Midterm 1 Flashcards
how does ddt work (as a toxin)
its a neurotoxin
opens sodium channels and causes over stimulation
what happens because DDT is a breakdown product
it lingers in environment
what does POP stand for
persistent organic pollutant
what is the TSCA and what country is it from
toxic substances control act
america
what is the Canadian equivalent to the TSCA
non-domestic substances act and domestic substances act
TSCA = NDSL+DSL
what are chemicals registered in the DSL considered
existing chemicals
what does a risk assessment (RA) establish
safe limits of exposure
what is a contaminant
chemical that exists in levels above those that normally occur in environment
NOT certain if causes environmental harm
what is a pollutant
chemical that exists in levels above those that normally occur in environment
Causes environmental harm
what is a toxicant
any chemical that has an adverse effect on an organism
what is a xenobiotic
a foreign chemical to a living organism
what is a toxin
a xenobiotic of natural origins that elicits as an adverse effect
what is ecotoxicology
specialized area of environmental toxicology that doesn’t include humans
what does environmental toxicology include
all organisms
all levels of biological organization
what does determining individual organism effects of xenobiotics require information on
- fate of transformation/metabolism/ biotransformation in organism
-interaction of xenobiotic with site of action
-impact on whole organism health
what is a ecotoxicological effects assessment
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
what is an adverse effect
abnormal, harmful effects that can be defined in terms of a specific biological response
what is a concentration - response relationship
a mathematical assessment of how an exposure term relates to the observation of a biological or toxicological effects
what 2 factors increase or decrease risk
- hazard: the harm that something will cause
- exposure: extent organism/environment is subjected to the hazard
what’s an ERA
and what does it do
ecological risk assessment
assess probability of a given (defined) adverse effect as a result of a human activity
what is EEC
expected environmental concentration
what are the questions in a risk assessment
- which concentration do we find in the environment? in Which ecosystems? What part of ecosystem?
- could these concentrations cause any harm ?
- (to answer 2) what is the relationship between dose and effect ?
- 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)
- should/could we reduce the risk?
what is a PEC
predicted environmental concentration
what is a PNEL
predicted no effect level
what is a PNEC
predicted no effect concentration
what does a higher risk quotient value mean
higher risk
what does a risk quotient value greater/equal to 1 mean
high risk
what does a risk quotient value less than 1 mean
low risk
what does a lower PNEC mean for risk ratio
higher
what does NEC mean
no effect concentration
what is current dogma of ERAs
cost of elimination of all chemicals is impossibly high
decisions in practical environmental management must always be Madde on the basis of incomplete info
what is an endpoint
measurable outcome
what are the general principles of toxicology
- you only find what you’re looking for
- the dose makes the poison
- only living material can measure toxicity
Are in vitro and in silico methods sufficient alone to estimate toxicity
no
what is bioavailability
the extent a substance becomes completely available to its intended biological destination
when does bioavailability of a toxicant become complicated
if administered via food/water
what is a dose
known concentration that is consumed or administered
what is hormesis
a biphasic dose response with a low dose of a toxicant causing stimulation or beneficial effect and a toxic effect at a high dose
what are the 3 main categories used by agencies in evaluation/regulation of toxic chemicals
- human epidemiology
- human controlled clinical exposures
- plant and nonhuman animal toxicity tests
what is the goal of toxicity test
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
what are the 3 functions that environmental toxicology can be simplified to
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
what is NOEC
no observed effect concentration
highest concentration NOT significantly different from control
what is LOEC
lowest observed effect concentration
lowest test concentration that IS significantly different from control
what has to be known to determine NOEC
LOEC
what is the LC50
median lethal concentration
concentration that kills 50% of organisms
what is the EC50
median effective concentration
sub lethal effects
what is the different between sublethal and acute
sublethal is a more significant portion of organism’s life
what are the statistical analysis of toxicity testing
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
what are additive effects
the toxicity of 2 chemicals when administered together equates the sum of the toxicity of each chemical when administered individually
what are antagonistic effects
the toxicity of 2 chemicals when administered together is less than the sum of the toxicity of each chemical when administered individually
what are synergistic effects
the toxicity of 2 chemicals when administered together is more than the sum of the toxicity of each chemical when administered individually
what are the two classifications of toxicity tests (based on length of exposure)
acute and chronic
what does a lower LC50 mean in terms of how toxic something is
lower = more toxic
what do acute toxicity tests focus on
mortality
what do chronic toxicity tests focus on
sub lethal effects
what is what species is used for toxicity tests based on
lab hardiness (/easy to cultivate in lab)
common
cheap
short lived
what are environmental quality guidelines
numerical concentrations or narrative statements that are recommended as levels that should result in negligible risk to environment
what is the goal of multi- species toxicity testing
to indicate potential population and higher adverse effects of toxicants
what is a microcosm
