Glossary
A
Absorbed dose
The amount of a substance absorbed into the body, usually per unit of time. The most common unit of dose is mg per kg body weight per day (mg/kg-day).
Absorption
The penetration of a substance into the body from the skin, lungs, or digestive tract.
Accuracy
The degree of agreement between a measured value and the true value; usuallyexpressed as +/- percent of full scale.
Acute toxicity
Any poisonous effect produced within a short period of time following exposure,usually up to 24-96 hours, resulting in biological harm and often death.
Attributable risk
The rate of a disease in exposed individuals that can be attributed to the exposure.This measure is derived by subtracting the rate (usually incidence or mortality) of the disease among nonexposed persons from the corresponding rate among exposed individuals.
B
Background level
the level of pollution present in any environmental medium attributable to natural or ubiquitous sources.
Bias
Any difference between the true value and that actually obtained due to all causes other than sampling variability.
Body burden
The total amount of a specific substance (for example, lead) in an organism, including the amount stored, the amount that is mobile, and the amount absorbed.
C
Carcinogen
A substance or agent that produces or incites cancerous growth.
Carcinogenic potency
The gradient of the dose-response curve for a carcinogen.
Case-control study
An inquiry in which groups of individuals are selected in terms of whether they do (the cases) or do not (the controls) have the disease of which the etiology is to be studied, and the groups are then compared with respect to existing or past characteristics judged to be of possible relevance to the etiology of the disease.
Case-fatality rate
A ratio of the number of deaths due to a disease to the number of cases of that disease in a specified period of time. It expresses the frequency with which affected individuals die of the disease.
Chromatid
One of the pair of stands, formed by longitudinal splitting of a chromosome that are joined by a single centromere in somatic cells during mitosis; one of tetrad of strands formed by lengthwise splitting of paired chromosomes during the diplotene stage of meiosis.
Chronic
Having a persistent, recurring or long-term nature. As distinguished from acute.
Cohort study
See prospective study.
Comparative risk
An expression of the risks associated with two (or more) actions leading to the same goal; may be expressed quantitatively (a ratio of 1.5) or qualitatively (one risk greater than another risk).
Confidence interval
A range of values (a1 < a < a2) determined from a sample of definite rules so chosen that, in repeated random samples from the hypothesized population, an arbitrarily fixed proportion of that range will include the true value, x, of an estimated parameter.
The limits, a1 and a2, are called confidence limits; the relative frequency with which these limits include a is called the confidence coefficient; and the complementary probability is called the confidence level. As with significance levels, confidence levels are commonly chosen as 0.05 or 0.01, the corresponding confidence coefficients being 0.95 or 0.99. Confidence intervals should not be interpreted as implying that the parameter itself has a range of values; it has only one value, a. On the other hand, the confidence limits (a1, a2) being derived from a sample, are random variables, the values of which on a particular sample either do or do not include the true value a of the parameter. However, in repeated samples, a certain proportion of these intervals will include a provided that the actual population satisfied the initial hypothesis.
Confounding factors
Variables that may introduce differences between cases and controls which do not reflect differences in the variables of primary interest.
Cost-benefit analysis
A formal quantitative procedure comparing costs and benefits of a proposed project or act under a set of preestablished rules. To determine a rank ordering of projects to maximize rate of return when available funds are unlimited, the quotient of benefits divided by costs is the appropriate form; to maximize absolute return given limited resources, benefits-costs is the appropriate form.
Critical toxic effect
The most sensitive and specific biological change which is outside of acceptable physiological variation.
Cross-sectional study
An epidemiological study design in which measurements of cause and effect are made at the same point in time.
D
De minimis risk
From the legal maxim "de minimis non curat lex" or "the law is not concerned with trifles."
Deposition
The transfer of substances in air to surfaces, including soil, vegetation, surface water, or indoor surfaces, by dry or wet processes.
Dispersion
A suspension of particles in a medium; the opposite of flocculation; a scattering process.
Dose
The amount or concentration of undesired matter or energy deposited at the site of effect. See also absorbed dose.
Dose-effect
The relationship between dose (usually an estimate of dose) and the gradation of the effect in a population, that is a biological change measured on a graded scale of severity, although at other times one may only be able to describe a qualitative effect that occurs within some range of exposure levels.
Dose-response
A correlation between a quantified exposure (dose) and the proportion of a population that demonstrates a specific effect (response).
Dose-response assessment
The process of characterizing the relation between the dose of an agent administered or received and the incidence of an adverse health effect in exposed populations and estimating the incidence of the effect as a function of human exposure to the agent.
E
Ecological fallacy
The inference that a correlation between variables derived from data grouped in social or other aggregates (ecological units) will hold between persons (individual units).
Environmental pathway
All routes of transport by which a toxicant can travel from its release site to human populations including air, food chain, and water.
Epidemiology
The study of the distribution and dynamics of diseases and injuries in human populations.
Excess deaths
The excess over statistically expected deaths in a population within a given time interval. Attempts are made to relate excess deaths to specific causes. Note that since every person can (and must) die only once, there can be no excess deaths over all time.
Expected deaths
The number of deaths statistically expected in a population in a given time interval obtained by summing the product of age-, sex-, and race-specific mortality rates from a standard population and person-years in each age, sex, and race category in the study population.
