Introduction to PFAS Nancy Tonkin, Technical Director, RPS

1. AN INTRODUCTION TO PFAS
Nancy Tonkin, Technical Director
RPS

2. • PFAS: Per- and polyfluorinated alkyl substances
• A man-made group of several thousand chemicals
• Invented in 1930s
• Resistant to grease, water, stains, chemicals, heat and fire
• Very strong C-F bond
• Very persistent in the environment
• Can be split into a number of groups, including perfluoroalkyl acids (PFAAs)
WHAT ARE PFAS?

3. The PFAS we know the most about often occur in the environment at higher
concentrations than other PFAS
Regulation of PFAS focuses on key PFAAs:
• PFOS, PFOA, PFHxS for human health
• PFOS and PFOA for ecological impacts
PFAAs

4. Referred to as long chain and short chain, dependent on length of carbon chain
Often hear about precursors (including fluorotelomers): more complex than PFAAs, and
generally the PFAS deliberately used in products. Can degrade in environment to form PFAAs
Long chain Short chain
PFAA CHEMISTRY
PFAAs: similar to detergent chemicals but hydrogen atoms replaced with fluorine atoms

5. • Protective treatments
• Polymer manufacture (Teflon)
• Surfactants – including aqueous film firefighting
foams (AFFF)
USES OF PFAS

6. MANUFACTURE AND USE OF SELECTED PFAS
Source: ITRC publication: History and Use of Per- and Polyfluoroalkyl Substances (PFAS), April 2020

7. PFAS IN THE NEWS AND MEDIA
The Guardian, February 2022
Reuters, October 2021
Chemistry World,
January 2021

8. • Experts generally say yes, if exposed to enough
• PFAS shown to accumulate in humans, especially blood, liver and kidneys
• Human population studies: association between some PFAS and variety of health
impacts (altered immune and thyroid function, liver disease, adverse reproductive &
development outcomes) Review by Fenton et al., 2020
• Laboratory studies indicate adverse effects on liver, thyroid hormones and a few
specific cancers in animals
• Globally, expert opinions vary on the levels that might be of concern
• EU TWI for PFOS and PFOA combined: 4.4 ng/kg bw/w (EFSA)
ARE THEY HARMFUL TO HUMAN HEALTH?
“To date, however, the basic fate and behaviour of
PFAS in the human body remains uncertain.”
Royal Society of Chemistry, 2021
Estimated 99% of people in
developed countries have
detectable concentrations
of PFAS in their blood

9. Effects demonstrated in laboratories for animals including
fish, birds and soil health
Actual impacts in the wild not clearly demonstrated but
typically hard to observe; screening values are being
exceeded
Bioaccumulation/biomagnification can result in much higher
exposures to
apex predators (and humans)
Evidence that PFAS can remain in mammalian tissue for
some time
ECOLOGICAL IMPACTS

10. Our monitoring data in rivers, lakes, groundwaters, estuaries
and coastal waters between 2014 and 2019 suggests that PFAS
is likely to be widely present in English surface waters and
groundwaters
PFAS IN THE ENVIRONMENT
• Primary sources are manufacturing, industrial sites etc
• Direct release to the environment in fire-fighting foams
• Numerous secondary sources including landfill and sewage
works, spreading of materials to land
• Persistence in environment means even if replacement
products have been in use for some time, residual source
may remain
• Highly mobile in water environment (especially short
chain)
• PFAS are almost everywhere!
“
“
Environment Agency, August
2021

11. Registration, Evaluation, Authorisation and restriction of Chemicals (REACH)
Regulation (EC, 2006)
PFOS:
• Persistent Organic Pollutant (POP) under the Stockholm
convention 2009.
• Water Framework Directive priority hazardous substance in EU directive
2013/39/EU
PFOA:
• Added to the Stockholm convention 2019.
The UK Drinking Water Inspectorate published guidance values for both
PFOS and PFOA.
PFHxS:
• Agreement to list on Stockholm convention 2022.
Some European countries, have derived screening/ threshold values for
additional PFAS compounds.
Source: ITRC publication: History and Use of Per- and Polyfluoroalkyl
Substances (PFAS), April 2020
PFAS REGULATION

