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Firefighters working safely with an effective fluorotelomer surfactant based foam blanket at Buncefield, UK.

Aspects of foam need careful consideration – Part 2

Part 1 in the January issue looked at PFOS as a legacy issue, why foam is so beneficial when dealing with large flammable liquid fires and how fluorotelomer surfactants provide critical fuel shedding capabilities necessary for reliable, effective and efficient firefighting operations. It began to explore some significant problems associated with fluorine free foam alternatives. Here we explore why that is the case and what causes these problems.

What causes this F3 flammability and breakdown?

Without fluorochemicals these Fluorine Free Foam (F3) agents have no fuel shedding capability and poor vapour sealing, due to elevated levels of hydrocarbon surfactants or detergents in the foam, attracting the hydrocarbon fuels into the foam bubbles1, with no mechanism to prevent it… except gentle application.

This means slower control and extinction, often resulting in bigger fires, more smoke and more potentially toxic run-off.

Fuel build up in this F3 blanket particularly when forcefully applied, can lead to sudden flashbacks and re-ignition1, more water and foam resources needed1-3, more damage and escalation with increased life safety risk for casualties, firefighters and other emergency responders. I would urge you to watch a 6 minute YouTube video …just Google “flammable firefighting foam!2”, its quite an eye opener.

This video shows the F3 flash and burn away on a range of hydrocarbon fuels, with 50% foam collapse typically after about 5 minutes. Another compelling side by side fire video confirms these findings3.

Direct comparison with C6 short chain Fluorotelomer surfactant based AFFFs exhibit neither flashbacks nor a burning foam blanket, and undergo no foam collapse even after 10 minutes1-3. With such fundamentally inherent F3 drawbacks caused by high detergency and no fuel shedding capability, how can F3 agents be an effective viable alternative to C6 AFFFs, based on the need for life saving fire performance?

Is persistence an invented problem?

Much has been made about persistence, defined as “the continued or prolonged existence of something 4”, which is not necessarily harmful. It’s a problem if it bioaccumulates while it persists, but if it doesn’t, why should it be a problem just sitting there peacefully existing?

Some interpret it differently suggesting persistence means it is “always harmful with an increased risk of bioaccumulation and transport” which is clearly incorrect and not proven. Along with an unbalanced application of the “Precautionary Principle5” which can distort facts and is also sometimes used with persistence to increase fears that fluorotelomers might behave like PFOS… one day! The guiding framework of 5 key elements: anticipatory action; accurate information; alternative assessment; full cost accounting; and participatory decision making process need to be carefully followed if this Precautionary Principle5 is to be invoked.

Concrete is man-made and persistent, but we can’t get enough of it, its everywhere… and exhibits none of these concerns, so why should C6 fluorotelomer surfactants when it is proven they are not bioaccumulative, have low toxicity and do not behave like PFOS or PFOA?

Recent studies on water fleas6 confirm that short chain C6 chemistry is less toxic and less hazardous than long chain C8 fluorochemicals with PFOA or PFOS. It also confirms that any C6 toxicity does not increase with increasing exposure, as some have tried to imply.

Table 1: Summarising variation in human half-life and blood levels of differing fluorochemicals from firefighting foams.

Table 1: Summarising variation in human half-life and blood levels of differing fluorochemicals from firefighting foams.

High aquatic toxicity

Detergent is the most aquatically toxic of all foam’s ingredients7, so it is not surprising that F3 agents are generally 10 times more toxic to fish than AFFFs, and often more so with other smaller aquatic organisms. If F3 can require 3 times more agent for a given sized fire, this could mean 30 times greater aquatic toxicity from a specific incident and plenty of dead fish floating on the water. How is that environmentally more acceptable, particularly in land locked water bodies like streams, ponds and lakes where they may struggle to re-populate. Fish eggs are usually killed at just 5ppm detergent concentrations and only 2 ppm can cause fish to absorb double the amount of other chemicals they would normally absorb which could prove harmful, although that concentration itself is not high enough to affect fish directly from the detergent7.

C6 Fluorotelomer surfactant based AFFF extinguished this ICAO level B test fire using Jet A1 fuel almost three times faster than the Fluorine Free Foam, which took 2minutes and 2 seconds to extinguish.

C6 Fluorotelomer surfactant based AFFF extinguished this ICAO level B test fire using Jet A1 fuel almost three times faster than the Fluorine Free Foam, which took 2minutes and 2 seconds to extinguish.

Key Fluorochemical differences

There are 3 important studies that highlight the differences between the current Fluorotelomer Process and the largely deceased Electrochemical Fluorination Process, which gave us PFOS and PFHxS (or PerfluoroHexane Sulfonate), which are no longer widely used for foam applications (except in China).

A recent study shows the half-life of PFOS in humans is typically 5.4 years, while PFHxS also behaves like PFOS with around 8.5 years. PFOA is significantly less at 3.5 years, while the alternative PFHxA (PerfluoroHexanoic Acid) the main breakdown product of C6 fluorotelomer surfactants, has an average half-life in humans of just 32days8, being fully excreted through the urinary system.

