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Ecotoxicology > Exam > Flashcards

Exam Flashcards

1
Q

Adverse Outcome Pathways

A
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2
Q

Oxidative stress

compounding factors

A

Technical:

  • Tissue/species specific variation for basic procedures

Biological

  • Age, sex
  • reproductive phase
  • tissue

Seasonal

  • Metals
  • Temprature
  • Food availability
  • Oxygen levels
  • UV exposure
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3
Q

Lake Apopka

A

Alligator population

  • From 1957-1981: Tower chemical Co. maunfactured both chlorinated and OP insecticides as well as copper based fungicide as a site 1.5 miles from lake Apopka.

Wastewater from the manufacturing process was discharged into an unlined pond.

During heavy rain in 1980 the percolation pond overflowed; discharged into lake

DDT and other chemicals contaminated the lake

DDT and other pesticides also entered lake as a result of extensive agriculture

DDT’s degraded products-DDE and DDD prime suspects for reproductive abnormalties

[Low hatching rates; depressed testosterone levels in males; raised estrogen levels in females; Mulitple egg cells in folicles; indeterminate male genitalia]

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4
Q

Aromatase in female fish

A

Aromatase inhibition - Reduced E@, Vtg synthesis - Impaired vitellogenesis - reduced fecundity

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5
Q

Fish intersex

A

Early 1980’s

‘Male roach’ were found to be developing eggs

The ‘pill’ affecting the sex of fish

estrogen

Male fish contained high amount of yolk protein precursor vitellogenin

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6
Q

Consequences of Biliary Excretion

A

Increased half-life when compound reabsorbed Toxic metabolites in the gut Increased hepatic exposure; enterohepatic recycling Gut bacteria alter absorption or toxicity of metabolites Saturation of the bile: liver necrosis

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7
Q

OECD Test 201

A

Algae (unicellular) - exposed for 72hrs Recorded density (growth) and growth rate Quality criteria - x16 increase in growth 3 days prior - test substance 80% of initial pH within 1.5 units, temp within 2 degrees

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8
Q

OECD Test 236

A

Acute toxicity test - Fish Embryo Static semi-static, flow-though Control, 5 concentrations, 7 fish/concentration 96h test; record mortalities at 24h intervals - Invalid test: 10% mortality D.O. falls below 60% uncertainty of test substance concentration (80%) pH change of 1 unit Reference substances Solvent controls

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9
Q

Dose Dose-response

A
  • Amount of substance administered/body weight - the dose (amount) that produces a specified effect (e.g. death) Toxicity is a function of exposure time AND dose
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10
Q

Biotransformation

A

2 Phases - Depends on, physiochemical propertied of compound - enzyme type & activity in target organs Phase I: adding a functional (reactive) group Phase II: conjugation to increase water solubility

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11
Q

Glyphosate

A

Herbicide Molecular weight = 161.1

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12
Q

Cyermethrin

A

Insecticide Molecular weight 416.3

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13
Q

Excretion Mechanisms

A

Gills: - low MW, non-polar organic; by diffusion - metals; active transport mechanisms - paracellular routes? Kidney - many compounds removed by filtration - MW

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14
Q

TBT and dogwhelks

A

Observed in 1970

Virilization of femal prosobranchs termed inposex

Formation of a penis and/or vas defence on female gonochoristic prosobranch species.

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15
Q

Absorption of toxins across the gut

A

Depends on physic-chemical properties of the compound Effected by pH - oesophagus neutral - stomach pH 2 anterior intestine ~pH 6 Lipid soluble: thought gut Weak acids: mostly stomach Weak bases, and some weak acids: small intestine Strong acids/alkali; carrier mediated Phagocytosis: e.g. botulinum toxin (micro-organisms, food type and ration size

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16
Q

Fluoxetine

A

Pharmaceutical Molecular weight = 309.33

17
Q

Absorption routes

A

Gills Gut Skin - Epidermis

18
Q

Endocrine distrupting Chemicals

A

Natural and sysnthetic hormones: Oral Contraception

Phyto-oestrogens: Present in food such as soyabeans, cabbage, grains

Alkylphenols and Alkylphenols ethoxylates (APE’s) - Industrial non-ionic, surfactants, detergents, paints, herbicides, pesticides, pulp and paper manufacturing

