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ENGR 202 > Risk Assessment > Flashcards

Risk Assessment Flashcards

1
Q

How may risk be defined when several different kinds or magnitudes of loss may occur?

A

Risk = (Probability of an undesired consequence) X (Size of the loss).

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2
Q

List 2 ways of reducing risk.

A

Reduce the size of the loss, and reduce the probability that the loss will occur.

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3
Q

List two categories of health risk that are commonly analyzed.

A

Carcinogenic and noncarcinogenic.

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4
Q

Measures to reduce/eliminate risk is only considered when both the carcinogenic and noncarcinogenic risk is unacceptable.

A

False - measures are considered when either carcinogenic or noncarcinogenic risk is unacceptable.

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5
Q

Eliminating exposure to a chemical altogether may be technically difficult or expensive.

A

True.

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6
Q

Exposure to chemicals can confer health benefits.

A

True - fluoride in water.

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7
Q

Determinations of acceptable risk must be free of judgment and depend on scientific facts.

A

False - deciding on acceptable risk levels involves a substantial amount of judgment.

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8
Q

Which organization provides criteria for chemical risk assessment?

A

EPA

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9
Q

When did the National Research Council (NRC) define a four-step process for risk assessment?

A

1983

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10
Q

List the steps of the NRC’s 4-step risk assessment process?

A

Hazard assessment, dose-response assessment, exposure assessment, and risk characterization.

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11
Q

Hazard assessment draws on available data from what 3 types of studies?

A

Laboratory studies, animals studies, and epidemiological studies.

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12
Q

Epidemiological studies are based on what observations?

A

They are based on observations of people in the real world.

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13
Q

Why is dose-response assessment considered one of the most difficult/controversial steps in a risk assessment?

A

There is usually insufficient data to characterize a dose-response relationship.

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14
Q

Exposure assessment measures the current magnitude, frequency, and duration of human exposure.

A

False - future exposure to an agent is considered.

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15
Q

Which risk assessment step includes discussion of the size, nature, and types of human populations exposed to an agent?

A

Exposure assessment.

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16
Q

Which risk assessment step results in an evaluation and description of the nature and severity of any effects, including carcinogenic and noncarcinogenic effects?

A

Hazard assessment.

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17
Q

Which risk assessment step determines whether there is any potential problem from exposure to a given chemical?

A

Hazard assessment.

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18
Q

Which risk assessment step seeks dose-response relationships for both carcinogenic and noncarcinogenic effects?

A

Dose-response assessment.

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19
Q

Exposure assessment commonly measures exposure directly, but indirect estimates are also available.

A

False - Exposure is more commonly estimated indirectly.

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20
Q

List 3 steps to indirect exposure estimation during exposure assessment.

A

(1) Using measured concentrations in the environment, (2) using models of chemical transport and fate in the environment, (3) and using estimates of human intake over time.

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21
Q

Which risk assessment step establishes the presence or absence of risks?

A

Risk characterization.

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22
Q

Which risk assessment step conveys information on how risk was assessed?

A

Risk characterization.

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23
Q

Which risk assessment step conveys information on where assumptions and uncertainties still exist?

A

Risk characterization.

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24
Q

Which risk assessment step conveys information on where policy choices must be made?

A

Risk characterization.

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25
Q

In practice, each risk assessment step has an individual risk characterization. This provides a basis of information from which to write what?

A

To write an integrative risk characterization analysis. (Idk)

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26
Q

The evaluation of chemical carcinogens relies heavily on what type of studies?

A

Animal studies.

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27
Q

What units are used for normalized doses of a chemical?

A

Milligrams per day of chemical per kilogram of body weight (mg/kg-day)

28
Q

Besides tumors, name 4 types of adverse health effects that might be identified in a hazard assessment.

A

Kidney damage, liver damager, nerve damage, and diseases such as diabetes.

29
Q

What occurs above the noncarcinogen dosage threshold?

A

Significant risks of injury, disease, and other adverse effects.

30
Q

Humans & other living organisms can often tolerate some degree of exposure to chemicals. When is a zero threshold considered instead?

A

In the case of carcinogens.

31
Q

Which risk assessment quantifies the dose actually received in a particular situation?

A

Exposure assessment.

32
Q

During exposure assessment, total exposure is determined by measuring/estimating what 3 aspects of exposure to a chemical?

A

Frequency, intensity, and duration.

33
Q

There are various pathways by which people can be exposed to chemicals in the environment. Which is the most significant route?

