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Environmental Toxicology > Midterm 1 (Lectures 1-5) > Flashcards

Midterm 1 (Lectures 1-5) Flashcards

1
Q

What are the 3 general principles of toxicology?

A
  1. You can only find what you’re looking for
  2. The dose makes the poison
  3. Only living material can measure toxicity
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2
Q

What is the purpose of the Canadian Council of Animal Care?

A

to ensure that animal based science in Canada takes place only when necessary and the animals in the studies receive optimal care

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3
Q

What are the 3 main categories used by agencies in evaluation & regulation of toxic chemicals?

A
  1. Human epidemiology
  2. Human controlled clinical exposures
  3. Plant and non-human animal toxicity tests
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4
Q

What is the purpose of ecotoxicity testing?

A

To provide data that can be used to establish safe concentrations of toxicants that will not cause adverse effects on ecosystems and evaluate toxicity samples collected from contaminated sites.

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5
Q

Environmental Toxicology can be simplified to the understanding of 3 functions:

A
  1. f(f) to describe the fate and transformation of the xenobiotic
  2. f(s) to describe the interaction of xenobiotic with the site or sites of action
  3. f(e) to describe the effects of the xenobiotic upon the biotic and ecological structures
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6
Q

5 parameters that must be understood to explain xenobiotic effects at ecosystem level:

A
  1. introduction of contaminant
  2. physiological and behavioural parameters (chromosomal damage, tumours, tertogenic effects
  3. community parameters (structure, diversity, trophic complexity)
  4. biochemical parameters (stress proteins, metabolic indicators)
  5. population parameters (population density, population range, age density)
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7
Q

What toxicity tests are single species?

A

Acute and chronic

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8
Q

What toxicity tests are multi species?

A

Microcosms, mesocosms, field studies

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9
Q

Principles of chronic toxicity tests:

A

Sublethal, longer (more significant portion of the organisms lifespan), more complex, more expensive

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10
Q

What are some examples of endpoints for chronic toxicity tests?

A

Behaviour, carcinogenesis, organ damage, growth, reproduction

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11
Q

Describe analysis of variance

A

hypothesis testing - test for significant difference from control and between all treatment groups

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12
Q

Where are acute and chronic toxicity test methods available?

A
  • American society for testing materials
  • Organization for economic cooperation and materials
  • National toxicology program
  • Environment canada
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13
Q

Name 5 advantages of standard methods

A
  1. tests are uniform and comparable to previous results
  2. can be replicated/confirmed by other laboratories
  3. data generated can be combined with those from other laboratories
  4. detailed listing of apparatus, dilution water, test material, test organisms
  5. can rank potency of chemicals because of uniformity of tests
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14
Q

Name 3 disadvantages of standard methods

A
  1. Often very specific, hard to apply to other situations or answer other questions
  2. may not be applicable to natural environment
  3. currently mainly single chemicals only, however there may be multiple chemicals combining in the real world. Can’t understand what the combination of chemicals does
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15
Q

Compare and contrast acute and chronic toxicity tests

A

Chronic:
- Sub lethal (growth, reproduction)
- More ecologically relevant
- Shows effect at much lower dose = designed to determine sub-lethal effects
- More labour intensive, takes longer, more expensive
Acute:
- drop dead testing
- time = 2 days (invertebrates) to 4 days (fish)
- LD50: often terrestrial, we know exactly what dose is being given
- EC50: effective concentration, lose equilibrium, sit on bottom = ecologically dead
- Not very ecologically relevant but quick, relatively cheap
- Rank hazards = lower LC50 = more toxic
- Usually precursor to chronic toxicity testing = useful in designing chronic toxicity tests

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16
Q

What makes a good test species?

