Chapter 10

Assume this curve represents the portion of test animals developing tumors from exposure to groundwater contaminant. What dose causes cancer in 1% of the population?

0.0034 mg/Kg

What would you recommend as a maximum safe exposure level for this food preservative?

0.01 gm/Kg, because this is well below the lowest dose that results in measurable toxic effects.

Assume this curve is from a study evaluating mortality in an indicator species from exposure to an herbicide. What is the LD50?

0.04 mg/Kg

At what concentration does this contaminant have its smallest toxic effect?

0.05 microgram per Kg

Assume the curve in Step 5 is from a drug trial evaluating the effectiveness of a new medicine. What dose produces the desired effect in 95% of the population?

1.2 mg/Kg

In which of the following years was the sea surface temperature more than 1ºC above the average temperature? Select all that apply.

1983, 1987, 1997

In which of the following years did the incidence of cholera reach its lowest level?

1989

The dose at which 50% of a population exhibits a toxic response is called the TD50. What is the TD50 for this food preservative?

8 gm/Kg

Which of the following is most likely to have high nitrates in its water supply?

A community surrounded by agriculture.

Although the authors disagree on the effectiveness of our current "innocent until proven guilty" approach, they do agree on one impact of requiring more comprehensive toxicity testing. On which of the following impacts would both authors agree?

Additional testing is time-consuming and difficult and may be technically impossible.

Which of the following has contributed to longer life spans in the United States?

All of the listed responses are correct.

Why are scientists interested in the effects of environmental hazards on wildlife?

Animals can serve as an early warning to the damage of environmental toxins.

Based strictly on increases in air pollution over the past few decades, where would we expect to see the greatest decrease in life spans? We would expect to see a decrease in life span in __________.

Beijing, China

________ is/are biodegradable and known to have (a) short persistence time(s).

Bt

Sort the examples below into the appropriate bin. Think about which factors could lead to more toxic substances being released into the environment (causes), the consequences that result from toxic substances in the environment, and possible solutions.

Causes: - commercial production of many chemicals - massive use of chemicals in food, agriculture, medicine, and industry Consequences: - contamination of soil, air and water - increase in reproductive disorders - bioaccumulation and biomagnification of toxins in the food chain Solutions: - consumer choice of low-toxicity products - stricter regulations requiring that consumer products be thoroughly tested before being released to market

Of the following U.S. agencies, ________ is primarily responsible for addressing issues regarding mercury pollution.

EPA

After much investigation, is discovered to be a drinking water contaminant. Which of the following federal agencies is responsible for regulation?

Environmental Protection Agency

In comparison to Porter, Marian Stanley suggests that current screening processes are adequate. Based on her essay, what might Stanley say about Porter's criticisms of the current approach?

Initial chemical screening triggers higher-level testing if there are any adverse effects.

For the graph you created in Step 3, what type of dose-response curve is this?

J-curve

Warren Porter compares the costs and benefits of current industry testing practices. Which of the following statements does he include as a benefit of the current approach?

Leads to greater economic activity

Porter describes some limitations of the current "innocent until proven guilty" approach. Identify the statement below that represents a limitation.

Linear dose response does not necessarily measure hormonal and immune responses.

Managing environmental risks requires assessing the relative danger or risks and planning appropriately. As mortal creatures, we assess risks to our health and well-being on a regular basis. For example, of the following potential causes of human death (data from 2012), which posed the greatest danger to human life?

Motor vehicle accident

You live in a city and the drinking water is tested for lead. After analysis, 8% of the homes tested had lead levels above 15 ppb. Is your city required to notify you?

No.

For each description, decide which type of environmental hazard it best represents.

Physical hazard: - suffering injury during an earthquake - exposure to UV light during everyday activities Chemical hazard: - exposure to bisphenol A in drinking water - ingesting synthetic pesticides on food Biological hazard: - suffering nutritional deficiencies from an intestinal parasite - contracting influenza and becoming ill Cultural hazard: - inhalation of carcinogens when choosing to smoke cigarettes - exposure to excessive UV light when going to a tanning salon

If you were on a legislative panel to review the Toxic Substances Control Act (TSCA) and wished to include new requirements based on the Precautionary Principle, which of the following policies would you include?

Require low physiological dose testing.

For the graph you created in Step 4, what type of dose-response curve is this?

S-curve with threshold

________ are best defined as substances that cause birth defects.

Teratogens

Assume that the scales for graphs (a) and (b) are identical. Compare the graphs. Which of the following statements is true?

The toxicant shown in (b) has a lower toxicity than the toxicant shown in (a).

