Indaver wants to ensure the safe processing of PFAS-containing waste at Indaver's facilities in Antwerp and to manage the impact of PFAS on the environment of the Indaver site. Indaver therefore commissions external experts to inventory, monitor and model the impact of the company on its environment, as well as assess any risks.
Inventory and monitoring
A comprehensive monitoring system has been set up to inventory PFAS emissions from the rotary kilns at the Antwerp site to surface water, soil and air.
The August 2023 VITO report Monitoring PFAS chimney emission from Indaver rotary kiln incinerator summarises the results of the 2021-2023 measurement campaign. This study was commissioned by the Flemish government and aimed to develop a measurement method for the sampling and analysis of PFAS in guided air emissions resulting in the draft LUC methodology LUC/VI/003. The study concludes, ‘Based on the 15 emission measurements (2021-2023) and High-resolution air quality modelling (IFDM), it can be calculated that the annual average and maximum daily average concentrations do not exceed the health advisory values of the temporary EFSA review framework’.
Indaver has further reduced its emissions thanks to an ongoing investment programme and continuous improvement:
- In 2022, improved treatment was achieved for the water from the wet flue gas cleaning plant of the rotary kilns;
- In 2023, the lignite filters of the flue gas cleaning plant were completely renewed.
As a result of these improvements, PFAS air emission concentrations decreased by 90% in 2023 compared to 2021.
Risk assessment and modelling
Based on the data collected, ARCHE Consulting carried out risk assessments to evaluate the potential impacts to humans and the environment. Regarding the evaluation of depositions, it should be mentioned that no assessment framework has been formally established. VITO therefore conducted studies to assess the potential exposure and health risks of PFAS depositions. This is both through exposure via inhalation of PFAS in the air (air concentration) and the possible effects on groundwater and soil via air deposition.
a. Risk assessment of exposure via inhalation of PFAS in air (air concentration)
With the help of High-resolution air quality modelling (IFDM), VITO calculated the geographical distribution of PFAS concentrations in the vicinity of Indaver in Monitoring PFAS chimney emissions from Indaver NV rotary kiln incinerator. VITO states, "Based on the average data of all measurement results (15 measurements), this calculation gives a maximum annual average concentration for total PFAS of 0.0104 ng/m³. For the EFSA components, it is 0.0030 ng/m³. Based on data from the 2023 measurement results (5 measurements), this calculation gives a maximum annual mean concentration for total PFAS 0.0016 ng/m³. For the EFSA components, it is 0.0003 ng/m³. Looking at the maximum daily average concentrations based on all 15 measurements, we find respective maxima of 0.25 ng/m³ (total PFAS) and 0.064 ng/m³ (EFSA components), also at some distance from the sources. Looking only at 2023, we then find 0.02 ng/m³ (total PFAS) and 0.004 ng/m³ (EFSA components), respectively."
In addition, VITO conducted research in 2022-2023 on the deposition of PFAS in the Study on PFAS in ambient air and depositions in the vicinity of Indaver and Stabroek. Deposition measurements were carried out at 4 sites, at different distances and wind directions from Indaver, in which VITO concluded that "The average EFSA concentrations at the four measurement sites are below the threshold value of the temporary assessment framework for ambient air EFSA-PFAS (0.4 ng/m³)."
Regarding the depositions, it was found that ‘In general, with a few exceptions, the depositions are quite stable over time, with ΣPFAS depositions below 40 ng/m²/day and EFSA-PFAS depositions between 0 and 6 ng/m²/day at five of the six months (Figure 11 and Figure 12). The highest depositions were measured in the period 27/07 to 24/08/2023 (month 6, deposition August 2023), which is mainly due to strongly increased PFOA deposition at all measurement sites (PFOA depositions of 78 to 112 ng/m²/day across the four measurement sites). The increased PFOA deposition occurs at all four measurement sites during that period.". No elevated PFOA was detected in Indaver's emission measurement results. This indicates that Indaver was not the source of the elevated deposition. VITO also states that ‘Possibly the high rainfall amount is a determining factor for these increased depositions, but the dataset is too limited to substantiate this strongly.’ For more information see the website, PFAS Flanders.
"The average EFSA-PFAS concentrations measured during the 6-month measurement period from March to August 2023 are well below the lower limit of the temporary assessment framework (0.4 ng/m³) at all measurement sites. It can therefore be concluded that no adverse health effects are to be expected from exposure to EFSA-PFAS via ambient air."
The average EFSA concentrations at the four measurement sites near Indaver meet the temporary assessment value of the Flemish ambient air EFSA-PFAS assessment framework (0.4 ng/m³). (PFAS air measurements in Zwijndrecht and surroundings)
b. Risk assessment of air deposition
ARCHE consulting evaluated the potential risks of air depositions both to groundwater and soil and to residents.