A
  • lab hardiness
  • common
  • known life cycle
  • cheap
  • short lived
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17
Q

Name 4 test organisms used in mammalian tests

A
  1. rodents
  2. mini pigs
  3. primates
  4. dogs
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18
Q

Define environmental quality guidelines

A

Numerical concentrations or narrative statements that are recommended as levels that should result in negligible risk to biota, their functions, or any interactions that are integral to sustaining the health of ecosystems and the designated resources they support

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19
Q

List 3 fields that include environmental toxicology

A
  1. environmental science
  2. classical toxicology
  3. eco toxicology
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20
Q

What was DDT used for and how did it impact the ecosystem?

A

DDT was used as an insecticide/agricultural pesticide and malaria/typhus control agent.
DDT kept sodium ion channels open in insects and wildlife causing constant stimulation of nervous system leading to death. Birds of prey suffered from egg shell thinning and poor survival of offspring as DDT impacted the eggshell gland and proper hormone synthesis. Gland couldn’t produce hard eggshells

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21
Q

What is the current status of chemicals and the environment?

A
  • chemicals are known
  • chemicals produced/manufactured deliberately
  • chemicals produced at >1 tonne per year
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22
Q

What is the cause+effect pathway?

A

Pollutant -> biochemical changes -> physiological changes -> whole organism responds -> population changes -> community composition -> ecosystems

23
Q

Name 2 ecosystem relationships

A
  1. interactions with physical aspects of environment
  2. interactions with same and other species
24
Q

What are some causes of current species extinction?

A
  • agriculture
  • deforestation
  • overharvesting ocean wildlife
  • invasive species
  • climate change
25
Q

What is a community?

A

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

26
Q

Name 4 community attributes

A
  1. # of species
  2. relative abundance of species
  3. nature of species interactions
  4. physical structure (habitat)
27
Q

List 5 effects of an exotoxicology analysis at the population level

A
  • Species abundance
  • Reductions or increases beyond natural fluctuations
  • Reproductive success
  • Alterations in genetics
  • Likelihood of extinction
28
Q

List 4 effects of an exotoxicology analysis at the community structure level

A
  • reductions/increases in community structure
  • Biodiversity changes
  • Species abundance/dominance
  • predator/prey interactions
29
Q

List an effect of an exotoxicology analysis at the ecosystem level

A
  • Changes in ecosystem processes (primary production, total system respiration, decomposition, nutrient cycling)
30
Q

List 2 effects of an exotoxicology analysis at the landscape level

A
  • Spatial distribution/extent of different habitat types within landscapes
  • Changes in size, shape, proximity of different habitats
31
Q

List 2 factors to increase or decrease risk

A
  1. hazard: the harm that something will cause
  2. exposure: extent organism/environment is subjected to the hazard
32
Q

Define ecological risk assessment

A

assesses probability of a given adverse effect as a result of a human activity. Requires good knowledge of the properties and effects of the chemical in question in complex ecosystems

33
Q

Name 2 of the 5 questions that ecological risk assessments answer

A
  1. could these concentrations cause any harm?
  2. should we and could we reduce this risk?
34
Q

What are 3 points of the current dogma of ecological risk assessments?

A
  1. cost of elimination of chemicals is impossibly high
  2. decisions must always be made on the basis of incomplete information
  3. currently use ~100,000 chemicals but only know ~1% of what we need to know
35
Q

What is the goal of multi species toxicity tests?

A

To indicate potential population and higher adverse effects of toxicant. Attempt to recreate complexity of natural systems

36
Q

Compare and contrast microcosm and mesocosm

A

microcosm:
- Multiple species
- Functional and structural endpoints
- Not all trophic levels
- E.g. <15m3 of water
- Easier to increase replicates
mesocosm:
- Multiple species
- Functional and structural endpoints (more endpoints)
- More trophic levels (no top level predators)
- E.g. >15m3 of water

37
Q

define limnocorrals (include differences between sealed and not sealed)

A

Enclosures placed in natural lakes/water bodies. Sealed = controlled addition of toxicant. Not sealed = control site vs. contaminated site

38
Q

what is an advantage and a disadvantage of a limnocorral?

