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ENVI 165 Long Exam 1 > Framework for Risk Assessment > Flashcards

Framework for Risk Assessment Flashcards

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1
Q

Risk Assessment Framework

5

A
  1. Problem Formulation
  2. Hazard Identification
  3. Dose-Response Assessment
  4. Exposure Assessment
  5. Risk Characterization

PHEDR

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2
Q

What is the main goal of problem formulation?

A

to figure out the technical and analytical approach

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3
Q

Subgoals of problem formulation

A

Goals:
1. Identify issues to be assessed
1. Identify goals, breadth, depth, and focus of risk assessment (like scope & limitations)
1. Establishes who the decision maker, stakeholders, risk assessor are

what, so what, who

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4
Q

Differentiate

Problem Formulation - Outputs

2

A

Conceptual model
* Taken from literature
* environmental stressors, pathways, sources, populations at risk, potential adverse effects

Analysis plan
* how to locate pollution data
* What chemicals of concern
* How to assess & measure doses, exposures
* what risk metrics to use
* Other technical requirements

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5
Q

Importance of Problem Formulation 3

A
  1. Ensure commitment of stakeholders & decision makers
  2. Better chance of finding acceptable policy solution
    * Stakeholders & DMs should be in process from very beginning — some sort of ownership on the decision
  3. Save time and resources
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6
Q

Explain the main challenge of Problem Formulation

A
  • Need to balance extensive dialogue & practical efficiency
  • Can take away time
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7
Q

Hazard Identification - Goal

A

to understand the extent of harm caused by a specific hazard

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8
Q

Hazard Identification - 4 subgoals

A
  1. determine adverse effects related to exposure
  2. do an RRL - choose from data & evaluate supporting scientific evidence (maganda ba)
  3. produce a list of potential toxic effects - so people know wtf is going on
  4. establish causation - describe nature & strength
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9
Q

List

Hazard Identification - Sources of Evidence

4

A
  1. Epidemiology
  2. Toxicology
  3. In-vitro studies
  4. In-silico studies
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10
Q

Describe

Epidemiology as a Source of Evidence for Hazard Identification

A
  • observational human studies
  • Mostly observational, about correlations
    * No controlling of variables/experimenting
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11
Q

Toxicology as a Source of Evidence for Hazard Identification

A

experimental animal evidence
* More definitive causation
* Arguments surrounding testing on animals
* Concerned w/ symptoms & doses
* we shifted towards this bc it’s unethical to do it on humans

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12
Q

In-vitro studies as a Source of Evidence for Hazard Identification

A

in-vitro studies – cell-based studies
* Eg. Ivermectin – tested on a petri dish
* Principle of emergent property: cell acting different outside of its system
* Works well for dermal absorption properties – Estee Lauder is leaning more towards in-vitro testing now

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13
Q

Define

Principle of emergent property

A

cell acting different outside of its system

it gains the property when it works with other components in a system, however the property does not manifest when the cell is by itself.

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14
Q

In silico stu stud as a Source of Evidence for Hazard Identification

A

computer modelling
* How a variant can mutate
* How substances will be stored, excreted etc. in & from body

Note Garbage in, garbage out – data should be quality to get quality conclusions
* Eg. MMDA claimed to have models that helped in their decision making, & their outputs were always crap – maam questions the data of MMDA
* Still needs data from other fields

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15
Q

What is assessed during Hazard Identification?

5

A
  • Contaminants, its degradation products, and metabolites
  • Determinants of toxicity
  • Adverse health effects – typically broad
  • Characterization based on effects, target organs, and mode of action
  • Weight of evidence analysis

wadcc

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16
Q

List

Determinants of hazards’ toxicity

6

A
  1. Level, frequency, and duration of dose/exposure
  2. Demographic of exposed populations
  3. Routes of exposure
  4. Absorption and metabolism of contaminants
  5. Physical form of contaminant
  6. Presence of other contaminants (synergistic or additive effects)
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17
Q

Describe

Adverse health effects

A
  • usually broad

Includes
1. Overt diseases (cancer, birth defects)
1. More subtle biological effects (alterations in gene expression)
1. Upstream effects - effects that can play an early role leading to disease

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18
Q

Define

Upstream effect

A

effects that can play an early role in leading to disease

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19
Q

Biological endpoint

A
  • A direct marker of disease progression;
  • Describes health effects (or probability of health effects) from exposure to a hazard
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20
Q

Define

mode of action

A

how substance affects the target cell or organs

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21
Q

Define

Weight of evidence analysis

A

judgment on whether the body of evidence available supports the conclusion that a substance is a hazard to humans

