Hazard Assessment and Contaminated Sites - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 564

Reproductive toxicity The ability to produce an adverse effect on any aspect of
reproductive capacity, function or outcome. It includes effects on the embryo, fetus,
neonate and prepubertal organism and on adult reproductive and neuroendocrine
systems (IEH 1999 ).
RfD Reference Dose (RfD). An estimate (with uncertainty factors spanning per-
haps an order of magnitude) of the daily exposure (mg/kg bw /day) to the general
human population (including sensitive sub-groups) that is likely to be without an
appreciable risk of deleterious effects during a life time of exposure. It is derived
from the NOAEL or the LOAEL by application of uncertainty factors that reflect
various types of data used to estimate RfD and an additional modifying factor,
which is based on professional judgement of the entire data base of the contami-
nant (IRIS 1996 ). Usually doses less than the RfD are not likely to be assoicated
with adverse health risks, and are therefore less likely to be of regulatory concern.
As the frequency and/or magnitude of the exposures exceeding the RfD increase, the
probability of adverse effects in a human population increases. However, all doses
below the RfD are not assumed to be “acceptable” (or risk-free) and nor are all doses
that exceed the RfD necessarily “unacceptable” (i.e., Result in adverse effects)
Risk The probability that, in a certain timeframe, an adverse outcome will occur in
a person, group of people, plants, animals and/or the ecology of a specified area that
is exposed to a particular dose or concentration of a contaminant, i.e., it depends on
both the level of toxicity of the contaminant and the level of exposure.
Risk Assessment The process of estimating the potential impact of a chemical,
physical, microbiological or psychosocial hazard on a specified human population
or ecological system under a specific set of conditions and for a certain timeframe
Risk management The process of evaluating alternative actions, selecting options
and implementing them in response to Risk Assessments. The decision making will
incorporate scientific, technological, social, economic and political information.
The process requires value judgements, e.g. on the tolerability and reasonableness
of costs.
Safety factor See factor. Safety factor usually refers to health-related concerns.
Stochastic A random probabilistic phenomenon
Teratogenicity The ability to produce a structural malformation or defect in an
embryo or fetus (IEH 1999 )
Threshold The lowest dose or exposure level which will produce a toxic effect
and below which no toxicity is observed (IEH 1999 ).
Threshold Dose The lowest dose which produces an effect and below which
no biological effect occurs. The acceptability and usefulness of the concept of
the experimental NOEL/NOAEL depends on the scientific rationale supporting the
existence and demonstrability of a threshold for responses produced by biologically
active contaminant. As used here, the term “threshold” designates that level of a