Scientific and engineering improvement of environmental risk management - Environmental Deterioration and Contamination: Problems and their Management - page 399

of the emissions from the production, transport, use and waste phases. Land devel-
opment and spatial planning should apply a multi-criteria evaluation system which
includes and considers all possible impacts when decisions on regional or national
projects or programs are made. At local level, site-specific data serve as the basis for
risk assessment and the risk reduction measures have a broader selection including site
remediation or rapid technological interventions such as aeration of, e.g., a lake or
removal of contaminated soil.
Risk assessment starts with devising the conceptual risk model of the problem or
contaminated site. Then, quantifying the risk follows in a stepwise procedure, using
optimal tiering with iteration. The number of iterative cycles depends on available
time and cost: if there is no time limit, a large number of tiers are acceptable. If
the time is limited and the funds are available, the site can be assessed in one step
by collecting all data at the same time—some of them unnecessarily. Efficient risk
assessment is an iterative procedure based on a conservative approach. It uses only
pessimistic assumptions (worst case or worst realistic case) and calculates the risk
value (risk quotient or risk characterization ratio) from the available data set (historical
data, existing databases). Sampling and site assessment are only necessary if the first
pessimistic evaluation gives a positive result.
There are details which influence the validity of environmental risk assessment of
contaminants such as heterogeneities of the environment, the physical and chemical
form of the contaminant, the presence of contaminant mixtures, complex interac-
tions in the environment, partition between physical phases, availability by water,
bioavailability of the contaminants, biotransformation and bioaccumulation of the
contaminants. The necessity to be conservative due to uncertainties and the cost of
worst-case estimations are all problems of risk management.
ERA of chemical substances should include all life-stages of a substance and the dif-
ferent exposure routes. Traditional ERA is possible to conduct very detailed modeling
of the predicted environmental concentrations and impacts of a chemical substance
on human population or ecosystem exposed. But the calculated quantitative risk is
related to one chemical substance at a certain location via one exposure route. Other
chemicals and impacts other than toxicity are not covered. The aggregation of the risk
components is not solved in a quantitative ERA. Some of the newly developed generic
ERA tools for exposure assessment are introduced briefly here:

- Targeted Risk Assessment (TRA) is a screening tool in support of the REACH

regulation and the management of chemical substances in Europe. The original
tool was launched by ECETOC in 2004, Version 2 in 2009 (ECETOC, 2009), the
latest version—ConsumerTRA_Ver3_2May2012.xls—is available in two forms:
as an integrated exposure/risk assessment tool covering worker, consumer and
environmental exposures; and as a standalone consumer exposure estimation tool
for inhalation and dermal exposures (ECETOC TRA, 2012);

- Advanced Reach Tool (ART) intends to support chemical safety assessments (CSA).

ART version 1.5 incorporates a mechanistic model of inhalation exposure and a
statistical facility to update the estimates with measurements selected from an
in-built exposure database or the user's own data. This combination of model
estimates and data produces more refined estimates of exposure and reduced
uncertainty (TNO, 2009; ART, 2013);