  • Assess which ones to follow/not follow
  • Look at methodology & method of analysis
  • Ex. cigarettes: tobacco is organic, formaldehyde is preservative, tar is carcinogen, nicotine is stimulant
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22
Q

Importance of Hazard Identification

A
  1. High quality scientific studies = best evidence
  2. Human data is the gold standard
  3. Use of Epidemiological studies
  4. Use of Toxicological studies
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23
Q

Issue w/ High quality scientific studies

A

best evidence, BUT
1. Not always available
2. Design and methodological limitations

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24
Q

Issue w/ Human data
1. Use of Epidemiological studies
1. Use of Toxicological studies

A

Studies examine occupational populations not representative of general population

aka, Done on healthier humans

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25
Issue w/ Use of Epidemiological studies
1. Limited by uncertainties on amount and duration of exposure; 1. Presence of potential confounders
26
Issue w/ Use of Toxicological studies
Challenge of determining relevance to humans
27
# List Dose-Response Assessment Goals | 2
* Characterize relationship between dose & adverse effect * To estimate toxicity values, the dose makes the poison *
28
Define adverse effects
likelihood/severity
29
How do we characterize dose & adverse effect?
Mathematical models: Dose-Response Relationship For each adverse effect To pinpoint with effect will come out first
30
Explain The dose makes the poison, and provide examples
Impt to estimate toxicity values bc everything can be poison given the right amount Ex * rashes from sun poisoning * too much oxygen → go blind * too much water → ??? i forgot
31
Differentiate Carcinogen vs noncarcinogen
Carcinogens * Mode are assumed to have no threshold * aka all levels have some risk * Ex. asbestos, PAHs Noncarcinogens * act in relation to a threshold * low levels may occur without adverse effects * Some concentrations will be okay, /then/ adverse effects happen * Ex. pollen, dust, asthma Both * after biological threshold, ↑ exposure = ↑ severity of adverse effect
32
How do we estimate toxicity values?
At what dose makes adverse effects start
33
T/F We are 100% sure that noncarcinogens are noncarcinogens
F * we are never really sure until someone gets cancer!
34
Which thresholds exist for **carcinogens**? How are they used?
* Model is fit to available data → derive slope of **dose response curve** * Cancer slope factor (CSF) or unit cancer risk (UCR) is derived from slope * With exposure data, CSF is used to characterize risk
35
Which thresholds exist for noncarcinogens? How are they used?
* NOAEL: no observed adverse effect level or * LOAEL: lowest observed adverse effect NOAEL & LOAEL are used as a point of departure (POD) for extrapolation for reference dose (RfD) * Used with exposure data to characterize risk
36
Define RfD
reference dose * dose without risk if chemical exposure occurs over a human lifetime
37
What is the value for Uncertainty Factors Values
Value of 10 for interspecies & intraspecies extrapolation
38
Differentiate Interspecies vs Intraspecies extrapolation
Interspecies * NOAEL from animal studies * We favor some animals over others bc of extrapolation factor * Farther it is = more extrapolation Intraspecies extrapolation * accounts for natural variability in response in human populations
39
What is an additonal factor for sensitive/vulnerable populations
RfD = (NOAEL / uncertainty factors) RfD: reference dose
40
What are the issues with thresholds for carcinogens & noncarcinogens?
Scientific evidence suggests contrary shit: * Noncarcinogens do not always have a threshold * Carcinogens may have a threshold “Carcinogenicity” determined to vary widely
41
What is a possible solution for issues regarding thresholds for carcinogens & noncarcinogens?
Use benchmark dose (BMD) to replace NOAEL/LOAEL * BMD: estimate of dose at which a specific increase in adverse effect (aka BMR) is apparent * BMR: benchmark response
42
List Important threshold variables (carcinogens & noncarcinogens) 2 carci+ 4 non + bonus 2
CSF - cancer slope factor UCR - unit cancer risk NOAEL - no observed adverse effect level LOAEL - lowest observed adverse effect level POD - point of departure RfD - reference dose New: BMD - benchmark dose BMR - benchmark response
43
Define Exposure assessment
to identify actual or likely exposure/dose in a given population
44
List Goals for Exposure Assessment 3
(1) Calculate and estimate potential exposures (2) Determine concentration of substance of interest (3) Describes substance and exposed population
45
How does Exposure Assessment calculate and estimate potential exposures?
* identifies heaviest/most likely exposure pathway * Informs you for management strategies
46
Which aspects of the **substance** are described whe doing an Exposure Assessment?
* magnitude * duration * timing * route of exposure
