Midterm 1

Question 1

Environmental Toxicology

Answer 1

the study of adverse effects of pollutants upon the structure and function of ecological systems

Question 2

Source/ Exposure pathways can be through a media of:

Answer 2

• Soil
• Air
• Water
• Food
• Consumer products

Question 3

Explain DDT/ DDE

Answer 3

• DDT is an agricultural pesticide and malaria/typhus control agent
• DDT is degradation to → DDE
• DDT/DDE = persistent pesticide/metabolite

Question 4

Biomagnification

Answer 4

organisms higher in the food chain accumulate higher levels of chemicals/toxicants than those lower down in the food chain

Question 5

Risk Assessments (RAs)

Answer 5

-There are regulatory agencies such as Health Canada that try to establish safe limits of exposure

-Regulatory agencies typically do separate RAs for
Humans
Non-human ecological effects (effects on ecosystems and their components)

Question 6

When you assess the risk of pollutants in an ecosystem, one needs to break down that question:

Answer 6

Pollutants → Biochemical changes → Physiological changes → whole organism responses (survival, growth, reproduction) → population changes → community composition → ecosystem

-When a chemical affects survival, growth and reproduction in the whole organism response then it is considered toxic but if it does not affect the organism in those 3 ways then it is not considered toxic

Question 7

Contaminant

Answer 7

• Chemical that exists at levels above those that normally occur in any component of the environment (ie above background levels)
• Non-naturally occurring/ anthropogenic chemicals and naturally occurring chemicals
• Establishing above background for naturally occurring chemicals from place to place and temporally can be difficult: metals, sulfur dioxide, nitrogen oxide…
• May or may not cause environmental harm

Question 8

Pollutant

Answer 8

• Chemical that exists at levels above those that normally occur in any component of the environment (ie above background levels)
• Non-naturally occurring/ anthropogenic chemicals (eg. pesticide) and naturally occurring (copper)
• Causes environmental harm ( eg. pesticide)

Question 9

Toxicant

Answer 9

Any chemical/ agent that has an adverse effect in a living organisms (e.g pesticide, gasoline, lead)

Question 10

Xenobiotic

Answer 10

A chemical foreign to a living organism

Question 11

Toxin

Answer 11

A xenobiotic of natural origins (i.e. made by plants or animals) that elicits an adverse effects
Examples of toxin are venom by a snake, black widow spider venom

Question 12

Ecotoxicology

Answer 12

• specialized area within environmental toxicology and within ecology
• Subdiscipline of environmental toxicology
• Includes all organisms except humans

Question 13

Biological organization (molecules…)

Answer 13

Molecules → cells → groups of cells → organisms → population → community → ecosystem → biosphere

Question 14

Molecules

Answer 14

groups of atoms, smallest unit of most chemical compounds (water, DNA)

Question 15

Cells

Answer 15

smallest functional unit of life

Question 16

Group of Cells

Answer 16

Tissues, organs, organ systems (Nervous tissue → Brain → Nervous system)

Question 17

Organisms

Answer 17

Individual living thing (Bison)

Question 18

Population

Answer 18

Group of organisms of one type that live in the same area (Bison Herd)

Question 19

Community

Answer 19

Populations that live together in a defined area (Hawk, snake, bison, grass)

Question 20

Ecosystem

Answer 20

Community and its not living surroundings (Hawk, snake, bison, grass,stream, rocks, air)

Question 21

Biosphere

Answer 21

The part of Earth that contains all ecosystem

Question 22

Ecology

Answer 22

• Is the study of the relationship between organisms and their environment
• Breaks down into environment and relationships

Question 23

Environment:

Answer 23

• Physical (Abiotic) – temperature, light pH for abiotic
• Chemical (Abiotic)
• Biological (Biotic)

Question 24

Ecological restoration

Answer 24

how to restore the environment that has already been damaged

Question 25

Community:

Answer 25

group of species that occupy a given area, interacting either directly or indirectly

Question 26

Community attributes:

Answer 26

• # of species
• Relative abundance of species
• Nature of species interaction
• Physical structure (i.e. habitat)