Carcinogenic risks

Noncarcinogenic effects. The potential for noncarcinogenic health effects is

evaluated by the ratio of exposure to toxicity, termed a Hazard Index. The equation

for estimating the Hazard Index is:

Hazard Index = ADDpot/RfD

(9)

For each exposure scenario, Hazard Indices should be estimated for the

consumption of each contaminated species.

Risk Estimates. USEPA (OSWER Directive 9355.0-30, 1991b) states that

where the cumulative carcinogenic risk to an individual based on reasonable

maximum exposure for both current and future use is less than 10-4 and the

noncarcinogenic hazard index is less than 1, further management action is not

warranted. The directive also states that site-specific conditions may lead the risk

manager to decide that 10-4 is an unacceptable risk based on some site-specific

reasons. The risk manager and risk assessor should apply these guidelines when

addressing potential human health risk at dredged material management sites.

Example 19: Carcinogenic Risk Estimate for Consumption of Flounder

ILCR = Lifetime Average Daily Intake H CSF

= 5.6 H 10 -7 mg/kg/day

Lifetime Average Daily Intake

= 7.7 (mg/kg/day) -1

CSF for total PCB

= 4.3 H 10 -6

ILCRI

EPA generally considers risks in the range of 10-6 to 10-4 as not indicating a potential human health risk.

Therefore, exposure to total PCBs due to the proposed dredging project is unlikely to present a

carcinogenic risk to the local human populations. However, this example calculates only risk from

exposure to total PCBs. The summed ICLR due to exposure to PCBs and other COCs may present an

unacceptable risk.

Note that there is uncertainty associated with this risk estimate because the USEPA currently emphasizes

the need for congener specific analyses in assessing risk from PCB exposure.

Chapter 4 Human Health Risk Assessment