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. Juhasza and Richard Stewartb

aFuture Industries Institute, University of South Australia, Australia bZiltek Pty Ltd, Adelaide, Australia

PFAS Exposure and Remediation

❖ High electronegativity ❖ High bond strength ❖ Limits oxidation of per-fluoro compounds ❖ Poly-fluoro compounds (+ precursors) may undergo transformation

• 1; A S L P -D I)

PFAS Exposure and Remediation

Aim: Assess the impact of soil amendments on: 1. PFAS leachability 2. PFAS bioavailability

RemBindTM technology, jointly owned by the CSIRO and Ziltek Pty Ltd, has been fully commercialised by Ziltek Pty Ltd (US Patent 8,940,958 B2) RemBindTM: Composite product comprising amorphous aluminium hydroxide, kaolin clay and activated carbon

PFAS Exposure and Remediation – Research Approach

Bench scale immobilisation studies RemBindTM formulations Application rates PFAS mobility ASLP-DI Effect of pH MEP PFAS bioavailability In vivo mouse model Fate of pure compounds Assessment of RBA

PFOS and PFHxS Leachability – Pre- and Post-Amendment

0 .0 2 .5 5 .0 7 .5 1 0 .0 0 .1 1 1 0 1 0 0 1 0 0 0

P F O S L e a c h a b ility in s o il Z 2 A m e n d m e n t a p p lic a tio n (% w /w ) P F A S ( g l

• 1; A S L P -D I)

R e m B in d 1 0 0 R e m B in d 2 0 0 R e m B in d 3 0 0

P F O S + P F H x S In te rim la n d fill a c c e p t a n c e c r it e r ia ( d o u b le c o m p o s it e lin e d ( 7  g l

• 1)

0 .0 2 .5 5 .0 7 .5 1 0 .0 0 .0 1 0 .1 1 1 0 1 0 0 1 0 0 0

P F H x S L e a c h a b ility in s o il Z 2 A m e n d m e n t a p p lic a tio n (% w /w ) P F A S ( g l

• 1; A S L P -D I)

R e m B in d 1 0 0 R e m B in d 2 0 0 R e m B in d 3 0 0

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

L ive r K id n e y G I F a e c e s U rin e C a rc a s s

PFBS PFHxS PFOS

4 5 6 7 8 5 1 0 1 5

P F C A C -c h a in le n g th U rin a ry e x c re tio n ( g )

8 9 1 0 1 1 1 2 1 3 1 4 2 4 6 8

P F C A C -c h a in le n g th L iv e r a c c u m u la tio n ( g )

Assessment of PFAS Bioavailability

❖ Short-chain PFAS were excreted in the urine; PFCA were excreted to a greater extent than PFSA. ❖ Urinary excretion decreased with increasing perfluoralkyl chain length. ❖ PFAS accumulated in the liver; increasing accumulation with increasing carbon chain length was observed for PFCA up to a cut off

• f C11.

❖ Linear dose-responses were observed; urinary excretion (PFBS, C4-C6 PFCA), accumulation in organs and / or carcass.

5 0 1 0 0 1 5 0 2 0 0 2 5 0 5 1 0 1 5 2 0 2 5

P F A S C o n s u m p tio n ( g ) 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 PFOA

Assessment of PFAS Relative Bioavailability

Z 2

5 1 0 1 5 2 0 2 2 2 4 2 6

P F A S (m g k g

• 1)

8 :2 F T S P F O A P F H p S P F H xS P F O S P F H x S P F H p S P F O S P F O A 8 : 2 F T S

5 0 1 0 0 1 5 0

P F A 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 A m e n d e d s o il

Z 2 Z 3 Z 4

5 0 1 0 0 1 5 0 2 0 0

S o il P F O A R e la tiv e B io a v a ila b ility (% )

Z 2 Z 3 Z 4

5 0 1 0 0 1 5 0 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 A m e n d e d s o il

Conclusions

❖ Amendment of PFAS-contaminated soil with RembindTM (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 RembindTM. ❖ Future research includes the development of new RembindTM formulations that can further reduce PFAS RBA.

Acknowledgements

Albert.Juhasz@unisa.edu.au