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Environmental Toxicology > Midterm 1 > Flashcards

Midterm 1 Flashcards

1
Q

how does ddt work (as a toxin)

A

its a neurotoxin

opens sodium channels and causes over stimulation

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2
Q

what happens because DDT is a breakdown product

A

it lingers in environment

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3
Q

what does POP stand for

A

persistent organic pollutant

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4
Q

what is the TSCA and what country is it from

A

toxic substances control act

america

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5
Q

what is the Canadian equivalent to the TSCA

A

non-domestic substances act and domestic substances act

TSCA = NDSL+DSL

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6
Q

what are chemicals registered in the DSL considered

A

existing chemicals

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7
Q

what does a risk assessment (RA) establish

A

safe limits of exposure

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8
Q

what is a contaminant

A

chemical that exists in levels above those that normally occur in environment

NOT certain if causes environmental harm

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9
Q

what is a pollutant

A

chemical that exists in levels above those that normally occur in environment

Causes environmental harm

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10
Q

what is a toxicant

A

any chemical that has an adverse effect on an organism

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11
Q

what is a xenobiotic

A

a foreign chemical to a living organism

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12
Q

what is a toxin

A

a xenobiotic of natural origins that elicits as an adverse effect

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13
Q

what is ecotoxicology

A

specialized area of environmental toxicology that doesn’t include humans

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14
Q

what does environmental toxicology include

A

all organisms
all levels of biological organization

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15
Q

what does determining individual organism effects of xenobiotics require information on

A
  • fate of transformation/metabolism/ biotransformation in organism

-interaction of xenobiotic with site of action

-impact on whole organism health

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16
Q

what is a ecotoxicological effects assessment

A

combination of analysis and inference of possible consequence of the exposure to a particular agent based on knowledge of the dose-effect (dose response/concentration) relationship with that agent in a particular organism, system, or population

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17
Q

what is an adverse effect

A

abnormal, harmful effects that can be defined in terms of a specific biological response

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18
Q

what is a concentration - response relationship

A

a mathematical assessment of how an exposure term relates to the observation of a biological or toxicological effects

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19
Q

what 2 factors increase or decrease risk

A
  • hazard: the harm that something will cause
  • exposure: extent organism/environment is subjected to the hazard
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20
Q

what’s an ERA

and what does it do

A

ecological risk assessment

assess probability of a given (defined) adverse effect as a result of a human activity

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21
Q

what is EEC

A

expected environmental concentration

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22
Q

what are the questions in a risk assessment

A
  1. which concentration do we find in the environment? in Which ecosystems? What part of ecosystem?
  2. could these concentrations cause any harm ?
  3. (to answer 2) what is the relationship between dose and effect ?
  4. What is the risk for a harmful effect ? (after you characterize the relationship between probable concentration in different parts of the environment and and the corresponding effects)
  5. should/could we reduce the risk?
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23
Q

what is a PEC

A

predicted environmental concentration

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24
Q

what is a PNEL

A

predicted no effect level

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25
Q

what is a PNEC

A

predicted no effect concentration

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26
Q

what does a higher risk quotient value mean

A

higher risk

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27
Q

what does a risk quotient value greater/equal to 1 mean

A

high risk

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28
Q

what does a risk quotient value less than 1 mean

A

low risk

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29
Q

what does a lower PNEC mean for risk ratio

A

higher

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30
Q

what does NEC mean

A

no effect concentration

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31
Q

what is current dogma of ERAs

A

cost of elimination of all chemicals is impossibly high

decisions in practical environmental management must always be Madde on the basis of incomplete info

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32
Q

what is an endpoint

A

measurable outcome

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33
Q

what are the general principles of toxicology

A
  • you only find what you’re looking for
  • the dose makes the poison
  • only living material can measure toxicity
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34
Q

Are in vitro and in silico methods sufficient alone to estimate toxicity

A

no

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35
Q

what is bioavailability

A

the extent a substance becomes completely available to its intended biological destination

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36
Q

when does bioavailability of a toxicant become complicated

A

if administered via food/water

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37
Q

what is a dose

A

known concentration that is consumed or administered

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38
Q

what is hormesis

A

a biphasic dose response with a low dose of a toxicant causing stimulation or beneficial effect and a toxic effect at a high dose

