Exam 3 Flashcards
BAF or BCF
BAF = conc of the organism in the enviroment/conc in the ambient enviroment
- Can be used to evaluate the effectiveness of a plant in metal accumulation and evaluate their potential use in metal remediation.
Factors from BAF
- pH , lower pH=higher BAF
- Organic matter content , lower OM content =higher BAF
- Clay content, lower clay content =higher BAF
- Cation exchange capacity , higher CEC =higher BAF
Bioaccumulation
Accumulation of substances in an organism
Occur when a organism absorped a substance at a rate faster than that at which the substance is lost by catabolism and excretion
Biomagnification
Concentration of toxin in an organism as a results of its ingesting other plants or animals in which the toxins are more widely disbursed.
Concentration increase with the trophic level.
Bioavailability
Fraction of ingested metal absorped into the systemic circulation
Bioaccessibility
Fraction of total metal that dissolves in the stomach and is available for absorption during transit through the small intestine
Kow
Kow=conc in octanol/conc in water
Below 1:High water solubility, low lipid solubility
Above 1: High lipid solubility, low water solubility
Is an important factor to understand the fate of an organic compound in ecosystem
Passive diffusion
- Organic molecules - there croess natural barriers
- Molecules must have som affinities with the barrier it self some affinity for the water that lies to the inside of the barrier.
- Molecules should have a resonable balance between lipid solubility and water solubility
Lipophillic xenobiotics in living organism
Identifies five types of sites
- Uptake
- Metabolism
- Action
- Storage
- Excretion
Toxicokinetics
- Include processes of uptake, distribution, metabolism
- Determine how much of a toxic compound reaches the site of action
Toxicodynamics
- Molecular interactions at the site of action
- Determine by the nature and degree of interaction between the toxic compound and the site of action
Phase 1
- Oxidation, hydrolysis, hydration, reduction
- Production of metabolites that contain OH-groups
- A polar group is either introduced or unmasked so the drug molecule becomes more water soluble and can be excreted
- Produce a water-soluble and less active metabolites
- Mocrosomal monooxygenase enzyme
phase 2
- Conjugation reaction
- Most conjugates are negatively charges and are readily excreted in bile or urine
- Sulfotransferases
Enzymatic metabolism of most lipophillic compounds
-Occurs in 2 phases
Xenobiotic -> Metabolite -> Conjugate
Phase 1 Phase 2
Half-life
Determine the time it takes to metabolize / eliminate 50 % of the drug or the compound from the body or plasma
First order kinetic
- Proportional
- Half-life is constant
- Rate of elimination is not constant
Zero order kinetic
- Half-life is not constant
- Rate of elimination is constant
Additivity
A combination of two or more chemicals is the sum of the expected individual response
A=20
B=30
A+B=50
Antagorism
Exposure to one chemical results in a reduction in the effect of the other chemical
A=20
B=30
A+B=5
Potentiation
Exposure to one chemical results in the other chemical producing on effects greater than if given alone
A=0
B=20
A+B=50
Synergism
Exposure to one chemical causes a dramatic increse in the effect of another chemical
A=5
B=10
A+B=100
OECD
- Internationally accepted guidelines as standard methods for safety testing
- Include earthworms toxicity testing standard protocols
- Are uses by professionals in industry, academia, and government involved in the testing and assessment of chemicals
Risk assessment
Risk quotient = PEC (predicted enviromental concentration) / PNEC (predicted enviromental no effect concentration)
Risk ratio >1 => Potential risk
Risk ratio <1 => Risk is low
-Combines on exposure assessment and a hazard identification
Alternative methods for ERA
- Use of microcosm and mesocosm studies
- Use of predictive models
- Use of vitro techniques
- Field studies
- Using live vertebrates
- Modeling work
Protective biochemical response
- Induction of monooxygenase enzymes => metabolites
- Induction of MT - binding protein
- Response that correct damage after it has occured
- Induction od stress protein
- DNA repair
- Conjugate by glutathione S-transferase
Biomarker for endocrine disruption
- Aromatase
- Vitellogenin
Kidney to toxic injury
- Chemicals in the systemic circulation are delivered to the kidnet in relative high amount
- Kidneys concentrate potential toxicants during the urine formation process, particularly exposing toxic substanes to the tebular cells
Formation of DNA adducts
- Correspond to covalent binding of the pollutant wtih DNA
- Can be used as a biomarker of exposure of genetoxic compounds
Ache (acetylcholineterase) inhibition
- Is a biochemical adverse effect induces by several organic insecticides
- Can induce neurotoxic symtoms in organism
- Induces an excess of acetylcholine in synapses
Acting carcinogenes
-Interact with and bind to neurophillic molecules
Density-dependent factors in population analyse
- Mutalism
- Prevalence of disease
Functional approach studies communities
- Can provide a simple measure of the state of a community or ecosystem
- Can measure the peration of the carbon cycle or nitrogen cycle in soils
Genotoxic
Carcinogens that interact with DNA resulting in mutation
- Mutagenic
- Can be complete carcinogens
- Tumorigenicity is dose response
- No theoretical threshold
Nongenotoxic
Carcinogens that modify gene expression but not damage DNA.
