Environmental Toxicology Notes Oct 10 - Neonicotinoids (Imidacloprid): most common pesticide - Issues: colony collapse disorder o Due to neonicotinoids o Disease (mites) o Habitat loss o Climate change - Most toxins become more toxic at higher temperatures (related to climate change) Frog deformities - Causes o Chemicals o UV exposure o Chytridiosis (fungus) o Trematodes Ozone and chlorofluorocarbons (CFCs) - Montreal protocol in 1988 banned CFCs - Ozone is a protective layer that blocks UV rays - Ozone thinning around equator area - However ozone is repairing at the north and south pole - Changing atmospheric circulation due to climate change - Very short lived substances (VSLSs) such as paint thinners and solvents Environmental Issues - Legacy issues (pesticides and industrial chemicals) o DDT - Recent issues (ozone depletion) - Emerging issues (ocean acidification due to CO2) o Complete loss of coral reef possible - All are caused by anthropogenic activities and typically involve some form of pollutant Pesticides and Industrial Chemicals - Minamata disease: mercury and fish consumption advisories in Great Lakes - Pesticides: DDT, colony collapse disorder - PPCPs: antibiotic resistance - Endocrine disruption: feminization/masculinization - Microplastics potentially an issue Ban of Chemicals - Mostly chlorinated
- Ecotoxicology: brings an ecological focus, looks at effects of chemicals on populations and communities o Not an individualistic view, more of a group view Structure and Function - Structure: what is present in the system (abundance, diversity, biomass) - Function: what the structural components are doing in the system (interactions between populations and abiotic environment o Flow of energy and nutrients o Primary production o Consumption of biomass o Providing food to predators o Processing organic matter (decomposition) Ecosystems - Temporal changes: daily vs seasonal changes - Spatial changes: change of place: different areas, stream segment versus river system Ecosystem states - Present state (structure and function) - Then you disturb it - Turns into a transient state - If it stops, the system can recover (resilience) and return to present state - If it does not stop, can move to a new state (regime shift)
Risk assessment 1. Assessment endpoints 2. Measures of effect (test endpoints) Assessment endpoints - Need criteria to identify risks - Explicit expressions of the actual value to be protected - Ecologically relevant - Responsive to the stressor - Societal value
- Unambiguous (specificity/minimal uncertainty) Endpoints and effect measures - Measurable characteristic (ex: test endpoints such as mortality, growth, reproduction) that is related quantitatively or qualitatively to the AE - Should consider both direct and indirect effects - Should integrate sensitivity and response time - Should have high diagnostic capacity - Should consider practicality issues Characterizing effects - toxicity involves three components o Potency - exposure concentration or dose o Time - duration of exposure o Response - just because you have exposure, doesn’t mean you will have an effect -
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