1. Charge Question 3-1 Comment Summary for HHCB Peer Review Panel Meeting January 9, 2014

2. 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. Response Themes 1.Completeness of Data 2.Quality Assurance and Quality Control of Data 3.Types of WWTPs Surveyed & Treatment Efficacy (anaerobic processes) Question 3-1

3. Completeness of Data General Consensus that Data is Representative – Are other isomers of HHCB also being detected? Do analytical methods measure total HHCB or are they isomer specific? – WWTPs have large diurnal flux in additional to daily and seasonal differences Assumed that studies relied upon are grab samples thus ranges presented may have bias. Quality Assurance and Quality Control – Blanks, replication, and method reporting limits – How are non-detect data handled within summary statistics? – Organic carbon and lipid normalization for sediments/fish – Surprising that filtered and unfiltered samples yield same ranges.

4. Completeness of Data Water Treatment Processes – Were highest levels of HHCB in effluents and effluent impacted streams related to WWTPs which do not have reliable nitrification? – What is the role, if any, of denitrification and anaerobic processes in general? – Were most systems evaluated using filters prior to discharge? Could explain the lack of difference among filtered and unfiltered samples

5. Recommendations Include QA/QC information for USGS datasets – Blanks, replication, and MRLs Include more discussion regarding USGS sampling locations – Kolpin et al. was highly biased towards known WWTP impacted streams Include organic carbon and lipid content if available Consider if transformation products and other isomers of HHCB have been monitored