Page 1 of 2

OPPT Proposed Draft Charge to External Peer Reviewers for the review of the TSCA 

Workplan Chemical Risk Assessment of HHCB

December 2012

The HHCB Workplan Assessment evaluated the environmental risk to the aquatic and terrestrial 

environments from the use of the polycyclic musk HHCB (CASRN 1222-05-5) as a fragrance 

ingredient in consumer and commercial products. Risk was calculated for scenarios including 

exposure to aquatic organisms through the water or sediment and exposure to terrestrial 

organisms through contact with contaminated soil.

Issue 1. General Organization of the Risk Characterization. The document describes the 

scope and conceptual plan for the HHCB environmental risk assessment (Chapter 1); 

provides information on chemistry, fate and transport, production, and uses (Chapter 2); 

and characterizes exposure, hazard, and risk (Chapter 3). Supporting information is 

provided in appendices. The risk assessment is intended to provide a clear and transparent 

summary of EPA’s analysis.

Question 1-1: Please comment on whether the characterization provides a clear and logical

summary of EPA’s analysis. Where necessary, please provide specific suggestions for 

improving the document. 

Question 1-2: Please comment on whether appropriate background information is provided 

and accurately characterized. Please provide any other significant literature, reports, or data 

that would be useful to complete this characterization, and if so, what are they? 

Issue 2. Chemistry, Environmental Fate and Transport, Production and Uses. The HHCB 

risk assessment document summarizes chemistry, environmental fate and transport, 

production, and uses of HHCB. This information is used to determine the likely extent and 

duration of environmental exposures and better understand the toxicity data. 

Question 2-1: Please comment on whether the information is used appropriately in the risk 

characterization. Please provide any specific suggestions for improving the assessment.

Issue 3. Environmental Exposure Assessment. Data on measured levels of HHCB in 

wastewater, surface water, sediment, soil, and biota are summarized and analyzed to 

characterize the range of potential environmental concentrations of HHCB. Monitoring 

data from the USGS NWIS data were combined with monitoring data from the published 

literature and are assumed to be representative of the range of HHCB concentrations in the 

US.

Question 3-1: Please comment on the use of data from multiple years and locations to 

characterize environmental concentrations in surface water and sediment in the US.
Page 2 of 2

Question 3-2: Please comment on the approach of using both the monitoring data from the 

literature and the USGS NWIS data.

Issue 4. Environmental Hazard Assessment. Ecotoxicity studies of acceptable quality were

identified and summarized for fish, aquatic invertebrates, aquatic plants, sediment 

invertebrates, terrestrial invertebrates, and terrestrial plants. The ecotoxicity 

concentrations of concern were calculated for the most sensitive species. Toxicity endpoints 

included acute and chronic toxicity to aquatic species, chronic toxicity to sediment 

organisms, and chronic toxicity to terrestrial invertebrates and plants.

Question 4-1: Please comment on the ecotoxicity studies selected to represent the most 

sensitive species in each of the risk scenarios (acute aquatic, chronic aquatic, chronic 

sediment, chronic terrestrial invertebrate, and chronic terrestrial plant). Please comment on 

the use of the marine copepod chronic value for chronic toxicity to aquatic species. Please 

provide discussion, suggestions, and references to support any recommendations for the 

hazard characterization.

Issue 5. Environmental Risk Characterization. Environmental risk for HHCB is 

calculated by comparing the measured environmental concentrations of HHCB to the 

ecological concentrations of concern from toxicity studies for each risk scenario. The range 

of environmental concentrations is incorporated in the analysis by calculating risk for both 

mean and upper limit concentrations. 

Question 5-1: Please comment on the calculation of risk derived from the different datasets 

and how they account for environmental variability. Please provide specific 

recommendations as needed for improving the risk characterization and references to support 

any recommendations.