A

A: native and developed communities within natural system, not lab bred
D: inclement weather and destruction of corral/organisms

39
Q

Define artificial stream and the difference between lotic or lentic

A

Lotic = flowing, lentic = nonflowing
Aquatic exposure stocked with organisms or organisms are allows to enter from natural waters. toxicant is added to water and functional and structural effects are monitored

40
Q

What are the two types of field surveys?

A
  1. baseline or pre-exposure and post exposure monitoring for adverse effects in wild organisms
  2. real-time whole organism (biomonitoring) = use of transplanted organisms an sentinels in the environment
41
Q

Define adverse outcome pathways

A

new approach to describe sequential chain of casually linked events at different levels of biological organization that lead to health effects on organisms

42
Q

List 3 locations where toxicant may affect organism

A
  1. whole organism
  2. protein
  3. gene
43
Q

What is the adverse outcome of acid rain?

A

pH of 5.6 lead to calcium depletion. Daphnia can’t live in low calcium environments and loss of daphnia = loss of organisms that consume daphnia. Causes loss of calcium from soils and watersheds

44
Q

How often is environmental effects monitoring conducted and how is it tested?

A

every 3 years unless no effects, then every 6 years. Tested by sub-lethal toxicity testing of effluent and field surveys

45
Q

List 3 ways pollutants and contaminants can enter the ecosystem as a result of human activity

A
  1. unintended release from human activities (nuclear accidents, shipwrecks)
  2. disposal of wastes (sewage and industrial effluents)
  3. deliberate applications (pest and vector control, fertilizers)
46
Q

Define primary, secondary, and tertiary sewage treatment

A

primary:
- sedimentation to remove suspended solids
- screening to trap solids
secondary:
- microbes+O2+mix to remove dissolved organic matter and convert to CO2, water and energy for growth
- settling tanks for secondary sedimentation
tertiary:
- UV, chlorination, ozonation

47
Q

List 3 major routes of land contamination and the pollutants associated with them

A
  1. waste dumping: wide range of pollutants
  2. pesticides: insecticides, rodenticides, fungicides, herbicides
  3. application of sewage to agricultural land: heavy metals, nitrates, detergents
48
Q

list 4 major routes of atmospheric contamination and their associated pollutants

A
  1. domestic chimneys: organic compounds
  2. chimneys of industrial plants, power stations etc: same as domestic chimneys + other pollutants depending on what the site does
  3. internal combustion of jet engines: CO2, hydrocarbons, lead
  4. pesticide applications: insecticides, fungicides, herbicides
49
Q

List 5 descriptors about metals

A
  1. many are global pollutants
  2. conductive
  3. reactive/form compounds with other elements easily
  4. catatonic tendency in solution (generally make positive ions when dissolved)
  5. tendency to combine (alloys are mixtures of metallic elements)
50
Q

Name 3 sources of metals

A
  1. naturally occurring in the earth’s crust
  2. mining and smelting
  3. not biodegradable
51
Q

What is biotic ligand model?

A

use to predict the degree of metal binding at the site of action (biotic ligand), this level of accumulation is in turn related to toxicological response

52
Q

Metal toxicokinetics is not fully understood, name 3 things the metal ion might do

A
  1. bind to metallothionein: renders it non-toxic
  2. deposition into insoluble forms in intracellular granules for longer-term storage or incorporation into biomolecules
  3. excretion in urine/feces
53
Q

Do animals need copper?

A

Yes, copper is a micronutrient in most organisms (hemoglobin, metabolism etc)

54
Q

what is wilson’s disease and how is it treated?

A

Wilson’s disease is a mutation in the gene that codes for copper transporting P-type ATPase that excretes excess copper into bile and plasma. Leads to liver disease if untreated. Treatment is chelation with copper chelation

Environmental Toxicology (4 decks)

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