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Transitioning to F3 foams

28 May 2022

AS REGULATIONS continue to be enacted restricting the use of Class B firefighting foams containing fluorosurfactants termed per- and polyfluoroalkyl substances (PFAS), all foams containing PFAS will soon become defunct, with aqueous film-forming foams, film-forming fluoroprotein foams and fluoroprotein foams being phased out. Ian Ross describes the regulatory changes ahead, key considerations and the questions that should be asked when planning the transition to F3 foams.

PFAS are persistent and mobile. In many countries, they’re being discovered in drinking water supplies above safe levels, with a drinking water supply well in Cambridgeshire recently described as having been impacted at four times the UK legal limit of 100 ng/L.

Existing regulations mean that C8 firefighting foams cannot be used as of 1 January 2023 if 100% containment isn’t achieved. That being so, foam stocks purchased in 2015 potentially need to be replaced. Additional regulations have recently been proposed that phase out all PFAS, so fluorine-free (ie F3) firefighting foams will eventually be adopted for all flammable liquid fire extinguishment tasks.

The detection of PFAS in surface waters, soils, biosolids, beer, cider, milk, eggs, game and livestock is an indication of their permanence and mobility in the environment. Exposure to a wide array of differing PFAS still used in firefighting foams via the ingestion of food and water continues while an understanding of their toxicology evolves. As levels of the legacy C8 PFAS diminish in human blood, some studies reveal that replacement PFAS are taking their place.

In Europe, a recent settlement at a district court in Sweden resulted in compensation being awarded to plaintiffs who had been exposed to PFAS in drinking water following elevated levels of PFAS in the blood being classified as a personal injury. This highlights the growing recognition of the potential human health risks associated with PFAS exposure, and may indicate the direction of future litigation.

There are several differing F3 foams that are widely available and have demonstrated comparable extinguishment performance to PFAS-containing foams. For the majority of Class B fire protection systems there should be no delay in implementing the transition to F3 foams.

The performance of F3 foams has been proven in multiple large-scale LASTFIRE tests, with some tests demonstrating that F3 foams performed better than certain C6 AFFFs.

Focusing on regulation

As part of the REACH regulations in Europe, no training with C8 foams was stipulated in 2019. From July last year, all organisations holding more than 50 kg of C8 foam across all the sites they operate have had to report the nature and volume of the foam to local regulators as a stockpile of persistent organic pollutants, with the Irish EPA highlighting €100,000 fines for non-compliance. As stated, from 1 January 2023, C8 foams cannot be used unless 100% contained and cannot be used at all from 4 July 2025.

However, this is only the start of the regulatory focus on fluorosurfactants in firefighting foams. Further regulations have been proposed by ECHA to address C6 PFAS, with these now being combined into an approach to regulate all PFAS in Europe.

The latest proposed regulations aim to put restrictions on placing PFAS-containing foams on the market and curtail their use and export. Foam transition periods of between 18 months and ten years are proposed depending on the sector type. For example, civil aviation will have five years to transition, while municipal Fire and Rescue Services are allowed 18 months.

Additional conditions are proposed six months after the restrictions come into force. They include the following:
•    PFAS-containing foams will only be allowed for Class B fires
•    a firefighting foam management plan to minimise the environmental emissions of PFAS as far as is technically and practically possible must be set up and implemented 
•    PFAS-containing wastes must be disposed of using appropriate treatment methods (excluding municipal wastewater treatment)
•    a limit of 1 mg/L is proposed for PFAS within fire suppression systems following the transition to F3 foams, noting that PFAS in fluorinated foam concentrates is typically 25g/L (2.5%)

Drinking water standards for PFAS continue to be set at exceptionally low levels in what may be perceived as a ‘race to the bottom’. The concern here is that, as compliance levels are set so low, they’re at comparable levels to those identified in multiple environmental matrices as ‘background’ detections (as is the case when it comes to rainwater).

The regulatory level for PFOA in drinking water was recently set at 2 ng/L in Illinois, while in Denmark a 2 ng/L level has been set for the sum of four individual PFAS including PFOA, perfluorooctane sulfonic acid, perfluorohexanesulfonic acid and perfluorononanoic acid.

Environmental profiling

When considering which F3 foam to purchase, it’s very important to assess the environmental consequences of using a new product. Foam suppliers can make multiple claims about the ‘environmental friendliness’ of replacement foams, but these claims must be independently verified.

Some foams have achieved third party certification from GreenScreen Certified, which reviews relevant environmental and human health data and provides three levels of certification: Bronze, Silver and Gold. However, most replacement foams have not been independently certified.

To assist with ensuring that the chosen brands of F3 foams don’t pose a future environmental hazard, it’s suggested the purchasers of foam stipulate foam vendors confirm that all components of the foams are readily biodegradable as per Organisation for Economic Co-operation and Development guidelines.

