Prioritizing PFAS mixtures and sites for focused ecotoxicology, ecological risk, assessment and risk communication

Transcription

1 Prioritizing PFAS mixtures and sites for focused ecotoxicology, ecological risk, assessment and risk communication Christopher J. Salice and Andrew East Director, Environmental Science and Studies; Associate Professor of Biology Towson University, Towson, MD

2 Colleagues and Collaborators Mr. Andrew East, Lab Manager, Towson U. Dr. Hunter Anderson, USAF Dr. Todd Anderson, Texas Tech University Dr. Jennifer Field, OSU Chris McCarthy, Jacobs Dr. Jamie G. Suski, EA, EST Dr. Adric Olson, Ph.D. student TTU Ms. Heather Lanza, M.S. student TTU Ms. Rebecca Cochran, M.S. student TTU Ms. Veronica Pereira, UG student TTU

3 Per- and Polyfluoroalkyl Substances and DoD Problem Statement PFAS in aqueous film forming foam (AFFF) Used since the 1970 s Widespread contamination possible Multiple sources and contamination profiles Considerable sampling Emerged contaminant issue but many data gaps Use, location, and identity of source contaminant Fate, transport, accumulation (current SERDP SON) Toxicity (eco-toxicity current SERDP projects) Relevant exposure profiles

4 PFASs: Why the concern? Globally distributed Measured in all manner of species and media Important characteristics Persistent Novel Properties

5 Drinking Water EWG.org

6 The focus thus far Number of Studies on Different PFASs PFOS PFOA

7 Barksdale AFB: Case Study Flat River FTA 02 Upper Trib Flag Lake Cooper s Cooper s & Flat River FTA 01 Mack s

8 Conceptual Model: Ecological Risk PFAS Exposure Pathways AFFF site Avian Reptilian SERDP Projects Surface PFASs Transport To surface (organism mediated) PFASs Transport To groundwater AFF Contamination Groundwater Dietary PFASs Transport To Surface Water and Sediments Amphibian Cutaneous & Gills Surface Water Gills Dietary Sediment Dietary Inverts Fish

9 BAFB: Ecological Risk PFAS Exposure Pathways AFFF site Surface PFASs Transport To surface (organism mediated) Flat River Flag Lake FTA 02 Upper Trib Cooper s Cooper s & Flat River FTA 01 AFF Contamination Mack s Surface Water Gills Dietary PFASs Transport To groundwater Groundwater Sediment PFASs Transport To Surface Water and Sediments Inverts Fish Salice et al., 2018

10 Characterization: PFASs in Water and Sediment Water and Sediment 7 sample events over 1 year Fish (mostly) 5 sample events over 1 year 6 PFASs PFOS PFOA PFBS PFHxS PFNA PFHpA

11 PFOS and PFHxS Water and Biota Water Concentration (ng/ml) PFHxS Water PFOS Water PFHxS Fish PFOS Fish Fish Concentration (ng/g dw) Water PFOS and PFHxS concentrations comparable with time Hypothesized lag period to incorporate PFOS into whole fish carcass

12 Ecotoxicity PFOS and PFOA most studies PFOS more toxic PFOS more relevant to BAFB PFOS Chronic SSD 3000 ppb Surface Water Gills Dietary Sediment Inverts Fish 0.6 ppb

13 A Closer Look: PFOS Ecotoxicity 0.6 ppb PFOS Chronic SSD Nominal Nominal 7 days Nominal >300 days Nominal 3000 ppb Nominal Challenges: Differences in life cycle Differences in Duration Differences in generation Endpoints (NOEC, LOEC, ECx) Measured vs. Nominal Simplifications: Versteeg et al. (1999)

14 A Closer Consideration: Nominal vs Measured Challenges: Tricky +/- 30% OK Details matter Assume- actual likely not greater than nominal* Measurement reduces uncertainty

15 PFOS Summary: Most studied Most toxic (~low ppb effect level) Exposure Duration Matters Experimental design matters There s still lots of variability How environmentally relevant?

16 Is PFOS our only concern? Next series of inquiries: What s out there? What mixtures are relevant? Where to extend effort?

17 What s out there? Obtained 2 data sets: PFASs in surface waters ~30 sites, ~20 PFASs PFASs in soil ~55 sites, ~20 PFASs*? Considerable variation: PFASs measured Number of samples sites/replicates

18 A quick look: Mixture Profile Water

19 A quick look: Mixture Profile Soil

20 Strategy: Conceptual Model Goal#1: to identify relevant PFASs for toxicity testing, etc. Goal#2: Vet a method for Goal 1 Consider multiple data inputs Data quality (influences confidence) Evenness Borrowed from Conservation Biology How well-mixed is a sample PFAS concentration

21 Implementation: Data Insight Endpoints Processing Analysis Output Data amount Data completeness Concentration Mixture characteristics Site specific Chemical specific Evenness and Diversity Estimates Proportional Concentration Rank/cluster Heatmaps Dendrograms By site By chemical Mixture and/or Site Specific Patterns

22 Implementation: Data amount? Data completeness? Concentration? Mixture characteristics? Priorities Highlight high quality data and then summarize by patterns and characteristics

23 Exploring Data by Site Major clusters on sample size (N) Smaller clusters other endpoints Green = High Red = Low

24 Exploring Data by Chemical Several Clusters On all endpoints PFOS PFHxS PFHPA PFOA Lots of samples Almost always analyzed for Frequently detected Generally NOT well-mixed

25 Chemical Specific Insights High Concentrations and Less Even Green = High Red = Low PFOS Low Concentrations and More Even

26 Finding a Relevant Mixture Mixture of dominant PFASs at well-mixed sites with high quality data in this dataset ~0.45 PFOS ~0.30 PFHxS ~0.15 PFOA ~0.10 PFHxA

27 Summary Goal#1: to identify relevant PFASs for toxicity testing, etc. Goal#2: Vet a method for Goal 1 Consider multiple data inputs Data quality (influences confidence) Evenness Borrowed from Conservation Biology How well-mixed is a sample PFAS concentration Identified what we think is a reasonable PFASmix for testing** See Today s Flash Poster Session! Method still in development but was useful to us Important to consider data quality and mixture characteristics

28 Summary: Insights PFOS a very relevant chemical for ER May be a driver Effects of co-occurring PFASs? PFHxS also relevant but few data Sample completeness leads to uncertainty For our analyses, next consider habitat or site characteristics

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30 Comparing SW and Soil Soil Water