Historically firefighters have been occupationally exposed to perfluoroalkyl substances such as PFOS, PFHxS and PFOA in AFFF firefighting foams. Many have subsequently been found to have high blood levels of these PFAS molecules. A recent landmark study1 has shown that regular blood donation or plasma donation can reduce PFAS blood levels and thus PFAS body burden substantially.
Exposure to PFAS is primarily through ingestion via food and water, and by inhalation via dust and aerosol droplets. Apart from workers in the fluorochemical industries, firefighters are the most likely group to be occupationally exposed to PFAS, as a result of using fluorine-containing Class B AFFF and related firefighting foams. Although individual firefighters applying foam at an incident should be wearing protective clothing and using breathing apparatus, other firefighters at an incident not using respiratory protection are exposed to a range of air-borne contaminants including PFAS in droplets from wind-blown foam and bursting bubbles. PFAS exposure during maintenance and training activities can also be significant as full PPE is not often used. The result is chronic exposure to PFAS via different pathways during their working lifetime. Unlike controlled industrial PFAS use, operational firefighting, by its very nature, has few opportunities to control PFAS exposure.
All PFAS molecules contain carbon-fluorine chains that are extremely environmentally persistent, bio-accumulative and toxic (PBT) to varying degrees with long elimination times in humans. Many PFAS are highly mobile in the air, soils and water and have become widely dispersed on a global scale and none are fully biodegradable. As a class of chemicals their persistence, bioaccumulation and toxicity profiles are considered to pose an unacceptable risk to health and they are coming under increasing scrutiny and control.
Human exposure and ‘safe’ levels
Exposure to PFAS contamination has been variously linked to a range of diseases and conditions including kidney, testicular and prostate cancer, as well as disturbances in thyroid function, liver function, endocrine disruption, reproductive impairment, delayed puberty, ADHD and reduced birth weights as well as a suppressed immune response and a reduced response to vaccination.2 Because of the long elimination times for PFAS and the potential for bio-accumulation, ‘safe levels’ are now considered to be in single digits for drinking water in ppt (ng/L) or blood contamination in ppb (ng/ml) – with some argument that there are no safe levels.
Recently the German Federal Environment Agency Human Bio-monitoring Commission has published health trigger levels for PFOS and PFOA in human plasma indicating when surveillance and intervention may be required. The HBM-I value below which health effects are considered unlikely is 5ng/ml (ppb) for PFOS and 2ng/ml for PFOA. HBM-II values above 20ng/ml for PFOS and 10ng/ml for PFOA (10ng/ml and 5ng/ml, respectively, for women of child-bearing age) indicate that immediate intervention is required. Values between HBM-I and HBM-II point to the need for source identification, surveillance and reduction or elimination measures.3
A number of studies have shown that firefighters have PFAS whole blood or plasma levels which greatly exceed the population average.4 The three PFAS molecules currently of most concern are PFOS, PFHxS and PFOA. Studies particularly in Australia and the US have highlighted this problem. Data we presented at the UN Stockholm Convention COP9 meeting in Geneva 2019, also published as part of an IPEN White Paper,5 for a large cohort of firefighters showed that those sampled had average PFOS (35±23ng/ml) and PFHxS (14±12ng/ml) plasma levels considerably greater than the general population with the majority exceeding the HBM-II value for PFOS, including some remarkably high individual values, above which harm is considered likely and which requires immediate intervention to reduce exposure (Fig.2A). Such high levels are of particular concern for female firefighters of child-bearing age or who are breast-feeding.
Elevated plasma PFOS levels resulting from exposure to PFOS-based foam are invariably associated with raised PFHxS levels (Fig.2B). The ratio PFOS/PFHxS is determined by foam composition, differing elimination half-lives for PFOS (3.4y) and PFHxS (5.3y), and length of an individual’s exposure.
A number of large-scale international studies have shown that average population levels for PFOS and PFOA, although now slowly decreasing, still lie between HBM-I and HBM-II.
Wider contamination issues have been documented from the uncontained use of firefighting foam both operationally and during training, often seen close to military airfields, civilian airports, fire stations or after major incidents such as Sandoz-Basel (1986), Coode Island (1991), or Buncefield (2005), especially in Australia, Europe and the United States where drinking water supplies have been affected resulting in exposure of the general population to PFAS contamination.
What can be done to reduce contamination levels in people who have been exposed?
Eradication or reduction to ongoing exposure to PFAS can reduce body burdens over time and prevent any further increases occurring. However, long PFAS elimination half-lives for humans means that there is potential for chronic adverse health effects.
Studies on how PFAS behaves in the human body have been limited but have shown that PFAS associate with proteins raising the potential for lowering PFAS levels by blood and/or plasma loss or removal,6-8,9a,9b as these are high in protein content.
The Melbourne Study
On the basis that PFAS may be able to be removed from the body by blood and/or plasma donation Fire Rescue Victoria initiated and funded a study of its possible effectiveness. Together with colleagues from Macquarie University and other experts we have recently published the results of this study in which a cohort of 285 firefighters with elevated PFAS blood levels (PFOS ≥ 5ng/ml corresponding to HBM-I), and who had not donated blood in the previous three months, were divided into three groups:
- A control group, against which no action was taken and the potential natural change in PFAS could be assessed compared to the other groups.
- A second group who donated blood every 12 weeks to assess possible elimination of PFAS by whole blood removal (including red blood cells and plasma).
- A third group who donated plasma every six weeks to assess the effectiveness of removal of PFAS associated with plasma protein.
The study ran over a period of 52 weeks, followed by a three-month follow-up period to assess that the effect was enduring. The results were clear. Substantial reductions in blood PFOS and PFHxS were observed for blood and plasma donation compared with the non-intervention control group:
- Plasma donation produced a drop in PFOS of ~-24% and for PFHxS ~-31%.
