Marnix Vangheluwe, Nathalie Briels, and Hadewych Vanhooren from ARCHE Consulting discuss the origins and escalation of the PFAS crisis in Flanders, Belgium.

Over the years, a shift toward lower acceptable tolerable weekly intake (TWI) values of PFOA (perfluorooctanoic acid) and PFOS (perfluorooctane sulfonate) – highly persistent chemicals within the PFAS group –  has been observed (Fig. 1) (Brunn et al, 2023)¹. This is primarily due to new findings on the substances to be assessed.

Fig. 1: Development of tolerable weekly intake amounts (TWI) from 2008 to 2020 (Brunn et al, 2023)¹
Origin of the PFAS crisis in Flanders

The strong shift towards lower TWI values for PFAS has led to the development of lower safe thresholds. It therefore came as no surprise that this race to the bottom triggered the PFAS crisis in Flanders (Belgium), in the context of PFAS measurements conducted for the soil compartment of a large ongoing infrastructure work (Oosterweel Project) around Antwerp. The Oosterweel Project (Oosterweelverbinding) is a massive infrastructure project in Antwerp, Belgium, designed to complete the Antwerp Ring Road (R1) and improve regional traffic flow (Fig. 2).

Fig. 2: The Oosterweel Project

The scale of the PFAS contamination was officially exposed in 2018-2021 during the excavation works, and the origin of the widespread PFAS contamination was traced to the 3M production site of 3M in Zwijndrecht. From as early as the 1970s until 2002, mainly PFOS-containing products were being produced in Zwijndrecht 3M. After 2002, PFOS production ceased but still more mobile shorter chain PFAS compounds were produced until the decision was made to stop all PFAS production at the 3M Zwijndrecht site in 2024.

Introduction of safety measures

As a response to the PFAS crisis, the Government of Flanders appointed a PFAS commissioner from June 2021 to December 2022. He was tasked with coordinating a structured approach with the partners within the Government of Flanders itself, as well as authorities, government organisations, and other stakeholders. The commissioner developed a temporary policy framework for dealing with PFAS contamination in different environmental compartments and installed a set of ‘No Regret Measures’ in a vicinity of 1.5-5 km around the site.

These No Regret Measures entailed the following:

Food

Do not eat eggs from your own chickens and do not eat home-grown small livestock. Do not use compost made from material from your own garden (<1.5 km).

Groundwater

Do not use your well water as drinking water, nor to make tea, coffee or ice cubes, or for cooking.

Soil and green waste

Avoid soil resuspension. Ensure that the soil is planted or covered with bark, for example. Children should not play on uncovered soil.

Health

Practice good hygiene: Wash your hands regularly and thoroughly, especially before eating, after playing outside, and after working in the garden. Clean your indoor environment regularly with a damp cloth.

Blood monitoring campaigns

As part of the health assessment, extensive blood sampling campaigns have been set up. An initial study on 796 persons (adults only) living within 3 km of the 3M site was conducted in 2021. In the period 2023-2025, a more extensive sampling campaign was conducted on 8,568 people (Eurofins, 2025).² Results showed a clear increase in PFOS blood levels closer to the site (Fig. 3).

Fig. 3: Overview PFOS blood concentrations (Eurofins, 2025b)³

For the evaluation of internal exposure to PFAS substances, the Human Biomonitoring Commission of the German Environment Agency (HBM Commission, 2020)⁴ developed toxicologically justified assessment values (HBM-I and HBM-II values). The HBM-I value corresponds to the concentration of a substance in human biological material below which, according to the current status of assessment, no adverse health effects are to be expected (i.e. PFOS 5 ng/mL and PFOA 2 ng/mL).⁵ In contrast to the HBM-I value, the HBM-II value (i.e. PFOS 20 ng/mL and PFOA 10 ng/mL) and women of childbearing age: PFOS 10 ng/mL and PFOA 5 ng/mL corresponds to the concentration of a substance in human biological material which, when exceeded, may lead to health impairment which is considered as relevant to affected individuals. The blood investigation results showed that 70% of the adults and 80% of the children had PFOS/PFOA levels below HBM-I. About 30% of the adults and 20% of the children have PFOS/PFOA concentrations where long-term negative health effects cannot be excluded.

Evaluation risks and remediation

On 29 October 2021, a safety measure was imposed on 3M pausing all PFAS-emitting processes unless it could be proven that these processes could be restarted without any negative impact on human health and the environment. ARCHE Consulting was in this regard appointed as an independent PFAS expert after approval by the Agency for Care and Health to evaluate all PFAS-related data of 3M on emissions to air, water, and soil and to estimate the possible impact on the population in the vicinity of the 3M site.

