16 July 2019

This Commission Regulation (EU) 2019/957 of 11 June, 2019 on amending Annex XVII to Regulation (EC) No 1907/2006 of the European Parliament and of the Council concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) as regards (3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl) silanetriol and TDFAs entered into force two weeks ago on 1 July, 2019.

Perfluorooctylsilanes with the EU abbreviation TDFA is a family of hazardous substances, which may be contained in water proof spray products as a surface modification agent to prepare hydrophobic surfaces for example useful as fabric conditioning agents and as adhesion promotor for a variety of materials used for cleaning and impregnating of ceramic kitchen/bathroom tiles, sanitary ware,  and shower/automotive glass with a thin hydrophobic nanofilm sometimes called “nanocover”.


A Danish research group from the Danish National Research Centre for Working Environment discovered more than ten years ago, that inhalation of such chemicals induced lung injury in experimental animals. Based on that and human intoxications, the Danish government banned these products.

In April 2016 The Danish EPA submitted a REACH Annex XV Report to EU with background documentation and suggested EU to restrict such hazardous chemical products in all member countries. After many years of negotiations the present regulation was developed.

The new EU regulation implies that from 2 January 2021 aerosol dispensers and pump spray products with such chemicals in a concentration equal to or greater than two parts per billion by weight of the mixtures containing organic solvents, must not be supplied for the general consumer use, however it is still allowed, if the product is labelled “for professional users only” and “fatal if inhaled” with the hazard pictogram GHS06:


In the regulation covers all chemicals included in the general group name:  “(3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyl)silanetriol and any of its mono-, di- or tri-O-(alkyl) derivatives”.  In principle that means an infinite number of substances but only a few derivatives are known and described.

The general structure is:

TDFA, where X = hydrogen or alkyl.

The many numbers in the EU preferred name are difficult to remember and to use, even for a chemist. However, the first part of the name in the parenthesis can be expressed more convenient as either:

  • 6:2 Fluorotelomer, or
  • 1H,1H,2H,2H-Perfluorooctyl

Some of the many possible existing substances (liquids) with a fluorooctyl chain and included in the regulation are listed in the tabel:

In the EU background documentation five specific chemicals are mentioned, among others:

(3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooctyl)trimethoxysilane; 1H,1H,2H,2H-perfluorooctyl trimethoxysilane; 6:2 fluorotelomer trimethoxysilane; CAS No. 85857-16-5; EC No. 288-657-1.

(3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooctyl)triethoxysilane; 1H,1H,2H,2H-perfluorooctyl triethoxysilane; 6:2 fluorotelomer triethoxysilane; CAS No. 51851-37-7; EC No. 257-473-3.

(3,3,4,4,5,5,6,6,7,7,8,8,8-Tridecafluorooctyl)triisopropoxysilane;1H,1H,2H,2H-perfluorooctyl-triisopropoxysilane; 6:2 fluorotelomer triisopropoxysilane; CAS No. 1240203-07-9.

Another chemical probably covered – but not mentioned – is:

1H,1H,2H,2H-Perfluorooctyldimethoxymethylsilane, 6:2 fluorotelomer dimethoxymethylsilane, CAS 85857-17-6.

Another relevant substance is the “dimer”:



Probably not, since there are analogue substances with shorter or longer alkyl chain, which may be used instead, for instances, these in the table:

In addition there are many non-regulated closely related chemicals such as:

  1. 1H,1H,2H,2H-Perfluorohexyltrichlorosilane; 4:2 fluorotelomer trichlorosilane; CAS 78560-47-1.
  2. 1H,1H,2H,2H-Perfluorohexylmethyldichlorosilane; (3,3,3,4,4,5,5,6,6-nonafluorohexyl)-methyldichlorosilane; CAS 38436-16-7.
  3. 1H,1H,2H,2H-Perfluorohexyldimethylchlorosilane; (3,3,4,4,5,5,6,6,6-nonafluorohexyl)-dimethylchlorosilane; CAS 119386-82-2.
  4. 1H,1H,2H,2H-Perfluorooctyltrichlorosilane; 6:2 fluorotelomer trichlorosilane; CAS 78560-45-9; EC no. 278-947-6. Registration 13 July 2016.
  5. 1H,1H,2H,2H-Perfluorooctylmethyldichlorosilane; CAS 73609-36-6.
  6. 1H,1H,2H,2H-Perfluorooctyldimethylchlorosilane; CAS 102488-47-1.
  7. 1H,1H,2H,2H-Perfluorodecyltrichlorosilane; 8:2 Fluorotelomer trichlorosilane; CAS 78560-44-8; C8 chemical.
  8. 1H,1H,2H,2H-Perfluorodecyldichloromethylsilane; CAS 3102-79-2; C8 chemical.
  9. 1H,1H,2H,2H-Perfluorodecyldimethylchlorosilane; CAS 74612-30-9; C8 chemical.
  10. 1H,1H,2H,2H-Perfluorododecyltrichlorosilane; 10:2 Fluorotelomer trichlorosilane; CAS 102488-49-3.