- Blood donation produced a lesser drop in PFOS of ~-8% and for PFHxS ~-12%.
These reductions were maintained during the 12-week follow-up period. Results for PFOA levels in either group also decreased but results were less reliable as the initial body burden was very low. Contamination of firefighter blood with PFOS and PFHxS is characteristic of historical exposure to first-generation Class B AFFF firefighting foams, which were based on C8 PFOS chemistry that relied on PFAs production by electrochemical fluorination (ECF). A side product of PFOS production was always the production of lesser amounts of C6 PFHxS (5–10%). Since the phasing out of PFOS-based chemistry in the early 2000s fluorotelomer chemistry has been used exclusively for Class B AFFF firefighting foams. Fluorotelomer foams do not and cannot contain either PFOS or PFHxS. However, fluorotelomer PFAS contained in foams are able to generate PFOA and related compounds of equal concern.
PFOS, PFHxS and PFOA are now all controlled both nationally and internationally with listing in the relevant Annexes of the UN Stockholm Convention, having been assessed by the Persistent Organic Pollutants Review Committee (POPRC) as posing an unacceptable risk to the environment and human health.
Significance of the Melbourne study
The study has shown for the first time with a statistically significant cohort size that: (i) both blood and plasma donation are effective in reducing PFAS blood levels, in particular PFOS and PFHxS, and thus PFAS body burden; (ii) blood and plasma donation are both simple and safe procedures; and (iii) no special additional medical procedures are necessary. Plasma donation is, on balance, to be preferred over whole blood donation. Plasma donation is more effective at PFAS removal, having approximately twice the concentration of PFAS found in red blood cells, and larger volumes may be taken more frequently as levels are restored within 24–48 hours compared to 4–6 weeks for whole blood. Moreover, plasma donation does not remove red and white cells or platelets from the circulation or deplete circulating iron levels.
For the full article, go to https://pubmed.ncbi.nlm.nih.gov/35394514/
References
1 Gasiorowski, R., Forbes, M.K., Silver, G., Krastev, Y., Hamdorf, B., Lewis, B., Tisbury, M., Cole-Sinclair, M., Lanphear, B.P., Klein, R.A., Holmes, N.J.C., and Taylor, M.P. (2022) “Effect of Plasma and Blood Donation on Perfluoroalkyl and Polyfluoroalkyl Substances in Firefighters in Australia, A Randomized Clinical Trial.” JAMA Network Open. 2022;5(4): e226257. doi:10.1001/jamanetworkopen.2022.6257.
2 Grandjean, P. Heilmann, C., Weihe, P., Nielsen, F., Mogensen, U.B., and Budtz-Jörgensen, E. (2017)” Serum vaccine antibody concentrations in adolescents exposed to perfluorinated compounds” Environ. Health Perspect. 125, 7 xx-xx.
3 Apel, P., Angerer, J. Wilhelm, M., Kolossa-Gehring, M. (2017) “New HBM values for emerging substances, inventory of reference and HBM values in force, and working principles of the German Human Biomonitoring Commission” Int. J. Hyg. Environ. Health 220 (x) 152-166.
4 Rotander, A.; Toms, L.M.; Aylward, L.; Kay, M.; Mueller, J.F. (2015) “Elevated levels of PFOS and PFHxS in firefighters exposed to aqueous film forming foam (AFFF)” Environ. Int. 82, 28-34; Toms, L.-M.L.; Thompson, J.; Rotander, A.; Hobson, P.; Calafat, A.M.; Kato, K.; Ye, X.; Broomhall, S.; Harden, F.; Mueller, J.F. (2014) “Decline in perfluorooctane sulfonate and perfluorooctanoate serum concentrations in an Australian population from 2002 to 2010” Environ. Int. 71,74-80.
5 Bluteau, T.; Cornelsen, M.; Holmes, N.J.C.; Klein, R.A.; McDowall, J.G.; Schaefer, T.H.; Tisbury, M.; Whitehead, K. (2019) “Perfluorohexane Sulfonate (PFHxS) – Socio-Economic Impact, Exposure and the Precautionary Principle” IPEN Expert Panel, UN Stockholm Convention POPRC15 Rome October 2019 <www.ipen.org>.
6 Wong, F., Macleod, M., Mueller, J.F., Cousins, I.T. (2014) “Enhanced Elimination of Perfluorooctane Sulfonic Acid by Menstruating Women: Evidence from Population-Based Pharmacokinetic Modelling” Environ. Sci. Technol. 48 (x) 8807-8814.
7 Lorber, M., Eaglesham, G.E., Hobson, P., Toms, L.M., Mueller, J.F., Thompson, J.S. (2015) “The effect of ongoing blood loss on human serum concentrations of perfluorinated acids” Chemosphere 118, 170-177.
8 Singer, A.B., Whitworth, K.W., Haug, L.S., Sabaredzovic, A., Impinen, A., Papadopoulou, E., and Longnecker, M.P. (2018) “Menstrual cycle characteristics as determinants of plasma concentrations of perfluoroalkyl substances (PFASs) in the Norwegian Mother and Child Cohort (MoBa study)” Environ. Res. 166, 78-85.
9a Genuis, S.J., Liu, Y., Genuis, Q.I., and Martin, J.W. (2014) “Phlebotomy treatment for elimination of perfluoroalkyl acids in a highly exposed family: a retrospective case-series.” PLOS ONE 9 (12) e114295.
9b Genuis, S.J., Curtis, L., and Birkholz, D. (2013) “Gastrointestinal Elimination of Perfluorinated Compounds Using Cholestyramine and Chlorella pyrenoidosa” ISRN Toxicol. pp. 1-8. #657849.
Dr Roger A. Klein
Nigel J.C. Holmes
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