With the help of the IMPACT model, a simple Gaussian Plume model used in Flanders (Belgium) ARCHE calculated the potential air concentrations and PFAS deposition fluxes. The latter were subsequently translated by ARCHE in soil and ground water concentrations. At the time of the assessment, no adequate inhalation and deposition thresholds were available for all PFAS compounds of concern. ARCHE consulting, in collaboration with VITO, carried out a study for the Flemish Environment Agency in which values were derived for the maximum permissible concentration of PFAS in the air (Vanhooren et al, 2024).⁶

In addition to these air quality standards, deposition assessment values were also derived for the first time (Van Holderbeke et al, 2024).⁷ These values indicate the maximum amount of PFAS that may settle on the ground per square metre per day (Table 1).

Table 1: Overview inhalation limits and deposition flux limits (short term and long term)

In 2024, 3M Zwijndrecht decided to stop all PFAS-emitting processes at their site. A remediation agreement and remediation covenant with 3M and other local actors have been established for a total amount of €571m, including the excavation of 70 cm soil depth in residential gardens, the use of non-invasive remediation techniques, and long-term monitoring in adjacent nature areas.

But the PFAS crisis in Flanders has not stopped here. As a result, a PFAS Action Plan for the whole of Flanders was being developed. This strategic plan with 50 actions for the period 2022-2024 brought various government partners together to make PFAS policy turn into tangible results. For example, a Hub for Substances of Very High Concern was created, which is a governance approach based on the functioning of the PFAS mission, which indicates a new structured approach for the policy on substances of very high concern, and which builds on the work method introduced by the commissioner in recent months.

In addition, a programme is being set up to monitor the health of local residents on a long-term basis. PFAS data were made available via the PFAS explorer: Open data environment of The Flanders Subsurface Database that was built as a central system where measurement data of PFAS in all different environmental compartments are brought together and visualised. Also, a dedicated PFAS website has been established to ensure all the information about the PFAS issues is available and continuously updated. All information and insights are shared with the general public via the website.

Finally, a Knowledge Center for Innovative PFAS remediation technologies (KIS) has been established, building further on the extensive know-how that Flanders has been developing over the years. This highlights a clear butterfly effect.

References

Brunn H, Arnold G, Körner W, Rippen G, Steinäuser KG and Valentin I, 2023. PFAS: forever chemicals-persistent, bioaccumulative and mobile. Reviewing the status and the need of their phase out and remediation of contaminated sites. Environmental Sciences Europe, 35 (1)20.
Eurofins, 2025a. Consortium Eurofins, Eurofins Belgium, Eurofins Forensics, Dr. Bernard Dirk, L-BioStat, Dr. Kate Hoffman, Dr. Veronica Vieira, Dr. Scott Bartell (2025), Large-scale PFAS blood test near the 3M factory in Zwijndrecht-Results report, commissioned by the Department of Care, 210p.
Eurofins, 2025b. Pictures taken from webinar EUROFINS:
https://www.youtube.com/watch?v=tHuNnJFluY8
HBM, 2020. HBM-II values for perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS) in blood plasma. Statement by the Human Biomonitoring Commission of the German Environment Agency
HBM, 2016. HBM I values for Perfluorooctanoic acid (PFOA) und Perfluorooctanesulfonic acid (PFOS) in blood plasma. Bundesgesundheitsbl 59, 1364 (2016). https://doi.org/10.1007/s00103-016-2437-1
Hadewych Vanhooren, Marnix Vangheluwe, Mirja Van Holderbeke, Arno Vanderbeke, Anthony Purece, Lieve Geerts, Ingeborg Joris, Michiel Maertens, Katleen De Brouwere, Kaat Touchant, Jan Peters, Patrick Berghmans, 2024. Bepalen toetsingswaarden voor PFAS in omgevingslucht en in depositie – omgevingslucht
Mirja Van Holderbeke, Arno Vanderbeke, Anthony Purece, Lieve Geerts, Ingeborg Joris, Michiel Maertens, Katleen De Brouwere, Kaat Touchant, Jan Peters, Patrick Berghmans, Hadewych Vanhooren, Marnix Vangheluwe, 2024. Bepalen toetsingswaarden voor PFAS in omgevingslucht en in depositie – depositie

Authors

Marnix Vangheluwe

Nathalie Briels

Hadewych Vanhooren

Please Note: This is a Commercial Profile

This article will feature in our upcoming April PFAS Special Focus Publication.