Midterm 1

Question 1

Natural compounds are not toxic.

Answer 1

false

Question 2

Socrates was executed by poisoning.

Answer 2

true

Question 3

Pharmaceuticals can be environmental pollutants.

Answer 3

true

Question 4

The Geneva Convention aims to reduce global mercury pollution.

Answer 4

false

Question 5

The units of fugacity are grams.

Answer 5

false

Question 6

Pollution causes more deaths than AIDS, malaria, and tuberculosis combined.

Answer 6

true

Question 7

One million Americans die prematurely due to pollution each year.

Answer 7

false

Question 8

A compound can be either toxic or nontoxic depending on the dosage.

Answer 8

true

Question 9

Home water filters typically rely on the Kow of carbon to be effective.

Answer 9

false

Question 10

Bioaccumulation does not require input of energy from the organism.

Answer 10

false

Question 11

Georg Ebers was: -an Egyptologist -a Swiss physician -a Roman poisoner -a chemist -an editor at Nature

Answer 11

an Egyptologist

Question 12

You have carefully extracted and concentrated pollutants from a water sample for analysis in the lab. You know that the concentrated samples could be unstable because you have increased their: -hydrophobicity -log Kow -log Koc -fugacity -BCF

Answer 12

fugacity

Question 13

Which of the following wavelengths of light is most likely to break down pollutants? -400 nm -500 nm -600 nm -700 nm -none of the above

Answer 13

400 nm (UV light)

Question 14

Your sister, the know-it-all physician, calls you to lament that the cancer drugs they use do not get into tumors and kill them. Having taken my class, you know that this is because: -there are biological mechanisms that limit accumulation. -they are not hydrophobic. -they have a low Kow, so they do not bioconcentrate. -Miss Know-it-All is not very good at administering drugs correctly. -they are so hydrophobic that they stick to the syringe.

Answer 14

there are biological mechanisms that limit accumulation

Question 15

There has been a pollutant spill at SIO pier, into the water. The University has contacted you for recommendations on how to rapidly reduce its toxicity. Which of the following pieces of data do you need to know to determine if the compound will concentrate in fish? -Koc -Kow -Kos -Kcl

Answer 15

Kow

Question 16

What are the breakdown products of DDT?

Answer 16

DDE and DDD

Question 17

What chemical property are we interested in when using Henry’s constant? -Volatility -Photostability -Dissolution -Adsorption

Answer 17

volatility

Question 18

What is the major source of alkaloids?

Answer 18

plants

Question 19

Bioconcentration involves what fundamental process discussed in the reading “Contaminant amplification in the environment”? -solvent depletion -solvent rotovaping -solvent switching

Answer 19

solvent switching

Question 20

Mercury exposure in Americans is most commonly caused from consumption of what? -shrimp -salmon -tuna -soybeans

Answer 20

tuna

Question 21

Where does methylation of inorganic mercury occur in the ocean? -all of the above -the water column -anoxic sediments -oxic sediments

Answer 21

anoxic sediments

Question 22

Carpets advertising strong stain resistance are commonly coated in what type of compound? -perfluorochemicals -neonicotinoids -polybrominated diphenyl ethers -phthalates

Answer 22

perfluorochemicals

Question 23

Paracelsus is best known for?

Answer 23

dose makes the poison

Question 24

The solubility of a compound in octanol is most directly related to its: -Koc -fugacity -BCF -Ks -concentration in water

Answer 24

BCF

Question 25

What is the major cause of pollution related human death? -Oil spills -Water pollution -Food pollution -Air pollution

Answer 25

air pollution

Question 26

Which compounds above are most likely to be persistent? Why?

Answer 26

Compounds A and C are the most likely to be persistent. They contain Chlorine and Bromine, both of which decrease the volatility of the compound and increase the lipophilicity. As such, they will persist in organisms better because they are less likely to leave the organism through reactions and more willing to stay in a lipid solvent.

Question 27

Which compound here is most useful for preventing malaria?

Answer 27

A

Question 28

Which compound here causes eggshell thinning?

Answer 28

A

Question 29

Which compound here is likely to be a flame retardant?

Answer 29

C

Question 30

Which compound here causes phocomelia (a birth defect)? What is the compound named?

Answer 30

Compound C, called Thalidomide, is known for causing a loss of limbs in children whose mothers took it while pregnant to combat morning sickness.

Question 31

Which compound here is likely to resistant to degradation in the environment? What makes it resistant?

Answer 31

Compound A, a PFC, has strong carbon-halogen bonds that are extremely hard to break down.

Question 32

Which compound here is likely to be found on a non-stick pan? Why is it non-stick?

