Midterm 1 Flashcards
What is environmental toxicology?
- study of adverse effects of pollutants upon the structure and function of ecological systems
What is toxicology?
- the study of adverse effects of chemical/ physical agents on living organisms
What are DDT and DDE?
Persistent pesticide/metabolite
Who still uses DDT and why?
- India (for malaria control)
- China (exported till 2008)
- Sub-Saharan Africa (malaria and public health)
- Korea (agriculture and public health)
What are POPs?
-persistent organic pollutants
What is biomagnification?
-organisms higher in the food chain accumulate higher levels of chemicals/toxic ants than those lower down in the food chain
What are some commonalities of global problems?
- often involves one or several chemicals
- have major impacts on the environment
- lack of effective/precautionary management
- due to anthropogenic activities
What are some pollutants?
-pesticides, pharmaceuticals, detergents, household products, plastics, mining and metals, textile mills etc.
Why are risk assessments conducted?
-to establish ‘safe’ limits of exposure
Why do we normally look at individual level effect?
-difficult to assess what effects an entire population
What is a contaminant?
- a chemical that exists at levels above those that normally occur in any component of the environment
- may or may not cause environmental harm
What is a pollutant?
- a chemical that exist is at levels above those that normally occur in any component of the environment
- cause environmental harm (eg. Pesticide)
What is a toxicant?
- any chemical/agent that has an adverse effect in a living organism
- not made by plants or animals
What is a xenobiotic?
-any chemical foreign to a living organism
What is a toxin?
A xenobiotic of natural origins
What is ecotoxicology?
- specialized area within environmental toxicology and within ecology
- includes all organisms, except humans
What is environmental toxicology?
- study of the impacts of pollutants upon the structure and function of ecological systems
- includes all organisms
What info is required to determine organism effects of xenobiotics?
- Fate and transformation in organism
- Interaction of xenobiotic with site of action
- Impact on whole organism’s health
What is an Ecological Risk Assessment (ERA)?
Combination of analysis and inference of possible consequences of the exposure to a particular agent based on knowledge of the dose-effect relationship with that agent in a particular organism, system or (sub)population
What is an adverse effect?
Abnormal, harmful, unwanted effect that can be defined in terms of a specific biological response
What are some ecotoxicology effect analyses at a population level?
- species abundance (reduction if endangered, increases if invasive)
- reproductive success
- alterations in genetics
- likelihood of extinction
What are examples of ecotoxicology effect analyses at the community level?
- biodiversity changes
- reductions/increases in community structure
- species abundance/dominance
- predator/prey interactions
What is the definition of risk?
Likelihood that a hazardous material will cause harm to humans or the environment
What two factors increase/decrease risk?
- Hazard: harm that something will cause
2. Exposure: extent organism/environment is subjected to the hazard
What does the Ecological Risk Assessment (ERA) do?
Assesses the probability of a given adverse effect as a result of a human activity
What are the questions in a risk assessment?
- Which concentration do we find in the environment? In which ecosystems and in which parts of the ecosystem?
- Could these concentrations cause any harm?
- What is the relationship between dose/concentration and effect?
- When we characterize the relationship between probable concentration in the different parts of the environment and the corresponding effects, what is the risk for a harmful effect?
- Should we and could we reduce this risk?
What is bioavailability?
Proportion of the toxicant that enters the organism and is therefore able to have an effect
What is a non-threshold toxicant?
Toxic in any amount
What is essential nutrient?
Has a therapeutic range or essential does range
-if too little or too much there is an increasing adverse effect
What is a threshold toxicant?
There is an adverse effect if it passes a certain threshold dose
What is hormesis?
A biphasic dose response with a low dose of a toxicant causing stimulation or beneficial effect and a high does inhibitory or toxic effect
What are two goals of toxicity testing?
- Provide data that can be used to establish safe concentrations of toxicant that will not cause adverse effects on ecosystems or components thereof
- Evaluate the toxicity of samples collected from contaminated sites
What does NOEC stand for?
No observed effect concentration
What does LOEC stand for?
Lowest observed effect concentration
What does LC50 stand for?
Median lethal concentration
What does EC50 stand for?
Median effective concentration
-referring to sub lethal effects
What do chronic toxicity tests look at?
- sublethal effects
- longer testing period
What are some advantages of standard methods?
- tests are uniform and comparable to previous results in other laboratories
- can be replicated and confirmed by other laboratories
- data generated can be combined with those from other laboratories
- can rank potency of chemicals
What are some disadvantages of standard methods?
- often very specific
- may not be applicable to natural environments
- currently mainly single chemicals only
What is Potentiation?
Similar to synergism but when one toxicant is given alone is does not have an effect
What is an antagonistic effect?
Decreased effect when two or more toxic ants are administered together
What is an additive effect?
When toxicants are administered together the response is equal to the added performance of each together
What is a synergistic response?
When toxicants are added together the response is much higher than expected
What are some factors of good test species?
- lab hardiness
- common (not endangered)
- known life cycle
- cheap
- short lived
What are multispecies toxicity tests used for?
- to attempt to recreate complexity of natural systems
- indicate potential population and higher adverse effects of toxicants
What are components of a microcosm?
- multiple species
- functional and structural endpoints
- not all trophic levels
- small size
- easy to increase replicates
What are some components of a mesocosm?
- multiple species
- functional and structural endpoints
- more trophic levels
- large in size
- not easy to increase number of replicates
What are adverse outcome pathways?
New approach to describe sequential chain of causally linked events at different levels of biological organization that lead to adverse health effects on ecosystems
What are examples of inorganic pollutants?
-metals, toxic gases
What are examples of organic pollutants?
- anything with carbons
- byproducts of combustion of trees
- organometals
How do contaminants and pollutants enter ecosystems?
- unintended release from human activities
- disposal of wastes
- deliberate applications
What are the major routes of contaminant entry to surface waters?
- sewage out falls
- runoff from land
- dumping at sea
- release from oil rigs and terminals
What occurs in the primary stage of sewage treatment?
- sedimentation to remove suspended solids
- screening to trap solids
What happens in the secondary stage of sewage treatment?
- use of microbes, o2 and mix to remove dissolved organic matter and convert to CO2, water and energy for growth
- still chemicals remaining
What happens in the tertiary stage of sewage treatment?
- UV, Chlorination, Oxidation
- gets rid of harsher chemicals
What are some routes of land contamination?
- waste dumping
- pesticide applications to agricultural land and forests
- control of insect disease vectors
What is global distillation?
The process of contaminant volatilizations followed by condensation resulting in long range atmospheric transport
What is mountain cold trapping?
High temperature volatilizations of contaminants at low elevation/base of mountain followed by condensation of contaminants at higher mountain regions
What is metallothionein?
A non-enzymatic, cysteine rich protein that binds metals
What is the purpose of metal ions?
-binds to proteins and renders it non-toxic
What is bioaccumulation?
-toxicant build up over time (net uptake)
What is bioconcentration?
Uptake from ambient environment only (not diet)
What is Kow?
Concentration of a solute in octanol/ concentration of solute in water
-higher Kow is more lipophilic
What is biotransformation?
The sum of the chemical reactions that occur within the body to alter the structure of a xenobiotic/ endogenous compound
What info is required to determine individual organism effects of xenobiotics?
- Fate and transformation in organism
- Interaction of xenobiotic with site of action
- Impact on whole organism’s health
What is detoxification?
-conversion into a less toxic form
What is bioactivation?
Conversion into a more toxic form
What is the function of biotransformation?
Conversion of xenobiotics into more hydrophilic less toxic forms
