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Environmental Toxicology > Chapter 5 - Part I > Flashcards

Chapter 5 - Part I Flashcards

1
Q

Environmental toxicology deals with the harmful effects of chemicals on ecosystems and their components. What modes of effects does this include?

A
  • delivery
  • transport
  • transformation
  • effects of pollutants
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2
Q

How do pollutants enter ecosystems?

A
  • discharges into the atmosphere
  • contamination of land
  • entry into water
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3
Q

What are pollutants that originate from a known source that can be tracked such as direct discharge from industrial or agricultural industried, waster storage, waste lagoon etc.?

A

point source

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4
Q

What are pollutants where the direct source is hard or impossible to track such as pesticides , fertilizers, household wastes, etc.?

A

non-point source

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5
Q

What factor regulates waste disposal, clean-up standards, transportation, and other aspects of waste discharge, clean-up, and environmental protection?

A

Environmental law

ex. new Georgia Clean Water Act

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6
Q

How are pollutants destroyed?

A

biodegradation

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7
Q

Which will degrade more rapidly?

A

hexane

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8
Q

Which will degrade more rapidly?

A

benzene

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9
Q

Which will degrade more rapidly?

A

2, 4-D

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10
Q

How can environmental pollutants relocate from their original source?

A

interface transport processes

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11
Q

What is the theoretical boundary between air and water, air and soil, and soil and water?

A

interface

plants and animals located here experience adverse effects

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12
Q

Which boundary is this interface inbetween?

A

top: atmosphere
bottom: soil

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13
Q

What boundary is this interface in between?

A

top: soil
bottom: ground water

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14
Q

How are contaminants released into the atomosphere?

A

photolysis

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15
Q

How are contaminants dispersed throughout the soil?

A
  • chemical transformation
  • microbial transformation
  • organism uptake
  • absorption/deabsorption
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16
Q

How do plants release toxins into the atmosphere?

A

volatilization

e.g. evaporation

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17
Q

How do plants uptake toxins from the soil?

A

absorption

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17
Q

What is it?

  • chlorinated hydrocarbon that was developed in the 1930s by the chemist Paul Muller
  • very effective insecticide and did not easily degrade in the environment
  • became popular during WWII and was instrumental in the reduction of such disease vectors as typhoid and malaria
  • responsible for saving millions of lives
A

DDT
dichlorodiphenyltrichloroethane

di-chloro-di-phenyl-tri-chloro-ethane

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17
Q

How was the use of DDT adopted on a global scale?

A

effectiveness and persistence

also cost effective

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18
Q

The use of DDT during the WWII era was rather prevalent because of its…

A

cost-effectiveness

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19
Q

What does ubiquity mean?

A

the state of being everywhere, omnipresence

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20
Q

After the wake of DDT and it’s effects on the environment, what publication launched a modern environmental movement?

A

Silent Spring, 1962
by Rachel Carson

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21
Q

What effects in laboratory animals were shown to be a result of exposure to DDT?

A
  • reproductive
  • teratogenic
  • neurological
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22
Q

When was DDT banned in the US?

A

1972

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23
Q

In the environment, what is DDT partially transformed in to?

A

DDR
dichlorodiphenyldichloroethylene

di-chloro-di-phenyl-di-chloro-ethylene

24
Q

Does DDE show negative effects similar to DDT?

A

yes

25
Q

What has been the result of DDT and DDE on the environment?

related to its ubiquity

A

Even after almost 40 years after its ban, DDT and DDE are detected in human milk, in Antarctica and Arctic ice, and in remote deserts where DDT has never been used.

26
Q

What is this structure?

A

DDT

27
Q

What is this structure?

A

DDE

28
Q

What is this structure?

A

DDA

29
Q

What is this structure?

A

TDE (DDD)

30
Q

During DDT metabolism, how is DDT transformed into TDE (DDD)?

A

-Cl/+H

31
Q

During DDT metabolism, how is DDT transformed into DDE?

A

-HCl

32
Q

During DDT metabolism, how is DDT transformed into DDA?