Answer 32

Compound A, teflon, would likely be found on a non-stick pan. The fluorines make this chemical very stable by reducing the volatility, meaning other compounds cannot easily react to and stick to it. It is also polar, making it hydrophilic; this will repel the oils found in food and prevent sticking as well.

Question 33

Who are these people?

Answer 33

The woman on the left is Rachel Carson. She wrote Silent Spring, which detailed the decline of frog populations and discussed the fact that humanity is too willing to rush into widespread use of any new compound without testing it for safety first, advocating for better screening of potentially toxic chemicals. The man on the right is Thomas Jukes, who argued against Carson’s main points. He criticized her by saying that humanity would return to the Dark Ages if we were to follow the ideas of Carson.

Question 34

Which one of these two started their career as a fisheries biologist?

Answer 34

Rachel Carson

Question 35

Which one of these two was a professor at UC Berkeley?

Answer 35

Thomas Jukes

Question 36

Which one had a radio show?

Answer 36

Rachel Carson

Question 37

Which one wrote a weekly editorial at Nature?

Answer 37

Thomas Jukes

Question 38

There has been a chemical spill at La Jolla Shores. You have been asked to predict what will happen to the pollutants based on knowledge of their physical properties. Which of the three compounds is likely to be removed by your home water filter?

Answer 38

C

Question 39

Which two of the three are likely to passively concentrate/ accumulate in fish?

Answer 39

A & C

Question 40

Shortly after the spill compound A has been detected at equivalent concentrations in the fish and water. What do you think its relative fugacity is in the fish vs the water why?

Answer 40

It is likely that the fish has a lower fugacity than the water. In order for the two things to have the same concentration, large amounts of the chemical needs to be moving into the fish because of the size difference between the two. A higher fugacity in the water means the compound will be happier moving into the fish and staying there, giving it a high concentration that is equivalent to the high concentration already existing in the water.

Question 41

Please explain the relationship between solubility in octanol and bioconcentration. In these paragraphs please explain the following points: i) the rationale for using this relationship, ii) how these properties are typically graphed on the x and y axis iii) which types of molecules fit the trend and which ones don’t iv) reasons why chemicals deviate and where they appear on the plot and finally v) specific examples of chemicals in each group.

Answer 41

i) octanol is a good lipid substitute, meaning that the octanol-water partition coefficient is a proxy for how a compound will partition out between lipids in an organism and the aquatic environment
ii) log Kow on x axis, log BCF on y axis, log Kow is directly proportional to log BCF (positive correlation, almost 1:1, although exact equations and calculations of the relationship have varied
iii) “well behaved” compounds (fit the trend) are typically those with log Kow between 2 and 5-6. For these, log Kow is a good predictor of log BCF.
iv) chemicals can deviate due to:
- biomagnification (higher log BCF than expected from log Kow)
- biological mechanisms (active exclusion) preventing accumulation (lower log BCF than expected from log Kow)
- high hydrophobicity leading to very slow equilibration (lower log BCF than expected from log Kow, log Kow>5-6, there is a negative relationship between log BCF and log Kow beyond this point)
- association with proteins rather than lipids (higher log BCF than expected from log Kow- log Kow is extremely low)
v) Given examples: DDT, PCBs, PBDEs- biomagnification; cancer drugs- active exclusion; HBCDs (flame retardants)- hydrophobic; organic mercury- associated with proteins

Question 42

Please describe the relationship between intracellular concentration of a chemical and its vapor pressure or fugacity as relates to Henry’s constant. i) How does this work to calculate intracellular chemical concentration. ii) Explain the name and difference between the property described by this relationship and what happens with pollutants occurs in complex food chains. iii) explain why these two phenomena differ.

Answer 42

i) Equation (C=f*Z, Z=1/Hc), C=concentration (tissue), f = fugacity (tissue, “escape potential”), Hc = Henry’s constant (concentration in air over concentration in water)
ii) Solvent switching/bioconcentration is described by this relationship. This is a passive movement of a pollutant into a “preferred” solvent (for example, the lipids of a fish). In complex food chains, biomagnification and bioaccumulation (the sum of bioconcentration and biomagnification) occur. Biomagnification causes increased concentration and fugacity of lipophilic pollutants in organisms at the top of the food chain.
iii) In solvent switching/bioconcentration, the passive movement of the pollutant will continue until fugacity is equal in the fish and the water (at which point the concentrationin the fish will be much higher for a very lipophilic chemical) at equilibrium. In solvent depletion/biomagnification, concentrations in the tissues of predators are incredibly high and fugacity in tissue is increased out of equilibrium (fugacity is higher in the organism than in the water). This is because energetic input in digestion removes the lipids of prey/depletes the solvent, while the same amount of pollutant remains and is sequestered in the body of the predator.