Replacing one group of extremely persistent and mobile man-made chemicals, such as PFAS, with another that possesses the same properties, such as siloxanes, will likely lead to future environmental liabilities for the foam user. The whole class of replacement siloxanes could be restricted as they’re very persistent and mobile.

Purchasers should also confirm that there are no carcinogenic, mutagenic or reprotoxic substances in the F3 foam formulations to help ensure the safety of foams for practising firefighters.

Measuring PFAS

In order to assess the concentration of PFAS in fluorinated foams, verify that F3 foams are fluorine-free and judge whether or not effective decontamination of fire suppression systems has been achieved, a comprehensive method of chemical analysis is required.

All PFAS-containing firefighting foams harbour fluorosurfactants, which are termed polyfluoroalkyl PFAS (or precursors), and for which standard chemical analysis isn’t effective. That said, chemical analytical methods that can detect these polyfluoroalkyl PFAS are available commercially and include Total Oxidisable Precursor (TOP) assay and Total Organic Fluorine Analysis by Combustion Ion Chromatography (TOF-CIC).

The content of PFAS in firefighting foams, and data to demonstrate that decontamination work has been successful, needs to be verified using one or the other in order to be able to comprehensively detect PFAS.

A significant mass of PFAS can adhere to the interior of fire suppression systems, so there’s a need for system decontamination before transitioning to F3 foams. Rinsing a fire suppression system multiple times with water has been shown to leave a significant PFAS residue within that then dissolves into the F3 foams. For example, a double water rinse of a fire suppression system in Australia between a PFAS foam and F3 foam resulted in 1.6 g/L PFAS subsequently being detected in the F3 foam. This concentration is six orders of magnitude (ie one million times) higher than target levels being set for PFAS in F3 foams in the US and Australia and three orders of magnitude (ie one thousand times) higher than acceptable levels recently proposed in Europe.

It’s recommended that swab tests are applied to effectively measure the mass of PFAS on the surface of a fire suppression system. The PFAS removed by the swabs can be assessed using TOP assay or TOF-CIC to quantify the polyfluorinated PFAS present.

It’s clear that, without effective fire suppression system decontamination, F3 foams are likely to exceed regulatory thresholds, contribute to environmental contamination or potentially impact human health if applied in repeat training or incident extinguishment. For example, there are concerns that repeat exposure to PFAS in mists of F3 foams used during fire training can lead to exposure if fire suppression system decontamination isn’t effective.

Technology assessment

Care needs to be taken in assessing the credibility of PFAS decontamination technologies. The typical approach to cleaning out and decontaminating fire suppression systems has involved draining the foam to be changed and applying a multiple water rinse of the fire suppression systems and firefighting equipment. However, and as previously highlighted, this approach will not effectively remove PFAS.

Water is a poor solvent to dissolve the crystalline bilayers of self-assembled PFAS that form lattices of supramolecular assemblies and bind on surfaces. As such, water – and hot water – cannot effectively decontaminate PFAS from fire suppression systems’ infrastructure. The analogy of trying to clean fat from a greasy frying pan with water holds true here. Repeat washes with water will not remove cooking fat.

Some PFAS decontamination technologies use coagulants, which have been described as cationic (ie positively charged) hydrocarbon surfactants that bind to anionic (ie negatively charged) PFAS and cause them to sediment. This technology will not be effective on the cationic PFAS present in many firefighting foams. Evidence of its success isn’t available as analysis of only a handful of anionic PFAS has been provided. Again, the analytical methods required to demonstrate that decontamination has been effective are TOP assay or TOF-CIC.

At Tetra Tech, we’re using a specialist biodegradable cleaning agent termed PFAScrub to effectively remove PFAS residuals from fire suppression systems. This technology has been shown to effectively remove PFAS from surfaces.

Waste disposal

The waste generated from decontamination requires disposal via a route that effectively destroys PFAS. New technologies are being made commercially available and use cement kilns and supercritical water oxidation, but thorough examination of their efficacy is required. For the immediate future, the US EPA is recommending that foam users store PFAS-containing foams while commercial solutions for their destruction evolve.

We’ve developed an approach that can separate PFAS from the cleaning agent as a concentrated form, meaning that the cleaning agent can be recycled and re-used. This can significantly reduce waste disposal costs and provide a more cost-effective decontamination solution.

Foam transition may appear to be a somewhat complex process and does require multiple fire engineering and environmental skill sets. Finding a team of consulting fire and environmental engineers together with experienced decontamination and fire engineering contractors will be essential.

Ian Ross PhD is Technical Director and Global Lead on PFAS at Tetra Tech (www.tetratecheurope.com)