Toxic Elements

1. The occurrence of cell membrane damage causing normal cells to be replaced with fibroblasts occurs in the heart because of a deficiency of which one of the following metals?

a. Selenium

b. Chromium

c. Silica

d. Copper

ANS: A

In humans, cardiac muscle is the tissue most susceptible to Se deficiency; with cell membrane damage,

normal cells are replaced with fibroblasts. This condition, known as cardiomyopathy, is characterized by

an enlarged heart consisting of predominantly nonfunctioning fibrotic tissue.

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2. In blood collection for chromium or other trace metal analysis, what aspect of specimen collection is critical?

a. Timing of the blood draw, whether morning or afternoon

b. Use of serum and not plasma

c. Using specially manufactured collection tubes with unique stoppers

d. Using a special tourniquet that does not cause hemolysis

ANS: C

Preanalytical handling of the specimen for chromium (Cr) analysis is critically important. Many specimen

collection products contain Cr in the rubber stopper or O-rings to add plasticity to the rubber. Special

rubber was created to manufacture evacuated blood collection tubes suitable for use in trace metal testing.

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3. What blood analyte does a toxic overdose of aluminum affect?

a. Acid phosphatase

b. Vitamin C (ascorbic acid)

c. Lactate dehydrogenase

d. Parathyroid hormone

ANS: D

Deposition of aluminum at the bone mineralization front and binding to parathyroid calcium receptors

interrupts physiological calcium exchange; the calcium in bone becomes unavailable for resorption into

blood, a process under the physiological control of parathyroid hormone (PTH). The usual parathyroid

response to these conditions decreases secretion of PTH.

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4. An individual is admitted to the hospital with markedly increased liver enzymes (transferases) and unusual behavioral changes noted by her family. A protein electrophoresis reveals decreased ceruloplasmin. Which one of the following toxic metals might be implicated in this individual's

symptoms?

a. Beryllium

b. Copper

c. Aluminum

d. Lead

ANS: B

The classical presentation of copper (Cu) toxicosis is represented by the genetic disease of Cu

accumulation known as Wilson disease. This disease is typified by hepatocellular damage (increased

transferases) and/or changes in mood and behavior caused by accumulation of Cu in central neurons.

Because most Cu circulating in blood is bound to ceruloplasmin, and ceruloplasmin formation is

decreased in Wilson disease, blood copper is less than normal.

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5. A byproduct of zinc and lead smelting, this metal is also used in the production of rechargeable batteries. Chronic exposure to this metal results in renal damage and breathing its fumes causes pulmonary congestion resembling chronic emphysema.

a. Beryllium

b. Copper

c. Cadmium

d. Aluminum

ANS: C

Cd is a byproduct of zinc and lead smelting. It is used (1) in industry in electroplating, (2) in the

production of rechargeable batteries, (3) as a common pigment in organic-based paints, and (4) in tobacco

products. Chronic exposure to Cd causes accumulated renal damage, while breathing the fumes of Cd

vapors leads to nasal epithelial deterioration and pulmonary congestion resembling chronic emphysema.

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6. Which one of the following is a toxic metal that produces Mees' lines upon overdose exposure by denaturing keratin in fingernails?

a. Aluminum

b. Arsenic

c. Chromium

d. Gadolinium

ANS: B

Several weeks after exposure to As, transverse white striae, called Mees' lines, may appear in the

fingernails of the exposed individual caused by denaturation of keratin by metals such as As, Cd, Pb, and

Hg.

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7. Lead produces a serious toxic effect when ingested because it:

a. irreversibly binds to heme iron in hemoglobin.

b. vasoconstricts cardiac blood vessels and vasodilates peripheral vessels.

c. depresses the central nervous system and induces coma.

d. does not allow for the incorporation of heme into the porphyrin molecule.

ANS: D

Lead inhibits aminolevulinic acid dehydratase (ALAD), one of the enzymes that catalyze synthesis of

heme from porphyrin. ALAD is also referred to as ferrochelatase and is important in incorporating heme

into protoporphyrin.