47
Which aspects of the **exposed population **are described whe doing an Exposure Assessment?
* size * nature * categories
48
Differentiate Exposure vs Dose
Exposure: chemical contact on outer boundary of the person Dose: amount of chemical taken in the body Note: * Sometimes dose < exposure * Not likely na dose = exposure
49
List Categories for Identifying Information 4
1. Characterizing **exposure setting** 2. Identify exposure **pathways** 3. **Quantify exposure** (magnitude, frequency, duration) 4. Quantify potential **human intake**
50
T/F Our main exposure pathways are the dermal, mucosal pathways, as well as our private parts
Private parts not really
51
How do we quantify exposure? 3
1. magnitude 2. frequency 3. duration
52
Unit for quantifying potential human intake
unit body weight per unit time mg/kg-BW/day * mg/kg - unit * BW - body weight * /day - Per unit time
53
Differentiate 2 types of exposure
Acute: bursts * relatively short period of time Chronic: Tends to be continuous * long periods of time, pwede pang lifetime
54
List Exposure Characterization Methods (Exposure Assessment) 6
1. Direct/Indirect measurements 2. Surveys 3. Biomonitoring 4. Modeling 5. Average Daily Dose (ADD) 6. Lifetime Average Daily Dose (LADD) DBSMAL
55
Differentiate Direct vs Indirect measurements
Direct: directly measure * Actual frequency, intensity, and/or duration Indirect: use an indirect metric * Sampling air, water, soil, or food products * number of headaches from fumes
56
What kinds of surveys show Exposure Characterization Methods? What issues arise from surveys?
* actual/hypothetical habits involving a particular exposure pathway * Problem: people overreport or underreport – produces uncertainty
57
How is biomonitoring an Exposure Characterization Method?
* we take **Biological samples/biomarkers** (Blood, hair, urine, fecal matter, etc) * also measure concentrations of **substances or metabolites** (But metabolites dont stay in the body for a long time)
58
How is Modelling an Exposure Characterization Method?
* Math modeling can estimate hypothetical exposure * Ex. COVID particles travelling in a bus wow p6)
59
Identify & Differentiate ADD vs LADD
Average Daily Dose (ADD) * Estimate of average daily dose level * acute/subchronic/chronic? * For non-cancer endpoints Lifetime Average Daily Dose (LADD) * Estimate of average daily **over a person’s lifetime** * Lifetime exposure for both cancer and non-cancer endpoints We are obsessed w/ lifetime exposures lol (ex. Blue light exposure)
60
Explain “Without exposure, there is no risk”
Risk will always be present, but our exposures vary. * Variability across popu = diff exposures (individuals, geography, and time) * Substances move across the environment So, we use exposure defaults
61
Define Exposure Defaults Why do we use them, when exposures vary?
assumptions about common exposure patterns * Ex. an average adult drinks 2L water per day and breathes 22 cu. meters of air per day * We make the generalization so that it’s easier for policy
62
Define Risk Characterization
To **synthesize** the risk for a **specific** population
63
List Goals of Risk Characterization 3
1. Make **judgement** on risk to population 2. Characterize **uncertainty** 3. **Synthesize** risk for a particular health effect from a particular substance. Note * Respond to original problem formulated * Allow for separation of policy judgements from scientific findings.
64
List Methods of Risk Characterization
1. Population cancer risk 2. Bright Line 3. Hazard Index 2. Margin of Exposure
65
Explain population cancer risk
Population cancer risk = CSF x LADD (Cancer Slope Factor, Lifetime Average Daily Dose) [All are acceptable] Risk of: * 1 in 1000000 * 1 in 100000 * 1 in 10000 Siyempre u want 1 in 1M but the others are fine; depends on manager
66
Explain Bright LIne
Standard intended to be **clear** and **prevent subjective** interpretation Usually uses calculated RfD to guide risk management < RfD is usually acceptable
67
Explain Hazard Index What values are below and above concern?
Relationship bet. actual pop exposure and an established RfD More specific way to compute acceptable risk (compared to just < RfD) HI < 1 - below RfD; low risk HI > 1 - above RfD; concern
68
What is a risk manager’s job?
* be a technical expert * must write v good executive summary (what politicians usually read)
69
Explain Margin of Exposure What values are below and above concern?
Compares exposure to a NOAEL or BMDL * MOE > 100 - relatively low risk * MOE = 1 - risk level is of concern
70
How does risk characterization help understand the greater risk of the most highly exposed?
* usually on a normal distribution graph For avg population (mean or median of exposure distribution) For individuals at highest end of exposure distribution (90th/ 95th/ 99th percentiles) * at greater risk (aka need to consider them the most)

ENVI 165 Long Exam 1 (6 decks)

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