- Nonmutagenic
- Threshold, reversible
- Tumorigenicity is dose responsive
- May function at tumor promotion stage
- No dirrect DNA damage
- Species, strain, tissue, specificity
Carcinogens - Multi stage process
Inhitiation -> Promotion -> progression
- Inhitiation -> gene mutation
- Promotion -> Enhanced proliferation
- Progression -> Further growth, invasion and metastasis
Endocrine system
Messenger system in the body
- uses hormones, signaling molecules which travel though the bloodstream
Endocrine - disrupting chemicals (EDC)
Exogenous chemical or mixture of chemicals that can interfere with any aspect of hormone action
Community
Group or association of population of 2 or more different species occupying the same geographical area
Synecology
Study of structures, development and distribution of ecological communities
Structural approach
- Changes related to changes in composition
- In these extreme cases, species may disappear altogehter from communities in which they are usually found
Nitrogen cycle
1) Nitrogen fixation
2) Nitrogen assimilation
3) Nitrogen ammonification
4) Nitrogen nitrification
5) Nitrogen denification
Endpoints - communities and ecosystem
Set of generic endpoints : Ecological entities and attributes that have been shown to indicate stress or ecposure at higher levels of ecological organization
Communities
- Number of species
- Species evenness
- Species diversity
- Pollution indices
- Community quality indices
- Community type
Ecossytem
- Biomass
- Productivity
- Nutrient dynamics
Pollution- sensitive organism
Organism that require good water quality to survive
Moderately pollytion-sensitive organism
Organism that can survive in fair water quality
Pollution-tolerant organism
Organism that can survive in poor water quality
Biological integrity
Associated with how “pristine” an enviroment is and its function relative to the potential or orginal staet of an ecosystem before human alterations where imposed
Shannon H-index
H=-SUM(Pi*ln(Pi)
Ecosystem
Include biological communities and abiotic proporties that are more generally related to the exchange of energy and nutrients along functionally defined groups of organism and their enviroments
Considere in risk assessment
- Risk
- Benefit
- Cost
Consensus-based assessments
Better understand of env issues.
Promotion of coordinated action by the participants.
Illegal
The potential illegality arises because env laws in the US and most other countries require protection independent of other laws. Ex) The US EPA cannot decide to stop enforcing the Clean Air Act because resources would be more effectively spent enforcing the Clean Water Act.
In addition, prioritization may assign high priority to hazards for which no legal authority for action exists.
Immoral
Most commonly arise from the accusation that technical analysis is used to minimize the legitimate subjective concerns of citizens or to ignore risks to small groups with particular exposures (e.g. indigenous people consuming traditional foods).
Consensus-based prioritization may also provide unequal protection. When prioritization is based on a stakeholder process, there is a potential for higher ranking of the risks that concern the most articulate and influential segments of the pop.
The potential benefits of a rational prioritization process must await a mandate from the highest levels of government to overcome the technical, social and legal issues.
Restoration
Recreating to some extent the ecological structure and function of a site disturbed by a remedial action or any other action.
Risk analysis
Involve quantitatively or quantitatively estimate of environmental risk
Incorporates qualitative or quantitative estimates of selected attributes of environmental hazards
Ex) adverse effects
Characterize how the environment or exposed pop of humans or fish and wildlife might respond by manifesting adverse effects linked to exposure.
Risk assessment:
Incorporates elements of administrative and management policy that reflect an individual’s or organization’s level of risk tolerance or acceptability.
Risk management:
Decisions are developed regarding hazards of environmental chemicals, biota exposed to those hazards, adverse effects associated or potentially associated with those exposures.
Mitigation action are crafted as part of the implementation of those decisions
Outcomes of those decisions are evaluated through monitoring and surveillance of activities.
Stakeholder
Either an individual, group or organization who is impacted by the outcome of a project. They have an interest in the success of the project.
Organism in a population
- Birth rate
- Death rate
- -Moves in and out
To characterize a population: Population size (N) Population density (N/area) Population growth: change of population through time
Projected population : Nt = N0.exp(rt)
Interaction between species
1) Competition
- Species complete for common resource.
- The pop growth rate of each species decrease the more they are of each species
2) Mutualism
- The species benefit from each other.
- The pop growth rate of each species increases the more there are of the other species.
Carrying capacity:
The number of individuals in a population that the resources of a habitat can support; the asymptote, or plateau, of the logistic and other sigmoid equations for population growth.
Density dependent:
competition, predation, mutualism, disease, etc. As population size approaches the carrying capacity of the environment, the intensity of density-dependent factors increases. For example, competition for resources, predation, and rates of infection increase with population density and can eventually limit population size.
Density independent
physical hazards, exposure to chemicals released in the environment, weather-related events, natural disasters. Other factors, like pollution, seasonal weather extremes, and natural disasters — hurricanes, fires, droughts, floods, and volcanic eruptions — affect populations irrespective of their density, and can limit population growth simply by severely reducing the number of individuals in the population.
Neoplasia
New growth or autonomous growth of tissue
Neoplasma
The lesion resulting from the noeplasia
Benign
Lesion characterized by expansive growth, frequently exhibiting slow rate of poliferation that do not invade sorrounding tissue
Malignant
Lesions demonstrating invasive growth, capable of metastases to other tissues and organs
Metastases
Secondary growth derived from a primary malignant neoplasm
Tumor
Lesion characterized by swelling or increase in size may or may not be neoplastic
Cancer
Malignant neoplasm: Autonomous growth of tissue
Carcinogen
A physical or chemical agent that causes or indices neoplasia
Maglignant neoplasm
invasive growth, spreads to other organs
Benign neoplasm
Slow proliferation, do not invade sorrounding tissue
