Forensic Toxicology

October 06, 2020 BY Falak Khan

Forensic Toxicology Quiz Crafted by -

Sudhanshu Shekher Tiwari

Assistant Professor

School of Forensic Science and Risk Management

Rashtriya Raksha University, Gujarat.

Introduction to Forensic Toxicology

Forensic toxicology is the use of toxicology and disciplines such as analytical chemistry, pharmacology and clinical chemistry to aid medical or legal investigation of death, poisoning, and drug use. The primary concern for forensic toxicology is not the legal outcome of the toxicological investigation or the technology utilized, but rather the obtainment and interpretation of results. A toxicological analysis can be done to various kinds of samples. A forensic toxicologist must consider the context of an investigation, in particular any physical symptoms recorded, and any evidence collected at a crime scene that may narrow the search, such as pill bottles, powders, trace residue, and any available chemicals. Provided with this information and samples with which to work, the forensic toxicologist must determine which toxic substances are present, in what concentrations, and the probable effect of those chemicals on the person.

Here is the List of Questions with Answers along with explanation

Que 1. Which of the following instrument is used to identify the organic drugs?

(A) Infra-red spectrophotometer

(B) Polymerase chain reaction

(D) Automatic blood analyzer

Answer: (A) Infra-red spectrophotometer

Explanation: Almost any compound having covalent bonds absorbs various frequencies of electromagnetic radiation in the infrared region of the electromagnetic spectrum. This region lies at wavelength longer than those associated with visible light, which range from approximately 400 to 800 nm, but lies at wavelengths shorter than those associated with microwaves, which are longer than 1 mm. For chemical purposes, we are interested in the vibrational portion of the infrared region. It includes radiations with wavelengths between 2.5 μm and 25 μm. In the early use of IR spectroscopy in 1882, William Abney managed to identify 52 benzene derivatives from the IR spectroscopy. IR spectroscopy is used to see the the functional group in the molecule as the bonds vibrates at certain wavenumber and it only vibrate at only certain allowable frequencies.

Que 2. Which of the following preservatives is used to preserve the blood in case of alcohol poisoning?

(A) EDTA

(B) Heparin

(D) Sodium chloride

Answer: (C) Sodium fluoride

Explanation: Sodium Fluoride prevents the breakdown of blood glucose (a process called glycolysis). The glucose concentration in NaF remains stable up to three days. Glucose breaks down to pyruvate and lactate with the sequential implementation of various enzymatic reactions. Sodium fluoride inhibits some enzymatic reactions, including the conversion of phosphoglycerate to phosphoenolpyruvate, and prevents glycolysis.

Que 3. Which of the following drugs of abuse is over 100 times as potent as morphine ?

(A) Fentanyl

(B) Psilocybin

(D) Mandrex

Answer: (A) Fentanyl

Explanation: Fentanyl is a powerful synthetic opioid that is similar to morphine but is 50 to 100 times more potent. It is a prescription drug that is also made and used illegally. Like morphine, it is a medicine that is typically used to treat patients with severe pain, especially after surgery. It is also sometimes used to treat patients with chronic pain who are physically tolerant to other opioids. Tolerance occurs when you need a higher and/or more frequent amount of a drug to get the desired effects.

Que 4. Toddy is manufactured from which of the following?

(A) Rice

(B) Palm

(D) Molasses

Answer: (B) Palm

Explanation: The toddy palm is native to India and Southern Pakistan, where it grows both wild and cultivated. It thrives in hot, low wastelands. The toddy palm gets its name from the popular Indian drink called toddy that is made of its fermented sap. The sap is very sweet and is ingested in both alcoholic and non-alcoholic forms. It will start to ferment just a few hours after it’s harvested, so to keep it non-alcoholic, it’s often mixed with lime juice.

Que 5. Pycnometer method is used to estimate which of the following property of alcoholic beverage?

