Ocean Dumping Risk Assessment: Analysis Of Uncertainties Imposed By Variability In Chemical Bioconcentration, Commercial Fish Landings, And Human Fish Consumption

Human consumption of marine organisms that have been contaminated by municipal sewage sludges dumped of the U.S. mid-Atlantic coast may pose significant health risks. In order to protect human health, researchers have modeled these risks. Such models have failed to reflect uncertainties imposed by parameter variability. An analysis was conducted to examine the effects of variability in bioconcentration, commercial fish landings, and seafood consumption on risk estimates. Calculated human health risks varied by three orders of magnitude when variability in these parameters was included in the risk model. Published bioconcentration factors (BCF) for DDT and for PCBs in different fish species were found to be log-normally distributed ( v = 5 . 0 , 0 = . 6 for DDT and p=5.2, a=.8 for PCBs) . This relationship was used to model health risks stemming from consumption of species for which BCF are unknown. The probability of health risks exeeding critical regulatory threshold (e.g. 10 -6) was estimated. Risk "contingency tables," indicating the probability of exceeding target risk thresholds under different model assumptions, were then compiled. Finally, distributions of BCF, commercial fish landings, and fish consumption were used in a Monte-Carlo simulation of human health risks. Results indicate that parameter variability can lead to a range of estimated health risks which straddles current risk-management thresholds. Thus, if not explicitly considered, this variability can lead to errors in risk-based decision-making.