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8. What is the specimen of choice for determining arsenic exposure in an individual and why?

a. Urine is the specimen of choice because arsenic is concentrated in and excreted predominantly by kidneys.

b. Whole blood is the specimen of choice because blood concentrations remain elevated for at least 48 hours after exposure.

c. Serum is the specimen of choice because arsenic moves into the serum phosphate pool and is easily measured with phosphate.

d. Plasma is the specimen of choice because arsenic attaches to coagulation factors and affects clotting times best assayed in a plasma sample.

ANS: A

Urine is the specimen of choice for As analysis because As is excreted predominantly by the kidney,

where it becomes concentrated. Blood is the least useful specimen for identifying As exposure because

blood As concentrations are elevated for only a short time after administration and rapidly disappear into

the large body phosphate pool.

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9. Both mercury and arsenic produce their symptoms of toxicity in a similar way. This includes:

a. deposition in bone causing interruption of physiological calcium exchange.

b. strong acid formation when dissolved in water leading to tissue toxicity.

c. binding to the sulfhydryl groups of protein causing loss of protein activity.

d. formation of protein adducts leading to protein denaturation in alveoli.

ANS: C

Arsenic also binds with any hydrated sulfhydryl group on protein, distorting the three-dimensional

configuration of the protein, thus causing it to lose activity. Mercury avidly reacts with sulfhydryl groups

of protein, causing a change in the tertiary structure of the protein with subsequent loss of the biological

activity associated with that protein.

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10. A four-member family of fish-loving vegetarians has become ill and visits their family practitioner. Their symptoms include stumbling (ataxia), visual field loss, and urinary difficulties. No Mees' lines are observed. Being environmentally conscious, they have their home examined for toxic gases. All tests are negative. Based on their history and symptoms, what toxic metal

might be to blame?

a. Cadmium

b. Iron

c. Arsenic

d. Mercury

ANS: D

The symptoms listed here, including ataxia, vision problems, and renal failure, all indicate possible

methylmercury poisoning. The most common source of mercury in the diet is through the aquatic food

chain, and humans are exposed to mercury through eating contaminated fish.

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11. A four-member family of vegetarians has become ill and visits their family practitioner. Their symptoms include stumbling (ataxia), visual field loss, and urinary difficulties. No Mees' lines are observed. Based on their symptoms and knowledge of the correct metal involved, what is the best therapy?

a. British anti-Lewisite (BAL)

b. Erythropoietin

c. Chelation therapy

d. Keratin

ANS: A

Treatment with BAL or penicillamine will mobilize mercury, allowing for its excretion in the urine.

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12. All of the following factors must be demonstrated before metal toxicity is considered a diagnosis except:

a. A source of metal exposure must be evident.

b. More than two organ systems must be affected.

c. Typical metal overdose signs and symptoms must be shown.

d. Abnormal metal concentration in the appropriate tissue must be evident.

ANS: B

The number of organ systems affected is not a critical consideration in this case. Diagnosis of metal

toxicity requires demonstration of all of the following factors: (1) a source of metal exposure must be

evident, (2) the patient must demonstrate signs and symptoms typical of the metal, and (3) abnormal

metal concentration in the appropriate tissue must be evident.

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13. When reporting the results of a urine metal analysis, such as urine chromium, how are the results reported?

a. In millimoles of drug per liter of urine per 24 hours

b. As micrograms of metal per milliliter of urine in a random specimen

c. In concentration units of the metal of interest per gram of creatinine

d. As milligrams of metal/deciliter of urine

ANS: C

The most common sample used is a random urine sample, and results are expressed in concentration units

for the metal of interest per gram of creatinine to normalize for excretion volume variances.

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14. Certain metals are essential for life at low concentrations and typically function as protein cofactors required for enzymatic reactions. These particular elements are located in which group(s) and row(s) of the periodic table?

a. Groups 6 through 12, row 4

b. Groups 1 and 2, rows 3 and 4

c. Group 1, row 5

d. Groups 13 through 16, rows 4 through 6

ANS: A

Elements in groups 6 through 12 in row 4 are essential for life but are required at low concentrations;

many are protein cofactors required for enzymatic activity. The gastrointestinal tract and the dermis

regulate intake of these to some degree, but overload will induce passive diffusion that can lead to

excessive concentrations and toxicity. Elements in rows 5 and below are classified as nonessential.

