Mass Balance Analysis as a tool for investigating fluorine-based chemical pollutants


The use and management of fluorine-based chemical pollutants is problematic, making better group approaches and analysis necessary.


Researchers from the AIST institute, Japan and Örebro University, Sweden have offered novel insight into how these chemicals disproportionally affect younger women, and offer new standards and techniques for better identifying organofluorines, many of which at present remain unknown.


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Image source: Adobe Stock Images / Motorolka





Hello and welcome to ResearchPod. Thank you for listening and joining us today.


In this episode, we look at the work of Nobuyoshi Yamashita and his team from the National Institute of Advanced Industrial Science and Technology (AIST), Japan and Leo Yeung and his team from MTM Research Centre at the Örebro University, Sweden. Together, they have studied man-made chemical pollutants called organofluorines, using the method of mass balance analysis, which is not only looking at a few or hundreds of substances but all potential toxic substances. Their findings have offered novel insight into how these chemicals disproportionally affect younger women, and offer new standards and techniques for better identifying organofluorines, many of which at present remain unknown.


Contamination from highly fluorinated substances is a global problem and one that poses a major threat to human health and the environment.  The man-made chemicals known as per- and polyfluoro alkyl substances or PFASs, a specific type of organofluorine compounds, have been produced since the 1970s. They are persistent organic pollutants known as POPs. These substances are especially dangerous not only due to their inherent toxicity, but because they can travel long distances from their sources of release and accumulate in the environment.


Although governmental action has been taken to both restrict and reduce their production and utilisation, research has revealed the problem posed by these chemicals is much worse than previously imagined. The studies designed to measure PFASs and their counterparts, have so far only managed to capture a relatively small proportion of the problem within their remit. But, experts now know this is only the tip of the iceberg.


Organofluorine compounds have been produced industrially for over four decades now. They are an occupational hazard for those directly involved in their production and utilisation. The production and use of perfluorooctanoic acid (PFOA) has been linked to several health conditions including prostate cancer, ulcerative colitis, cerebrovascular disease and diabetes. Meanwhile another organofluorine compound known as perfluorooctane sulfonic acid (PFOS) have been linked to negative health outcomes such as endocrine disruption, reduced sperm quality, and clinical chemistry effects.


Organofluorine compounds are a major industrial pollutant, and they impact humans and the environment downwind of industrial processes. The compounds are also commonly found in pesticides and pharmaceuticals. Studies have been carried out to assess human impact according to macro-sociological demographic factors such as age and gender. Investigations of blood samples using the tool of mass balance analysis discovered higher levels of contamination in younger women. It was postulated that females are exposed to higher quantities of the chemical compounds through the frequent use of personal care products.


However, no-one is immune from the hazardous impact of PFASs, POPs, and the like; these chemicals have been found in our food, in our water supplies and in the air. Research has revealed a particularly worrisome risk from the ingestion of these chemicals, but even simply breathing in a household environment, it seems, is enough to elevate our exposure: PFASs and POPs have been detected in house dust and indoor air.


So, what exactly is being done about the hazards posed by organofluorine compounds? Once experts began to realise the dangers of those chemicals first produced in the 1970s, they were either phased out or outright banned. These earlier PFASs of a long chain variety were subsequently replaced by shorter chain PFASs assumed to be much less harmful in both toxicity and persistent effects. Nevertheless, in time, these shorter chain analogues were discovered to be on a par with their earlier counterparts and were deemed just as dangerous.


In 2018 the Organisation for Economic Co-operation and Development published a list of PFASs on the global market. The hazardous impact of organofluorine compounds has also been addressed by the Stockholm Convention on Persistent Organic Pollutants, known as POPs, an international environmental treaty to protect both human health and the environment, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of POPs. Both PFOS and PFOA have been included by the convention since 2009 and again more recently in 2019.


Even with these official interventions in play, there remains a significant problem. Inorganic fluorine is the most abundant halogen on Earth. We know there are only a dozen or so natural organofluorines found in tropical and sub-tropical plants. So, if we detect the presence of an organofluorine substance in the environment we can pretty much guess that its origins are man-made. The known abundance of these chemicals emanating from industrial processes necessitate the means for accurate identification and assessment of their concentrations.


So far, governmental monitoring has only concentrated on a few selected PFASs and, as the authors note, “there is always a time gap from production and use of new PFASs for researchers to be able to report their occurrence.” As an example, a replacement product for a PFOA known as GenX first came into commercial use in 2009, but there was nevertheless a six-year wait for the first scientific reports to become available. One of the hold-ups was the availability of reference standards against which to identify a new compound. It is for this reason many compounds still remain unidentified. It is always difficult to accurately assess the concentration of compounds without such reference standards.


To gain knowledge on the amounts of organofluorine compounds, Japanese, American and Chinese researchers used the concept of mass balance analysis back in 2007. The concept is used to find out the amounts of unidentified fluorinated substances in a sample. By measuring the concentration of organofluorine, the amounts of PFAS, fluorinated pharmaceutics and pesticides, the difference between the measured concentrations of organofluorine and the sum of PFAS is indicative of the amounts of unknown fluorinated substances contained within the sample. The method is used in conjunction with other tools supporting the measurement of organofluorines involving extraction and enrichment procedures.  Researchers are now in the process of developing standards so that these methods can be conducted with more accuracy.


Recently Yeung and his team at Örebro University have been using this method to analyse human blood samples with respect to gender and age. This work has refined previous studies by working with demographics to gain a clearer picture of who is more impacted by organofluorines and how. This and other recent studies have demonstrated the need for further urgent work in this field of study.


One of the most striking findings of recent times was the revelation in one study in air that the PFAS concentration was only around 1%. This means the remaining 99% is comprised of the unknown. We as humans are therefore exposed to a significant proportion of unknown organofluorine compounds daily. They are in the products we consume, the water we drink, and in the air we breathe.


Our methods for detecting these compounds could be more sensitive and selective than they currently are. At the AIST Dr. Yamashita and Dr. Taniyasu have established the first international standard method for PFAS analysis. And there is further hope on the horizon. As the author says:


“We are developing new methods to identify these unknown compounds using various advanced analytical techniques using high resolution Orbitrap mass spectrometer and artificial intelligence technology.”


In February 2023 the European Chemicals Agency published the PFAS restriction proposal prepared by authorities in Denmark, Germany, the Netherlands, Norway, and Sweden. The aim of the proposal is to reduce the emission of PFAS into the environment and make products and processes much safer than they are now. The US company 3M, one of the major producers of PFAS, phased out the production of both PFOS and PFOA in 2002. The company has announced it will cease production of PFAS by the end of 2023. While this is laudable, the problem of PFAS remains a global one in light of the persistent properties of these chemicals. We need better solutions to prevent further contamination and to clean up our drinking water.


Dr. Yamashita is the chairperson of the Consortium for Analysis and Remediation of PFAS and is based in Japan. The consortium has established a platform for industry-academia-government collaboration to promote common recognition and standardisation. Both he and Yeung want to welcome enthusiastic people to join their research team and to work for a better future.


That’s all for this episode, thanks for listening. You can find links to Yamashita and his team and Yeung and his team’s research paper in the show notes for this episode and, as ever, be sure to subscribe to ResearchPod to hear more of the latest science news.

See you again soon.

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