(A) Ethyl alcohol content

(B) Total acidity

(D) Higher alcohol content

Answer: (A) Ethyl alcohol content

Explanation: The proof of an alcoholic beverage is a measurement of its ethanol content. The proof of spirit and wine is defined as the percentage by volume of ethanol. The traditional method for determination of proof uses a pycnometer or a small, accurately graduated hydrometer. Recently, the European Community has adopted a reference method for ethanol determination in spirits, based on two steps. The first step is a prescribed distillation stage and the second step allows a choice from three different methods of measuring the density of the distillate: (1) pycnometry: time consuming and susceptible to error; (2) electronic densimetry: measurement of the oscillations of a vibrating U-tube, this method is simple and fast; (3) densimetry using hydrostatic balance: this method is also fast with the new generation of instrumentation.

Measuring the density followed by conversion into alcohol concentration using official alcohol tables is an officially recognized method for alcohol determination in distillates. Accepted instruments for measuring the density for subsequent alcohol determination include pycnometers, hydrometers, and digital density meters.

Que 6. Alcohol is oxidised to acetaldehyde in the liver by

(A) Peroxidase

(B) Glyoxylase

(D) Alcohol dehydrogenase

Answer: (D) Alcohol dehydrogenase

Explanation: The mammalian alcohol dehydrogenases (ADHs) are a family of enzymes that catalyze the oxidation and reduction of a wide variety of alcohols and aldehydes. They are abundant in the liver but are present to different extents in other tissues. The individual members of this family have different but overlapping substrate specificities, and probably play a general detoxifying role. They have attracted considerable interest due to their key role in the metabolism of ethanol (beverage alcohol), which modulates the effects of ingested ethanol on the body. Individual differences in ADH isozymes and expression affect risk for alcoholism, tissue damage, and developmental abnormalities including fetal alcohol spectrum disorders. In this chapter, we focus primarily on the human ADHs and their role in the metabolism of endogenous and dietary alcohols, including ethanol.

Que 7. Parathion is metabolised to which of the following?

(A) p-nitrophenol and diethyl phosphate

(B) o-nitrophenol and ethyl phosphate

(D) m-nitrophenol and dimethyl phosphate

Answer: (A) p-nitrophenol and diethyl phosphate

Explanation: Parathion is a deep brown to yellow liquid with a faint odor of garlic. It is an organic phosphate insecticide which acts as an inhibitor of cholinesterase, and as such it is highly toxic by all routes of exposure. It may be found as a liquid or as a dry mixture where the liquid is absorbed onto a dry carrier. Major metabolic products /of parathion metabolism in animals are 4-nitrophenyl phosphate, diethyl hydrogen phosphorothionate, diethyl hydrogen phosphate & p-nitrophenol. The reaction resulting in the formation of diethyl hydrogen phosphorothionate & p-nitrophenol requires the same cofactors such as oxygen & reduced nicotinamide adenine dicucleotide , as the biotransformation of parathion into 4-nitrophenyl phosphate

Que 8. Dhatura poisoning resembles with which of the following?

(A) Kuchala poisoning

(B) Opium poisoning

(D) Rati poisoning

Answer: (B) Opium poisoning

Explanation: Datura stramonium (DS), known as Jimson weed is a wild-growing herb. The entire plant especially the foliage and seeds, is toxic due to its content of tropane alkaloids. The contained atropine, L-hyoscyamine and L-scopolamine cause anticholinergic syndrome, which results from the inhibition of central and peripheral muscarinic neurotransmission

Que 9. Which one of the following is an active metabolite of chloral hydrate?

(A) Chlorpromazine

(B) Trichloroethanol

(D) Methylphenidate

Answer: (B) Trichloroethanol

Explanation: Chloral hydrate is metabolized by the liver and erythrocytes to form trichloroethanol (an active metabolite). The reduction of chloral hydrate to trichloroethanol (the major metabolite) is catalyzed by alcohol dehydrogenase and other enzymes. A small but variable amount of chloral hydrate and a larger portion of trichloroethanol are oxidized to trichloroacetic acid (an inactive metabolite), mainly in the liver and kidneys. Trichloroethanol may also be conjugated with glucuronic acid to form trichloroethanol glucuronide (urochloralic acid), an inactive metabolite. The quantities of metabolites excreted in the urine appear to be quite variable not only between different individuals but may even vary in the same individual on different days.

Que 10. Morphine dependence is best characterised by which of the following?

