Risk management is important in areas other than public policy 

 making. It also provides the public with information on which to base 

 individual decisions regarding where to harvest aquatic food or- 

 ganisms, which species to harvest, and how much to consume. In 

 other words, where to fish, what to fish, and whether to eat what 

 one catches. 



The guidance manual discusses the four major components of the 

 risk assessment process: hazard identification, dose-response 

 assessment, exposure assessment, and risk characterization. 



Hazard identification involves defining the toxicological hazards 

 (toxicity profiles) posed by each chemical contaminant. Toxicity 

 profiles are based on each chemical's physical, chemical, and 

 metabolic properties, and on toxicological effects (also called 

 "dose-response effects"). Noncarcinogenic effects (that is, all 

 harmful effects other than causation of cancer, including birth 

 defects) are summarized in the toxicity profile for each chemical of 

 concern. The guidance manual also describes the "weight-of- 

 evidence" approach used by EPA to classify chemicals according 

 to their carcinogenic (cancer-causing) potential. 



Dose-response assessment is one factor in hazard identification. 

 Data on the relationship between the contaminant dose and the 

 observed "response" (effect on the test organism) are used to 

 determine the toxicological potency of a substance. For car- 

 cinogens, there is presumably a finite risk of cancer, even at low 

 doses. For noncarcinogens, chemicals that induce effects other 

 than cancer, such as nervous system damage, liver effects, skin 

 disorders, and birth detects, there is usually a dose below which 

 adverse biological effects are not observed. This is called the 

 "no-observed-adverse-effects level" or NOAEL. The EPA risk 

 assessment approach is based on the use of dose-response data 

 from epidemiological (human disease) studies or from bioassays 

 of the animal species that are most appropriate for estimating a 

 response in humans. Lacking this information, a measure of 

 toxicological potency is derived from the dose-response relation- 

 ship for the most sensitive species tested (usually a laboratory 

 strain of rats or mice). Results of laboratory experiments are then 

 extrapolated to humans. 



A standardized set of dose-response data then takes into account 

 all the appropriate laboratory animal and epidemiological studies 

 available for each of approximately 200 chemicals provided by EPA 

 in a computerized data base. The data base is called the Integrated 

 Risk Information System (IRIS, EPA 1987). Periodically updated 

 versions of the IRIS data base are also available in document 

 format from EPA or from the National Technical Information Ser- 

 vice. Data on new chemicals are continually added as they become 

 available. 



Components of the 

 Risk Assessment 

 Process 



Hazard Identification 



Dose-Response 

 Assessment 



D5 