12. International:
• EU Chemicals Strategy – PFAS
• Precautionary approach
• US EPA PFAS Strategic Roadmap
• Research, restrict, remediate
• Australia: PFAS National Environment
Management Plan (Version 2, 2020)
UK:
• DEFRA and EA PFAS Initiative
• coordinated programme of work to
develop our approach to managing the
risk from PFAS
POLICY AND STRATEGY

13. UK REACH work programme:
• 2021-2022: HSE & EA PFAS Regulatory Management Options
Appraisal (RMOA) – results due summer 2022
• 2022-2023: published June 30th 2022, PFAS identified as first of five
priority actions
EA PFAS Risk Screening Project:
• Large scale monitoring programme completed (Phases 1-3)
• Phase 4 to begin in 2022
• Further monitoring of ambient soil concentrations and landfills
• Detailed assessment of problem sites
• Development of good practice guidance for regulators
CIRIA:
• Guidance on PFAS in soil and water environments
WHAT IS HAPPENING NOW?

14. CHALLENGES OF MANAGING LEGACY LAND CONTAMINATION
Multiple source areas
Complex history of use and storage, lack of records
Incident response
Other sources of PFAS
Understanding fate and transport
Sampling and analytical limits
Setting remedial objectives – aim vs what is achievable
Funding
Divestment
Regulatory uncertainty
Lack of screening criteria
Not an excuse to do nothing!

15. UNDERSTANDING THE CONCEPTUAL SITE MODEL
Risk based approach
Pollutant linkages:
Contaminant (source) receptor
• Identifying source areas
• Which receptors are important
• How do PFAS move in the environment?
pathway

16. RETENTION IN SOILS
‘Typical’ contaminants:
• Infiltration of rainfall leads to ongoing
infiltration from vadose (unsaturated)
soils down to groundwater
• Migration in groundwater to downstream
receptors is often considered when
assessing risks
Unsaturated
soil
‘Typical’ contaminant
Leaching to
groundwater

17. PFAS:
• Retained in surface soils much longer than
most other contaminants
• Some infiltration to groundwater still occurs
• Wicking to the surface can occur as a result
of wetting-drying cycles
• Offsite transport is often dominated by
surface water flows
Unsaturated
soil
PFAS
‘Wicking’ to
surface
Leaching to
groundwater
RETENTION IN SOILS
Stormwater run-off

18. REMEDIATION: WHAT ARE WE AIMING FOR?
• Contaminated Land under Part 2A “significant potential of significant harm”
• Managing 3rd party liabilities
• Planning “suitable for use”
• Environmental and sustainability policy – environmental betterment
• Managing reputational risks

19. WHAT IS POSSIBLE?
• Removing all PFAS is not possible
• A simple risk-based approach may not be achievable
• May need to incorporate the concept of ‘reasonably practicable’:
o what is achievable based on available technologies
o environmental sustainability of the overall solution
o proportionality between costs and risks
• Important that all risks are managed
https://www.defence.gov.au/environment/pfas/oakey/managementactivities.asp
HAZARD VS RISK VS PRACTICABLE

20. • A group of compounds which have been,
and still are, widely used in industry
• Increasing evidence they are harmful to
human health and the wider environment
• Attracting increasing media and public
attention around the world
• Feature on political agendas and are
subject to increasing legislation
• Challenges include major gaps in scientific
data, including toxicology of many PFAS,
and analytical capability
• Wide range of primary and secondary
source areas
SUMMARY
• Very persistent and highly mobile in water
environment, now widespread in UK
surface waters
• Soil sources are likely to remain for a long
time
• Important to understand the conceptual site
model and what is possible/ practicable for
remediation

21. Thank you
nancy.tonkin@rpsgroup.com