Expected loss
The quantity obtained by multiplying the magnitude of health or environmental effect loss by the probability (or risk) of that loss and adding the products. The expected loss is the average loss over a large number of trials; one must reflect on the appropriateness of its use in cases for which there will be only one, or a few, trials.
Exposure
The time integral of the concentration of a toxicant which is in the immediate vicinity of various ports of entry (such as lung, GI tract and skin). Qualitatively, contact between a potentially harmful agent and a receptor (e.g., a human or other organism) that could be affected.
Exposure assessment
The process of measuring or estimating the intensity, frequency, and duration of human exposures to an agent currently present in the environment or of estimating hypothetical exposures that might arise from the release of new chemicals into the environment.
Extrapolation
In risk assessment, this process entails postulating a biologic reality based on observable responses and developing a mathematical model to describe this reality. The model may then be used to extrapolate to response levels which cannot be directly observed.
F
Failure modes and effects analysis
A tool to systematically analyze all contributing component failure modes and identify the resulting effects on the system.
False negative results
Results which show no effect when one is there.
False positive results
Results which show an effect when one is not there.
Fault tree analysis
A technique by which many events that interact to produce other events can be related using simple logical relationships permitting a methodical building of a structure that represents the system.
Food chain
Dependence of a series of organisms, one upon the other, for food. The chain begins with plants and ends with the largest carnivores.
G
Gamma Multihit Model
A generalization of the one-hit dose-response model which provides a better description of dose-response data.
Gaussian distribution model
A commonly used assumption about the distribution of values for a parameter, also called the normal distribution. For example, a Gaussian air dispersion model is one in which the pollutant is assumed to spread in air according to such a distribution and described by two parameters, the mean and standard deviation of the normal distribution.
H
Hazard
A condition or physical situation with a potential for an undesirable consequence, such as harm to life or limb.
Hazard assessment
An analysis and evaluation of the physical, chemical and biological properties of the hazard.
Hazard identification
The process of determining whether exposure to an agent can cause an increase in the incidence of a health condition.
Health effect assessment
The component of risk assessment which determines the probability of a health effect given a particular level or range of exposure to a hazard.
Health risk
Risk in which an adverse event affects human health.
Healthy worker effect
The difference in mortality risk due to selection forces between a population of active workers healthy enough to have been (and remain) employed and the general population which includes sick and disabled persons. If working in a safe environment, such a population of active workers has been variously estimated to have a mortality risk 60-90% that of the general population.
Hockey stick regression function
A dose-response curve that shows zero response up to a presumed physiological threshold value and then a linear increase thereafter.
I
ICRP
International Commission on Radiological Protection.
Incidence
The number of new cases of a disease in a population over a period of time.
Indicator organisms
A species, whose presence or absence may be characteristic of environmental conditions in a particular area of habitat; however, species composition and relative abundance of individual components of the population or community are usually considered to be a more reliable index of water quality.
Individual risk
The risk to an individual rather than to a population.
In vitro
Outside the living organism.
In vivo
Within the living organism.
Isopleth
Lines on a graph connecting points of constant value; e.g., isopleths of visibility are lines of equal visibility.
J
K
L
Latency period
The period of time from exposure to an agent to the onset of a health effect.
Lethal concentration fifty (LC50)
A calculated concentration [in air] which when administered by the respiratory route is expected to kill 50% of a population of experimental animals during an exposure of four hours. Ambient concentration is expressed in milligrams per liter.
A calculated concentration in water which is expected to kill 50% of a population of aquatic organisms after a specified time of exposure. Concentration is usually expressed in milligrams per liter or ppm.
Lethal dose fifty (LD50)
A calculated dose of a chemical substance which is expected to kill 50% of a population of experimental animals exposed through a route other than respiration. Dose is expressed in milligrams per kilogram of body weight.
Logit model
A dose-response model which, like the probit model, leads to an S-shaped dose-response curve, symmetrical about the 50% response point. The logit model leads to lower "very safe doses" than the probit model even when both models are equally descriptive of the data in the observable range.
Log-probit model
A dose-response model which assumes that each animal has its own threshold dose, below which no response occurs and above which a tumor [or other effect] is produced by exposure to a chemical.
M
Multistage model
A carcinogenesis dose-response model where it is assumed that cancer originates as a "malignant" cell, which is initiated by a series of somatic-like mutations occurring in finite steps. It is also assumed that each mutational stage can be depicted as a Poisson process in which the transition rate is approximately linear in dose rate.
Mutagen
A substance that can induce alterations in the DNA of either somatic or germinal cells.
N
O
Oncogenic
A substance that causes tumors, whether benign or malignant.
One-hit model
The basic dose-response model based on the concept that a tumor can be induced by a single receptor that has been exposed to a single quantum or effective dose unit of a chemical.
P
Plume
The cloud of steam or smoke that comes from a chimney stack and blows downwind. Also, the contaminated portion of groundwater that moves past a source of pollution.
PMR
Proportionate mortality ratio.
Population at risk
A limited population that may be unique for a specific dose-effect relationship; the uniqueness may be with respect to susceptibility to the effect or with respect to the dose or exposure itself.
