New study published on potential health risks of mineral wool

A new study has been published regarding the health concerns associated with the insulation material mineral wool (also referred to as Manmade Vitreous Fibres or MMVF).

The way its safety is supposed to be ensured has been called into question by the implications of this scientific study. The study is entitled 'Critical Choices in Predicting Stone Wool Biodurability: Lysomal Fluid Compositions and Binder Effects' and was published January 2021 in Chemical Research and Toxicology. The authors are Ursula G Sauer, Kai Werle, Hubert Waindock, Sabine Hirth, Olivier Hachmoller and Wendel Wohlleben

To understand the importance of this new 2021 study, it is necessary to have some context regarding the history of concerns over potential health risks related to mineral wool. The EU Classification, Labelling and Packaging (CLP) Regulation (EC) No 1272/2008 classifies mineral wool as a “suspected human carcinogen”. However, the so-called “note Q” allows for ‘exoneration’ from this classification under certain conditions. The conditions imply in vivo, i.e. animal testing (rather than in vitro, i.e. using test tubes). Mineral wool produced before 1996, which is still found in the building stock, generally does not meet these requirements.

The new 2021 study, authors of which include several employees of BASF SE and which received funding and materials from Kingspan Insulation Ltd, confirms that in 2002, the International Agency for Research on Cancer (IARC) of the World Health Organisation, incorrectly associated in vivo biopersistence with in vitro abiotic dissolution, as it confused multiple critical choices to test the latter, including stimulant fluids, leaching and the removal of binder. Abiotic dissolution testing helps to predict biodurability of mineral wool fibres in the lung. Assessing biodurability is fundamental to measure the hazard potential of the mineral wool fibres, including carcinogenicity. The new study confirms that the absence of the binder element had rendered previous studies misleading. It tested six mineral wool samples, which were representative of the products marketed to consumers, to show that the binder has actually a relevant effect on the testing. It found that commercial mineral wool was completely, but not necessarily uniformly, covered with binder. Removing the binder for testing accelerated the average dissolution rate by +104 percent to maximum + 273 percent, while its presence of the reduced dissolution rates.

The new study also highlights how IARC, and other earlier studies, failed to consider further crucial elements when assessing abiotic dissolution. In particular, they failed to differentiate between leaching (i.e. incongruent dissolution, where some components dissolve more rapidly than others) and structural transformation (i.e. transformation that includes changes to fibre length, fibre composition, and reprecipitation of gel layers).

Also, IARC had not properly addressed the impact that different simulant fluids can have on abiotic dissolution as well as the flow rate that removes ions during testing, when it presented the view that mineral wool should no longer be regarded as carcinogen in 2002.

The 2021 article concludes that a robust prediction of whether mineral wool may be exonerated from classification as a carcinogen may have to consider parameters other than those used in studies conducted so far, in an approach toward correlation with in vivo biodurability, but exactly this is a data gap for mineral wool with binder

The experiments conducted for the 2021 study published in Chemical Research and Toxicology included examples of mineral wool that is supposed to fulfil the conditions specified in EU law to exonerate mineral wool from the general obligation to be labelled as suspected carcinogen. The results call into question studies published by authors who work for the mineral wool industry which determined that the chemical composition of certain mineral wool is exonerated from the general EU classification as suspected carcinogen.

In 2019, an article, whose authors include employees of the major mineral wool producer Rockwool, had stated that the in vitro fibre dissolution rate is a key parameter in determining in vivo biopersistence, i.e. how long mineral wool fibres persist in living organisms. The new, 2021 article implicitly criticises that, whereas earlier studies based on the original test protocol of the mineral wool industry association EURIMA recommended a test setup regarding flow cells exactly as used in the new study, the 2019 “adoption” changed that setup by adding a stirrer, without possibly necessary compensation.

Also, the correlation of in vitro with in vivo biopersistence remains to be established. This implies that the test methods applied by the mineral wool industry might actually not demonstrate that the conditions for exoneration from the classification as suspected carcinogen under EU law are fulfilled.

When asked about the new study, Jan te Bos, Director General of the European Insulation Manufacturers Association (Eurima), stated: “Stone wool insulation is one of the most tested and studied building materials anywhere in the world and has been extensively used for many decades. Hundreds of scientific studies have concluded that stone wool is safe to manufacture, install, and live alongside. These studies have looked at hundreds of thousands of person-years among workers in stone wool, glass wool, and other mineral wool manufacturing plants as well as data on people who installed stone/glass/mineral wool in different kinds of buildings. Taken together, these studies support the same conclusion: when used as intended, stone wool poses no human health or environmental risk.”

He added: “On the study to which you refer, "Critical Choices in Predicting Stone Wool Biodurability: Lysosomal Fluid Compositions and Binder Effects", it is important to note that the three determining factors in toxicity assessment of fibres, particles and dust are: Dose, Dimension and Durability. Regrettably, the study's authors chose only to focus on Durability, while disregarding Dose and Dimension. What's more, they erroneously assume an established correlation between abiotic dissolution testing in-vitro and bio-persistence testing in-vivo. These serious scientific deficiencies invalidate their conclusions. Combined with the fact that the study was conducted and sponsored by two direct competitors of the mineral wool insulation industry, these factors lead us to believe that this study was not designed as a true and genuine contribution to scientific progress.”

On Eurima’s final point, it should be noted that of course the scientific studies that support mineral wool come from the industry itself.

It is important to understand the mineral wool industry’s relationships with the boards that supposedly regulate it. The European Certification Board for Mineral Wool Products (EUCEB) is an association of the mineral wool industry in Luxembourg. It describes its mission as voluntarily certifying that mineral wool fibres have a chemical composition within the ranges of exonerated reference fibres, which have been tested in accordance with European protocols and shown to be in conformity with the note Q. EUCEB has appointed the Belgian Construction Certification Association (BCCA) as certification body. The mineral wool industry has formed and controls EUCEB. Its management board consist exclusively of members from five large mineral wool producers. EUCEB’s (or similar) certification is essential for the marketing of mineral wool. It is this set-up that further convinces those who are concerned about the health risks of mineral wool that it is well past time for the European Union to pay much closer attention to the prevention of those risks for construction workers and home-owners handling the material.

Concerns regarding mineral wool have been going on for some time and indeed EU Today published a special report in 2018 asking Is it time to legislate the Mineral Wool industry more tightly at EU level?. It has to be hoped that the findings of the 2021 scientific study will encourage the European Union to do just that. The potential health concerns around mineral wool for those installing, removing or disposing of it – whether construction workers or DIY home-owners – are serious and include not only the carcinogen factor, but also fears over a link to Chronic obstructive pulmonary disease (COPD).

There is an opportunity for the European Union to address this issue during their revision of the EU rules on classifying substances. In October last year, the European Commission announced in its Chemical Strategy for Sustainability that it will amend the EU Classification, Labelling and Packaging (CLP) Regulation (EC) No 1272/2008. In March, Environment Commissioner Virginijus Sinkevičius told the EU Environment Ministers that the Commission will "soon publish" the roadmap for that revision. Officials from his department had told an expert group meeting at the beginning of the month that the revision would indeed start in April. At a later event, they pushed back the intended time for issuing the eventual legislative proposal to 2022. It is important that European workers and home-owners receive better protection than they currently receive regarding the potential health risks of mineral wool insulation and the 2021 study supports closer EU attention being paid to this material.

Image: By Achim Hering - Own work, CC BY 3.0,

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Gary Cartwright

Gary Cartwright

Gary Cartwright is publishing editor and Brussels correspondent of EU Today.

An experienced journalist and author, he specialises in environment, energy, and defence.

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