Mercury in Fish Mercury Is a Highly Toxic Metal Found in Neon Signs

question 163

Multiple Choice

Mercury in Fish
Mercury is a highly toxic metal found in neon signs, fluorescent lights, older thermometers, and certain kinds of telescopes. It can also be found in something that many people eat on a regular basis: fish. The mercury we might find in a can of tuna is most likely an indirect result of the coal industry. Mercury, which is naturally found in coal, is released into the air when coal is burned. It finds its way into waterways via mercury-laced rain.
Mercury accumulates in certain kinds of fish through a process called biomagnification. Biomagnification occurs when a substance enters the food chain in small amounts at the very bottom and then increases in concentration in animals higher up on the food chain. Once a fish eats another creature containing mercury, the mercury does not leave that fish's body but instead is stored in fat. Therefore, the mercury continually accumulates as more mercury-contaminated fish are eaten.
Despite the toxicity of mercury and the widespread nature of fish contamination, there is no need for the public to be overly apprehensive. Many popular fish, such as salmon, catfish, or tilapia, are generally safe to eat. Other fish, especially tuna and grouper, should only be eaten in moderation. Young children and pregnant women should be especially cautious about how many servings of mercury-contaminated fish they have per week. It is recommended that people in these groups not eat more than 2 servings of mercury-contaminated fish per week. Fish with the highest levels of mercury include shark, swordfish, and king mackerel. All people should avoid eating large amounts of these kinds of fish, and no one should eat these fish more frequently than once a month.
Why does the author include the detail regarding the coal industry in the first paragraph?

• A)To state an opinion regarding the unethical practices of the coal industry.
• B)To introduce the explanation of biomagnification.
• C)To explain the direct reasoning behind mercury's presence in waterways.
• D)To provide factual information regarding mercury's presence in the air.

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Definitions:

Diffusion

The process by which molecules intermingle as a result of their kinetic energy of random motion, leading to a net movement from a region of higher concentration to one of lower concentration.

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The resistance of the peripheral blood vessels, which impacts blood pressure and flow throughout the body.

Cardiac Output

The volume of blood the heart pumps through the circulatory system in one minute, a critical measure of heart function efficiency.

Blood Viscosity

A measure of the thickness and stickiness of an individual's blood, influencing how easily blood flows through the vessels.