Part III:
Guidance on Peer Review of Human Health Risk Assessments for Federal Contaminated Sites in Canada

• Is the purpose of the risk assessment clear? (i. e., why is the risk assessment being conducted?)

• Is the scope of the risk assessment clear? (e. g., on- site versus offsite, current versus future land use, all types of receptors, etc.)

• Is Health Canada the only regulatory agency to be satisfied with the risk assessment? (i. e., is the site to remain under federal control or is provincial approval also required?)

• Note that some of the information requested below may be provided in a supplemental (environmental site assessment, or ESA) report rather than the risk assessment report. If so, indicate the title of the report(s)
here.

• Does the report include a description of historical land uses?

• If groundwater on the site, or in the vicinity of the site (within 500m), is used as a source of potable water,
was the groundwater tested?

• Are all relevant site characteristics documented (e. g., soil type, direction of groundwater flow, distance to nearest surface water body)?

• Does the report include a site plan?

• If the report refers to groundwater monitoring wells, are borehole logs and details of the monitoring well
installations provided?

1.2 Sample Collection

• Have all relevant media been tested (e. g., soil, groundwater)?
• Make a note here if any other media were tested as well (e. g., surface water, sediment, soil gas, indoor air,
outdoor air, vegetation and/ or other biota).

• Is there a description of the sampling methodologies?

• Did the sampling methodologies follow a standard method, such as from the CCME, the U. S. EPA, province,
etc.?

• Were sufficient samples collected from the appropriate locations such that you are confident that the likely
maximum concentration has been found? (i. e., were all ‘hot spots’ and known/ suspected areas of contamination
sampled?)

1.3 Sample Analyses

• Were the chemical analyses completed by a laboratory that was certified by CAEAL or other organization for the analyses?

• Does the report or referenced ESA report include laboratory Certificates of Analysis?

• If on- site contaminants are known to degrade (e. g., TCE → vinyl chloride), were analyses conducted for those degradation products?

1.4 Identification of Chemicals of Potential Concern (COPCs)

• Did the list of contaminants that were selected for analysis include all those typically associated with the historical uses of the site?

• Were all COPCs screened using CCME guidelines?
• If no, list the agencies from which other screening guidelines were obtained (province, the U. S. EPA, etc.).

• For guidelines from agencies other than the CCME, were the selected guidelines appropriate for the samples,
chemical analyses, and land uses at the site?

• Are the units of measurement the same as those of the guidelines?

• Are degradation products identified as COPCs even if not detected?

• Were COPCs screened using the maximum measured on- site concentration?

• If a statistic other than the maximum concentration was used for COPC screening, is the selected statistic (mean, upper confidence limit of the mean, specified percentile value, etc.) appropriate and defensible given sample size and other factors?

2. E XPOSURE A SSESSMENT

• Is the use of the property (for purposes of the risk assessment) clearly explained?

• If there is a potential for offsite exposures, are offsite land uses and receptors identified?

• Were exposure calculations conducted using the maximum measured on- site concentration( s)?

• If the maximum concentration was not used, was the selected statistic (mean, upper confidence limit of the
mean, specified percentile value, etc.) appropriate and defensible given the sample size and other factors?

2.1 Receptors and Pathways

• Have all relevant receptor age groups been identified (infant, toddler, child, teen, adult)?

• If all relevant receptor age groups have not been identified, has the most sensitive age group been identified?

• Have all relevant exposure pathways been considered?

• For those pathways that were excluded, was their exclusion adequately justified?

• Were all receptor exposure characteristics (body weight, inhalation rate, etc.) drawn from accepted Canadian
sources (e. g., Health Canada, Compendium of Canadian Human Exposure Factors for Risk Assessment
(Richardson, 1997), the CCME, etc.)?

• If an alternate source for receptor characteristics was used, was this because no Canadian data or value has been published?

• If alternate sources for exposure characteristics were used, was the source/ citation clearly documented?

• If alternate sources for exposure characteristics were used, are the assumptions appropriate and adequately justified?

• Were assumptions regarding exposure duration and exposure frequency appropriate and adequately justified?

• Does the report include sample calculations?

• Can those calculations be reproduced? (i. e., check the math)

2.2 Environmental Fate Modelling

• Are models used to predict the environmental fate of any COPC? (e. g., is a model used to estimate the groundwater concentration from the soil concentration? Or to predict the rate of migration of a COPC in groundwater? Is an equation used to predict the indoor air concentration of a volatile substance from the concentration in soil or groundwater? Etc.)

• If yes, are the names, sources and citations for the model( s) identified?

• Has the model( s) been peer reviewed or published by an authoritative source (e. g., the CCME, Environment
Canada, the U. S. EPA, etc.)? (i. e., is the model ‘generally accepted’?)
• If a unique model was created from first principles, seek comment and assistance from an appropriate expert to
determine its validity and applicability.

• Is the selected model( s) designed for the type of application to which it was applied?

• Are all model assumptions and equations explained?

3. H AZARD A SSESSMENT

• Were all toxicological reference values (TRVs) drawn from Health Canada?

• If no, was it because Health Canada had no TRV for the subject COPC?

• Are the selected TRVs clearly stated, with references, for each chemical and each pathway?

• Are the health effects associated with each COPC and the basis for the TRVs described?

• If dermal absorption is a pathway evaluated, are dermal absorption factors drawn from Health Canada advice?

• If no, were the sources of dermal absorption factors referenced?

• Has 100% oral bioavailability been assumed? (If a variable representing bioavailability is not included, then 100% is implicitly assumed).

• If no, were the values based on tests of on- site soil?

• If no tests of on- site soil were conducted, did the study or literature from which the oral bioavailability value was obtained investigate sites with the same soil characteristics? (similar grain size [fine or coarse], same
type of soil [sand, silt, clay, etc.], similar organic carbon content, etc.)

• If inhalation was a pathway evaluated, was absorption by this pathway assumed to be 100%? (if a variable
representing inhalation bioavailability is not included, then 100% is implicitly assumed).

• If inhalation absorption was less than 100%, was the source of the inhalation absorption factor referenced and is it appropriate to the contaminant?

4. R ISK C HARACTERIZATION

• Are the results of the risk assessment clear?

• For chemicals and pathways affecting the same target organ, are the hazard quotients summed for non-
cancer effects?

• Are all non- cancer hazard quotients less than 0.2 (or other level defined as acceptable)?

• For carcinogens, have risks been summed for chemicals and pathways causing the same form of cancer?

• Are all cancer risks less than 1 x 10 -5 (or other level defined as essentially negligible)?

• Is the uncertainty of the results discussed?

5. R ISK M ANAGEMENT

• If any non- cancer hazard quotients exceed 0.2 or any cancer risks exceed 1 x 10 -5 , are remedial or risk
management measures proposed?

• If yes, are the proposed measures consistent with the spatial scale of the site and the magnitude of the risks?
(i. e., do the risk management options appear to be ‘over- kill’?)

• If ongoing monitoring or risk management measures are recommended, is the responsible department or agency
clearly identified, if other than the Client department that solicited the risk assessment?

6. O VERALL C OMMENTS