Population dose (population exposure)
The summation of individual radiation doses received by all those exposed to the source or event being considered.
Precision
A measure of how consistently the result is determined by repeated determinations without reference to any "true" value.
Prevalence
The number of existing cases in a population who have the disease at a given point (or during a given period) of time.
Probit analysis
A statistical transformation which will make the cumulative normal distribution linear. In analysis of dose-response, when the data on response rate as a function of dose are given as probits, the linear regression line of these data yields the best estimate of the dose-response curve. The probit unit is y = 5 + Z(p) , where p = the prevalence of response at each dose level and Z(p) = the corresponding value of the standard cumulative normal distribution.
Process wastes
Any designated toxic pollutant or combination of pollutants, whether in wastewater or otherwise present, which is inherent to or unavoidable resulting from any manufacturing process, including that which comes into direct contact with or results from the production or use of any raw material, intermediate product, finished product, byproduct or waste product and is discharged into the navigable waters.
Proportionate mortality ratio (PMR)
The fraction of all deaths from a given cause in the study population divided by the same fraction from a standard population. A tool for investigating cause-specific risks when only data on deaths are available. If data on the population at risk are also available, SMRs are preferred.
Prospective study
An inquiry in which groups of individuals are selected in terms of whether they are or are not exposed to certain factors, and then followed over time to determine differences in the rate at which disease develops in relation to exposure to the factor. Also called cohort study.
Q
R
Random error
Indefiniteness of result due to finite precision of experiment. Measure of fluctuation in result upon repeated experimentation.
Rate
In epidemiologic usage, the frequency of a disease or characteristic expressed per unit of size of the population or group in which it is observed. The time at or during which the cases are observed is a further specification.
RAUs
Risk analysis units.
Relative potency
A comparison of the potency of two or more reference chemicals. Potency of a test chemical is reviewed at all levels of biological organization (subcellular, cellular,animal, human).
Relative risk
The ratio of the rate of the disease (usually incidence or mortality) among those exposed to the rate among those not exposed.
Reliability
The probability a system performs a specified function or mission under given conditions for a prescribed time.
Reproducibility
The degree of variation obtained when the same measurement is made with similar instruments and many operators.
Response
The proportion or absolute size of a population that demonstrates a specific effect. May also refer to the nature of the effect.
Retrospective study
See case-control study.
Risk
The potential for realization of unwanted, adverse consequences to human life, health, property, or the environment; estimation of risk is usually based on the expected value of the conditional probability of the event occurring times the consequence of the event given that it has occurred.
Risk analysis
A detailed examination including risk assessment, risk evaluation, and risk management alternatives, performed to understand the nature of unwanted, negative consequences to human life, health, property, or the environment; an analytical process to provide information regarding undesirable events; the process of quantification of the probabilities and expected consequences for identified risks.
Risk assessment
The process of establishing information regarding acceptable levels of a risk and/or levels of risk for an individual, group, society, or the environment.
Risk estimation
The scientific determination of the characteristics of risks, usually in as quantitative a way as possible. These include the magnitude, spatial scale, duration and intensity of adverse consequences and their associated probabilities as well as a description of the cause and effect links.
Risk evaluation
A component of risk assessment in which judgments are made about the significance and acceptability of risk.
Risk identification
Recognizing that a hazard exists and trying to define its characteristics. Often risks exist and are even measured for some time before their adverse consequences are recognized. In other cases, risk identification is a deliberate procedure to review, and it is hoped, anticipate possible hazards.
S
SMR
Standardized mortality ratio.
Stack effect
Used in reference to air, as in a chimney, that moves upward because it is warmer than the surrounding atmosphere.
Stack emissions
Effluents released into the atmosphere from the exhaust flue of a building; usually refers to pollutants but can refer to steam or other nonpolluting effluents.
Standard deviation
A measure of dispersion or variation, usually taken as the square root of the variance.
Standard geometric deviation
Measure of dispersion of values about a geometric mean; the portion of the frequency distribution that is one standard geometric deviation to either side of the geometric mean; accounts for 68% of the total samples.
Standardized mortality ratio (SMR)
The ratio of observed deaths in a population to the expected number of deaths as derived from rates in a standard population with adjustment of age and possibly other factors such as sex or race.
Standard normal deviation
Measure of dispersion of values about a mean value; the positive square root of the average of the squares of the individual deviations from the mean.
Statistical significance
The statistical significance determined by using appropriate standard techniques of statistical analysis with results interpreted at the stated confidence level and based on data relating species which are present in sufficient numbers at control areas to permit a valid statistical comparison with the areas being tested.
Steady state exposure
Exposure to an environmental pollutant whose concentration remains constant for a period of time.
Synergetic
Working together; an agent that works synergistically with one or more other agents.
Synergism
An interaction between two substances that results in a greater effect than both of the substances could have had acting independently.
Synergistic effects
Joint effects of two or more agents, such as drugs that increase each other's effectiveness when taken together.
Systematic error
A reproducible inaccuracy introduced by faulty equipment, calibration, or technique.
T
Threshold
A pollutant concentration [or dose] below which no deleterious effect occurs.
Threshold dose
The minimum application of a given substance required to produce anobservable effect.
Topography
The detailed delineation of the geographic features of a locality.
U
Uncertainty analysis
A detailed examination of the systematic and random errors of a measurement or estimate; an analytical process to provide information regarding the uncertainty.
V
W
Watershed
Land area from which water drains toward a common watercourse in a natural basin.
X
Y
Z
Zero order analysis
The simplest approach to quantification of a risk with a limited treatment of each risk component (e.g. source terms, transport, health effects, etc.).
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Some other potentially useful glossaries are:
Atmospheric Chemistry and Air Quality Glossary (1999 Version)
URL:
http://www.shsu.edu/~chemistry/Glossary/glos.html
Air Quality Glossary
URL:
http://www.teleport.com/~hanrahan/glossary.htm#critpol
WATERSHEDDS Glossary
URL:
http://h2osparc.wq.ncsu.edu/info/glossary.html
Water Quality Association Glossary of Terms
URL:
http://www.wqa.org/WQIS/Glossary/GlossHome.html
Environmental Economics Glossary
URL:
http://www.damagevaluation.com/glossary.htm
Introduction
1. Risk: Webster's Dictionary:
the possibility
of suffering
harm or loss.
National Academy of Sciences (paraphrased):
the probability
and magnitude
of a hazard
Douglas Brown-Crawford (U.N.C.):
a rational belief
that an event might possibly occur
in light of existing evidence.
2. Risk A collection of approaches and disciplines
analysis: devoted to all aspects of risk issues
(includes risk assessment, risk
communication, and risk management).
3. Risk the characterization of adverse effects from
assessment: exposure to hazards.
characterization = probability, uncertainties,
analytic techniques, and models)
4. Risk an interactive exchange of information and
communication: opinions among individuals, groups, and
institutions regarding risk.
5. Risk the evaluation, selection, and implementation
management: of alternative risk control actions.
6. Hazard to determine whether a particular agent
identification: is causally linked to particular health
effects.
7. Dose-Response to determine the relation between the
Assessment: magnitude of exposure and the probability
of occurrence of health effects in question.
8. Exposure to determine the extent of human exposure
Assessment: before or after the application of regulatory
controls.
9. Risk to describe the nature and often the
characterization: magnitude of human risk, including
attendant uncertainty.
Desirable Attributes of Risk Assessment Reports ***
General Attributes (for each section)
A. explicit: model validity
uncertainty, assumptions
research needs
B. fair: clear language
peer review
alternate views of risk assessments
(both overall and components)
________________________________________________________________
0. Executive Summary
scope, objectives, key findings
1. Hazard Identification (does it cause cancer?)
weight of the evidence (known, probable, possible, etc.)
2. Dose Response Evaluation (R=unit risk)
central tendency, upper and lower bound estimates
3. Exposure Assessment (D=dose)
sources, pathways, sub-populations, routes of exposure
4. Risk Characterization (P=RxD)
summary statements, integrate components, analogies
________________________________________________________________
*** -- adapted from "Presentation of Risk Assessments of
Carcinogens," American Industrial Health Council, 1989.
Hazard Identification
1. risk group: a group for which a risk assessment is being
performed (i.e., humans).
2. test group: a group which is exposed to a risky agent in an
experimental environment (i.e., test animals, or
humans in a "natural experiment"); also called
experimental group.
3. control a group which is not exposed to a risky
group: agent which is used for comparison with the test
group (i.e., animals or humans).
4. short term A. chemical structure
tests: B. in vitro (in the test tube)
Bacteria mutagenesis
DNA repair
Mammalian mutagenesis
Sister chromatid exchange
cell transformation
C. in vivo
D. chronic bioassays
5. initial A. gross differences in weight over time
critiques B. gross differences in survival over time
of animal C. control data may be unstable
studies:
6. hierarchy human data
of data appropriate route of exposure
selection: lifetime exposure, lifetime observation
< lifetime exposure, lifetime observation
< lifetime exposure and < lifetime observation
7. other A. exposures (route, dose)
uncertainty: B. interactions (synergism,antagonism,potentiation)
C. classification (of exposures or diagnosis)
D. extrapolation (to low dose or between species)
E. matching control and test groups
test and risk groups
(confounders: age,sex,etc.)
8. null there is no difference between the
hypothesis: test group and control group
9. types of type 1 = false rejection of the null hypothesis
statistical type 2 = false acceptance of the null hypothesis
error: type 3 = asking the wrong question
type 4 = wrong method
type 5 = wrong action
The Fourfold Table
Disease
+ -
Exposure _____________________
| | |
+ | A | B | A + B (total exposed)
|_________|_________|
| | |
- | C | D | C + D (total non-
|_________|_________| exposed)
A + C B + D
(total (total
sick) not sick)
1. R exp = A / (A+B)
2. R non = C / (C+D)
3. Relative Risk = R exp / R non
4. Attributable Risk = R exp - R non
Hazard Identification Endpoints
1. cancer: usually based on incidence of tumors,
may also be based on:
a) type of tumors (malignant in test group)
b) time of tumor appearence (earlier in test group)
c) # of tumors per subject (more in test group)
2. genotoxicity: (short term tests)
includes mutations, damage to DNA, chromosomes
supports hazard I.D. of carcinogens and mutagens
3. developmental: effects in embryo, fetus, newborn
4. reproductive: fertility
5. systemic includes cardiovascular, central nervous system
toxicity: immunological, kidney, liver, respiratory
6. skin/eye primary irritant
irritant:
7. Critical for multiple effects, the effect most
effect: sensitive to dose. Classifications of Carcinogens
EPA
A: Human Carcinogen: sufficient evidence in humans
B: Probable
Human Carcinogen: B1: limited evidence in humans
B2: sufficient evidence in animals
C: Possible
Human Carcinogen: limited evidence in animals
D: Not classified: inadequate evidence
E: No evidence of
carcinogenicity: at least two studies
IARC: International Agency for Research on Cancer
1: Human
Carcinogen: sufficient human data
2A: Probable: limited human data
and
sufficient animal data or
sufficient animal and other data
2B: Possible: limited human data
or
sufficient animal data or
limited animal and other data
3: Not data do not fit into
Classifiable: any of the above groups
4: Probably lack of carcinogenicity in
Not: human and animal studies
NTP: National Toxicology Program (Health and Human Services)
known carcinogen: sufficient evidence from human studies
suspect carcinogen: reasonably anticipated to cause cancer
GENETOX: database from Chemical Information Systems, Inc.
(genetic assays)
sufficient positive: tumor induction shown
limited positive: indication of tumor induction
Exposure Scenarios
1. PMI = point of maximum impact
(in PTPLU, it is the location of the
maximum one hour concentration)
2. MEP = maximum exposed persons:
3. MEI = maximum exposed individual
= 70 years x 365 days/year x 24 hours/day at PMI
(i.e., worst theoretical case for exposure)
4. MPI = maximum plausible individual
= 30 years x 365 days/year x 24 hours/day at PMI
(i.e., it is implausible that exposure would occur
over the entire lifetime)
5. MLI = most likely individual
= 9 years x 365 days/year x 17 hours/day at PMI
(i.e., given our mobile population, it is most likely
that exposure would occur under these conditions)
Biokinetic Based Models
----> alveolar space ---->
|
|
|----> lung blood ----------->|
| |
| |
|<---- fat tissue <-----------|
| |
|<---- vessel poor groups <---|
| (muscle) |
| |
|<---- vessel rich groups <---|
| (intestines) |
| |
|<---- liver metabolism <-----|
| |
__________| |__________
| |
| |
metabolites metabolites
(linear (Michaelis-Menton
kinetics) kinetics)
EXPOSURE AND DOSE
1. exposure = C(t) = concentration
in environment X duration
2. relative
source
contribution = contributions from other exposures
(e.g., drinking water, food, etc.).
3. intake = total amount of material taken in
during a time interval
I(t) = C(t) X ROI X time
(ROI = rate of intake)
e.g., breathing
4. uptake = total amount of material taken up by organ
during a time interval
U(t) = I(t) X fd (where fd=fraction deposited)
e.g., how much taken up by lungs
5. retention = R(t) = fraction of material remaining
in organ at time t
e.g., coughing
6. organ
burden = B(t) = amount of material in an organ at time t
e.g., actually in organ
7. integral
organ
burden = D = integral of B(t)
over time interval
e.g., usually called "dose"
8. dose = ideally, a measure of primary damage occurring
during a time interval
e.g., certain biomarkers
Definitions of Dose
1. dose: the amount of a substance available for
metabolic processes of an organism
following exposure and absorption into an organism.
2. dosimeter: an instrument to measure dose.
(often measures exposure rather than dose)
3. absorbed the amount of a substance penetrating across
dose: the exchange boundaries of an organism,
via physical or biological processes,
after contact.
4. delivered the amount of substance available for
dose: interaction with any particular organ or cell
(i.e., the target organ)
5. administered the amount of substance given to a human or animal
dose: in dose response studies,
especially through ingestion or inhalation
(technically, it is an exposure, not a dose,
because it does not account for absorption)
6. applied the amount of substance given to a human or animal
dose: in dose response studies,
especially through dermal contact.
(technically, it is an exposure, not a dose,
because it does not account for absorption)
7. dose-response Often based on administered dose
curve: rather than absorbed or delivered dose
8. dose rate: dose per unit time (e.g., mg/day),
often normalized to body weight (e.g., mg/kg/day)
9. exposure exposure per unit time
rate: (compare to dose rate)
10. Multiple EPA assumes same toxicity for all routes
routes: unless shown otherwise
Dose Concepts
1. zero dose response goes to origin
threshold: (i.e., one molecule can cause cancer)
2. nonzero there is a safe level
threshold: (i.e., it has a NOEL)
3. NOEL: no observed effect level
4. NOAEL: no observed adverse effect level
5. LOAEL: lowest observed adverse effect level
_____________________________________________________________
exposure effects
starts induction detected
|---------------|---------------|
effective latency
exposure
_____________________________________________________________
6. induction: to stimulate a biological reaction
7. latency: the time from induction to
detected health effect
8. effective
exposure: the exposure that leads to induction
9. Hazard maximum background
Index: daily dose + dose = actual dose
reference reference
dose dose
(i.e., for non-zero threshold toxicants)
10.Uncertainty safety factors
factors: (the preferred term is uncertainty factors)
(also called "database factors")
11.Dose
Scaling: converting animal to human dose; based on:
body weight (simplest and most common method)
statistical regression (by multiple species)
caloric demand
lifespan (note: humans live disproportionately long)
body surface area (based on metabolism of homeotherms)
Dose Response
1. linearized a derivation of the multistage model that assumes
multistage linearity at low doses (our homework calculations
model: are from the linearized multistage model).
ORIENTATION
(MEDLARS, TOXNET, IRIS, etc.)
1. MEDLARS: MEDical Literature Analysis and Retrieval System
MEDLARS is the collection of databases managed by the
National Library of Medicine.
MEDLARS Service Desk: 1-800-638-8480
Everything defined on this page is part of MEDLARS.
2. GRATEFUL
MED: Software used to access any database in MEDLARS.
It costs about $30, and comes with a password and
account number for MEDLARS. It also includes a
a small notebook of guidelines, with free updates
issued every year.
3. MEDLINE: the best-known of the MEDLARS databases.
System for finding health-related journal articles
(most of the entries include brief abstracts).
MEDLINE is accessed through GRATEFUL MED, but
can also be used on the second floor of South Library
(on a computer using CD-ROM technology).
4. TOXNET: TOXicology data NETwork
TOXNET (a network of databases) is part of MEDLARS.
TOXNET contains IRIS, TRI, HSDB, and other
health-related databases.
5. IRIS: Integrated Risk Information System
Risk assessment information on specific chemicals.
6. Searches
for IRIS: (Use GRATEFUL MED, Direct Access, TOXNET)
(for more information, see the pamphlet entitled
"TOXNET - A Brief Guide to Searching its Files")
The prompt for your command is "USER:"
the actual command: explaination of command:
FILE IRIS - accesses the IRIS
database
BENZENE (NAME) - specifies all information
on a specific chemical
PRT INDENTED CAR REFS - prints data (indented form)
on carcinogens, references
STOP Y - exits IRIS
Refined Risk Assessment
I. Executive Summary
A. facility description
B. key exposures
1. substances emitted
* 2. MEI
* 3. sensitive receptors
* 4. isopleths
C. summary of risks (cancer, non-cancer)
II. Risk Assessment
A. hazard identification (cancer, non-cancer)
B. exposure assessment
1. Q, C (PTPLU, etc.)
* 2. define zones of impact: areas of elevated C
* 3. census information and sensitive receptors
* 4. other exposure pathways
C. dose response assessment (R)
D. risk characterization
1. key exposures:
PMI
* sensitive receptors
* isopleths
2. P (risk at PMI)
3. E.C. (excess cases)
* 4. A.C. (acceptable concentrations)
5. Uncertainty analysis
upper and lower limits
compare to existing standards
* III. Conclusions
* IV. Risk Management Options
V. Appendix
1. calculations
2. printouts
3. references
* = may be optional in a screening risk assessment
Principal Components of Outrage
more less
outrage vs. outrage
1. coerced vs. voluntary
2. industrial vs. natural
3. exotic vs. familiar
4. memorable vs. not memorable
5. dreaded vs. not dreaded
6. catastrophic vs. chronic
7. unknowable vs. knowable
8. outside vs. individual
control control
9. unfair vs. fair
10. immoral vs. moral
11. suspicious vs. trusted
source source
12. unresponsive vs. responsive
process process
__________________________________________
13. vulnerable vs. average
populations populations
14. delayed vs. immediate
effects effects
15. affects vs. does not affect
future future
generations generations
16. identifiable vs. statistical
victims victims
17. not vs. preventable
preventable
18. few benefits vs. many benefits
19. media vs. no media
attention attention
20. opportunity vs. no opportunity
for collective for collective
action action
__________________________________________
Conclusions
A. Risk = hazard + outrage
B. The public responds more to outrage than to hazard.
C. Activists and media amplify outrage, but they don't create it.
D. When hazards are high, risk communicators should nurture outrage.
When hazards are low, risk communicators should reduce outrage.
E. Companies and agencies usually can't reduce outrage until they
change their own organizations.
Risk Communication Taxonomy
Problems Strategies
1. Source
1A. Planning
1A1. establishing respect publics for political power:
need for risk involve all interested parties
communication involve them early (pro-active)
continue seeking out
1A2. objectives set realistic, clear objectives for:
information and education
behavioral change
emergency information
negotiation
1A3. time limits plan ahead
1B. Roles
1B1. legal role explain your role
match authority with responsibility
1B2. social role recognize emotions, speak with passion
use examples and anecdotes
1C. Staff
1C1. credibility enlist credible sources:
laws, literature
consultants, academics
agencies, local citizens
key political figures
1C2. expertise develop policies and procedures
develop library, seminars, case studies
oversight of staff
1D. Leadership
1D1. internal conflict select a single credible spokesperson
1D2. interagency conflict coordinate with various authorities
1E. Evaluation
1E1. need for a evaluate strengths and weaknesses
pro-active approach ongoing training
Problems Strategies
2. Message
2A. Planning:
2A1. risk definitions state assumptions, objectives
address qualitative concerns
(especially outrage) 2B. Roles:
2B1. message context be cautious about risk comparisons,
explain intent of comparisons
2B2. uncertainty explain data gaps
levels of confidence
expert disagreements
uncertainty does not preclude action
2C. Staff:
2C1. jargon simple, nontechnical language
adapted for different publics
2C2. complexity supporting documents ("white paper")
adapted for different publics
2D. Leadership:
2D1. completeness practical actions for individuals,
(defined by nature of risk, benefits,
leaders) uncertainty of risks and benefits,
several measures of risk,
alternatives, management issues
what you can and cannot do
2E. Evaluation:
2E1. biased reports independent review of message
authors should be accountable
Problems Strategies
3. Channels
3A. Planning:
3A1.poor relations
establish your media objectives:
with media long term relationships
consider media needs
respect deadlines
3B. Roles:
3B1. sensationalism study what makes a story newsworthy
(politics, scandal, danger)
present a pro-active position
3C. Staff:
3C1. communication allow for confirmation needs:
breakdown provide hotline for rumor control
provide multiple channels
3D. Leadership:
3D1. choosing proper experiment with emerging approaches
channels (e-mail, meeting formats, etc.)
