Firefighting foams – Reebok redux · place in a number of venues. Most notable are the three...
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INDUSTRIAL FIRE JOURNAL / April 2008 EQUIPMENT SPOTLIGHT 18 alternatives. Both sets of manufacturers – fluorine- based and fluorine-free – have steadfastly maintained that their products are safe and work for their intended uses. However one thing is clear, fluorotelomer-based AFFF surfactants have been tested and shown to be effective in the severest of cases: real and challenging Class B fires. A primary debate about fluorotelomer-based products centers on the perceived similarity to PFOS, the presence and/or generation of perfluoro- carboxylic acids (PFCAs) such as perfluorooctanoic acid (PFOA), and the ultimate breakdown products of these surfactants. The fate and toxicology of these breakdown products has been brought into full view at the three major Reebok conferences. First and foremost, fluorotelomer-based surfactants do not contain or degrade to PFOS. They are not made with PFOA or PFCAs. The predominant breakdown product from the six-carbon (C6) based fluorotelomer surfactants (Field 2003) is commonly referred to as the 6:2 fluorotelomer sulfonate (6:2 FtS). They may also contain trace levels of PFOA and the C6 acid, perfluorohexanoic acid (PFHxA). Fluorotelomer producers are working toward the elimination of trace levels of PFOA, PFOA precursors, and related higher homologue chemicals from finished products by 2015 under the US Environmental Protection Agency (EPA) global stewardship program. The highlighted red box on the left side of Figure 1 calls out the 6:2 FtS structure (where n = 6). Although there have been numerous articles and conference presentations that purport the 6:2 FtS to be a PFOS analog (sometimes incorrectly referred to as H-PFOS), the scientific data do not support this allegation. The physical, chemical, biopersistence and toxicological properties of 6:2 FtS are not similar to PFOS. Biopersistence The results of a 6:2 FtS biopersistence screening study were presented at the September 2007 Reebok conference. The data presented are shown in Figure 2 (publication in preparation). This screening study involves oral dosing of male rats for 10 days followed by an 84-day recovery period. The study determined total organic fluorine levels in plasma, liver, and fat. It provides a screening measure of what toxicologists refer to as biouptake and bioclearance. The AUCINF, or area under the curve integrated to infinity, provides a relative integrated measure of the absorbed dose of the compound studied. A compound that is absorbed and quickly eliminated or is simply not absorbed will have a low relative AUCINF. It is very clear from Figure 2 that the 6:2 FtS, the C6 acid (PFHxA), and the two commercial fluorotelomer-based firefighting surfactants have extremely low values when compared to PFOS. In this study, PFOA is also lower when compared to PFOS. Toxicology (aka “hazard”) A second part of the debate seems to focus on the potential hazards of PFHxA and the 6:2 FtS. These two compounds can be both contaminants in the final products as well as potential degradants once the AFFF agents are used. The debate however has O ver the past six years, a debate about fluorinated firefighting foams has taken place in a number of venues. Most notable are the three Reebok Stadium meetings held in Bolton, UK between 2002 and 2007. Those who attended these meetings and read the numerous articles in fire industry publications, including the most recent article in the December 2007 issue of IFJ, know that the debate about the efficacy and safety of fluorinated versus fluorine-free fire fighting foams rages on. In the end, what matters most is the safety and protection of lives and property at risk and the delicate balance of this goal with the potential risk to the environment. The title of the talk presented by one of the co-authors of this article, Dr. Korzeniowski of DuPont, really does get to the heart of the issue: “Safety and protection – be sure.” The presentation clearly showed that science must frame the debate. Not hearsay. Not emotion. In many flammable liquid fires where these agents are used, lives and valuable property are at ultimate risk – complete loss. All chemicals have inherent hazards to people and the environment and may be harmful if not used responsibly. The key is to use the right chemical(s) for the task needed to ensure that what is used is truly the best “fit-for-purpose.” Over the past several years there has been a substantial shift from PFOS-based AFFF agents to equally effective AFFF agents containing fluorotelomer-based surfactants (see figure 1). With the withdrawal of the PFOS-based products due to their persistence, bioaccumulative and toxic properties (beginning in May 2000) and their subsequent regulation by various national governments, makers of fluorotelomer-based products began more intensive study of the toxicology and environmental fate of their products. Based on the concerns raised by PFOS, Class B agent customers also began to look for fluorine-free © Fluorotelomer and ECF Products : Different Chemistry ECF produced materials have up to 30% branched isomers at the fluorinated chain end and contain odd and even carbon chain lengths Fluorotelomers (Telomerization) ECF (E lectroC hemical F luorination) H(CH 2 ) n SH Sales Products F(CF 2 ) n SO 3 X F(CF 2 ) n SO 2 N(R)CH 2 CH 2 OH CF 2 =CF 2 (TFE) F(CF 2 ) n I F(CF 2 ) n CH 2 CH 2 I F(CF 2 ) n CH 2 CH 2 OH Even number, straight chains, No Branching Polymers n> 8 ; Surfactants n=6 primarily Sales Products F(CF 2 ) n SO 2 F n = 6,8,10,12, even PFOS n = 8; PFH x Sn=6 PFBS n = 4 Fluorotelomer Alcohol Fluorotelomer Iodide Perfluoroalkyl Iodide Perfluoroalkyl sulfonamido ethanol F(CF 2 ) n CH 2 CH 2 SO 3 X: FT Sulfonate AFFF Surfactant Products Stephen Korzeniowski (DuPont) and Tom Cortina (Fire Fighting Foam Coalition) reflect on the fluorine-free vs fluorinated foams debate that was brought to the fore during last year’s Reebok conference. Figure 1; comparison between fluorotelomer -based and PFOS-based chemistry. Firefighting foams – Reebok redux www.industrialfirejournal.com
Transcript of Firefighting foams – Reebok redux · place in a number of venues. Most notable are the three...