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39
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 nonhuman animal toxicity tests
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40
Q

what is the goal of toxicity test

A

to provide data that can be used to establish safe concentrations of toxicants that will not cause adverse effects on ecosystem or the organisms within

evaluate the toxicity of samples collected from contaminated sites

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41
Q

what are the 3 functions that environmental toxicology can be simplified to

A

f(f) to describe the fate and transformation and transformation of the xenobiotic

f(s) to describe the interaction of the xenobiotic with the site(s) of action

f(e) to describe the effects of the xenobiotic upon the biotic and ecological structures

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42
Q

what is NOEC

A

no observed effect concentration

highest concentration NOT significantly different from control

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43
Q

what is LOEC

A

lowest observed effect concentration

lowest test concentration that IS significantly different from control

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44
Q

what has to be known to determine NOEC

A

LOEC

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45
Q

what is the LC50

A

median lethal concentration

concentration that kills 50% of organisms

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46
Q

what is the EC50

A

median effective concentration

sub lethal effects

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47
Q

what is the different between sublethal and acute

A

sublethal is a more significant portion of organism’s life

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48
Q

what are the statistical analysis of toxicity testing

A

analysis of variance (hypothesis testing) - test for significant difference from control and between treatment groups

regression analysis - fit a line to your data and compare relationship between x and y

49
Q

what are additive effects

A

the toxicity of 2 chemicals when administered together equates the sum of the toxicity of each chemical when administered individually

50
Q

what are antagonistic effects

A

the toxicity of 2 chemicals when administered together is less than the sum of the toxicity of each chemical when administered individually

51
Q

what are synergistic effects

A

the toxicity of 2 chemicals when administered together is more than the sum of the toxicity of each chemical when administered individually

52
Q

what are the two classifications of toxicity tests (based on length of exposure)

A

acute and chronic

53
Q

what does a lower LC50 mean in terms of how toxic something is

A

lower = more toxic

54
Q

what do acute toxicity tests focus on

A

mortality

55
Q

what do chronic toxicity tests focus on

A

sub lethal effects

56
Q

what is what species is used for toxicity tests based on

A

lab hardiness (/easy to cultivate in lab)

common

cheap

short lived

57
Q

what are environmental quality guidelines

A

numerical concentrations or narrative statements that are recommended as levels that should result in negligible risk to environment

58
Q

what is the goal of multi- species toxicity testing

A

to indicate potential population and higher adverse effects of toxicants

59
Q

what is a microcosm

A

artificial simplified ecosystems rear are used to simulate or predict the behaviour of natural ecosystems under controlled conditions

60
Q

what endpoints are used in microcosms

A

functional (movement of energy through ecosystem) and structural (structure of population present)

61
Q

do microcosms look at all trophic levels

A

no

62
Q

do microcosms look at multiple species

A

yes

63
Q

what is a mesocosm

A

any outdoor experiment that examines the natural environment under controlled conditions

64
Q

what are similarities/differences between micro and mesocosm

A

both multiple species

both use structural and structural endpoints (but meso are more developed)

meso used more trophic levels (no top level predators though)

65
Q

what are limnocorrals

A

enclosures placed in natural bodies of water

66
Q

what are the 2 types of limnocorrals

A

sealed (controlled addition of toxicant) and not sealed (controlled site vs contaminated site)

67
Q

what are the advantages of linocorrals

A

native and devoted communities within natural system

can also add caged animals

low cost

68
Q

what are the disadvantages of limnocorrals

A

bad weather could cause destruction of corral/ organisms

safety risks and permits needed around risk with addition of toxicants in water

can’t control all biotic factors, your toxicant, and other pollutants

69
Q

what does lotic mean

A

flowing

70
Q

what does lentic mean

A

not flowing

71
Q

what is EEM and what does it do

A

environmental effects monitoring

monitors pulp mills and mines

72
Q

what kind of testing does EEM include

A

sub lethal toxicity tests

field surveys

73
Q

what is biomonitoring

A

use of transplanted organisms as sentinels in the environment

74
Q

what is a sentinel

A

a species that responds to ecosystem change/variability in a timely and measurable way

75
Q

what kind of endpoints are used in biomonitoring

A

whole organism and/or biochemical endpoints

ex: behaviour, survival, growth, plasma cortisol, global gene expression

76
Q

what does ESL stand for

A

early life stage

77
Q

what is a watershed

A

a geographical area that drains to a common point

includes aquatic system as well as the land that drains into the aquatic system

78
Q

what is TMDL

A

total maximum daily wasteload

79
Q

what are the ways that contaminants enter ecosystems through human activities

A
  • unintended release from human activity (ex: nuclear accident)

-disposal of waste (ex sewage)

