PFAS at the State Level: Case Study from Minnesota

Transcription

1 PFAS at the State Level: Case Study from Minnesota Presented to the Water Science & Technology Board National Academy of Sciences Ginny Yingling Hydrogeologist May 17, 2018

2 PFAS in Washington County, MN 2002 MN began investigating PFAS contamination in Washington Co. Sources: Chemical plant (on-site disposal) 3 associated legacy waste disposal sites Dumpsite that accepted WWTP biosolids / sludges Others? 5/17/2018 2

3 Co-Mingled Mega-Plume Over 150 sq. mi. 4 major aquifers 8 municipal systems (>140,000 residents) >2,600 private wells (790+ drinking advisories) Much larger than predicted by modeling PFBA most widespread More PFBA in source areas More mobile Distribution controlled by: Bedrock features PFAS chemical properties Groundwater pumping Groundwater - Surface water interactions 5/17/2018 3

4 Managing a Public Health Crisis Amidst Multiple Uncertainties Evolving analytical capacity Evolving risk assessment Evolving understanding of PFAS fate & transport Evolving understanding of PFAS sources 5/17/2018 4

5 Evolving Analytical Capacity 2002 no standard method available and very few commercial labs testing for PFAS Method 537 does not include PFBA a primary contaminant at the East Metro sites MN Public Health laboratory developed on method tailored to PFAS found in source areas Analyte list and detection limits have evolved over time Creates an on-going sense of crisis as new detections occur Analytical methods out-paced toxicological studies 5/17/ MDL (µg/l) PFAS Method Detection Limits Over Time PFOA PFOS PFBA PFPeA PFHxA PFBS PFHxS

6 Evolving Risk Assessment Initially unable to tell exposed residents anything about potential human health effects Used novel risk assessment approach: Extrapolating from animal studies not appropriate due to long half-lives in humans : use of serum levels and long-half lives resulted in much lower PFOA and PFOS guidance values MN Guidance Values (ug/l) Evolving advice = public confusion and sense the problem is getting worse 5/17/ PFOA PFOS PFBA PFBS PFHxS* * *Interim advice levels 6

7 MN Approach to PFAS in Drinking Water Additivity calculation used if chemicals affect same organ(s) by similar mechanism Provides a way to add up chemicals with different toxic potency Health Risk Index (HI) - Sum of each chemical concentration divided by it s drinking water criteria: HI = PFBA [conc.] + PFBS [conc.] + PFOA [conc.] + PFOS [conc.] + PFHxS [conc.] * If HI > 1, considered same as a single PFAS exceeding its drinking water criteria *PFHxS value is a surrogate until an HBV can be set 5/17/18 7

8 Evolving Understanding of Fate & Transport and PFAS Sources Extreme solubility and mobility of PFBA created a MUCH larger plume than expected Defining the extent of affected areas complicated by ubiquity of PFBA in urban surface water and groundwater (airborne deposition?) Plume delineation further complicated by many possible PFAS sources (AFFF, stormwater, spills, waste disposal, land application of biosolids, etc.) Extreme persistence of PFAS created unexpected transport pathways and multiple discrete plumes miles from source areas Discovery of new areas = sense of problem getting worse 5/17/2018 8

9 Groundwater flow Surface water or stormwater flow 5/17/2018

10 Remedial Actions Limited Technologies Available Drinking Water Granular Activated Carbon (GAC) Tested commercially available point-of-use systems (GAC & RO) City of Oakdale water treatment plant Residential carbon filters Site Cleanups Excavation Containment Pump & Treat 6/15/

11 Biomonitoring Exposed adults in affected East Metro communities: 3 rounds: 2008, 2010, initial participants (164 completed) PFOS, PFOA, and PFHxS in 100% PFAS serum levels decreased for residents drinking treated water, but Mean concentrations > national means NHANES PFOS PFOA PFHxS 5/17/

12 PFCs in Homes and Gardens Study (PiHGS) PFOS, PFOA, and PFBA detected in all soil samples Frequency similar in study & reference areas Concentrations higher in study area: PFOS > PFBA > PFOA? Short-chain PFAS still present in drinking water Produce results consistent with other plant uptake studies: Carboxylates > sulfonates Short-chain > long-chain PFBA bioaccumulated in edible parts?? Scher, et al., /15/

13 Statewide Investigations Fish sampling & consumption advisories 3 chrome plating facilities identified as PFOS sources Ambient groundwater monitoring Fire training site investigations 3 sites identified with drinking water contamination Wastewater treatment plant effluent Landfill sampling (groundwater, leachate, condensate) Air & precipitation monitoring MPCA developing a prioritized list of possible sources 5/17/

14 Wish List Toxicological studies of PFAS commonly found in humans and the environment PFHxS (urgent) PFNA, PFHpA, PFBS, PFBA (especially as chemistries shift to shorter-chain PFAS) Standard analytical methods with expanded analyte lists Including shorter-chain PFAS and key percursors Validation of sample collection protocols no more urban legends Better understanding of PFAS additivity 5/17/2018 Better information about PFAS use (past & present) Prioritized list of sources Volumes, timelines, and precursors More treatment & remedial technologies Including inexpensive, point-of-use, DIY systems for homeowners 14

15 Acknowledgements MDH Environmental Health Division MPCA Closed Landfill & Superfund Minnesota Public Health Laboratory Minnesota Geological Survey Valley Branch Watershed District West Central Environmental Consultants Washington County Interpoll Laboratories Barr Engineering 3M Company Weston Solutions Antea Group Agency for Toxic Substances and Disease Registry (ATSDR) U.S. Geological Survey Cities of Oakdale, Lake Elmo, Woodbury, Cottage Grove, Afton, Maplewood, Newport, Saint Paul Park Grey Cloud Island, West Lakeland, and Denmark Townships 5/17/

16 Disclaimer This work was partially funded through a cooperative agreement grant from the Agency for Toxic Substances and Disease Registry (ATSDR) and the Center for Disease Control (CDC). The opinions expressed are those of the author and do not necessarily reflect the official views of ATSDR, the CDC, the Department of Health and Human Services, or the Minnesota Department of Health. 5/17/

17 Thank you! 17

18 Questions? 18

19 More Information and References MDH general PFAS Information: MDH Health Risk Limits: MPCA PFAS Investigations: Scher, D.P., J.E. Kelly, C.A. Huset, K.M. Barry, R.W. Hoffbeck, V.L. Yingling, R.B. Messing (2018) Occurrence of perfluoroalkyl substances (PFAS) in garden produce at homes with a history of PFAScontaminated drinking water. Chemosphere, 196: