GLOSSARY
Term
BMD
CSAF
DNEL
Dose-Response Curve
EDM
False Threshold DoseResponse
Harmonization of Risk
Methods
Hazard Quotient
HEMP
Hormesis
HRA
IURF
Linearized DoseResponse
LOAEL
Definition
Benchmark Dose. A dose or concentration that produces a predetermined change
in response rate of an adverse effect (called the benchmark response or BMR)
compared to background. The lower bound statistical estimate of dose associated
with the BMR is the BMDL. The BMDL is often used as a point of departure for
deriving an OEL.
Chemical Specific Adjustment Factor. A methodology to use chemical-specific data
on toxicokinetics (the disposition of a chemical in the body) and toxicodynamics (the
impact of the chemical dose at the level of the target in the body) to inform human
variability in susceptibility and interspecies differences in response to chemicals.
The approach is used to replace default uncertainty factors for intraspecies and
interspecies variability for deriving exposure guide values such as OELs.
Derived No Effect Level. The level of exposure above which humans should not be
exposed. The DNEL is used as part of the risk characterization as the health effect
benchmark in the European Community regulation on chemical registration or
REACH (Registration, Evaluation, Authorization and Restriction of Chemicals).
The estimated relationship between the changes in the level of toxic response over
a series of exposures or doses. Dose-response curves can cover different portions
of the relationship starting at zero dose and extending through higher doses that
might induce frank or clinically apparent toxicity.
Exposure Data Management
A dose-response pattern for which risk at very low dose increase rapidly from zero
exposure and then decreases in a non-monotonic manner until the response is
close to zero and then it proceeds upward monotonically to high toxicity at high
dose.
Increasing understanding and developing basic principles and guidance on specific
chemical risk assessment issues. Harmonization enables efficient use of resources
and consistency among assessments. For additional information see the
International Programme on Chemical Safety Harmonization Project site).
A ratio of the measured or estimated exposure and the occupational exposure limit
or other exposure guide value. As values reach and exceed unity concern for
potential health risk increases.
Hazard and Effects Management Process
A decreasing dose response at doses up from zero in which there is actually a
stimulatory response from the exposure such that there is a beneficial effect on
health. Example: some studies have indicated that one or two drinks of alcohol
seem to be somewhat protective of heart disease.
Health Risk Assessment
Inhalation Unit Risk Factor. The upper- bound excess lifetime cancer risk estimated
to result from continuous exposure to an agent at a concentration of 1 ug/m 3 in air.
This term is often used for cancer risk assessments for the general populations
exposed by the inhalation route.
A method of extrapolating to estimate toxic responses outside the range of the data
in the low dose region that is often applied for biological effects that might be
induced without a true threshold. That is, some adverse effect is predicted at the
lowest exposure and this response increases linearly with dose such that twice any
exposure is equal to twice the predicted risk. This is a common technique for
cancer risk assessments.
Lowest Observed Adverse Effect Level. The lowest tested dose or concentration of
a substance that has been reported to cause harmful (adverse) health effects in
people or animals.
Monotonic
A dose response which is continuously increasing or decreasing with increasing
dose.
NOAEL
No Observed Adverse Effect Level. A tested dose or concentration of a substance
that has not been reported to cause harmful (adverse) health effects in people or
animals.
OEL
Occupational exposure limit – an exposure during employment activity that is
considered to not present an unreasonable risk for a working lifetime as determined
by those who set it. It is usually applicable as a ceiling limit or a time-weighted
average for 15 minutes (short-term) or 8 hours per day (full-shift), 5 days a week,
50 weeks/year for a working lifetime.
OEL-D
The level of quantitative risk estimated at any current OEL provided as part of the
OEL documentation.
POD
Point of Departure. The point on the dose-response curve from which dose
extrapolation is initiated. This point can be the lower bound on dose for an
estimated incidence or a change in response level from a dose-response model
(BMDL), or a NOAEL or LOAEL for an observed effect selected from a dose
evaluated in a health effects or toxicology study.
RBOEL
Risk Based Occupational Exposure Limits – limits set based on a quantitative
estimate of residual risk present for exposure at the exposure limit. Often set at 1 in
1000.
RfC
Reference Concentration. An estimate (with uncertainty spanning perhaps an order
of magnitude) of a continuous inhalation exposure for a chronic duration (up to a
lifetime) to the human population (including sensitive subgroups) that is likely to be
without an appreciable risk of deleterious effects during a lifetime. It can be derived
from a NOAEL, LOAEL, or benchmark concentration, with uncertainty factors
generally applied to reflect limitations of the data used. Generally used in U.S.
Environmental Protection Agency (EPA) non-cancer health assessments for
exposure by the inhalation route.
Threshold DoseResponse
A method of dose-response assessment that is often applied for biological effects
that have a finite dose or threshold below which there is no expected adverse effect
on anyone in the exposed population. This is a common assumption for risk
assessments for most non-cancer effects.
Uncertainly Factors: Mathematical adjustments applied to the POD when
developing IDLH values. The uncertainty factors for IDLH value derivation are
determined by considering the study and effect used for the POD, with further
modification based on the overall database.
Weight-of-Evidence. Extent to which the available biomedical data supports a
conclusion, such as whether a substance causes a defined toxic effect, whether the
effect observed is relevant to human risk, or whether an effect occurs at a specific
exposure level of concern. The WoE concept includes the integration of the totality
of all lines of evidence considering their relevance and reliability to support an
overall conclusion.
Uncertainty Factors
WoE
AIHA Webinar:
The New Era of Global Exposure Limit Setting Processes – Harmonization on an OEL Hierarchy Approach
Date presented:
April 11, 2013
Presenters:
Chris Laszcz-Davis, MS,CIH; Karen Niven, PhD, MSc, RSP, CFIOSH, FFOH; Michael Jayjock, PhD, CIH; Andrew
Maier, PhD, CIH, DABT; Renee Kalmes, MSPH, CIH; Susan Ripple, MS, CIH; Donna Heidel, MS, CIH