Phthalates - plasticizers, apints, inks, adhesives

Biphenol A - expoy resins: food cans, bottle tops water pipes

Pesticides - DDT dieldrin, lindane

Polycholrinated Biphenyls (PCBs) - electrical transformers, hrdraulic fuel, flame retardants

Dioxins (product of combustion), Antifouling agents, heavy metals (cadmium, lead and mercury)

19
Q

Excretion Mechanism: Liver

A

Especially important for Large polar and amphipathic substances that cannot be filtered by kidney Excreted in the bile, produced by hepatocytes Compound eliminated with faeces Bile production is an active process - transporters for neutral, anionic, cationic compounds

20
Q

Endocrine disrupting agents: definition

A
  • an exogenous agent that interferes with the, synthesis, secretion, transport, binding, action or elimination of natural hormones in the body that is responsible for the maintenance of homeostatis, reproduction, development and/or behaviour.
  • An endocrine disruptor is an exogenous substance that causes adverse effects in an intact orgainism, or it’s offspring, subsequent to changes in endocrine function.
21
Q

Chemical Distribution

A

Depends on frequency of exposure site of entry into the animal effect of pollutant on blood flow and distribution Plasma concentration will greatly influence equilibrium between blood and tissues - small molecules : pores in capillaries, dissolve in lipid membranes

22
Q

Nonylphenol

A

Detergent Molecular weight = 220.35

23
Q
A
24
Q

Exposure via Gills

A

large surface area small diffusion distance high blood flow few cell layers mucous cells offer some protection trade of with respiration

25
Q

Absorption with the Gut in wild

A

Differences in anatomy and feeding behaviour In aquatic species - large differences in gut lumen chemistry between marine and freshwater fish

26
Q

Chemical Distribution and Plasma Proteins

A

Plasma proteins may facilitate distribution of compounds: - lipoproteins bind DDT - Cu binds to albumins Implications: - reduce the free concentration of the poison in plasma - restrict distribution; but enhance uptake? - saturation of the blood; toxic thresholds - possible to displace the toxin??

27
Q

Biomarker test for toxcology in the aquatic environment

A
  • Baterial
    • Ames test, Mutatox, umu-test, chromo-test
  • Biochemical / Molecular
    • DNA adduct analysis
    • Strandbreak measurements
    • Mutation spectra and expression of genes
  • Cytogenetical
    • Micronucleus assay
    • Chromosomal aberration
28
Q

Biomarkers

A

a biological response to chemical or radiations that gives a measure of exposure/effect at a cellular, tissue, organ, individual or population level

29
Q

Biomarkers at different levels of biological orgainisation

A
  • Behavioural biomarkers
  • Physiological biomarkers
  • Histopathological biomarkers
  • Genetic biomarkers
  • Molecular & biochemical biomarkers
30
Q

Antiflouling Paints

A

tributyltin TBT

First observed in Crassotrea gigas

Ball shaped shell deformaties in adults and decline of annual spatfall (Alzieu et al. 1980)

Lead to break-down of local oyster production with marked economic consequences.

Lab and field test revealed link between TBT exposure.

31
Q

Target tissue and Tissue localisation?

A
  • Lipophilic compounds in fatty tissues - Metals: gills, liver, kidney - Brain; low permeability to polar substances, will absorb non-polar compounds e.g. methyl mercury.
32
Q

OECD Test 202

A

Daphnia Principle: immobilisation of test organism due to toxicity 50% immobilisation = EC50 Immobile not able to swim within 15 sec after agitating container Test criteria: -

33
Q

Main biotransformation reactions

A

Phase I: - most common: oxidation, reduction, hydrolysis - most ecotoxicological studies on oxidation reaction Phase II: - glutathione conjugation, removes creative intermediates

34
Q

Metabolisation of Chemicals

A

Facilitate excretion of lipophilic chemicals transform chemical into less toxic forms metabolite more polar than parent compound plasma half life decreases

Ecotoxicology (1 decks)

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