  • deliberate applications (ex: pesticides and fertilizers)
80
Q

what happens in heavy rain vs dry weather for combined sanitary waste and storm water

A

dry: stormwater and wastewater are carried to sewage treatment plant together

heavy rains: exceeds capacity of combined sewage system an raw sewage flows into waterways

81
Q

what kind of sewage treatment does most of Canada have

A

secondary

82
Q

what is global distillation

A

the process of contamination volatilization followed by condensation resulting in long range atmospheric transport

83
Q

what is global fractionation

A

more volatile chemicals are transported further than less volatile chemicals

84
Q

what is the grasshopper effect

A

referes to multiple volatilization and condensation events that result in long range atmospheric transport of chemicals

85
Q

what are mountain cold trappings

A

high temperature volatilization of contaminants at low level elevation/base of mountains followed by condensation of contaminants at higher mountain regions

86
Q

what is the AEF

A

anthropogenic enrichment factor

87
Q

are metals biodegradable

A

no

to get rid of them from environment you have to physically remove contaminated sediments

88
Q

what sort of ions do metals tend to make when dissolved

A

cation (positive)

89
Q

what is the biotic ligand model used to predict

A

used to predict the degree of metal binding at site of action (biotic ligand)

this level of accumulation is in turn relayed to a toxicological response

90
Q

how can water chemistry decrease metal toxicity

A

if other molecules compete with toxin for binding to the gills

91
Q

what is a metallothionein

A

non-enzymatic, cysteine rich protein that binds to metals and renders it non-toxic

92
Q

how does a metallothionein render a metal non toxic

A

suquesters it so can’t react with other biomolecules in a cell

93
Q

what are the three possible routes for a metal ion in a body

A

bind to metallothionein

deposition into insoluble forms in intracellular granules for longer term storage or incorporation into biomolecules (competes with essential metals and become incorporated into proteins, enzymes, etc.., causes malfunctions)

excretion in urine or feces

94
Q

is the chronic or acute guideline lower (usually)

A

chronic

(longer the duration of exposure the worse the effects at lower doses)

95
Q

why are so many organic pollutants toxic

A

a lot of organic pollutants are non-polar which can get through lipid bilayer (assuming they’re small enough)

96
Q

when is hydrophilicity promoted

A

when the substance carries a charge or when a compound has a high proportion of polar groups

97
Q

what does it mean for a molecule to be polar and non polar

A

polar = uneven electron distribution

non polar = even electron distribution

98
Q

what is polarity often measured by

A

octanol water purification coeffiecient (Kow)

99
Q

what does a higher Kow mean

A

more lipophilic

100
Q

what is bioaccumulation

A

how much of a toxin accumulates in an organism over time

101
Q

what is the factor in bioaccumulation

A

time

102
Q

what is BAF

A

bioaccumulation factor

103
Q

how is bioaccumulation determined

A

net uptake (diet, respiration, dermal absorption) - emilination + growth dilution)

104
Q

what sort of testing is bioaccumulation measured in

A

field scenario

105
Q

what is bioconcenration

and how is it determined

A

uptake from ambient environment only (no diet)

uptake fron ambient environment (no diet) - elimination and growth

106
Q

what is BCF

A

bioconcentration factor

107
Q

what sort of testing finds bioconcentration

A

laboratory tests

108
Q

what is biomagnification

A

accumulation of toxin up trophic levels

109
Q

what is the factor in biomagnification

A

trophic level is the factor

110
Q

what is the CEPA

A

canadian environmental protection act

111
Q

In CEPA criteria, how many parameters need to be met for the criteria to be met

A

only need to meet parameter for one parameter

112
Q

what did CEPA 1999 do

A

categorized the DSL

prioritization process to identify substances that should be subject to a screening assessment

113
Q

what happens in phase 1 metabolism

A

oxidative, reduction, hydrolysis

114
Q

what happens in phase 2 metabolism

A

conjugation
synthesis

115
Q

what does determining individual organism effects of xenobiotics require info on

A
  1. fate and transformation in organism
  2. interaction of xenobiotic with site of action
  3. impacts on whole organism health
116
Q

what is biotransformation

A

the sum of the chemical rxns that occur within the body to alter the structure of a xenobiotic/endogenous compound

117
Q

what is the function of biotransformation

A

conversion of xenobiotics into hydrophilic less toxic forms

decrease intracellular concentration via excretion

118
Q

what are the 2 ways that toxicity can be affected

A

conversion into a less toxic form (detoxification)

conversions into a more toxic form (bioactivation)

Environmental Toxicology (3 decks)

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