Toxicology Excellence for Risk Assessment (TERA)

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Phone: 513-542-7475
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Email: TERA@TERA.org

World Trade Center Independent Peer Review

Charge to the Panel


Selecting Chemicals of Potential Concern (COPC)

1. Were the sampling data (air monitoring, bulk samples, indoor sampling) used to select potential COPCs (pages 5-7) the most appropriate for assessing the potential for exposure in residences in Lower Manhattan?  Are you aware of additional data that should be considered?   

2.  Comment on the screening methods that were used to select potential COPCs (including health standards, exposure scenarios, and exposure input parameters, Appendix B).  As detailed in this report, does the screening process for COPCs appropriately inform the decision process for selecting COPCs within residences in Lower Manhattan ?  

3.  As a result of the screening process, were the appropriate COPCs chosen? 

  • Should any of the chemicals that were considered in the screening analysis, but finally excluded from the final COPC list, be selected as COPCs?
  • Are there any other compounds that should be considered in the screening analysis or selected as COPCs?
  • Should any chemicals that were selected as CPOCs be removed from the COPC list?

Benchmarks for COPC

4.  Comment on overall methods used to develop benchmarks for the selected COPCs.  

  • Are the definitions of the three tiers reasonable (pages 9-10)?

  • Comment on the ability of the three tiers, as defined, to provide adequate protection of public health.

  • Benchmarks were developed based on either relevant and appropriate environmental standards, risk-based criteria, or adaptation of occupational health standards  – are there any other approaches that would better meet the needs of this situation?

5.  Benchmarks based on risk-based criteria for indoor air (PAH, Dioxin, Asbestos, pages 16-20):  

Chemical Specific Issues - Were the appropriate Reference Concentrations (RfCs) and/or inhalation cancer potency estimates selected as the basis of the risk-based criteria?[1] 

  • PAHs – is the use of a relative potency approach for carcinogenicity-based benchmarks appropriate given the actual PAH compounds measured in site samples?

  • Dioxins - Is the slope factor in the draft dioxin reassessment the appropriate
    value to use for development of the benchmark for dioxin?  Is the dioxin benchmark appropriately protective in light of the background dietary exposure to dioxin?

  • Asbestos and Fibrous glass – is it appropriate to base benchmarks on the Millet and Hays (1994) K factor analysis?

Exposure Issues:

  • Comment on whether the exposure scenarios used will protect the public health of all potentially exposed populations.

  • Are children adequately protected by the risk-based criteria as developed?

  • Was the assumption of 1 year/30 year exposure period for Tier I/III reasonable for development of risk-based screening criteria for contaminants in air?

  • Were appropriate exposure input parameters selected to develop the risk-based criteria?

  • Would the use of existing environmental standards or occupational exposure limits have been a more appropriate method for analysis of residences near the WTC site?

6.  Benchmarks based on risk-based criteria for settled dust (PAH, Dioxin, pages 17-20)   

Chemical Specific Issues - Were the appropriate Reference Doses (RfDs) and/or oral cancer potency values applied to estimate risk from exposure to settled dust components?

Exposure Specific Issues:

  •  Comment on the appropriateness of developing risk-based criteria based on wipe sampling data for evaluating the potential health risks posed to residents living near the WTC site.

  • Is estimating dose using a mass/area approach, as described in Appendix D, appropriate, or would estimating dose using a mass/mass approach provide better estimates of exposure to contaminants in settled dust?

  • Were the appropriate exposure scenarios and exposure input parameters applied to analysis of residences near the WTC site?  Are children adequately protected?

  • Would the use of existing health standards or occupational exposure limits have been a more appropriate method for analysis of residences near the WTC site?

7.  Benchmarks based on existing environmental standards (lead, page 15)  (Lead 

  • Were the standards used applied in a manner that is appropriate given their derivation/purpose?

  • Are other existing standards available that would be more appropriate for the analysis of residences near the WTC site?

  • Does using environmental standards for this exposure situation adequately protect children?

  • Would the use of risk-based criteria or occupational exposure limits have been a more appropriate method for analysis of residences near the WTC site?

8.  Benchmarks based on occupational exposure values (Fibrous Glass, Crystalline silica, pages 21-24) 

  • Was the method of deriving benchmarks from occupational health standards (divide by 10 for Tier 1 and 100 for Tier III) appropriate?

  • Can you recommend a more appropriate method for applying occupational standards to environmental exposures?

  • Would the use of existing health standards or risk-based criteria have been a more appropriated method for analysis of residences near the WTC site?

  • Does using environmental standards for this exposure situation adequately protect children

[1] Note that this discussion also applies to the discussion of these chemicals in risk-based criteria for settled dust.

 

                                 © 2008 Toxicology Excellence for Risk Assessment