Federal Contaminated Site Risk Assessment In Canada Part I: Guidence on Human Health Preliminary Quantitive Risk Assessment (PQRA)

2.4.2 Identification of Potential Receptors

The receptors likely to visit or inhabit a site will depend on land use and may include members of the general public, departmental personnel, members of specific population subgroups, etc. Exposure calculations may be done for all potential receptors/receptor age groups or only for those critical receptors that are confirmed to have the greatest exposure per unit of body weight per day. Due to the nature of federally owned and operated properties, receptors will often include employees of the custodial department and members of the general public. Members of specific population subgroups (Native Canadians, for example) may also access the site. Critical receptors in all such subgroups should be evaluated if it is anticipated that these groups would be exposed to on-site contaminants.

Age groups to be addressed are those specified by Health Canada (1994) and the CCME (1996): infants (0 to 6 months of age); toddlers (7 months to 4 years of age); children (5 to 11 years); teens (12 to 19 years); and adults (20+ years of age).

In the case of industrial properties, there may be concern regarding risks posed to construction workers during occasional short-term work on-site, particularly work involving soil excavation. If, in the opinion of the risk assessor, soil excavation may present significant risks to these construction workers, even over short time periods, this receptor should also be included in the risk assessment.

2.4.3 Identification of Operable Exposure Pathways

One or more exposure pathways may not be functional at a given site. Operable and inoperable exposure pathways should be identified and a rationale provided for pathways deemed inoperable (i.e., to be excluded from exposure calculations) at the subject site.

2.4.4 Problem Formulation Checklist

Table 2 presents an example checklist to aid in, and summarize, the problem formulation for the subject site. It identifies land use, receptors, and operable/inoperable exposure pathways. This or a similar checklist should be included with the risk assessment report.

Table 2: Problem Formulation Checklist

Land Uses (check [ ] as appropriate)	Receptor Group(s) (check [ ] as appropriate)	Critical Receptors (check [ ] as appropriate)	Exposure Pathways (check [ ] as appropriate)
Agricultural	General public	Infant	Soil ingestion
Residential/urban parkland	Employees	Toddler	Soil dermal absorption
Commercial with daycare	Construction workers	Child	Particulate inhalation
Commercial without daycare	Canadian Native communities	Teen	Vapour inhalation
Industrial	Other (specify)	Adult	Groundwater ingestion
Other (specify)		Other (specify)	Water dermal absorption
			Produce ingestion
			Fish ingestion
			Wild game ingestion
			Other (specify)
			Other (specify)
			Other (specify)
			Other (specify)

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