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43 Cards in this Set
- Front
- Back
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objectives of risk assessment and risk management
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assesses risks and benefits
balance risk and benefits set target levels of risk set priorities for program activities estimate residual risks and extent of risk reduction after steps are taken to reduce risk |
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why do risk analysis?
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to establish regulatory limits (acceptable levels) for chemicals in the food supply, the environment, or the workplace
to determine if remedial action is necessary (establish clean up levels, determine which exposure pathways are most important to develop preventative measures, and determine which environmental media is most involved to select cleanup procedures) to determine land use options |
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hazard
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threat to human health or the environment
cultural - living conditions, smoking, diet chemical - in air, water, food, soil physical - ionizing radiation, noise, fire, floods biological - toxins, bacteria, viruses |
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risk
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probability that a given hazard will cause harm
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safety
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freedom from danger, risk or injury
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risk assessment
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the systematic risk characterization of potential adverse health effects resulting from human exposure to hazardous agents
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risk management
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the process of weighing intervention alternatives and selecting the most appropriate action based on the results of risk assessment and social, economic, and political concerns
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risk communication
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the process of making risk assessment and risk management information comprehensible to politicians, lawyers, judges, business and labor, environmentalists, and the public
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characteristics of risk
(increased or decreased "acceptability") |
increased - voluntary, familiar, detectable by person, fair, noncatastrophic, well understood, natural, trusted source, visible benefits
decreased - involuntary, unfamiliar, undetectable, unfair, catastrophic, poorly understood, artificial, untrusted source, no visible benefits |
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2 components that typically define risk
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1. existence of a hazard
2. likelihood or probability of exposure to the hazard risk = (hazard) x (probability of exposure) |
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factors that influence risk perception
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personal control over the exposure at hand
availability factor (how readily do people associate harm with the hazard?) dread factor (increases with delayed, unknown, unfamiliar, or potentially catastrophic harm) |
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risk SHOULD be defined by 3 components
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1. existence of a hazard
2. likelihood of exposure to hazard 3. perception risk = (hazard) x (probability of exposure) x (perception) |
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risk assessment process
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HAZARD IDENTIFICATION (identifying chemical, physical, or biological agents that may cause adverse effects)
DOSE-RESPONSE (determining what dose/concentration of the agent causes adverse effects EXPOSURE ASSESSMENT (estimating the type and magnitude of chemical exposure) --lead to --> RISK CHARACTERIZATION (estimate the incidences of health effects under various conditions of exposure) |
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hazard identification
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does the agent cause adverse effects?
data analysis relation contaminant and exposure to disease produced characterization of contaminant behavior with body inference whether toxic effect in one setting (e.g. in animals) will occur in other settings (e.g. humans) |
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sources of information for hazard identification
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human epidemiological and clinical studies
animal data in-vitro data structure-activity relationship (in silico) *in silico - could a structure be a risk because it looks like another structure? |
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a positive bioassay in animals is sufficient proof of ______
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a cancer hazard in humans
(humans are at least as sensitive as the most sensitive animal species) |
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exceptions to the ability to compare animal cancer with human cancer
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kidney tumors in male rats
(rats produce the 2mu globulin protein which is an important in the mechanism of carcinogenesis, humans don't) |
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the cosmetics directive of the european union
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a regulatory framework for phasing out animal testing. it establishes a prohibition to test finished cosmetics products and cosmetic ingredients on animals, and a prohibition to market in the european community finished cosmetic products and cosmetic ingredients included in cosmetic products which were tested on animals
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REACH
(registration, evaluation, authorization, and restriction of chemicals) made by the EU |
entered into the force in june 2007
aim - to improve the protection of human health and the environment through the better and earlier identification of the intrinsic properties of chemical substances requirement - manufacturers and importers will be required to gather information on the properties of their chemical substances which will allow their safe handling, and to register the information in a central database run by the European Chemicals Agency Dilemma - what to do about the nearly 100,000 chemicals in use for which there is no or limited toxicity data? |
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dose-response assessment
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what doses or concentrations are adverse effects observed in humans?
