PFAS Exposure and Bioavailability Albert L. Juhasz a and Richard - PowerPoint PPT Presentation

Application of Soil Amendments for Reducing PFAS Exposure and Bioavailability Albert L. Juhasz a and Richard Stewart b a Future Industries Institute, University of South Australia, Australia b Ziltek Pty Ltd, Adelaide, Australia

PFAS Exposure and Remediation 1 0 0 0 1 0 0 - 1 ; A S L P -D I) 1 0 P F A S (  g l 1 0 .1 0 .0 1 0 .0 2 .5 5 .0 7 .5 1 0 .0 A m e n d m e n t a p p lic a tio n (% w /w ) ❖ High electronegativity ❖ High bond strength ❖ Limits oxidation of per-fluoro compounds ❖ Poly-fluoro compounds (+ precursors) may undergo transformation

PFAS Exposure and Remediation Aim : Assess the impact of soil amendments on: 1. PFAS leachability 2. PFAS bioavailability RemBind TM technology, jointly owned by the CSIRO and Ziltek Pty Ltd, has been fully commercialised by Ziltek Pty Ltd (US Patent 8,940,958 B2) RemBind TM : Composite product comprising amorphous aluminium hydroxide, kaolin clay and activated carbon

PFAS Exposure and Remediation – Research Approach Bench scale immobilisation studies RemBind TM formulations Application rates PFAS mobility PFAS bioavailability ASLP-DI In vivo mouse model Effect of pH Fate of pure compounds MEP Assessment of RBA

PFOS and PFHxS Leachability – Pre- and Post-Amendment 1 0 0 0 1 0 0 0 P F O S L e a c h a b ility in s o il Z 2 P F H x S L e a c h a b ility in s o il Z 2 1 0 0 - 1 ; A S L P -D I) - 1 ; A S L P -D I) 1 0 0 1 0 R e m B in d 2 0 0 1 0 P F A S (  g l P F A S (  g l R e m B in d 1 0 0 P F O S + P F H x S In te rim la n d fill 1 a c c e p t a n c e c r it e r ia ( d o u b le R e m B in d 1 0 0 -1 ) c o m p o s it e lin e d ( 7  g l R e m B in d 2 0 0 1 R e m B in d 3 0 0 0 .1 R e m B in d 3 0 0 0 .1 0 .0 1 0 .0 2 .5 5 .0 7 .5 0 .0 1 0 .0 2 .5 5 .0 7 .5 1 0 .0 A m e n d m e n t a p p lic a tio n (% w /w ) A m e n d m e n t a p p lic a tio n (% w /w )

PFAS Bioavailability – Research Approach ❖ C57BL/6 mice – well established breed ❖ 10 day exposure study (9 + 1) ❖ For each treatment – 4 operational units, each comprising 3 mice ❖ PFAS (0.01-1.0 µg kg -1 ), contaminated soil (1% w/w) or amended soil (up to 10% w/w) added to AIN93G chow ❖ PFAS-AIN93G chow supplied ad libitum ❖ Health, consumption, excretion data monitored daily ❖ Following exposure, PFAS concentration in tissue / excreta is determined ❖ Determine dose-response and bioavailability endpoints ❖ Determine PFAS relative bioavailability in soil using pure compounds as the reference

Assessment of In Vivo PFAS Distribution 1 5 PFHxS PFOS L ive r U rin a ry e x c re tio n (  g ) K id n e y G I 1 0 F a e c e s U rin e C a rc a s s 5 0 4 5 6 7 8 P F C A C -c h a in le n g th 8 L iv e r a c c u m u la tio n (  g ) PFBS 6 4 2 0 8 9 1 0 1 1 1 2 1 3 1 4 P F C A C -c h a in le n g th

Assessment of PFAS Bioavailability 2 5 P F A S a c c u m u la tio n - k id n e y a n d liv e rs (  g ) PFOS ❖ Short-chain PFAS were excreted in the urine; 2 0 PFCA were excreted to a greater extent than PFSA. ❖ Urinary excretion decreased with increasing 1 5 perfluoralkyl chain length. ❖ PFAS accumulated in the liver; increasing PFOA 1 0 accumulation with increasing carbon chain length was observed for PFCA up to a cut off 5 of C11. ❖ Linear dose-responses were observed; 0 urinary excretion (PFBS, C4-C6 PFCA), 0 5 0 1 0 0 1 5 0 2 0 0 2 5 0 accumulation in organs and / or carcass. P F A S C o n s u m p tio n (  g )

Assessment of PFAS Relative Bioavailability 2 0 0 P F O S R e la tiv e B io a v a ila b ility (% ) U n a m e n d e d s o il 1 5 0 1 5 0 U n a m e n d e d s o il 2 6 A m e n d e d s o il 8 :2 F T S A m e n d e d s o il P F A S R e la tiv e B io a v a ila b ility (% ) P F O A 1 0 0 2 4 P F H p S 5 0 P F H xS 1 0 0 - 1 ) 2 2 P F A S (m g k g 0 Z 2 Z 3 Z 4 2 0 2 0 0 P F O A R e la tiv e B io a v a ila b ility (% ) 1 5 5 0 1 5 0 P F O S 1 0 1 0 0 5 5 0 0 0 P F H x S P F H p S P F O S P F O A 8 : 2 F T S Z 2 0 Z 2 Z 3 Z 4 S o il

Conclusions Acknowledgements ❖ Amendment of PFAS-contaminated soil with Rembind TM (at 5% w/w) reduced PFAS leachability by > 99% ❖ Dose-response studies highlighted differences in PFAS fate in vivo → this has implications for bioavailability endpoint monitoring. ❖ PFAS RBA in contaminated soil was reduced by > 75% when soil was amended with 5% w/w Rembind TM . ❖ Future research includes the development of new Rembind TM formulations that can further reduce PFAS RBA.

Albert.Juhasz@unisa.edu.au