24 Questions
What is the main difference in the toxicity of arsenic compounds?
All of the above
What is a common way that humans are exposed to arsenic?
All of the above
What is a symptom of arsenic toxicity?
All of the above
In what forms is arsenic found in the environment?
Both inorganic and organic compounds
What is a possible effect of long-term exposure to arsenic?
Kidney failure
How does the rate of vaporization of metallic mercury change with temperature?
It increases with higher temperatures
What is the main form of mercury used in thermometers?
Metallic or elemental form
Which of the following is NOT a nonessential metal?
Manganese
What is the basis for the effectiveness of pesticides and drugs?
The selectivity of toxicity
Why are antibiotics selectively toxic to microorganisms?
Because antibiotics target specific biological processes
What is an example of antagonism in toxicology?
Atropine counteracting poisoning by organophosphate insecticides
What is an essential metal that is necessary for the production of red blood cells?
Cobalt
What is an example of synergism in toxicology?
Alcohol enhancing the effect of antihistamines
Why may age be important in determining the response to toxicants?
Because some chemicals are more toxic to infants or the elderly than to young adults
What is the main pathway of exposure to metals?
Direct and indirect pathways
What is the reason why some metals are considered essential for good health?
Because they have important biological roles
What is the definition of toxic?
Having the characteristic of producing an adverse health effect
What is the term for the total amount of a toxicant administered to an organism at specific time intervals?
Dose
What is the term for the adverse effect that a chemical or physical agent might produce within a living organism?
Toxicity
What is the term for the substance that causes a harmful effect when in contact with a living organism at a sufficiently high concentration?
Toxicant
What is the term for the amount of toxicant reaching the organ that is adversely affected by the toxicant?
Target organ dose
What is the term for the means by which an organism comes in contact with the substance?
Exposure
What type of exposure occurs over a brief period of time, generally less than 24 hours?
Acute exposure
What is the term for the science that deals with the study of the adverse effects that chemicals or physical agents may produce in living organisms under specific conditions of exposure?
Toxicology
Study Notes
Essential and Nonessential Metals
- Magnesium, manganese, and molybdenum are cofactors for enzymatic reactions.
- Nonessential metals have no known beneficial role in biological function, including beryllium, cadmium, lead, mercury, thallium, titanium, and uranium.
Toxicology of Selected Metals
Arsenic
- Arsenic is a gray-colored metal found in the environment in both organic and inorganic compounds.
- Inorganic arsenic occurs naturally in many kinds of rock.
- Arsenic is used in herbicides and insecticides.
- The toxicity of arsenic compounds is extremely variable and depends on the animal species, form of arsenic, route of exposure, and rate and duration of exposure.
- Symptoms of toxicity include nausea, vomiting, abdominal pain, diarrhea, garlic odor on breath, headache, vertigo, fatigue, paresthesia, paralysis, and kidney failure.
Mercury
- Mercury is found in the environment in metallic or elemental form, as inorganic compounds, or as organic mercury compounds.
- Mercury metal is used in thermometers and electrical switches.
- Mercury can combine with other elements to form inorganic and organic compounds, which is the basis for the effectiveness of pesticides and drugs.
Factors Affecting Toxicity
- Age may be important in determining the response to toxicants.
- Sex may be a factor, with male rats being 10 times more sensitive to liver damage from DDT than females, and female rats being twice as sensitive to parathion as males.
- The presence of other chemicals may decrease (antagonism) or increase (synergism) toxicity.
Metal Toxicity
- Metals are extensively used in commercial and industrial applications, leading to exposure through direct and indirect pathways.
- Smelting, welding, grinding, soldering, printing, and product manufacturing operations may lead to metal exposure.
Classification of Metals
- Essential metals have important biological roles and are necessary for good health, but can be toxic at high concentrations.
- Examples of essential metals include cobalt, copper, and iron.
Basic Definitions
- Toxic: having the characteristic of producing an adverse health effect.
- Toxicity: any toxic effect that a chemical or physical agent may produce in a living organism.
- Toxicant: any substance that causes a harmful effect when in contact with a living organism at a sufficiently high concentration.
- Dose: the total amount of a toxicant administered to an organism at specific time intervals.
- Target organ dose: the amount of toxicant reaching the organ that is adversely affected by the toxicant.
- Exposure: the means by which an organism comes in contact with a substance, including through air, water, soil, food, or medication.
- Acute exposure: exposure over a brief period of time (generally less than 24 hours).
Learn about the effects of various metals on biological systems, including essential and non-essential metals, their roles, and toxicity.
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