Identify Likely Sources of Uncertainty

Identify Likely Sources of Uncertainty

Obviously, any assumption or measurement introduced into the assessment will

have some degree of uncertainty associated with it. In a human health risk

assessment, the discussion of uncertainty should address the following assessment

elements:

a. The quality and quantity of contaminant concentration in sediment and

surface water.

b. The quality and quantity of available data on seafood catch statistics and

biota.

c. Use of EPCs in uncooked or whole fish based on modeling of sediment

concentrations.

d. Use of surrogate fish species concentration data to estimate average daily

intake.

e. Exclusion of dermal and ingestion exposure pathways to the water column.

f. Use of default exposure frequency and duration variables, body weight, life

expectancy, and population characteristics.

g. Incomplete understanding of the interaction of contaminants with each

other, the mechanism of action of the compounds, and the use of toxicity

factors, with their inherent uncertainties such as dose extrapolation and

The major sources of uncertainty in ecological risk assessment includes:

a. Selection of sensitive ecological receptors.

b. Choice of assessment and measurement end points.

c. Relationship between the assessment and measurement end points.

d. Physical and chemical attributes of the COCS (e.g., partitioning

coefficients).

e. Bioaccumulation potential of the COCs.

f. Bioavailabilty of the COCs.

g. Uncertainties in the fate and transport or food chain models.

h. Biological characteristics of the representative species such as foraging

range, ingestion rates, migration patterns.

Chapter 5 Uncertainty Analysis