Hazard Assessment and Contaminated Sites - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 558

12.5.11 Uncertainty and Variability in Hazard Assessment
As with other components of Risk Assessment, the sources and magnitude of uncer-
tainty and variability in Hazard Assessment should be identified, estimated and
taken into account in decision making.
12.5.12 Sources of Toxicological and Tolerable Intake Data
There are many sources of toxicological appraisal and toxicologically-based guid-
ance values. The nature of the guidelines may be affected by the need to address
local issues or the incorporation of local science policy.
In Australia a hierarchy of sources was developed to assist risk assessors in
the selection of sources of information so that their Risk Assessments would be
acceptable to regulatory agencies. The hierarchy has sources grouped into “lev-
els” which are given in the order of preference. In general, published Australian
ADIs should be used, but other data may be used with appropriate justification.
All documents, particularly those in the lower categories require rigorous appraisal
for relevance, validity and accuracy. Other jurisdictions are likely to have lists of
acceptable sources or similar hierarchies.
Acknowledgement The material in this chapter is derived from Environmental Health Risk
Assessment Guidelines for Assessing Human Health Risks from Environmental Hazards (NHMRC
2004 ) and is used with permission. The material has been summarised by Andrew Langley
for this topic chapter. The principal author and editor of the original publication was Andrew
Langley. Jack Dempsey and Les Davies co-wrote the Hazard Identification - Toxicology sec-
tion and Roscoe Taylor and Andrew Langley co-wrote the Hazard Identification - Epidemiology
section.
Qualifier As the topic is about contamination, the word “contaminant” is used in this chapter and
generally refers to chemical agents that are not naturally occurring but the term may also refer to
physical or microbiological agents in some circumstances.
Glossary
Adapted from NHMRC (1999)
ADI Acceptable Daily Intake. The daily intake of a chemical which, during a life-
time, appears to be without appreciable risk, on the basis of all the facts known
at the time. It is expressed in milligrams per kilogram of body weight per day
(mg/kg bw /day) (WHO 1989 ). For this purpose, “without appreciable risk” is taken
to mean that adverse effects will not result even after a lifetime of exposure.
Furthermore, for a pesticide residue, the acceptable daily intake is intended to give a
guide to the maximum amount that can be taken daily in the food without apprecia-
ble risk to the consumer. Accordingly, the figure is derived as far as possible from
feeding studies in animals. See also “Guidance values”, “RfD” and “TDI”.