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Lecture 10 Risk assessment.pdf Flashcards
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Lecture 10 Risk assessment.pdf Flashcards
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What is risk in the context of risk assessment?
Risk is the possibility or probability of suffering harm from a hazard.
What does the risk paradigm in risk assessment involve?
The risk paradigm includes contaminants, receptors, exposure pathways, and the assessment of risk.
Why is risk assessment considered important in regulatory science?
Risk assessment is essential as it may require action even without full scientific understanding of a hazard, setting default procedures to bridge gaps in scientific knowledge.
What are the phases involved in Environmental Sites Assessment for Risk Assessment?
The phases include Phase I - Assessment, Phase II - Characterization, Phase III - Remediation, and Phase IV - Management Verification.
What does Risk Assessment Verification involve in Environmental Sites Assessment?
Verification includes sampling to confirm estimates, management plan development, and a technical scientific assessment of risks.
What are the benefits of risk assessment according to the Natural Research Council?
- Helps rank contribution to overall risk - Helps identify risks that are easily reduced or eliminated - Helps clarify what is known and not known about the situation - Provides quantitative information for decision-making
What are some applications of risk assessment mentioned in the text?
- Health Canada regulations for foods and drugs - Canada Council of Ministers of the Environment - National Contaminated Sites Program - Canada Wide Environmental Standards - Ontario Ministry of Environment - Site-specific cleanup guidelines for contaminated soils - CEPA (Canadian Environmental Protection Agency)
What are the stages of risk assessment outlined in the text?
1. Problem Definition 2. Identify Contaminant 3. Receptor Analysis 4. Pathways Analyses 5. Exposure Assessment 6. Toxicity Assessment 7. Risk Characterization 8. Uncertainties 9. Critique
What stages were part of the Risk Assessment Framework in the past?
- Problem Definition - Contaminant Screening - Receptor Screening - Pathway Analysis - Conceptual Exposure Model - Exposure Assessment - Toxicity Assessment - Risk Characterization - Qualitative Stage - Quantitative Stage
What factors are considered in the Problem Definition stage of risk assessment?
- Purpose - Management goals - Policy context - Audience - Hazard definition - Receptors - Level of funding
Identify Contaminant
Single compounds or complex mixtures with a few compounds driving toxicity. Found in contaminated soil, air pollution, or other sources of exposure.
Receptor Analysis
Involves studying organism species or groups exposed to stressors. A scenario is defined for the average person, considering age, gender, and other factors. Sensitive subpopulations, like children, are of recent interest. Exposure length, latency for cancer, and routes of exposure are defined.
Pathways Analyses
This step determines the environmental fate leading to exposure of the receptor. Routes of exposure are evaluated, and the amount of exposure is quantified using methods like DOSE, measurements, and modeling.
Exposure Assessment (1)
Involves quantifying exposure from multiple routes like air, water, soil, sediments, diet, and others.
Exposure Assessment (2)
The exposure (g of chemical/day) is calculated as Concentration x Intake Rate for ingestion, inhalation, and dermal contact. Total exposure is the sum of exposure from food, air, and dermal contact.
What does EDI stand for in exposure assessment?
Estimated Daily Intake
What is the formula to estimate dose for each exposure medium?
EDI = IR x C x B x EF x ED / BW
What does IR represent in the dose estimation formula?
Intake rate (m3 air/day or kg food/day)
What does C represent in the dose estimation formula?
Chemical concentration (mg/m3 air or mg/kg food)
What does B represent in the dose estimation formula?
Bioavailability factor (fraction of chemical available for uptake in organism)
What does EF represent in the dose estimation formula?
Exposure frequency (days/year)
What does ED represent in the dose estimation formula?
Exposure duration (days)
What does BW represent in the dose estimation formula?
Body weight (kg)
What is the exposure factor formula in the context of EESA10?
Exposure factor = 3 d/week x 52 weeks/year x 4 years
What are the components of total EDI in exposure assessment?
Total EDI = EDI food + EDI air + EDI dermal
What is a fundamental assumption in chemical risk assessment regarding noncancer effects?
Noncancer effects have thresholds
What is the main difference in risk assessment approach between carcinogenic and non-carcinogenic effects?
Carcinogenicity has no threshold, while noncancer effects have thresholds
What are the key steps in the assessment of noncarcinogenic hazards?
1. Exposure assessment to measure or estimate dose in mg/kg/day 2. Hazard identification to establish a range of noncancer effects and select one as the basis
What is the process for determining dose-response relationship in non-carcinogenic hazard assessment?
Conduct a chronic rodent bioassay to determine the NOAEL (No Observed Adverse Effect Level) and LOAEL (Lowest Observed Adverse Effect Level) from the graph.
How is the reference dose (RfD) derived in non-carcinogenic hazard assessment?
The RfD is derived from the rodent NOAEL or LOAEL by dividing it by uncertainty factors to make it lower and more protective.
What does the hazard quotient (HQ) indicate in risk characterization for non-carcinogenic hazards?
The hazard quotient is unitless and indicates the potential for harm at the actual or estimated dose compared to the reference dose.
What are the weight of the evidence categories for carcinogenicity defined by IARC?
Group 1: Carcinogenic to humans, Group 2A: Probably carcinogenic to humans, Group 2B: Possibly carcinogenic to humans, Group 3: Not classifiable as to carcinogenicity to humans, Group 4: Probably not carcinogenic to humans.
What is the purpose of the cancer slope factor in carcinogenic hazard assessment?
To estimate the potency of a carcinogen by calculating the cancer risk per mg/kg/day based on chronic rodent bioassay data.
What does RMOS (Relative Margin of Safety) calculate in the assessment of carcinogenic hazard?
RMOS calculates the exposure level that results in an acceptable risk, comparing the Risk specific Dose (RsD) to the acceptable risk based on the slope factor. An RMOS of 1 indicates an acceptable risk.
What is the Precautionary Principle?
When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not fully established scientifically.
How does the Precautionary Principle apply according to the European Commission Communication in 2000?
It applies where scientific evidence is insufficient, inconclusive, or uncertain, and preliminary scientific evaluation indicates that there are reasonable grounds for concern that potentially dangerous effects may be inconsistent with the high level of protection chosen by the EU.
What are some examples of the precautionary approach mentioned in the text?
International agreements like the Kyoto Protocol on global climate change, Montreal Protocol on ozone-depleting chemicals, US Toxic Substances Control Act, European Union's REACH program for new chemicals, and the use of the CCA wood preservative.
What are some lost opportunities for precaution mentioned in the text?
Widespread long-term use of asbestos, large-scale development and use of synthetic organic chemicals (e.g., DDT), depletion of global fisheries, and food industry practices amplifying mad cow disease and causing human illness.
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