3E. Evaluation:
3E1. inaccuracies study what the media know
provide background material
follow up on reports
Problems Strategies
4. Receiver
4A. Planning:
4A1. public apathy listen to the audience
learn their objectives
attract attention by
addressing their objectives
4A2. macro vs. relate policies to individual action:
micro-objectives what would you do?
4A3. time do not overload with information
4B. Roles:
4B1. public trust be honest:
keep promises
admit mistakes
identify with audience:
follow norms of dress,
behavior, and language
4C. Staff:
4C1. poor listening use multiple media
(T.V., radio, papers)
repeat the message
4C2. risk literacy develop a "consumer's guide"
(joint community effort)
4D. Leadership:
4D1. problems after leave room for new options
key decisions
4E. Evaluation:
4E1. unpredictability recognize and study different publics:
pretest messages
interviews, focus groups, surveys
look for hidden agendas
References:
1. National Research Council (U.S.), Committee on Risk Perception
and Communication, Improving Risk Communication, National
Academy Press, Washington, D.C., 1989.
2. Covello, V., Sandman P., and P. Slovic, Risk Communication,
Risk Statistics, and Risk Comparisons: A Manual for Plant
Managers, Washington, D.C.: Chem. Manufacturers Association, 1988.
3. Davies J.C., Covello V.T., and F.W. Allen, Risk Communication,
Risk Communication : proceedings of the National Conference on
Risk Communication, held in Washington, D.C., January 29-31,
1986, Washington, D.C.: Conservation Foundation, c1987.
4. Hance, B.J., Chess, C., and P. Sandman, Industry Risk
Communication Manual: Improving Dialogue with Communities,
Boca Raton, Florida: Lewis Publishers, 1990.
Risk Comparisons: should not be primary basis of decisions
multiple comparisons might help overcome problems
should be approached with extreme caution
Hierarchy of Risk Comparisons
1. most acceptable approaches:
compare with standards
e.g., EPA, OSHA, etc.
compare risks at different times
e.g., now compared to last year
compare with different estimates of the same risk
e.g., ours compared with EPA, Sierra Club, etc.
2. less desirable approaches:
compare risk of action with no action
e.g., if we buy control equipment, if we don't
compare alternatives
e.g., landfill risk is x, incinerator is y
compare with same risk in other places
e.g., L.A. compared to Denver
3. even less desirable approaches:
compare average risk with a peak risk
e.g., exposures at home vs. at the plant gates
compare specific risk to all sources of an effect
e.g., 3% of the total lung cancer risk
4. marginally acceptable approaches:
compare to cost
e.g., reducing risk would cost x dollars
compare to benefits
e.g., this chemical would save lives in hospital use
compare occupational with environmental
e.g., public vs. in the plant
compare with other risks from same source
e.g., chemical x compared to y from the same source
compare to other risks of same disease
e.g., lung cancer from chem. x vs. radon
5. rarely acceptable approaches:
suggest acceptability of risk
e.g., chem. x versus driving your car
suggest surrendering of rights
e.g., chem. x versus smoking a cigarette
based on unfamiliar risk of a familiar activity
e.g., chem. x versus aflatoxin in peanut butter
Reference: Covello, Sandman, and Slovic, 1988.