INDUSTRIAL FIRE JOURNAL / April 2008
EQUIPMENT SPOTLIGHT
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alternatives. Both sets of manufacturers – fluorine-based and fluorine-free – have steadfastlymaintained that their products are safe and work fortheir intended uses. However one thing is clear,fluorotelomer-based AFFF surfactants have beentested and shown to be effective in the severest ofcases: real and challenging Class B fires.
A primary debate about fluorotelomer-basedproducts centers on the perceived similarity to PFOS,the presence and/or generation of perfluoro-carboxylic acids (PFCAs) such as perfluorooctanoicacid (PFOA), and the ultimate breakdown products ofthese surfactants. The fate and toxicology of thesebreakdown products has been brought into full view atthe three major Reebok conferences.
First and foremost, fluorotelomer-based surfactantsdo not contain or degrade to PFOS. They are not madewith PFOA or PFCAs. The predominant breakdownproduct from the six-carbon (C6) based fluorotelomersurfactants (Field 2003) is commonly referred to as the6:2 fluorotelomer sulfonate (6:2 FtS). They may alsocontain trace levels of PFOA and the C6 acid,
perfluorohexanoic acid (PFHxA). Fluorotelomerproducers are working toward the elimination of tracelevels of PFOA, PFOA precursors, and related higherhomologue chemicals from finished products by 2015under the US Environmental Protection Agency (EPA)global stewardship program.
The highlighted red box on the left side of Figure 1calls out the 6:2 FtS structure (where n = 6). Althoughthere have been numerous articles and conferencepresentations that purport the 6:2 FtS to be a PFOSanalog (sometimes incorrectly referred to as H-PFOS),the scientific data do not support this allegation. Thephysical, chemical, biopersistence and toxicologicalproperties of 6:2 FtS are not similar to PFOS.
Biopersistence The results of a 6:2 FtS biopersistence screening studywere presented at the September 2007 Reebokconference. The data presented are shown in Figure 2(publication in preparation). This screening studyinvolves oral dosing of male rats for 10 days followedby an 84-day recovery period. The study determinedtotal organic fluorine levels in plasma, liver, and fat. Itprovides a screening measure of what toxicologistsrefer to as biouptake and bioclearance. The AUCINF, orarea under the curve integrated to infinity, provides arelative integrated measure of the absorbed dose ofthe compound studied. A compound that is absorbedand quickly eliminated or is simply not absorbed willhave a low relative AUCINF. It is very clear from Figure2 that the 6:2 FtS, the C6 acid (PFHxA), and the twocommercial fluorotelomer-based firefightingsurfactants have extremely low values whencompared to PFOS. In this study, PFOA is also lowerwhen compared to PFOS.
Toxicology (aka “hazard”) A second part of the debate seems to focus on thepotential hazards of PFHxA and the 6:2 FtS. Thesetwo compounds can be both contaminants in thefinal products as well as potential degradants oncethe AFFF agents are used. The debate however has
Over the past six years, a debate aboutfluorinated firefighting foams has takenplace in a number of venues. Most notableare the three Reebok Stadium meetings
held in Bolton, UK between 2002 and 2007. Thosewho attended these meetings and read thenumerous articles in fire industry publications,including the most recent article in the December2007 issue of IFJ, know that the debate about theefficacy and safety of fluorinated versus fluorine-freefire fighting foams rages on.In the end, what matters most is the safety and
protection of lives and property at risk and thedelicate balance of this goal with the potential risk tothe environment. The title of the talk presented byone of the co-authors of this article, Dr. Korzeniowskiof DuPont, really does get to the heart of the issue:“Safety and protection – be sure.”
The presentation clearly showed that science mustframe the debate. Not hearsay. Not emotion. Inmany flammable liquid fires where these agents areused, lives and valuable property are at ultimate risk
– complete loss. All chemicals have inherent hazardsto people and the environment and may be harmfulif not used responsibly. The key is to use the rightchemical(s) for the task needed to ensure that whatis used is truly the best “fit-for-purpose.”
Over the past several years there has been asubstantial shift from PFOS-based AFFF agents toequally effective AFFF agents containingfluorotelomer-based surfactants (see figure 1).