A

through a series of transformations
DDT->TDE->DDM(U:S)->DDNU->DDOH->intermediate->DDA
-Cl/+H -> -HCl -> +2H -> -HCl -> +HOH -> +2H -> +O

33
Q

What was a consequence of removing DDT from the world market?

A

malaria infection rates spiked

infections today: 300 to 500 million

DDT activists vouch for limited reintroduction

34
Q
  • Mercury poisoning in 1956
  • linked to local plastics factory that was dumping mercury into the bay
  • fish and shellfish consumption resulted in high levels of methylmercury
A

Minamata Bay
Kyushu, Japan

35
Q

How is methylmercury formed?

A

it is formed from mercury via its methylation by ubiquitous microorganisms

36
Q

What were the health effects on humans following the Minamata Bay mercury incident?

A
  • difficulty walking, swallowing, speaking, and hearing
  • loss of brain weight and volume (brain atrophy)
  • high rate of birth defects - severe brain damage, mental impairment, and delayed development
36
Q

How did mercury poisoning enter into the human system following the Mnamata Bay incident?

A

biomagnification of methylmercury in the marine food chain with humans at the top of the chain

37
Q

Pollution or Contamination?

  • agricultural chemical
  • air pollutants
  • biological contaminants
  • carcinogens
  • chemicals
  • extremely hazardous substances
  • microorganisms
  • radiation
  • soil contaminants
  • toxic substances
A

pollutants

38
Q

What is a compound or chemical element present in air, water, food soil, dust, or other environmental media?

A

environmental chemical

39
Q

What is the Third National Report on Human Exposure to Environmental Chemicals attempting to do?

A

quantify exposure to 148 common environmental chemicals

40
Q

What is an ecosystem?

A

populations and communities residing in a defined area

aquatic or terrestial

41
Q

Ecosystems can be composed of what two compartments?

A

abiotic - air, water, soils, and sediments
biotic - animal and plant life

42
Q

What are the layers of the atmosphere?

A
  • troposphere
  • stratosphere
  • mesosphere
  • thermosphere
43
Q

What layer of the Earth is contamination of the most concern?

A

troposphere

44
Q

What is the composition of atmospheric air?

A
  • oxygen, nitrogen
  • “trace amounts” of chemical such as: carbon monoxide, sulfur dioxide, hydrogen sulfide, nitric acid, ammonia, formaldehyde, lead, oxides of nitrogen, particulates, etc..
  • atmospheric water
45
Q

Which air pollutant do these sources produce?

A

carbon monoxide

46
Q

Which air pollutant do these sources produce?

A

nitrogen oxides

47
Q

Where do about half of atmospheric pollutants come from?

A

industrial discharges

48
Q

How can airborne chemicals enter into chemical reactions?

A

via oxidation and photolysis

49
Q

What does this picture respresent?

A

chemical oxidation in air and formation of acid rain

50
Q

In what kind of environment is this photolysis occuring?

A

clean environment

51
Q

In what kind of environment is this photolysis occuring?

A

polluted environment

52
Q

What are the fates of chemicals in the air?

A
  • input
  • dispersion
  • transport
  • reactions
  • removal
53
Q

Water contamination can affect humans directly as well as indirectly. How can contaminations affect humans indirectly?

A

1) digestion of fish and shellfish
2) decrease of food base in aquatic environments
3) decrease biodiversity in squatic environments
4) impair the cycle of elements in the Biosphere

54
Q

What are some sources of contaminants?

A
  • industrial waste
  • agriculture
  • pharmaceuticals
55
Q

What are some types of contaminants?

A
  • insecticides and herbicides
  • heavy metals
  • petroleum hydrocarbons
  • chlorinated solvents (PCB)
  • solluted suspended sediment
  • estrogen mimicking compounds
56
Q

How do chemical contaminats move within water medium?

A

water turbulence and diffusion

57
Q

What can chemicals in the water interact with?

A
  • sediments
  • suspended particles in water column
  • plants and animals residing there

Environmental Toxicology (9 decks)

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