Lecture 4 - DA Flashcards
What is the problem with organic toxicants? Why are organisms more susceptible to industry manufactured organic toxicants?
Organisms didn’t evolve to be resistant to organic toxicants, especially industry manufactured ones.
Define an organic toxicant, and inorganic toxicant.
Organic - chemical with carbon as the main structural element
Inorganic - chemical without carbon as the main structural element
Name 6 examples of organic toxicants.
Hydrocarbons Halogenated hydrocarbons Endocrine disrupting chemicals Pharmaceuticals Detergents Effluents
What is the polarity and solubility (water and lipid) of hydrocarbons?
Low polarity
High lipid solubility
Low water solubility
What enzyme pathway do hydrocarbons have a biological effect on? Give 2 specific examples.
Detoxifying enzyme pathways
Cytochrome P450 enzymes (CYP) and EROD enzyme pathway
What are halogenated hydrocarbons?
Hydrocarbons with halogens such as fluorine, bromine, and iodine.
What physical properties do halogenated hydrocarbons have?
Stable, uncreative, and viscous.
Are halogenated hydrocarbons soluble in water? What about oil?
Not soluble in water, but is in oil.
Name 3 general halogenated hydrocarbons. Are they very toxic or moderate?
Organochlorines
Organobromines
Organofluorines
Very toxic, have been blacklisted.
How are halogenated hydrocarbons taken in by aquatic organisms? What about terrestrial?
Aquatic - uptake from diet, and surrounding water.
Terrestrial - uptake from diet, dermal, and inhalation.
How do algae handle halogenated hydrocarbons? Are they susceptible to it?
Algae adsorb them, they arent susceptible, but still pool it.
What are two major pools of halogenated hydrocarbons?
Algae and sediment.
Where do halogenated hydrocarbons go once taken in?
Goes to the blood, then skeletal muscle. Is metabolised there, and redistributed to fat. If the organism is able, it will excrete it instead of fat storage.
Name a major route of metabolising halogenated hydrocarbons. Name an example of a pathway using this.
Hydroxylation, done by liver microsomal mixed function oxidase - MFO.
EROD pathway uses this.
Where are unmetabolised high chlorine content halogenated hydrocarbons stored?
In lipids.
Can unmetabolised halogenated hydrocarbons cross the placental barrier? Is it present in breast milk?
Can cross the barrier.
Is present in breast milk.
What is a cumulative toxicant? Are halogenated hydrocarbons a cumulative toxicant?
Repeated doses are additive. Halogenated hydrocarbons are cumulative.
What effect do halogenated hydrocarbons have on liver weight? What organelle proliferates? What effect does it have on steroid hormones?
Increases liver weight
Smooth ER proliferates
Degrades steroid hormones
What is a characteristic response to halogenated hydrocarbons from all animals?
Reproductive problems.
What are dioxins?
Extremely toxic compounds, formed as unwanted byproducts during synthesis of other compounds.
What interaction do dioxins have with soil? Is this a problem for plants?
Binds tightly to soil, therefore not a problem.
Do dioxins leach? Can they be degraded?
They do not leach.
Can be degraded, but has a long half-life.
What effect do dioxins have, and where does it accumulate?
Teratogenic effects, deformities, and reproductive problems.
Slowly accumulates in the liver.
Are endocrine disrupting chemicals natural or synthetic?
Can be both.
Name 5 endocrine disrupting chemicals.
Some pesticides, metals, some halogenated hydrocarbons, oestrogen, and androgen.
Where do endocrine disrupting chemicals come from?
Domestic sewage, cattle feedlot, agricultural runoff, effluents, landfills, mining activity.
What are thyroid hormones responsible for?
Metabolism and metamorphosis.
Name 3 sex hormones.
Oestrogen, progesterone, and testosterone.
What does an oestrogenic disruption cause?
Feminisation of males, reduced fertility.
What is does an anti-oestrogenic disruption cause?
Altered maturation, reproductive problems
What does an androgenic disruption cause?
Masculinisation of females.
What does an anti-androgenic disruption cause?
Reproductive problems
What are pharmaceuticals?
Synthetic compounds developed to treat diseases, are targeted and specific.
How do pharmaceuticals enter the environment?
After passing through humans, into sewage.
What are three types of detergents?
Anionic
Cationic
Non-ionic
What do anionic detergents contain?
Sulphate, sulphonate, carboxylate ions.
What do cationic detergents contain?
Ammonium salts.
What do non-ionic detergents contain?
Alkylphenol ethoxylates - APEs
What is nonylphenol? How is it released?
Common non-ionic detergent. Released in industrial effluents.
What is nonylphenol similar in structure to? What does this lend it?
Similar to oestrogen, binds to oestrogenic receptors - is oestrogen mimmicking.
What endpoint is useful for measuring nonylphenol?
Meaure vitellogenin in male fish. Is normally found in female fish.
Oestrogen mimicking effects of nonylphenol will cause vitellogenin presence in male fish.
What are effluents?
Cocktail of chemicals.
The ability of a chemical to bioconcentrate is related to what? What is a major factor influencing this?
Rate of uptake vs rate of elimination.
Affected by lipid solubility.
Define bioconcentration.
Process by which chemicals enter the organism from the environment.
Define bioaccumulation.
Like bioconcentration, along with accumulation of chemicals from diet.
Define biomagnification.
Like bioconcentration and bioaccumulation, tissue concentration of chemicals increase at higher trophic levels - ie mercury in sea creatures.
What is the bioconcentration factor?
The ability of an organism to accumulate a toxicant from the environment.
How is the bioconcentration factor calculated?
Take the concentration of the chemical in the tissue, divided by the concentration in the environment (water or soil).
What is the octanol-water partition coefficient?
Kow. Is a chemical method of expressing the lipophilicity of a chemical.
How is Kow calculated, and what is done to linearise it?
Is logged to linearise.
Log Kow = log ([toxicant in octanol] / [toxicant in H2O])