With the withdrawal of the PFOS-based productsdue to their persistence, bioaccumulative and toxicproperties (beginning in May 2000) and theirsubsequent regulation by various nationalgovernments, makers of fluorotelomer-basedproducts began more intensive study of thetoxicology and environmental fate of their products.Based on the concerns raised by PFOS, Class B agentcustomers also began to look for fluorine-free
©
Fluorotelomer and ECF Products : Different Chemistry
ECF produced materials have up to 30% branchedisomers at the fluorinated chain end and containodd and even carbon chain lengths
Fluorotelomers (Telomerization) ECF (ElectroChemical Fluorination)
H(CH2)nSH
Sales Products
F(CF2)nSO3X
F(CF2)nSO2N(R)CH2CH2OH
CF2=CF2 (TFE)
F(CF2)nI
F(CF2)nCH2CH2I
F(CF2)nCH2CH2OH
Even number, straight chains, No BranchingPolymers n> 8 ; Surfactants n=6 primarily
Sales Products
F(CF2)nSO2F
n = 6,8,10,12, even PFOS n = 8;
PFHxS n = 6
PFBS n = 4
Fluorotelomer Alcohol
Fluorotelomer Iodide
Perfluoroalkyl Iodide
Perfluoroalkyl sulfonamido ethanol
F(CF2)nCH2CH2SO3X: FT Sulfonate
AFFF Surfactant Products
StephenKorzeniowski(DuPont) and
Tom Cortina(Fire Fighting
FoamCoalition)
reflect on thefluorine-free vs
fluorinatedfoams debate
that wasbrought to the
fore during lastyear’s Reebok
conference.
Figure 1; comparisonbetween fluorotelomer-based and PFOS-based
chemistry.
Firefighting foams – Reebok redux
www.industrialfirejournal.com
INDUSTRIAL FIRE JOURNAL / April 2008
EQUIPMENT SPOTLIGHT
20
no place for innuendo and must be based on realhazard data. Extensive data on PFHxA werepresented at the US EPA PFOA Information Forum inJune 2006 that gave a very favorable initialtoxicology (hazard) profile (AGC Chemicals, AsahiGlass, 6/8/06). Additional information waspresented at the September 2007 Reebok conferencethat further supported the favorable toxicologyprofile of PFHxA. Preliminary data were shared onfour major toxicology end points: sub-chronictoxicity in rats, reproductive toxicity in rats,developmental toxicity in rats, and genetic toxicity. Itwas noted at this conference that PFHxA was neither
a selective reproductive nor a selective developmentaltoxicant. In addition it was clearly shown to be neithergenotoxic nor mutagenic. Combining these data withthose presented in June 2006 provides significantevidence that this particular end product has a lowhazard profile based on current data.
Based on recent groundwater studies (Field 2003),the 6:2 FtS has been shown to be the likely ultimatedegradation product of the fluorotelomer-basedsurfactants used in today’s AFFF agents. Thescreening study cited above (Figure 2) indicated thatthe 6:2 FtS had a low relative biopersistencepotential. The 6:2 FtS had a high NOEC (no observedeffect concentration) in the 90-day early life stagetrout study. Results presented at the Reebokconference in September 2007 provided preliminarynew results on environmental effects as well asbioconcentration (BCF) and bioaccumulation (BAF) inrainbow trout. Although the data were preliminary innature, the results were clear and compelling.Moreover both the BCF and the BAF values suggestlow concern for bioaccumulation from water or diet.The data strongly suggested that 6:2 FtS is notbioaccumulative according to published regulatorycriteria and affirmed that it doesn’t behave like PFOS.
Conclusion Firefighting foams that contain fluorotelomersurfactants stand on a substantial foundation ofscientific data. They are the most effective agentscurrently available to fight flammable liquid fires andare safe for their intended uses in military, industrial,and municipal settings. The suggestion that fluorine-free alternatives are safer and environmentallysuperior is simply not based on available science, andcertainly not based on the information presented atthe Reebok conferences. �
The DuPont OvalLogo is a regis-
Fire Fighting Foam Coalition
The Fire Fighting Foam Coalition, Inc. (FFFC) is not-for-
profit trade association whose members are manufac-
turers, distributors and users of aqueous film-forming
foam (AFFF) fire fighting agents and their chemical
components. FFFC represents member’s interests on
all issues related to the environmental acceptability of
fire fighting foams. The Coalition is a clearing house
for information, supports the development of industry
positions, and interacts on behalf of members with
relevant government organizations.
For more information contact www.fffc.org
522474
81507
9070 17865760 1467
0
100000
200000
300000
400000
500000
600000
PFOS PFOA PFHxA 6-2FTS AF3FS 1 AF3FS 2
Test substance
AU
CIN
F/D
ose
Note: Value is shown on top of each bar
PFOS >> PFHxA, 6-2 FTS,
and both AFFF FS
Behavior is very different in
Biopersistence Screen Test
Internal Dose Comparison using Blood AUCINF/Dose (normalized)
(F 1157) (F 1157N)
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