MT 2 Flashcards
What is the soil half life of imidacloprid?
1-2 years
What is the water half-life of imidacloprid?
30-160 days
What molecular effect do neonicotinoids have?
agonize nicotinic acetylcholine receptors and take ACh’s place on receptors, preventing its breakdown by acetylcholine esterase
What biological effect do neonicotinoids have?
causes neurotoxicity like tremors, paralysis and death by constantly activating receptors (irreversible)
What Kow value does imidacloprid have and how is it interpreted?
Kow = 0.57
Not bioaccumulative (hydrophilic instead)
What concentrations of imidacloprid, clothianidin and thiamethoxam are acutely toxic in bees?
<2 ug
What are some effects neonicotinoids have in bees?
- learning
- memory
- olfactory/gustation
- flight navigation/orientation
- foraging
How did neonicotinoids affect songbirds in Saskatchewan?
caused weight loss and delays in migration
What is a potential issue when creating neonicotinoid guidelines from lab tests?
lab species’ sensitivity may be lower than species in the ecosystem, so creating guidelines that protects a wide range of species may be challenging
What are Species Sensitivity Distributions and what are they used for?
plots the sensitivities of different number of species onto a curve
used to predict a concentration that can safely protect a given proportion of species (i.e 50%)
How did neonicotinoids affect salmon eggs during acute testing?
15 ug/L exposure to thiamethoxam caused 25% decrease in fertilization, overall exposure caused abnormal growth
no effect from clothianidin or mixture of neonics
How did neonicotinoids affect salmon eggs during chronic testing?
imidacloprid caused increase in estrogen/thyroid receptors
clothianidin caused decrease in glucacorticoid receptor 2, increase in estradiol at 0.15 ug/L (affects gonad development, causes feminization)
no effect from thiamethoxam exposure
How do neonicotinoids affect non-fish species?
rats = imidacloprid caused abnormal LH/FSH levels, ovarian damage; clothianidin in low doses altered male gonad development
birds = general exposure lowered fertilization success, decreased egg thickness and size, lowered offspring survival
mammals = increased aromatase (testosterone –> estrogen enzyme) activity
What is a toxicity modifying factor?
environmental (i.e pH), chemical or biological (i.e age, nutrition, sex) factors that may affect the toxicity of a substance
What did the PMRA review into different pesticides find?
varying impacts on bees/pollinators, and suggested altering practices (i.e no application of fruiting plants during bloom) but all three (imidacloprid, clothianidin and thiamethoxam) are still registered for use
What are some sources of PAHs?
- crude oil
- burning of oil/gas/coal
- burning of trees/houses
- using cigarettes
Give some examples for PAHs
- benzene
- naphthalene
- benzo[a]pyrene
How are PAHs classified in Canada and what does it mean?
- Schedule 1
- means there is a toxic risk to both human (Health Canada) and non-human (Environment Canada) health
What are OSPWs?
Oilsand process-affected water
Any water in contact with oilsands
How can oil spills affect wildlife?
- acutely through death via suffocation (gills/lungs), drowning, hypothermia, inhalation of toxic vapours
- chronically through altering reproductive and immune systems, metabolism of PAHs into harmful intermediate molecules that can damage DNA/RNA, can cause cancer, can affect development
What is an endocrine axis?
a specific pathway of a given hormone and all the organs involved in its expression
What responses does the pituitary gland initiate?
ACTH (in adrenal gland) = production of glucocorticoids
FSH/LH (in testes/ovaries) = production of sex hormones
GH (in various tissues) = growth
PRL (in mammary glands) = production of milk
TSH (in thyroid) = production of thyroid hormones
How did atrazine affect frogs?
male frogs had mutated testes, had ovaries and eggs, and some were completely feminized
What is the mechanism behind atrazine?
activates aromatase (testosterone –> estrogen)
