 billion for 1992 • Americans spent $57.3 billion between 1988 and 1995 - Cocaine $38 billion - Heroin $9.6 billion - Marijuana $$7 billion

Drug Concentration and Distribution

• Highest concentrations of poison found at the site of administration - Large quantity in GI tract and liver - Oral Ingestion - Lungs - indicative of inhalation - Tissue surrounding injection site - IV or intramuscular injection Just because the toxic material is present in the gut, does not provide sufficient evidence that it was the cause of death. Absorption and transport to the site of action must be demonstrated

Methylenedioxymethamphetamine (MDMA): Ecstasy, XTC, X, Adam, Clarity, Lover's Speed

• Increase heart rate and blood pressure and alertness: stimulant and psychedelic effects • High doses: malignant hyperthermia (increased body temperature) leading to muscle breakdown and kidney and cardiovascular failure and death • Chronic use: permanent damage to neurons that release serotonin and memory impairment • MOA: increased release and decreased reuptake of norepinephrine and dopamine -Many ecstasy users in raves or nightclubs chew on baby pacifiers to alleviate jaw clenching and teeth grinding. -MDMA is similar to the stimulant amphetamine and the hallucinogen mescaline. When taken orally, usually in a tablet or capsule, the effects can last 3 to 6 hours. Confusion, depression, sleep problems, anxiety, and paranoia have been reported to occur even weeks after the drug is taken.

Gamma-hydroxybutyrate (GHB): Grievous Bodily Harm, G, Liquid Ecstasy, Georgia Home Boy

• Involved in poisonings, overdoses, date rapes and fatalities • CNS depressant that can relax or sedate • Higher doses: slow breathing and heart rate GHB can be produced in clear liquid, white powder, tablet, and capsule forms, and it is often used in combination with alcohol, making it even more dangerous.

Hallucinogens and Dissociative drugs

• LSD(lysergicaciddiethylamide) • Mescaline • PCP(phencyclidine) • Ketamine • Dextromethorphan Others are mescaline (San Pedros and Peyote cactus), which was used by native Americans in their religious rituals, and psilocybin (psychedelic alkaloids or "magic" mushrooms).

The CSI Effect

• PopularCSI-liketvshows - Glamorize the field of forensics - Overstate the accuracies of forensic techniques - Exaggerate the abilities of forensic science • Criminalinvestigaton • DNA testing • Skewspublicperceptionofreal-worldforensics - Jury members - Prosecutors a phenomenon brought on by the popularity of CSI-like television shows watched by millions nightly. The unrealistic techniques and results portrayed in these programs have set up an expectation by laypersons that forensic cases should be solved quickly (after all, these shows only last an hour) and with absolute accuracy (the criminal is always caught based on the evidence). This especially is of concern in the courtroom setting.

Ethanol Toxicity

• Therapy - Acute Toxicity • Supportive care for respiratory depression, hypoglycemia • Dialysis - Dependency • Disulfiram (Antabuse) • Drug interactions - Benzodiazapines - Acetaminophen

Courtroom Testimony

• Toxicological reports may be introduced as evidence • Forensic Toxicologist as an Expert Witness - Interpret findings of data and any associated opinions Expert Witness - one who possesses the knowledge or experience in subject matters beyond the range of ordinary or common knowledge or observation. The final duty of a forensic toxicologist is that of an expert witness. Expert witnesses must be qualified based on experience, education, job training, publications, acceptance as a witness in other cases, and professional board certification.

Physiological effects of cocaine

•Constricted blood vessels, increased heart rate and blood pressure • Bizarre,erratic and violent behavior • Tremors, vertigo, muscle twitches, paranoia •Sudden death from cardiac arrest or seizures followed by respiratory arrest There are many medical complications associated with cocaine use. Cocaine will also block the reuptake of norepinephrine (adrenaline) and cause cardiovascular effects.

LSD (lysergic acid diethylamide)

•Derived from a rye fungus; can be mixed with binding agents to produce tablets or microdots or blotter acid • Effectscanlast12hours • Psychosis-devastating psychological effects; dramatic mood swings •Flashbacks:visual disturbances, colored flashes - synthesized in the 1940s - This compound is not found in nature. - However, the monoethyl form is found in morning glory seeds, but is not as potent except in very high amounts. - The compound is also found in rye fungus and may have contaminated grain and contributed to the "witch spells" in the Salem witch trials. A proponent of LSD was Timothy Leary. He developed an 8-circuit model of consciousness and LSD was necessary to achieve higher levels of consciousness. In the 1960s, he coined the phrase, "turn on, tune in, drop out".