A second recent study of Queensland firefighters9 compared to a control group of University students and office workers showed 21 to 34 times higher levels of PFOS and PFHxS in firefighters blood than the control group, which you would expect. The interesting thing is that traces of PFOA, PFHxA, the 6:2 Fluorotelomer Sulfonate or other fluorotelomer surfactant breakdown products, were not found in blood from either the firefighters or the control group. A range of novel fluorochemicals were found in firefighters blood, but they were all shown to have originated from PFOS and its related substances, which has become a legacy issue related to PFOS and the Electrochemical Fluorination Process alone.

Table 2: Breakdown of incident types attended from Australian firefighter Study10 with percent of fires requiring mostly water alone or some fluorine free Class A foam.

Table 2: Breakdown of incident types attended from Australian firefighter Study10 with percent of fires requiring mostly water alone or some fluorine free Class A foam.

Australian firefighter study

The third landmark study at Monash University of over 300,000 Australian firefighters10 showed reduced mortality rates from a strong “healthy worker” effect. Yet career, paid part time and volunteer firefighters all suffered a trend of increasing prostate cancer risks, with a significant increase from vehicle fires attended.

It acknowledged a likely cause being the wide-range of inhalation and skin contact hazards occurring at fire incidents, many known or possible carcinogens like toxic gases, smoke, fumes, Polycyclic Aromatic Hydrocarbons [PAH], oxidation and pyrolysis products… and more.

Of all fire incidents encountered generally around 82% were of the structural, vehicle and bush fire types, where only water or Class A fluorine free foam would normally be used. Class B firefighting foams were not even mentioned.

Conclusions

The UK Environment Agency11 has confirmed that all foam and firewater run-off pollutes the environment whether fluorinated or fluorine free, and the most effective agent at putting the fire out fast should be chosen. Whilst any fluorinated surfactants in foam are considered by some to be undesirable, they are necessary for such reliable, swift and effective fire performance, whilst arguably delivering less undesirable environmental outcomes in many situations than completely fluorine free foams (F3).

F3 agents cause many problems, not least increased life safety risks, slower fire control, likely more agent usage, more firewater run-off, more resulting damage and disruption, plus potentially 30 times more toxicity to the receiving aquatic environment. How can this be beneficial?

Short chain C6 fluorotelomer surfactants minimise any adverse environmental impacts by fast, effective, efficient use of minimal resources, achieved through reliable fuel shedding capabilities, without bioaccumulation potential, without human health problems and only low aquatic toxicity.

These C6 agents allow firefighters to deal with incidents quickly and safely, reducing flashbacks and escalation potential, minimising property damage and resource usage, reducing business and social disruption, potential job losses and injuries, and delivering the greatest net benefit to environmental and societal values.

Surely we should be “ring-fencing” PFOS based products as unacceptable, and choosing the alternative very different C6 fluorotelomer based foams, that are shown to be capable of securing a safer and better future for all.

For more information, email [email protected]

References

1. Jho C, 2012 – “Flammability and degradation of fuel contaminated fluorine-free foams”, International Fire Fighter, Dec 2012, MDM publishing.

2. “Flammable firefighting foams! “(You Tube video), 2012 – Laboratory testing to verify fuel pickup of F3 foams www.youtube.com/watch?v=IuKRU-HudSU

3. “AFFF v fluorine free foam” (You Tube video), 2013 – Slower extinction and poorer burnbacks during comparative testing, www.youtube.com/watch?v=3MG2fogNfdQ

4. Oxford English Dictionary(on-line)- Definition of Persistence, May 2015 http://www.oxforddictionaries.com/definition/english/persistence

5. European Commission (EU), 2000 – Communication from the Commission on the Precautionary Principle, http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=COM:2000:0001:FIN:EN:PDF

6. Barmentlo SH et al, 2015 – Acute and Chronic toxicity of short chain Perlfuoroalkyl substances to Daphnia magna, Env. Pollution, 198, 47-53. http://www.ncbi.nlm.nih.gov/pubmed/25553346

7. Lenntech, 2015 – Summary of detergent impacts in freshwater ecosystems. http://www.lenntech.com/aquatic/detergents.htm#ixzz3UbwykSGh

8. Russell, Nilsson, Buck, 2013 – Elimination Kinetics of PerFlouroHexanoic Acid in Humans and comparison with mouse, rat and monkey, Chemosphere, Sep2013 ISSN 1879-1298 http://www.biomedsearch.com/nih/Elimination-kinetics-perfluorohexanoic-acid-in/24050716.html

9. Rotander (2015) Novel Fluorinated Surfactants Tentatively Identified in Firefighters Using LC-QTOF-MS/MS and a Case-control Approach, Environ. Sci. Technol. 49(4) 2 pp2434-2442 DOI 10.1021/es503653n http://pubs.acs.org/doi/abs/10.1021/es503653n

10. Glass et al, 2014 -Final Report Australian Firefighters’ Health Study, Centre for Occupational and Environmental Health, Monash University http://www.coeh.monash.org/downloads/finalreport2014.pdf

11. Gable, 2014 – “Firefighting foams: fluorine vs non-fluorine”, UK Environment Agency , Fire Times, Aug-Sep 2014.

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Mike Willson has over 25 years experience in the fire industry across many sectors including Aviation, Refineries, Brigades, bulk fuel storage, much of it involved in flammable liquids as a technical specialist on Class B foams, their application and associated foam delivery systems.