Lecture 3 Flashcards
Ecotoxicology = ___________ + ____________
Ecology + Toxicology
Define ecotoxicology:
Branch of toxicology concerned with the study of toxic effects, caused by natural and synthetic pollutants, to the constituents of ecosystems - animals (including humans), vegetable, microbial - in an integrated context
The study of harmful effects of chemicals on ecosystems =
ecotoxicology
Substance present in greater than natural concentration as a result of human activity =
contaminant
Substance that occurs in the environment at least in part of human activity and which has a deleterious effect on living organisms =
pollutant
Foreign chemical not produced in nature and not considered a constitutive component of a biological system =
xenobiotic
Processes at one level take their mechanisms from the level below and find their consequences to the level above =
SCALES
SETAC:
Society of environmental toxicology and chemistry
Give me some characteristics of legacy pollutants - ORGANICS
- Contain carbon and more than 1 C-H covalent bond
- C-H = low polarity, low water solubility
- Behaviour (fate/toxicity) dependent upon structure (size, shape, functional groups)
- Natural or anthropogenic sources
PAHs =
Polycyclic Aromatic Hydrocarbons (PAHs)
T or F: PAHs are natural chemicals that are present every time you burn something
T
Describe some characteristics of PAHs:
- 2+ fused benzene rings
- decomposition, pyrolysis reactions
- exist as complex mixtures
- persistent (years to decades)
- natural and anthropogenic sources but mainly anthropogenic
Benzo(a)pyrene is a ____
PAHs
Name 3 natural sources of PAHs
1) Wildfires
2) Oil underground
3) Volcanoes
Name 3 anthropogenic sources of PAHs
1) Burning trash
2) Deforestation (burn wood)
3) War, terrorism, vandalism, theft
PAH fate: with an increased molecular weight the following occurs:
_________________ volatilization
_______________ bioaccumulation
________________ absorption to particles
_________________ solubility (increased Kow)
________________ environmental persistence
- decreased
- increased
- increased
- decreased
- increased
What are some biological fates of PAHs in land (3)
- degradation by soil microbes
- metabolism by plants
- metabolism by soil invertebrates
What are some biological fates of PAHs in water (3)
- degradation by microbes in water and sediment
- metabolism by algae
- metabolism by zooplankton, fish, mammals, and birds
Physical effects of PAHs include:
smothering, reduced light (penetration will impact photosynthesis)
Habitat change effects of PAHs:
- alter pH
- decrease oxygen
- decrease food availability
Toxicity effects of PAHs:
- mainly on cellular membranes and enzyme-bound membranes (easily bind to lipids and penetrate the cells)
- metabolized PAHs are reactive, bind DNA and cause carcinogenesis
PCBs =
POLYCHLORINATED BIPHENYLS *2 benzene rings not fused together
Name some PCB industrial use:
- dielectric fluids in transformers and capacitors
- coolant
- lubricant
- PVC in electrical wires
- caulking sealant
- wood floor polish
Name some PCB properties
- low water solubility (high in solvents/fats)
- low vapor pressure
- high dielectric constant
- high flashpoint
*chlorination impacts physical properties (increased chlorination = increased lipophilicity and reduced vapor pressure)
What is the trade mark name for PCBs?
Aroclors
T or F: PCBs bioaccumulate up food chains in fatty tissues; fatty-fish consumers are most at risk
T
T or F: PCBs are persistent, resist breakdown; cycle between air, water and soil
T
T or F: PCBs are considered a PBT substance
T persistent, bioaccumulative and toxic
______ are chemical substances that persist in the environment, bioaccumulate through the food web, and pose a risk of causing adverse effects to human health and the environment
POPs
Organophosphate insecticides are derivatives of _______________
orthophosphoric acid
Organophosphate insecticides were initially developed as ___________
nerve gas agents to paralyze and kill people
T or F: Organophosphate insecticides have a higher water solubility than PCBs, PAHs, etc
T
Can organophosphate insecticides be considered DDT alternatives ?
Yes because the 1/2 life is shorter, days to weeks
What is the mechanism of action of organophosphate insecticides?
They inhibit acetylcholinesterase activity which blocks acetylcholine metabolism which then causes muscular rigidity/paralysis in insects