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Which of the following is NOT a condition that involves Aluminum toxicity?

a. Dialysis

b. dementia

c. Cardiac arrythmia

d. encephalopathy

c. Cardiac arrythmia

Which of the following is a condition that involves Thallium toxicity

a. Cardiac arrythmia

b. Acute Hair loss

c. Water retention

d. Wilson's Disease

b. Acute Hair loss

Trivalent Antimony is concentrated in red blood cells and the liver, whereas the pentavalent state predominates in the ?

a. Serum

b. White Blood Cells

c. Kidneys

d. Liver only

a. Serum

Which of the following is NOT a toxic form of Arsenic?

a. Arsenate

b. monomethylarsonic acid

c. DMA

d. aresenocholine

d. aresenocholine

Urine B2-Microglobulin is used in the Occupational exposure monitoring of which Toxic Element?

a. Chromium

b. Cobalt

c. Cadmium

d. Copper

c. Cadmium

Which form of Chromium is insoluble and does not readily cross membranes?

a. Cr(3+)

b. Cr(6+)

c. Cr(2+)

d. Cr+

a. Cr(3+)

Which of the following is NOT a mechanism of Cobalt toxicity?

a. binding of sulfhydryl groups

b. disruption of intracellular calcium homeostasis

c. generation of reactive oxygen species

d. oxidative phosphorylation

d. oxidative phosphorylation

Lead avidly forms covalent bonds with the sulfhydryl group of cysteines in proteins. True or false?

a. true

b. false

a. true

The World Health Organization has defined blood Lead concentrations greater than ?? in adults as indicative of significant exposure.

a. 20 ug/dL

b. 100 ug/dL

c. 30 ug/dL

d. 1 ug/dL

c. 30 ug/dL

If ICP-MS is used to measure Lead concentrations, it is essential to sum which three masses to account for the natural isotopic variation of Lead in the environment.

a. 206, 207 and 209 m/z

b. 206, 207 and 208 m/z

c. 208, 209 and 210 m/z

d. 206, 209 and 210 m/z

b. 206, 207 and 208 m/z

What toxic element was formerly used in rodent poisons?

a. Cadmium

b. Nickel

c. Thallium

d. Mercury

c. Thallium

Atomic Absorption is an optical technique in which an ion in the sample is converted to a __________ ____________ atom of that element by a flame or graphite furnace and introduced into the light of a spectrophotometer? (fill in missing gaps)

a. ground state

b. energized state

c. vacuum state

d. polarized state

a. ground state

In Mass Spectrometry What kind of ion is formed when a molecular ion breaks into smaller pieces?

a. Positive ion

b. Fragment ion

c. Parent ion

d. negative ion

a. Positive ion

Which Toxic Element has been implicated in Alzheimer's disease?

a. Aluminum

b. Mercury

c. Cobalt

d. Lead

a. Aluminum

Which Toxic Element is currently used to treat parasitic disease?

a. Aluminum

b. Cobalt

c. Antimony

d. Thallium

c. Antimony

Which of the following could account for drug toxicity following a prescribed dose?

a. Decreased renal elimination leading to increased free drug concentration

b. Using a single drug as opposed to multiple drugs for treatment

c. Using a different route administration than is typically used for that drug

d. Increased drug metabolism caused by central nervous system disease

a. Decreased renal elimination leading to increased free drug concentration

Aluminum, arsenic, lead, molybdenum and manganese are most often measured using:

A. GC-MS

B. ICP-MS

C. LC-MS

D. TOF-MS

B. ICP-MS

Samples for trace element analysis can easily be contaminated by the environment.

A. True

B. False

A. True

Matrix-assisted laser desorption ionization time-of-flight is a useful tool in the identification of microbial fingerprints.

a. True

b. False

a. True

High-resolution mass spectrometry is capable of identifying molecules of less than 0.0001 dalton mass.