Which of the following statements is supported by the data in the graph?

There is a positive correlation between sea surface temperature and the incidence of cholera.

You live in a community with lead pipes, but the water always tests free of lead. Which of the following is your water provider most likely doing?

Treating the water with a chemical.

Assume you know that people drinking the groundwater would be exposed to concentrations of this contaminant less than 0.05 microgram per Kg. Which of the following statements represents the best judgment of the risks of this exposure?

Twenty percent or more of individuals can be expected to experience toxic effects at this level of exposure.

Which term describes a type of toxicant that overactivates the immune system?

allergen

Assume the toxic effect observed is decreased egg production in females. Given this information and the shape of the curve, what type of toxin is this likely to be?

an endocrine disruptor

On average, it appears that over the past 25 years, improved air quality in the United States has resulted in __________ in the lifespan of the average individual.

an increase of about five months

Figures such as these ________.

are used by scientists in risk assessment

The problems with the Puget Sound killer whale population have taught us to __________.

be very careful when adding new chemical compounds to natural environments

Mercury is not readily excreted; it is stored in mammalian body tissues. This is best described as ________.

bioaccumulation

Is this statement supported or not supported by the data on the graph? As global warming causes sea surface temperatures to increase in the future, the incidence of cholera in Bangladesh will also increase.

cannot be determined from the graph

Which of the following describes the greatest health risk posed by air pollution? Air pollutants __________.

damage blood vessels in human lung

How is the population of killer whales in the Puget Sound changing? The killer whale population is __________.

declining in animals of all ages

Louis Guillette is most famous for his studies ________.

describing reproductive and developmental abnormalities in alligators Florida lakes

Transport of airborne toxicants, a specific problem in agricultural environments, is called pesticide ________.

drift

The goal of the Stockholm Convention is to ________.

end the use and release of 12 POPs shown to be the most dangerous

The graph in (c) is one type that may occur when a test animal is exposed to a(n) ________.

endocrine disruptor

The book Our Stolen Future was important because it ________.

focused on the impacts of endocrine-disrupting chemicals on humans

What value of LD50 indicates low toxicity?

high

Based on the health problems of Puget Sound killer whales, we would expect to find __________.

high levels of polychlorinated biphenyls in salmon in the Puget Sound

What does the red graph line represent?

incidence of cholera

The Toxic Substances Control Act regulates ________.

industrial chemicals

Based on the description of its effect, can you identify the type of toxicant?

look at site

Can you identify the steps in the scientific method that correspond to Hunt's experiments?

look at site

Drag the labels to identify the components of Hunt's experiment. Labels may be used once, more than once, or not at all.

look at site

Drag the terms on the left to the appropriate blanks on the right to complete the sentences.

look at site

Drag the terms on the left to the appropriate blanks on the right.

look at site

Drag type of experiment on the left to the example of experiment on the right.

look at site

Place the steps leading from birth control pills to frog population declines in order.

look at site

Studies of endocrine disruptors have shown that they are closely associated with all of the following except ________.

lung cancer

Aquatic animals such as fish and frogs are especially good indicators of water pollution because ________.

most chemicals are water soluble so they enter these organisms through drinking or skin absorption

Infectious disease accounts for ________% of deaths globally.

nearly 25

Properties of toxicants likely to build up in animals through bioaccumulation are ________.

non-biodegradable, lipid-soluble

Synergistic effects of toxicants that are mixed together ________.

often are multiplicative (the mixed toxicants may multiply each other's effects)

Toxicants that interrupt essential biochemical processes in organisms by blocking one or steps in important biochemical reactions are known as ________.

pathway inhibitors

Which of the following contaminants appears poised to be next to be fully regulated?

perchlorate

Rachel Carson's book Silent Spring primarily focuses on the environmental problems associated with ________.

pesticide toxicity

Living on a fault line that is prone to earthquakes is an example of a __________ hazard.

physical

Risk is determined using the statistical description called __________, which helps us to determine the likelihood of a certain event occurring.

probability

What does the left y-axis show?

sea surface temperature anomaly, in degrees Celsius

The health problems of Puget Sound killer whales include __________.

symptoms similar to AIDS

Nicotine and alcohol have been shown to be harmful to a fetus in the womb in that they can lead to birth defects. Nicotine and alcohol are, therefore, potential __________.

teratogens

The bald eagle, osprey, and peregrine falcon all are ________.

top consumers susceptible to eggshell damage caused by DDT

An organism, such as a mosquito, that transmits a disease-causing organism to a host is called a ________.

vector