What is PFAS?
PFAS stands for "per- and poly-fluorinated alkyl substances", a family of synthetic chemicals that do not break down naturally. Estimates of the number of PFAS compounds vary from around 4,700 (OECD) to over 10,000 depending on the definition used. They are commonly called "forever chemicals" because they persist in the environment and human body indefinitely.
PFAS are synthetic chemicals that build up in soil, water, plants, animals, and people. Safety limits are evolving. Some authorities have set very low safe intake levels. When PFAS levels exceed these limits, it is a public health concern.
PFOA Classification
In November 2023, the World Health Organization's International Agency for Research on Cancer (IARC) classified PFOA as a Group 1 carcinogen: carcinogenic to humans.
Source: International Agency for Research on Cancer (IARC), Monographs Volume 135, November 2023Understanding IARC Group 1 Classification
IARC classifies hazard, not risk. Group 1 means there is enough evidence that PFOA can cause cancer in humans. It does not mean everyone exposed will develop cancer.
Other Group 1 agents include asbestos, tobacco smoke, and processed meat. These substances have very different actual risk levels depending on how much exposure someone has and for how long. The classification tells us the hazard is real. Individual risk depends on the nature and extent of exposure.
Health Hazard Classifications
PFOA (Historic Discharges 1950s-2012)
IARC Group 1 Carcinogen (November 2023)
Classification: "Carcinogenic to humans", the highest cancer hazard classification
EEA-NH4 (Current Discharges 2012-Present)
Reproductive Toxicity Category 2 (supplier self-classification)
Classification: "Suspected of damaging fertility or the unborn child" (reprotoxic)
EEA-NH4 is a fluorochemical used as a replacement for PFOA in manufacturing. The classification above is its UK supplier's self-classification, recorded in ECHA's database rather than determined by ECHA; the Environment Agency (2023) records that EEA-NH4 has no harmonised or mandatory classification. Corrected 25 September 2026: this box previously presented it as an ECHA classification.
C8 Science Panel Findings (PFOA)
Probable Links to 6 Conditions:
- Kidney cancer (Barry et al., 2013)
- Testicular cancer (Barry et al., 2013)
- Thyroid disease (Knox et al., 2011)
- Ulcerative colitis (a bowel disease) (Steenland et al., 2013)
- High cholesterol (Steenland et al., 2009)
- Pregnancy-induced hypertension, a high blood pressure disorder of pregnancy which can include pre-eclampsia (Stein et al., 2009)
Based on a study of 69,030 participants
Summary: PFOA was used at the Hillhouse industrial estate for around 60 years, first by ICI, then by AGC Chemicals Europe. It is now classified as carcinogenic to humans. AGC replaced PFOA with EEA-NH4 in 2012. EEA-NH4 has not been tested for cancer risk, but it is classified as suspected of harming fertility and unborn children.
Comparison with Other Regulated Substances
| Substance | Environmental Persistence | UK Restrictions |
|---|---|---|
| Lead in petrol | Does not degrade (lead is an element) | Phased out 2000 (Motor Fuel (Composition and Content) Regulations 1999) |
| Asbestos | Does not degrade [mineral fibre] | Import/supply banned 1999 (Asbestos (Prohibitions) Regulations) |
| PFOA | Indefinite (does not break down in nature) | EU ban 2020 (retained in UK law as assimilated law) |
| EEA-NH4 | Indefinite (does not break down in nature) | Not restricted (as of February 2026) |
Sources: UK legislation (Motor Fuel Regulations 1999; Asbestos Regulations 1999); ECHA classification database; IARC Monographs. Note: This table shows regulatory timeline; it is not intended to imply toxicological equivalence between these substances.
PFOA Phase-Out and Replacement
PFOA use at the Hillhouse estate ceased in 2012 following regulatory phase-out. AGC then began using EEA-NH4 (a fluorochemical used as a replacement for PFOA in manufacturing) as a replacement processing aid. Key points:
- EEA-NH4's UK supplier self-classifies it as "reprotoxic" (suspected of damaging fertility or the unborn child); the classification is recorded in ECHA's database, not determined by ECHA
- In its 2026 consultation (GBCLP 009), the Health and Safety Executive proposed classifying EEA-NH4 as a suspected carcinogen (Category 2), which it described as a borderline case, based on rat studies of 52 and 104 weeks; it also proposed classifying it as a reproductive toxin (Category 1B). The consultation closed on 1 May 2026 and we have not yet recorded the outcome (details). Corrected 26 September 2026: this line previously said no long-term cancer studies had been completed, which the studies HSE relied on show was wrong.
- The Environment Agency's 2023 risk evaluation describes EEA-NH4 as "very persistent" (it doesn't break down) and "mobile" (it spreads easily through soil and water)
- About 783 kg was discharged into the River Wyre in 2019, the latest published figure (AGC's data, in the Environment Agency's April 2023 risk evaluation)