requires quantitative toxicity data often involves extrapolation of animal data to human exposure levels involves extrapolation from high does to low doses |
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internal dose
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the amount of an agent that actually enters the body
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administered dose
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amount of an agent given, usually by mouth or injection
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total dose
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sum of all individual doses
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ADI
(dose-response) |
acceptable daily intake - determined by applying safety factors to the highest dose in human or animals studies that does not cause toxicity (WHO pesticides and food additives)
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RfD
(dose-response) |
reference dose - estimated daily dose that is likely to have no appreciable adverse effects during a life time exposure
essentially what is allowable in an environment RfD = NOAEL (LOAEL) _______________ UF x UF2 x UF3... x MF |
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safety factors for risk assessment of non-cancer effects
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all uncertainty factors have a value of 10:
human variability extrapolation of animal --> human use of less than chronic exposure data use of LOAEL (lowest observed adverse effect level) use of NOAEL (no observed adverse effect level) incomplete data base modifying factor (MF) (0-10) - reflects qualitative assessment of the quality of the data |
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example for RfD
1. NOAEL = 50mg/kg/day (epidemiological data) 2.LOAEL - 50mg/kg/day (90 day sub chronic study in rats) |
1. RfD = 50/10 x 1 = 5mg/kg/day
2. RfD = 50/10x10x10x10 x1 = 0.005 mg/kg/day |
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carcinogens are thought to not have a _____
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threshold
(they extrapolate) |
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major EPA assumptions and defaults for hazard and dose response
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select human data over animal data
use animal data when human data is inadequate apply standard uncertainty factors to scale between species apply linearized multistage model for low dose extrapolation of carcinogens |
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exposure assessment
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what exposures are experienced or anticipated under different conditions?
characterize the exposure setting identify the actual or potentially exposed populations identify routes of exposure (exposure pathways) estimate magnitude of exposure |
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specific questions to be addressed in exposure assessment
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which environmental compartment contain hazardous material?
what is the concentration of the hazardous agent in various environmental media how long is each exposure and how often does this exposure occur? what seasonal and climatic variations alter exposure? bioavailability are there susceptible populations at risk of exposure? |
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input for conceptual site model development
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who may be exposed?
how may they be exposed? how are contaminants transported to targets? what info is missing? how does exposure change through time? |
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risk characterization
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what is the estimated incidence of an adverse health effect under the various conditions of exposure described in the exposure assessment?
depends on the dose-response and exposure assessment estimates the potential for adverse health effects to occur includes evaluation of assumptions and uncertainties involved includes a summary of the information |
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risk assessment uncertainties
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hazard identification - use of animal data and negative epidemiological studies
human exposure evaluation - modeling vs. ambient and monitoring vs, biological monitoring dose-response evaluation - extrapolation form high to low dose and extrapolation from animals to humans risk characterization - quantitative or qualitative |
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qualitative risk assessment
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qualitative characterizations where health risks are identified but not quantified
qualitative risk estimations where chemicals are ranked or classified by broad categories of risk semi-quantitative approaches where effect levels (e.g. NOAEL) are used in combination with uncertainty factors to establish "safe" exposure levels |
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qualitative risk assessment: EPA classification of carcinogens
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group a - carcinogenic to humans
group b - probably carcinogenic to humans croup c - possibly carcinogenic to humans group d - not classifiable as to human carcinogenicity group e - evidence of non-carcinogenicity for humans |
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legal definition of acceptable risk
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de minimis concept (law does not concern itself with trifles)
in some cases, the computed risk is so small that it does not justify regulation designed to protect down to a level of one in a million (essentially zero, virtually a "safe dose") |
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how do you identify intervention strategies and prioritize?
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"risk-based" approach - define an acceptable level of risk and do whatever it takes to reduce risk to that level
"risk informed" approach - define an acceptable level of risk, and see whether or not risk can be reduced to that level given economic, political, and social considerations (if so great, if not, redefine the acceptable level of risk) |
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"risk based approach" to interventions
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1. define an acceptable level of risk
2. refer back to the quantitative risk assessment to determine what exposure or dose confers that level of risk 3. identify intervention strategies to achieve limit of exposure or dose to that required, and calculate the costs of each option 4. pick the intervention that costs the least |
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"risk informed approach" to interventions
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1. define an acceptable level of risk
2. refer back to the quantitative risk assessment to determine what exposure or dose confers that level of risk 3. identify intervention strategies to achieve limit of exposure or dose to that required, and calculate the costs of each option 4. determine if all the options are at odds with economic, political, and social considerations |
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risk communication and risk management are destined to fail unless they are structured as a _________ process
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two-way
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human limitations to risk communication
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its hard to think clearly about risk
peoples perceptions of risk are often inaccurate risk information my frighten and frustrate the public presentation format is very important |
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who the public trusts
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more afraid of...
anything that has to do with industry communications from politicians decision making processes that are closed less afraid of... anything connected with consumer goods communications from neutral experts open decision making process |
