More knowledge is required about the extent to which GenX substances accumulate in fish. This information is essential to calculate safe concentrations in water for lifetime fish consumption by humans and wildlife. The fact that the information is unavailable means it is currently not possible to derive an indicative water quality standard for GenX.

This is shown by an assessment of the available literature that RIVM carried out by order of the Dutch Ministry of Infrastructure and the Environment.

Manufacturer Chemours (based in Dordrecht, the Netherlands) uses the GenX  technology to make plastics (fluoropolymers) for the production of Teflon. The GenX technology was introduced in 2012 to replace PFOA and uses FRD-902 and FRD-903 as alternative perfluoro compounds. The indicative water quality standard is necessary for the assessment of the discharge permit for FRD-903.

Accumulation in fish

RIVM uses the European Water Framework Directive methodology to derive indicative water quality standards. The standards protect the water ecosystem and guarantee that people, birds and mammals can consume fish from the water without suffering any adverse effects. The substances in GenX are relatively non-toxic for water organisms themselves, but can create problems if they end up in the food chain via fish.

For the GenX substances, RIVM has determined the concentration in fish considered not to have a negative impact on human health upon lifetime consumption. This safe level in fish should then be used to calculate the corresponding safe concentration of the GenX substances in water. However, this is not possible because data on the uptake of these compounds by fish from the water are not available. RIVM recommends to investigate the accumulation of GenX by fish in more detail. This can be done in a laboratory study or by analysing fish and water in which GenX substances have been found.