A. True

B. False

A. True

In ion-exchange chromatography, solute mixtures are separated by virtue of the:

a. Partition coefficient between the two liquids

b. Steric exclusion based on pore sizes of the column

c. Magnitude and charge of ionic species

d. Hydrophilic beads of cross-linked dextran

c. Magnitude and charge of ionic species

In the clinical toxicology laboratory, it is common to use .............. to measure drugs of abuse.

a. Atomic absorption

b. Thin-layer chromatography

c. Electrophoresis

d. Gas chromatography coupled mass spectrometer

d. Gas chromatography coupled mass spectrometer

The soft ionization technique that uses a UV-absorbing compound upon which the analyte of interest is placed and eventually vaporized into a plume of ions directed into the mass analyzer is:

a. inductively coupled plasma ionization.

b. electrospray ionization

c. atmospheric pressure photoionization.

d. matrix-assisted laser desorption ionization.

d. matrix-assisted laser desorption ionization.

In which one of the following mass spectrometers does the fragmentation of ions take place after they have been separated by their m/z (mass/charge) value in a first stage?

a. In a mass spectrometer interfaced with a gas chromatograph

b. In a quadrupole-trapping spectrometer

c. In a tandem mass spectrometer

d. In an inductively coupled plasma mass spectrometer

c. In a tandem mass spectrometer

An individual has eaten a large meal of seafood including shellfish and haddock before submitting a urine specimen for metal analysis. What metal would likely be present in a high concentration in his urine specimen?

A. arsenic

B. copper

C. mercury

D. cadmium

A. arsenic

Lead inhibits ________, an enzyme that catalyzes synthesis of heme from porphyrin

A. ATPase

B. RNA polymerase

C. glutathione peroxidase

D. aminolevulinic acid dehydrogenase

D. aminolevulinic acid dehydrogenase

Which of the following reasons best explains why elemental toxicity is difficult to diagnose?

A. physicians are poorly informed about prevalence of toxic elements

B. laboratories are unable to properly test for toxic elements

C. signs and symptoms in elemental toxicity mirror numerous disease states

D. elemental toxicity is relatively rare in developed countries

C. signs and symptoms in elemental toxicity mirror numerous disease states

Analysis of toxic elements is recommended in which of the following presentations?

A. renal disease due to chronic hypertension

B. unexplained, bilateral neuropathy

C. chronic inflammation of the liver

D. no history of exposure on record

B. unexplained, bilateral neuropathy

Which of the following correctly identifies an accepted approach to elemental exposure?

A. wait and see if symptoms become more severe

B. prospective chelation challenges with postchelation laboratory assessments

C. enhanced absorption

D. antidotal treatment

D. antidotal treatment

The toxicity of Cd, As, Hg, and Pb are similar in regard to damage of which organ?

A. eye

B. kidney

C. pancreas

D. distal phalanges

B. kidney

Which element in its hexavalent state is toxic while in its trivalent state is considered largely benign?

A. Cr

B. Hg

C. Pb

D. As

A. Cr

Which element in its elemental state is largely benign unless inhaled while its inorganic form is the basis for the phrase "mad as a hatter"?

A. As

B. Cr

C. Pb

D. Hg

D. Hg

Regarding Ni exposure, _______ Ni compounds are more rapidly absorbed and eliminated compared to the ________ forms

A. soluble, gaseous

B. insoluble, soluble

C. soluble, less soluble

D. alloyed, pure

C. soluble, less soluble

The measurement of biological samples from a worker for elements found in a workplace following occupational exposure assesses which of the following?

A. the air concentration of the measured element

B. the nutritional status of the worker

C. the worker's ability to schedule time off

D. the effectiveness of environmental control strategies used in the workplace

D. the effectiveness of environmental control strategies used in the workplace

Which of the following metals at serum level of >60 ug/L interrupts normal calcium exchange in bone and leads to osteomalacia?

A. Copper

B. Aluminum

C. Lead

D. Beryllium

B. Aluminum