Louisiana (Cont.)

baseline risk assessment that does not consider site-specific conditions during or

after remediation. It is consistent with the USEPA's CERCLA guidance, and also

incorporates some components specific to Maine. For example, it provides default

exposure factors for residents of Maine which will be useful in developing human

health exposure assessments and risk characterizations for dredged material

management activities in Maine.

This manual has eight sections, each corresponding to a separate step in the

risk assessment process.

a. Section 1 describes the preliminary steps for a risk assessment, which

includes visiting the site and defining the study area.

b. Section 2 describes how to conduct a hazard identification. Hazard

identification involves developing or reviewing a sampling plan and

analytical methods, as well as collecting, analyzing, and summarizing

data.

c. Section 3 is an exposure assessment. To conduct an exposure assessment,

the assessor must construct exposure scenarios, estimate exposure point

concentrations, and estimate doses of the contaminants to "populations of

concern."

d. Section 4 is a dose-response assessment which integrates the toxicity of

specific contaminants with the exposure scenarios for a specific receptor

coming into contact with those contaminants. In the dose-response

assessment, both noncarcinogenic and carcinogenic effects must be

considered. Exposure is considered to be chronic (>7 years) in this

assessment, as well.

e. Section 5 describes risk characterization using the incremental lifetime

cancer risk (for carcinogenic compounds) and the Hazard Index (for

noncarcinogenic compounds).

f. Section 6 requires a risk assessment for subchronic (2 weeks to 7 years)

and acute (2 weeks) exposures.

g. Section 7 is an analysis of uncertainty.

h. Section 8 requires the risk assessment to prepare the selection of cleanup

target concentrations. The following components must be included in this

step: "backcalculations" of factors to derive target exposure point

concentrations, an evaluation of the effects of leaching to groundwater,

and a comparison of the concentrations of chemicals on the site to

regulatory standards and guidelines.

In addition to the eight sections of the document, there are some appendices

which provide more details for conducting a human health risk assessment. The

appendices explain procedures for developing a cancer potency factor and

reference dose for deriving exposure factors and target exposure point

A20

Appendix A Summary of Federal, State, and Regional Guidance