A

Inhalation.

34
Q

How are concentrations of chemicals in the environment estimated when direct measurements aren’t available?

A

Using mathematical models & calculation methods.

35
Q

Estimating the dosage an individual receives from different exposure pathways is generally done by measurement.

A

False - models and assumptions are used.

36
Q

What data is required to form models to estimate chemical dosages from different exposure pathways?

A

Quantities of air, water, and soil ingested by adults and children.

37
Q

Cancer is treated as a stochastic response, meaning that any dose carries a risk.

A

True - threshold is zero.

38
Q

Cancer is treated as a stochastic response, meaning that increased dosages increase the severity of a response.

A

False - severity doesn’t increase, but the likelihood of occurrence does.

39
Q

The potency factor of a chemical is based on what curve?

A

The dose-response curve.

40
Q

The potency factor is the incremental cancer risk for a CDI of 1 what?

A

1 mg/kg-day of chemical.

41
Q

What does CDI stand for?

A

Chronic daily intake.

42
Q

What is the formula for incremental lifetime cancer risk?

A

CDI * Potency Factor

43
Q

What is the formula for CDI?

A

(Average daily does in mg/day) / (body weight in kg)

44
Q

What level of risk for a known/suspected carcinogen is considered acceptable by the EPA?

A

Lifetime risk level of 10^-6 (one chance in a million) or less.

45
Q

What level of risk for a known/suspected carcinogen is considered serious and a high priority by the EPA?

A

Lifetime risk level of 10^-3 (one chance in a thousand) or more.

46
Q

Carcinogen risk levels in what range are considered acceptable, but require case-specific judgement (gray area)?

A

Between 10^-6 and 10^-4.

47
Q

How is acceptability of gray area carcinogen risks determined?

A

By judging in comparison to background cancer rates.

48
Q

Most risk assessments don’t consider contaminated waste disposal sites or leaking underground storage tanks.

A

False.

49
Q

In the case of contaminated waste disposal sites or leaking underground storage tanks, how can exposure to toxic chemicals occur?

A

Via ingestion of contaminated drinking water or contaminated soil, as well as via inhalation of vapors given off by soil or water.

50
Q

In all cases, exposure occurs for the duration of an individual’s lifetime.

A

False - many cases of exposure occur only during a portion of an individual’s life.

51
Q

What dosage is a key parameter to characterize the safe dose of a noncarcinogenic chemical?

A

The No Observable Adverse Effects Level (NOAEL).

52
Q

Give a formula for RfD of a non-carcinogen in terms of available NOAEL data from animal studies.

A

RfD (mg/kg-da) = NOAEL/ (UF X MF),
where UF is the uncertainty factor and MF the modifying factor.

53
Q

Any dose equal to or greater than the RfD does not pose a known health concern.

A

False - any dose equal to or less than the RfD does not pose a known health concern.

54
Q

What metric is used in risk assessments to compare an actual dose of a chemical to the reference dose?

A

The hazard quotient (HQ).

55
Q

Give a formula for the hazard quotient.

A

HQ = Average daily dose (ADD) during exposure period (mg/kg-da) / Reference dose (RfD)(mg/kg-da)

56
Q

The average daily dose (ADD) used for noncarcinogens is similar to what metric used for carcinogens?

A

CDI

57
Q

There are no known adverse effects from exposure if HQ is less than or equal to what number?

A

1.0

58
Q

What is the acceptable risk (HQ value) for a noncarcinogen as per the EPA?

A

HQ ≤ 1.0

59
Q

If several chemicals are present, the HQ values for individual chemicals are multiplied together to yield a hazard index (HI).

A

False - HQs are summed together for the HI.

60
Q

Why do risk assessment procedures require some degree of professional judgment?

A

Due to the many uncertainties that characterize each step of the process.

61
Q

Name 3 sources of uncertainty in risk assessments.

A

Measurement errors, modelling the relationship between contaminant sources and the amounts that reach receptors, and uncertainty/variability from one individual to another.

62
Q

The practice of environmental risk assessment has always included uncertainty as an explicit component of the analytical framework.

A

False - but modern risk assessment does.

63
Q

Traditional risk analysis relies on what two things?

A

Various safety factors and the use of conservative (worst-case) assumptions.

64
Q

How do modern/advanced risk assessments present risk?

A

As a probability distribution, rather than a single value.

65
Q

What term is used to refer to presenting risk as a probability distribution?

A

Probabilistic risk assessment.

ENGR 202 (8 decks)

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