Exposure Assessment 



Exposure assessment is the process of determining what human 

 populations are exposed to chemicals of concern; the pathways by 

 which they are exposed; and the magnitude, frequency, and dura- 

 tion of the exposure. An exposure assessment for contaminated 

 fish and shellfish involves 



• Analysis of tissue concentrations of contaminants in aquatic 

 organisms; 



• Analysis of the exposed human population, including fisheries 

 harvest activities, rates of consumption of fish and shellfish, 

 diet composition, and other population-related factors; and 



• Estimation of the ingested dose of each food species by sub- 

 group within the exposed population (for example, age groups, 

 ethnic groups, and fishermen versus nonfishermen) and by 

 geographic location. 



This analysis of a subgroup's overall exposure is called "integrated 

 exposure analysis." 



Tissue Concentration Analysis. Studies to determine concentra- 

 tions of contaminants in tissues of aquatic biota must be designed 

 carefully. Features to consider include study objectives, species of 

 concern, sampling locations, and sampling times. Examples of the 

 relationship between possible objectives and various sampling 

 strategies are provided in the guidance manual. The manual also 

 provides guidance on selecting species for the study and on 

 performing statistical analyses of the resulting data. 



Exposed Population Analysis. The analysis of exposed popula- 

 tions includes four steps: 



• Identify the potentially exposed population by fishery harvest 

 area; 



• Describe the demographic and aquatic harvesting activities of 

 the population; 



• Characterize catch and consumption patterns; and 



• Estimate average consumption rates 



The first three steps typically involve conducting surveys of the 

 potentially exposed population. The guidance manual discusses 

 survey methods, data analyses, and data reporting formats. The 

 summary exposure variable for use in subsequent steps of risk 

 assessment is the average consumption rate. The manual pro- 

 vides guidance for calculating average consumption rates for each 

 harvested species and, if data are available, for each segment 

 within the human population. 



The manual also shows how to use alternative consumption rates 

 derived by other investigators. Decision makers in each state or 

 locality may choose whether to collect site-specific data on human 

 consumption patterns, or to use typical values derived from other 

 studies. Individuals can also be given the opportunity to determine 

 their own personal consumption patterns if risk assessment site 

 results are presented on the basis of "risk per meal of fish per week" 

 or a similar approach. 



D6 