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Risk assessment of impact on groundwater and soil
ARCHE Consulting carried out risk assessments for 2 scenarios. The first scenario concerns emitted historical PFAS compounds based on the reference year 2022, where these impacts were considered as emission levels over Indaver's 30-year operations (ARCHE, Expert opinion Characterisation of historical PFAS air emissions and risk assessment for INDAVER). The current sharply reduced emissions (reference year 2023) were used in a second scenario to predict impacts over a future time horizon of 100 years (ARCHE, Expert opinion Characterisation of PFAS emissions in air and risk assessment INDAVER reference year 2023). (ARCHE, Expert opinion Characterisation of PFAS emissions in air and risk assessment INDAVER reference year 2023).
‘Worst case’ conditions were assumed in each of the risk assessments.
Regarding the historical situation, ARCHE concludes : ‘"he modelled groundwater concentration for sum PFAS (14.1-50.5 ng/L) does not exceed the 500 ng/L (for sum PFAS) drinking water limit. During the 30-year time frame, all major PFAS components are below the 3 μg/kg-dw limit used by OVAM as a limit for free use of soil (OVAM, 2021) and thus no risks are predicted via enrichment to the soil compartment."
For the future situation, ARCHE judges "The modelled groundwater concentration for ΣPFAS (1.2-3.5 ng/L) due to current INDAVER emissions does not exceed the 100 ng/L drinking water limit. For the soil compartment, the modelled soil concentrations (INDAVER contribution) ranging from 0.06-0.19 μg/kg-ds are significantly lower than the limit of 3 μg/kg-dw used by OVAM as a limit for free use of soil (OVAM, 2021) and therefore no risks are predicted via enrichment to the soil compartment either."
Based on the results of both these expert opinions, it can be concluded that no risk is predicted to humans from chronic exposure via inhalation of the PFAS emissions considered. No risks were also predicted via enrichment of the soil compartment (soil and groundwater) in terms of Indaver's contribution.
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Risicobeoordeling van impact op de mens
Regarding the historical and future situation, ARCHE concludes in both expert opinions that "Based on the comparison of the peak concentrations of PFAS in the air compartment at ground level with the inhalation toxicology-based limits, it can be concluded that no risk is predicted to humans from chronic exposure via inhalation of the PFAS compounds considered in this study. The calculated risk quotients are even orders of magnitude below 1 for most PFAS compounds This finding confirms VITO's conclusion. The conclusion is that background PFAS in the wide environment of INDAVER is also an important source for the effective PFAS compounds measured in the immission monitoring network."
Moreover, for the current situation, "The contribution of INDAVER's 2023 emissions to the measured values (2022-2023 measurement campaigns) ranges from 0.3% to 1.9% of measured ΣPFAS air concentrations and 1.4% to 14.1% of measured ΣPFAS deposition fluxes." Consequently, Indaver's emissions contribute a maximum of 15% to the measured deposition.
Finally, it examined how PFAS emissions translate into a possible increased PFAS load in the blood of INDAVER's neighbours (ARCHE, Expert opinion impact PFAS on concentrations in blood, reference year 2023): "The percentage contribution of INDAVER's incineration processes to PFAS blood concentrations in children and adults relative to the whole environment (incl. other sources) is very limited. As much as 97 to 99% of the PFAS concentrations expected in blood by inhalation at these four sites are from sources other than INDAVER's combustion processes. INDAVER's contribution to total measured air concentrations on the one hand, and to related blood concentrations on the other, is generally limited to <1%, with a maximum blood contribution of 2.5%. Based on the current guidance values established by EFSA and the German Human Biomonitoring Commission, no health effects are expected at the current contribution of INDAVER via inhalation."
c. Risk assessment of impact on surface water
Indaver recognises that the persistent nature of PFAS compounds and the continuously advancing scientific understanding at European level, gives rise to a number of draft proposals for directives that will potentially define future Flemish policy. Indaver currently already complies with these draft proposals and directives (e.g. Water Framework Directive).
Since April 2022, Indaver has been treating all industrial wastewater via end-of-pipe treatment using 8 activated carbon filters. This includes 2 streets of 4 activated carbon filters each. A risk assessment of Indaver's water discharge carried out by Arcadis shows that the discharge has no significant impact on nature.
Regarding PFAS emissions to the water compartment, Indaver has achieved the following results through continuous improvement:
Conclusions
Due to the rapid evolution of measurement techniques, measurement accuracy and insights into the impact of substances on the environment and people, the context in which Indaver operates is changing rapidly. We invest in new technology as soon as it becomes available and also participate in scientific research ourselves.
Studies carried out by experts show that Indaver has no relevant contribution to the pollution of the Westerschelde and North Sea. Recent and ongoing measurement campaigns (emissions, deposition) show that Indaver's emissions have no impact on the health of local residents.