artificial simplified ecosystems rear are used to simulate or predict the behaviour of natural ecosystems under controlled conditions
what endpoints are used in microcosms
functional (movement of energy through ecosystem) and structural (structure of population present)
do microcosms look at all trophic levels
no
do microcosms look at multiple species
yes
what is a mesocosm
any outdoor experiment that examines the natural environment under controlled conditions
what are similarities/differences between micro and mesocosm
both multiple species
both use structural and structural endpoints (but meso are more developed)
meso used more trophic levels (no top level predators though)
what are limnocorrals
enclosures placed in natural bodies of water
what are the 2 types of limnocorrals
sealed (controlled addition of toxicant) and not sealed (controlled site vs contaminated site)
what are the advantages of linocorrals
native and devoted communities within natural system
can also add caged animals
low cost
what are the disadvantages of limnocorrals
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
what does lotic mean
flowing
what does lentic mean
not flowing
what is EEM and what does it do
environmental effects monitoring
monitors pulp mills and mines
what kind of testing does EEM include
sub lethal toxicity tests
field surveys
what is biomonitoring
use of transplanted organisms as sentinels in the environment
what is a sentinel
a species that responds to ecosystem change/variability in a timely and measurable way
what kind of endpoints are used in biomonitoring
whole organism and/or biochemical endpoints
ex: behaviour, survival, growth, plasma cortisol, global gene expression
what does ESL stand for
early life stage
what is a watershed
a geographical area that drains to a common point
includes aquatic system as well as the land that drains into the aquatic system
what is TMDL
total maximum daily wasteload
what are the ways that contaminants enter ecosystems through human activities
- unintended release from human activity (ex: nuclear accident)
-disposal of waste (ex sewage)
- deliberate applications (ex: pesticides and fertilizers)
what happens in heavy rain vs dry weather for combined sanitary waste and storm water
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
what kind of sewage treatment does most of Canada have
secondary
what is global distillation
the process of contamination volatilization followed by condensation resulting in long range atmospheric transport
what is global fractionation
more volatile chemicals are transported further than less volatile chemicals
what is the grasshopper effect
referes to multiple volatilization and condensation events that result in long range atmospheric transport of chemicals
what are mountain cold trappings
high temperature volatilization of contaminants at low level elevation/base of mountains followed by condensation of contaminants at higher mountain regions
what is the AEF
anthropogenic enrichment factor
are metals biodegradable
no
to get rid of them from environment you have to physically remove contaminated sediments
what sort of ions do metals tend to make when dissolved
cation (positive)
what is the biotic ligand model used to predict
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
how can water chemistry decrease metal toxicity
if other molecules compete with toxin for binding to the gills
what is a metallothionein
non-enzymatic, cysteine rich protein that binds to metals and renders it non-toxic
how does a metallothionein render a metal non toxic
suquesters it so can’t react with other biomolecules in a cell
what are the three possible routes for a metal ion in a body
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
is the chronic or acute guideline lower (usually)
chronic
(longer the duration of exposure the worse the effects at lower doses)
why are so many organic pollutants toxic
a lot of organic pollutants are non-polar which can get through lipid bilayer (assuming they’re small enough)
when is hydrophilicity promoted
when the substance carries a charge or when a compound has a high proportion of polar groups
what does it mean for a molecule to be polar and non polar
polar = uneven electron distribution
non polar = even electron distribution
what is polarity often measured by
octanol water purification coeffiecient (Kow)
what does a higher Kow mean
more lipophilic
what is bioaccumulation
how much of a toxin accumulates in an organism over time
what is the factor in bioaccumulation
time
what is BAF
bioaccumulation factor
how is bioaccumulation determined
net uptake (diet, respiration, dermal absorption) - emilination + growth dilution)
what sort of testing is bioaccumulation measured in
field scenario
what is bioconcenration
and how is it determined
uptake from ambient environment only (no diet)
uptake fron ambient environment (no diet) - elimination and growth
what is BCF
bioconcentration factor
what sort of testing finds bioconcentration
laboratory tests
what is biomagnification
accumulation of toxin up trophic levels
what is the factor in biomagnification
trophic level is the factor
what is the CEPA
canadian environmental protection act
In CEPA criteria, how many parameters need to be met for the criteria to be met
only need to meet parameter for one parameter
what did CEPA 1999 do
categorized the DSL
prioritization process to identify substances that should be subject to a screening assessment
what happens in phase 1 metabolism
oxidative, reduction, hydrolysis
what happens in phase 2 metabolism
conjugation
synthesis
what does determining individual organism effects of xenobiotics require info on
- fate and transformation in organism
- interaction of xenobiotic with site of action
- impacts on whole organism health
what is biotransformation
the sum of the chemical rxns that occur within the body to alter the structure of a xenobiotic/endogenous compound
what is the function of biotransformation
conversion of xenobiotics into hydrophilic less toxic forms
decrease intracellular concentration via excretion
what are the 2 ways that toxicity can be affected
conversion into a less toxic form (detoxification)
conversions into a more toxic form (bioactivation)