Environmental Risk Analysis
(H.S. 469)
Exam #1: Review of Terms and Concepts
risk toxicological issues
"de minimus non curat lex" risk group, experimental group
risk analysis test group, control group
risk assessment nonzero threshold toxicants
risk communication zero threshold toxicants
risk management NOEL, NOAEL, LOAEL
mathematical issues experimental dose range
risk vs. uncertainty pharmacokinetic based modeling
statistical error (types 1-5) exposure
integrals, derivatives micro-environments
ln x, (exp)x direct measurement of exposure
accuracy vs. precision exposure scenario
risk assessment predictive exposure assessment
Hazard identification reconstructive exposure
Dose-response assessment assessment
Exposure assessment dose
Risk characterization delivereddose
risk assessment models absorbed dose
rating models administered dose
analytical models applied dose
numerical models intake, uptake
air dispersion models retention, organ burden
UNAMAP, Gaussian plume models integral organ burden
rollback models biologically significant dose
regional trajectory models bioassays of chemical carcinogens
box and multibox models Ames test
grid models, physical models
Eulerian, Lagrangian classification of:
PTPLU carcinogens
stability classes, mixing height
buoyancy induced dispersion Tolerance distribution models
gradual plume rise logit
anemometer, receptor probit
stack downwash Weibull model
surface water models hit target models
groundwater models Single hit
partitioning Multihit
Henry's law Multistage
Octanol model free approaches
epidemiologic issues linear model
retrospective, prospective studies databases
incidence, prevalence TOXNET
standard mortality ratio (SMR) IRIS
proportionate mortality ratio (PMR) IARC
relative risk NTP
attributable risk
Environmental Risk Analysis
(H.S. 469)
Exam #2: Review of Terms and Concepts
tools * measures of risk -- deaths per:
descriptive statistics lifetime vs. day
Boolean algebra people vs. people near facility
event trees pollutant released vs. absorbed
initiating event ton of chemical vs. dollars profit
accident sequence facility vs. corporation
fault trees
* suggestions for
uncertainties risk communication problems
completeness
modeling decision trees
Pessimist's decision model
heuristics Optimist's decision model
representativeness Minimization of regret model
availability Maximization of average payoff
anchoring
framing ethical models of risk
Utilitarian
biases Egalitarian
overconfidence Elitist
conjunction fallacy Libertarian
hindsight bias
tradeoffs with money economic models of risk
de minimus Willingness to pay
Equitable allocation
risk communication problems Human capital
"Noise" consumerism
message problems
source problems risk management options
channel problems advisory
receiver problems technological
economic
risk communication objectives regulatory
information
behavioral change trans-scientific
emergency response
negotiation
* risk comparisons
5 categories of
risk comparisons
(best to worst)
* = see handouts
ENVIRONMENTAL RISK ANALYSIS (H.S. 469)
Assignment
1. Briefly summarize a risk communication task you have faced
in your job. If you have worked in environmental or occupational health, this should be easy. If not, select an issue in which you are knowledgeable (from other classes, your own reading, etc.).
2. Using the handout ("Risk Communication: Problems and Strategies"), list the problems (by number) you have encountered in the above task. List any problems not addressed in the handout.
3. Using the above handout (under "Strategies"), list the actions taken to address the problems listed above. Did they work? Why or why not? List any useful actions not described in the handout.
4.List any questions you have about this sheet. The purpose
of this assignment is to understand risk communication problems and suggestions as summarized in the handout (and, of course, to improve the handout).
H.S. 469
CARB (California Air Resources Board)
PTPLU (PoinT PLUme)
Inputs
1. title of output
2. MKS (meter-kilogram-second) mode?
3. ambient temperature
4. anemometer height
5. mixing height
6. wind profile exponents
7. emission rate
8. physical stack height
9. stack gas temperature
10. stack gas velocity
11. stack diameter
12. receptor elevation above ground
Assumptions
13. gradual plume rise?
14. stack downwash?
15. buoyancy induced dispersion?
16. dispersion parameters
Other
17. output units
18. results to screen, printer, or file?
Input summary
19. source conditions
20. meterological conditions
Output
21. maximum concentrations under
different conditions
Acronyms
1. CEPP: Chemical Emergency Preparedness Program,
Interim Guidance, EPA Chemical Profiles
2. CHEMTRACK: Testing Priority Committee Data Base,
from National Toxicology Program
3. CHIP: Chemical Hazard Information Profiles
used for TSCA chemical assessment
4. CHRIS: Chemical Hazards Response Information System,
produced by U.S. Coast Guard for use in spill situations.
5. DWCD: Drinking Water Criteria Documents
Used for Safe Water Drinking Act
5. FSTRAC: Federal-State Toxicology and Regulatory Alliance
Committee, Summary of State and Federal Drinking
Water Standards and Guidelines, March, 1988.
6. GENETOX: On-line database from The Chemical Information
System (CIS); Genetic assay studies developed by EPA.
7. HAD: Health Assessment Documents,
Used by Office of Air Quality Planning and Standards
8. HEA: Health Effects Assessments (HEA); Primarily air
documents, health data for listing in CAA.
9. HEED: Health and Environmental Effects Documents;
Summaries of health hazard literature for use by EPA
10.HEEP: Health and Environmental Effects Profiles;
Summaries of health hazard literature in RCRA.
11.HSDB: Hazardous Substances Databank,
National Library of Medicine TOXNET
12.IRIS: EPA's Integrated Risk Information System
Toxicity, carcinogenicity, drinking water and risk
management data
13.ISHOW: Information System for Hazardous Organics in Water
14.NATICH: National Air Toxics Information Clearinghouse
air toxics information collected from Federal, State,
and local agencies
15.RTECS: Registry of Toxic Effects of Chemical Substances, NIOSH
Risk Management
A. risk attitudes
1. maximize average
2. pessimist
3. optimist
4. minimize regret
B. ethical systems
1. utilitarian
2. egalitarian
3. elitist
4. libertarian
C. economic outgrowths
1. willingness to pay
2. equitable allocation
3. human capital
4. environmentalism
D. legal outgrowths
1. economic
2. regulatory
3. advisory
4. technological