14 risk assessment 2 Flashcards
what is daphnia sp.?
what is toxicity testing?
alot of work
-daily monitoring
-daily maintenance
what is the toxicity testing graph?
what does the toxicant concentration log scale?
what is chemical testing?
-testing single chemicals or mixtures
-mortality, reproduction, other endpoints-deformities
what is environmental testing?
-an example from brazil
-testing environmental media
-predict adverse effects in field organisms
what are test kits?
-provide everything needed (including animals)
-all media, food, etc
-detailed test protocols
what is the suite of aquatic test organisms used in australia?
how do we measure environmental effects?
-sometimes its obvious
-mass mortalities
-hidden mortalities
what are mass mortalities?
-rare (must be high exposure)
-most often increases in mortality not apparent; few extra dead animals often spread over large areas (depends on surveillance)
-often contaminated animals may leave an area before dying and so are never counted
-can be difficult to prove cause
-mortality may not be the most sensitive effect
what are hidden mortalities?
-often only evidence is the absence of a species where it once was or where it ‘should be’
-difficult to prove cause and effect; many unknown environmental variables may explain absence
mortalities may indirectly caused by chemicals
-neurological damage can change behavior
-immunosuppression can result in disease
-endocrine disruptors can effect reproduction
what is kalamazoo river?
-contaminated with PCBS from paper recycling
-almost 80 miles of river flood plain contaminated
-risk assessment predicted severe impacts on all wildlife
-one single data point is worth a ton of prediction
what are passerines?
-eat emergent aquatic insects
-amenable to nest boxes
-eggs collected
-young monitored
what are minks?
-very sensitive to PCBs
-predicted to be no mink population
-found a small but healthy population
-low population mainly due to urban development
-“habitat suitability” studies
-mink do not live in carparks
what are the objectives of risk assessment?
-evaluate the risks
-environmental contaminant, drugs, pesticides, industrial chemical
-evaluate uncertainty data
-set target levels of exposure
-food, air, water, work place
-provide information to agencies
-regulatory agencies, manufacturers, environmental/consumer agencies
what is risk characterization?
what is NOAEL?
what are hazard quotients (HQ, risk)?
-evaluate the observed exposure to some form of reference dose that is assumed to be just below the threshold for effects, the NOAEL, usually called reference dose (RfD)
what is the use of uncertainty factors graph?
what is the worst case scenario?
assume all variable are at their most ‘conservative’
-most sensitive species
-most contaminated food
-if risk is negligible in this scenario then all other scenarios must be at lower risk
-risk is said to be ‘de minimis’
-de minimis refers to a level of risk that is too small to be concerned with, some refer to as a ‘virtually safe’ level
-caution: worse case scenarios are a double edged sword, they can be very misleading if risk is not de minimis
always expect the unexpected graph?