(A) Constricted pupils

(B) Masked face

(D) Anorexia

Answer: (D) Anorexia

Explanation: Morphine dependence can actually make the body function differently than it did without morphine. This is defined as a physical dependence and can be characterized by the lack of chemical reaction in the brain due to suddenly removing morphine from a system that has become dependent on the drug. Morphine can also cause a psychological dependence when taken for prolonged periods of time. A psychological dependence is characterized by an individual thinking they need to take a drug in order to function properly, even though there is no actual chemical or physical need for it. When an individual develops a psychological dependence before a physical dependence on morphine, it can often lead to a more aggressive dependency or addiction.

Que 11. Which enzyme regulates the metabolism of opiates?

(A) SULT 2

(B) CYP 2D6

(D) MT

Answer: (B) CYP 2D6

Explanation: Opioids undergo phase 1 metabolism by the CYP pathway, phase 2 metabolism by conjugation, or both. Phase 1 metabolism of opioids mainly involves the CYP3A4 and CYP2D6 enzymes. The CYP3A4 enzyme metabolizes more than 50% of all drugs; consequently, opioids metabolized by this enzyme have a high risk of drug-drug interactions. The CYP2D6 enzyme metabolizes fewer drugs and therefore is associated with an intermediate risk of drug-drug interactions. Drugs that undergo phase 2 conjugation, and therefore have little or no involvement with the CYP system, have minimal interaction potential.

Que 12. Consumption of which of the following causes blindness?

(A) Amphetamine

(B) Morphine

(D) Methanol

Answer: (D) Methanol

Explanation: As little as 10 mL of pure methanol when drunk is metabolized into formic acid, which can cause permanent blindness by destruction of the optic nerve. 15 mL is potentially fatal, although the median lethal dose is typically 100 mL (3.4 fl oz) (i.e. 1–2 mL/kg body weight of pure methanol).

Que 13. Methanol toxicity is due to the formation of which of the following?

(A) Formic acid due to the action of dehydrogenase enzyme in liver

(B) Formic acid due to the action of dehydrogenase enzyme in kidney

(D) Formic acid due to the action of protease enzyme in kidney

Answer: (A) Formic acid due to the action of dehydrogenase enzyme in liver

Explanation: As a clear, colourless, volatile liquid with a weak odour, methanol is difficult to differentiate from other forms of alcohols such as ethanol.4,5 Methaanol is rapidly absorbed not only after oral ingestion but by inhalation or after cutaneous exposure and becomes oxidised in the liver to formaldehyde and to formic acid, metabolites which are more toxic than methanol itself and which inhibit mitochondrial ATP production. Methanol poisoning can be life threatening and blinding. Early ocular symptoms and signs include photophobia, blurred vision, and painful eye movements as well as sluggish pupil reactions, reduced visual acuity, and optic disc oedema with tortuous retinal vessels. Histopathologically, circumscribed myelin damage behind the lamina cribrosa of the optic nerve has been reported.6 The electrophysiological changes following acute methanol ingestion suggest that methanol affects photoreceptors, Muller cells, and the retrolaminar portion of the optic nerve.7 Treatment is by drug elimination (for example, haemodialysis) and inhibition of metabolism of methanol to toxic formic acid by competitive inhibition of the enzyme alcohol dehydrogenase (ethyl alcohol or fomepizole

Que 14. Kozelaka and Hine method is used for the quantitative estimation of

(A) Formic acid due to the action of dehydrogenase enzyme in liver

(B) Opium

(D) Cannabis

Answer: (A) Formic acid due to the action of dehydrogenase enzyme in liver

Que 15. The following is a poisonous mushroom species:

(A) Amanita phalloides

(B) Morchellaesculenta

(D) Cantharelluscibarius

Answer: (A) Amanita phalloides

Explanation: Amanita phalloides (the death cap mushroom) contains the most deadly toxin (the amanita toxin) of all poisonous mushrooms. Reported mortality after ingestion of Amanita phalloides ranges from 25% to 50%.26 The lethal dose of amanita toxin is 0.1 mg/kg body weight and therefore severe poisoning can occur with as little as 5 to 7 mg of amanita toxin, an amount that can be present in a single mushroom.26 The amanita toxin is eliminated by the kidneys and usually is undetectable in the plasma 48 hours after ingestion.

Forensic Toxicology

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