In addition, all of these chemicals can be degraded and metabolized to a perfluoroalkanoic acid, which will be non-degradable in the environment. Five of the chemicals in the lists will be degraded specifically to the banned perfluorooctanoic acid (PFOA). Thus these chemicals are both toxic and an environmental hazard, but the basis for the regulation was only toxicity.


The impact will probably be very limited, although the regulation has been underway for a decade, and the EU system has used much effort. Some reasons:

  • Only the use in spray products and for consumer use is banned.
  • Such products will, however, also be very hazardous in occupational settings in spite of the warning label, because, there are no occupational limit values and standard analytical methods. Furthermore, there may not be safe levels.
  • In addition, the professional products may unintended be used by do-it-yourself builders.
  • Because only substances with a fully fluorinated hexyl chain (6:2 fluorotelomers) are covered, other even more hazardous substances with a shorter or longer fluoroalkyl chain are not regulated and may be used as alternatives.
  • The even more toxic related perfluorinated chlorosilanes are neither regulated.
  • The serious environmental hazards posed by all these related chemicals should have been included in the assessment and regulation.
  • Commercial use of perfluorinated chemicals should only be permitted for research and analysis.
  • If these many thousands hazardous existing fluorochemicals are regulated case by case, this work is a never-ended story.

Relevant papers by the Danish research group:

Nørgaard AW, Jensen KA, Janfelt C, Lauritsen FR, Clausen PA, Wolkoff P (2009). Release of VOCs and particles during use of nanofilm spray products. Environ Sci Technol 43: 7824-7830.

Nørgaard AW, Larsen ST, Hammer M, Poulsen SS, Jensen KA, Nielsen GD, Wolkoff P (2010). Lung Damage in Mice after Inhalation of Nanofilm Spray Products: The Role of Perfluorination and Free Hydroxyl Groups. Toxicol Sci 116(1): 216-224.

Nørgaard AW, Wolkoff P, Lauritsen FR (2010). Characterization of nanofilm spray products by mass spectrometry. Chemosphere 80(11): 1377-1386.

Nørgaard AW, Janfelt C, Benassi M, Wolkoff P, Lauritsen FR (2010). Nebulization ionization and desorption ionization analysis of reactive organofunctionalized silanes in nanofilm products. J Mass Spectrum 46: 402–410.

Larsen ST, Dallot C, Larsen SW, Rose F, Poulsen SS, Nørgaard AW, Hansen JS, Sørli JB, Nielsen GD, Foged C (2014). Mechanism of Action of Lung Damage Caused by a Nanofilm Spray Product. Toxicol Sci 140(2): 436–444.

Duch P, Nørgaard AW, Hansen JS, Sørli JB, Jacobsen P, Lynggard F, Levin M, Nielsen GD, Wolkoff P, Ebbehøj NE, Larsen ST (2014). Pulmonary toxicity following exposure to a tile coating product containing alkylsiloxanes. A clinical and toxicological evaluation. Clin Toxicol (Phila) 52(5): 498-505.

Nørgaard AW, Hansen J, Sørli J, Levin M, Wolkoff P, Nielsen G, Larsen ST (2014). Pulmonary Toxicity of Perfluorinated Silane-Based Nanofilm Spray Products: Solvent Dependency, Toxicol Sci 137(1): 179-188.

Sørli JB, Nørgaard AW, Hansen JS, Levin M, Larsen ST (2015). An In Vitro Method for Predicting Inhalation Toxicity of Impregnation Spray Products. Altex 32(2): 101-111.

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