Heavy metals and toxicology

Question 1

What are the general properties of metals?

Answer 1

High reflectivity (luster), high electrical conductivity, high thermal conductivity, mechanical ductility and strength.

Question 2

What characteristic of metals is significant in toxicology?

Answer 2

Metals exhibit variable oxidation states and may react in biological systems by losing one or more electrons to form cations.

Question 3

What is the primary way metals are redistributed in the environment?

Answer 3

By geological and biological cycles.

Question 4

List the main routes of human exposure to metals.

Answer 4

• Oral ingestion
• Inhalation
• Dermal contact

Question 5

What is the main source of oral ingestion of naturally occurring metals?

Answer 5

Drinking water drawn from contaminated groundwater sources and food.

Question 6

What factors influence dermal exposure to metals?

Answer 6

• Dose
• Vehicle
• Molecular volume
• Counter ion
• Valence
• Protein reactivity
• Tissue deposition
• Solubility
• pH

Question 7

What is the role of metal transporters in the body?

Answer 7

They regulate metal ion homeostasis and transport metals into cells.

Question 8

Fill in the blank: Metals are excreted through _______.

Answer 8

[fecal, biliary, urinary elimination, sweat, storage in hair and nails]

Question 9

What are exposure biomarkers for metals?

Answer 9

Concentrations in blood, urine, nails, and hair.

Question 10

What is a critical indicator of metal retention in the body?

Answer 10

Biological half-life.

Question 11

What is one mechanism by which toxic metals disrupt normal function?

Answer 11

Binding of inappropriate toxic metals in enzymes.

Question 12

What role do reactive oxygen species (ROS) play in metal toxicity?

Answer 12

They can damage macromolecules such as proteins and DNA.

Question 13

What factors impact metal toxicity?

Answer 13

• Dose
• Route of exposure
• Duration
• Frequency of exposure
• Age at exposure
• Gender
• Capacity for biotransformation

Question 14

What are some signaling pathways affected by metal exposure?

Answer 14

• MAPK cascades
• Src family kinases
• AP-1
• NF-κB
• MTF-1
• Nrf2
• HIF-1α and HIF-2α
• STAT family

Question 14

What metals are linked to cancer through epigenetic changes?

Answer 14

• Nickel
• Cadmium
• Arsenic
• Chromium

Question 15

List the exposure-related factors that impact metal toxicity.

Answer 15

• Dose
• Route of exposure
• Duration
• Frequency of exposure

Question 16

What host-based factors can impact metal toxicity?

Answer 16

• Age at exposure
• Gender
• Capacity for biotransformation

Question 17

What lifestyle factors can influence metal intoxication levels?

Answer 17

• Smoking
• Alcohol ingestion

Question 18

What are some examples of medicinal metals used in therapy?

Answer 18

• Aluminum
• Bismuth
• Lithium
• Gold

Question 19

What is the primary route of occupational exposure to arsenic?

Answer 19

Manufacture of pesticides, herbicides, and other agricultural products.

Question 20

How is inorganic arsenic absorbed and excreted in the body?

Answer 20

Well absorbed (80% to 90%) from the gastrointestinal tract and excreted primarily in urine.

Question 21

What are the acute symptoms of arsenic poisoning?

Answer 21

• Fever
• Anorexia
• Hepatomegaly
• Melanosis
• Cardiac arrhythmia
• Terminal cardiac failure

Question 22

What is the half-life of cadmium in humans?

Answer 22

More than 26 years.

Question 23

How does arsenic induce carcinogenic effects?

Answer 23

By inducing chromosomal abnormalities and inhibiting DNA repair mechanisms.

Question 24

What is the main source of lead in the environment?

Answer 24

Human activity ## Footnote Lead is not biodegradable and poses ecotoxicity concerns.

Question 25

What are the primary sources of lead exposure for children?

Answer 25

Lead-containing paint, household dust, soil ## Footnote Hand-to-mouth transfer is a major route for infants.

Question 26

What form of mercury is more hazardous, liquid or vapor?

Answer 26

Vapor ## Footnote Mercury vapor is readily absorbed and poses significant health risks.

Question 27

What happens to mercury vapor once it enters the body?

Answer 27

It is oxidized to divalent inorganic mercury and distributed to all tissues ## Footnote A significant portion crosses the blood–brain barrier.

Question 28

What is the primary route of excretion for converted inorganic mercury?

Answer 28

Mainly in urine and feces ## Footnote Approximately 10% of mercury vapor is exhaled within a week.

Question 29

What is nickel primarily used for?

Answer 29

Metal alloys, electroplating, batteries, pigments, catalysts, and ceramics ## Footnote Nickel is widely used in various industries.

Question 30

How is nickel absorbed in the body?

Answer 30

About 25% to 35% of inhaled nickel is absorbed into the blood ## Footnote Intestinal absorption occurs through calcium or iron channels.

Question 31

What are the metals generally accepted as essential?

Answer 31

Cobalt, copper, iron, magnesium, manganese, molybdenum, selenium, zinc ## Footnote These metals can produce target organ toxicity.

Question 32

What is cobalt's role in human health?

Answer 32

Cobalt is essential as a metal cofactor in vitamin B12 ## Footnote It is critical for red blood cell production and the prevention of pernicious anemia.

Question 33

What are the essential roles of copper in the body?

Answer 33

Components of cytochrome c oxidase, lysyl oxidase, copper/zinc superoxide dismutase ## Footnote Disruption can lead to severe health consequences.

Question 34

What is the primary function of iron in the body?

Answer 34

Essential for erythropoiesis and a key component of hemoglobin ## Footnote Iron exists in ferrous (2+) and ferric (3+) forms.

Question 35

How is iron absorbed in the gastrointestinal tract?

Answer 35

Through divalent metal transporter protein 1 (DMT1) ## Footnote Iron is either stored in ferritin or exported into the portal circulation.

Question 36

What is hereditary hemochromatosis?

Answer 36

A condition of excessive iron absorption due to hepcidin insufficiency ## Footnote Leads to iron deposition in organs and various health complications.

Question 37

What is magnesium's role in the body?

Answer 37

A cofactor for many enzymes involved in fundamental cellular reactions ## Footnote Important for glycolysis, citric acid cycle, and energy metabolism.

Question 38

What is the significance of zinc in the body?

Answer 38

Involved in over 300 enzymatic reactions and essential for immune function ## Footnote Zinc is vital for growth and development.

Question 39

What are the main sources of human exposure to aluminum?

Answer 39

Food and drinking water ## Footnote Occupational exposure occurs during mining, processing, and welding.

Question 40

What are the major target organs for aluminum toxicity?

Answer 40

Lung, bone, and central nervous system ## Footnote Most cases of aluminum toxicity are found in patients with chronic renal failure.

Question 41

How does aluminum relate to Alzheimer disease?

Answer 41

Associated with pathological lesions in brain tissue ## Footnote Elevated aluminum levels may be a consequence of the disease rather than a cause.

Question 42

What is the primary use of lithium in medicine?

Answer 42

Treatment for mania and bipolar disorders ## Footnote Lithium carbonate and lithium citrate are commonly used.

Question 43

What is the main route of lithium excretion?

Answer 43

Kidneys ## Footnote 80% of filtered lithium is reabsorbed.