EVR 1001 Ch. 10

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?

1983

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

1989

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

A community surrounded by agriculture.

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

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

Louis Guillette is most famous for his studies ________.

Describing reproductive and developmental abnormalities in alligators Florida lakes

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

EPA

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

Infectious disease accounts for ________% of deaths globally.

Nearly 25

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

Pathway inhibitors

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

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

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

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

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

damage blood vessels in human lungs

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

declining in animals of all ages

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

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

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

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

non-biodegradable, lipid-soluble

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?

not " Linear dose response has served as an effective tool for chemical testing.OR "The chemical industry can test actual products—not just active ingredients—when needed."

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?

not 0.0018 mg/Kg

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

not 0.3 gm/Kg, because this is the first point where the curve rises above the X-axis.

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

not 5 gm/Kg

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?

not Additional testing is unnecessary because no single comprehensive program is appropriate for all industrial chemicals. OR "The cost of additional testing is prohibitive."

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

not Department of Health and Human Services OR Food and Drug Administration

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

not Graphs (a) and (b) show results for the same toxicant, but graph (a) shows a higher dose than graph (b). OR "Graphs (a) and (b) show results for the same toxicant, but graph (b) shows a higher dose than graph (a)."

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

not S-curve with threshold

Figures such as these ________.

not represent typical dose-response curves for endocrine disruptors OR "allow scientists to determine the exact quantity of a toxicant that will harm humans"

Synergistic effects of toxicants that are mixed together ________.

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

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

perchlorate

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