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Survey and environmental/health assessment of fluorinated substances in impregnated consumer products and impregnating agents

1 Background, goal and target group

• 1.1 Background
  • 1.1.1 Chemistry
  • 1.1.2 Production and useg
  • 1.1.3 Global pollutants
  • 1.1.4 Known polyfluorinated substances
  • 1.1.5 Projects on perfluorinated substances carried out previously in Denmark
• 1.2 Purpose
• 1.3 Methods applied for the survey

1.1 Background

During the past years an awareness has arisen on a new type of persistent organic pollutants containing an alkyl chain, typically between 4 and 12 carbon atoms, with all or most hydrogen atoms replaced by fluorine. This makes the chain very stable and practically non-degradable in the environment. The substances also contain a more reactive functional group, which may be an alcohol, a carboxylic acid, a sulfonic acid, a phosphoric acid or their derivatives.

Several hundred of these polyfluoroalkyl or perfluoroalkyl^[2] compounds are known today. These substances are all surface active substances with an extreme low surface tension, and they repel water, grease and dirt, and are therefore used as detergents or impregnating agents in a number of industrial- and consumer products under trade names like Scotchgard^®, Baygard^®, Gore-Tex^®, Zonyl^® and Stainmaster^®.

1.1.1 Chemistry

Perfluorooctane sulfonic acid (PFOS) is the best known perfluorinated compound. PFOS has a linear perfluoroalkyl carbon chain of 8 and a sulfonic acid functional group.

In the year 2000, the American company 3M that was the main producer of the substance, voluntarily ceased the production and sale of PFOS and related compounds, because PFOS surprisingly was found in high concentrations widespread in the environment, included in remote areas such as the Arctic.

PFOS-related compounds were introduced on the List of Undesirable Substances of the Danish EPA in 2004 and are nominated for the Stockholm Convention (2005) List of POP Substances. The European Parliament and the EU Council of Ministers have regulated these substances by the Directive 2006/122/EC of 12 December 2006 on “Restriction on the marketing and use of certain dangerous substances and preparations (perfluorooctane sulfonates)”. According to this directive, PFOS compounds may no longer be marketed or used as a substance or component in preparations in concentrations above 0.005 (w/w) or above, or may no longer be marketed in semi-processed products or articles in a concentration of 0.1% or above by June 27^th 2008. However, some exceptions from the limitations exist, for example within the use of photographic coatings for film, paper or printing plates.

As a substitute for PFOS, 3M is now, for example, producing and trading perfluorobutane sulfonate (PFBS) and its derivatives. The chain length of PFBS is the half of PFOS, and chain lengths of less than 6 carbons are in these types of chemicals considered to be less toxic and less environmentally dangerous.

Another known compound is perfluorooctanoic acid (PFOA), which as the ammonium salt is used for manufacturing fluoropolymers (such as Teflon^®).

PFOA may occur as impurity in products of fluoropolymers, such as coated non-stick kitchen ware (Washburn et al. 2005). PFOA is also emitted from industries that are manufacturing fluoropolymers. Such type of manufacturing does not take place in Denmark.

PFOA and other perfluorocarboxylic acids (PFCA) with shorter or longer carbon chains can also occur as impurities or as a decomposition product of fluorotelomers, which are used for similar purposes as the formerly used PFOS derivatives (Washburn et al. 2005).

Fluorotelomers are polyfluoroalkyl compounds produced by telomerisation, a process in which a molecule, called telogen, reacts with two or more unsaturated molecules in the ethylene family, called taxogens. The principal reaction is:

Telomers are thus polymers with a functional group in the end. When trifluoromethyl iodide, as an example, reacts with tetrafluoroethylene, then straight, short-chain telomers are obtained with the general formula: CF₃[CF₂CF₂]_nI where n is between 1 and 10. Such telomers have odd number carbon atoms. An even carbon number may be obtained by the reaction of pentafluoroethyl iodide with tetrafluoroethylene, e.g. the so-called C₈-chemistry for surfactant production:

Fluorotelomers are polyfluorinated and precursors of perfluoroalkyl carboxylates. They have non-fluorine substituted hydrogen atoms in between the fluorocarbon chain and the functional group, which often is an alcohol, such as in 1H,1H,2H,2H-perfluorodecanol (8:2 FTOH):

Fluorotelomers are considered to be less environmentally problematic than the PFOS compounds, but they are also persistent in the environment, since they can be degraded to PFOA or other related problematic compounds.

The functional group in a fluorotelomer can also be a substituted sulfonamide as in a perfluorooctane sulfonamide betaine telomer, which is used in fire fighting foams for fighting fires at oil rigs, oil terminals and airports.

1.1.2 Production and use

The world production of polyfluorinated compounds is estimated to be about 10,000 tonnes per year. The world production of fluorotelomers in the years 2000 to 2002 was 5,000 to 6,000 tonnes per year alone (Prevedourous et al., 2006). This production has probably increased considerably since then, which is confirmed by a Swedish and Norwegian study from 2006, which states that the annual global fluorotelomer production is around 10,000 tonnes. The authors also state that about 50% of this production goes to the impregnation of textile consumer products, e.g. in all-weather clothing, carpets and upholstery (Schulze and Norin, 2006)

In earlier surveys impregnation of textiles, carpets, leather, paper and cardboard were the dominating use area for perfluorinated chemicals and amounted to more than half of the total use. Fluorotelomers can be sprayed on the surface of a subject or be integrated permanently into a polymer surface. Impregnated paper and cardboard are used for packaging of food (e.g. popcorn bags for microwave oven) and foodstuff (e.g. paper bags for dry feed for dogs and cats) in order to prevent breakthrough of grease. The use areas for perfluorinated compounds are probably quite stable but the trend is to substitute PFOS related chemicals with fluorotelomers and fluorinated compounds with shorter perfluoroalkyl chains than C₈ (Poulsen et al., 2005).

1.1.3 Global pollutants

Polyfluorinated compounds have become a global environmental problem. The substances occur everywhere in indoor air, household dust, outdoor air, earth, sediment, sludge, groundwater, rainwater, surface water, animals and humans, but the occurrence of the individual compounds vary from place to place. The compounds have been found even in remote polar areas, including Greenland (Giesy and Kannan 2002; Bossi et al., 2005ab; Jensen et al., 2006).

The polyfluorinated substances are being upconcentrated through the food chain. As opposed to the most common persistent organic pollutants (POPs) polyfluorinated compounds are not concentrated significantly in fatty tissue. In contrary they are associated to proteins in blood and internal organs, such as spleen, lever and kidney. Polar bears have very high concentrations of several fluoroalkylated compounds, especially PFOS, because of the placement of the polar bear in top of the arctic food chain. Studies from the Danish National Institute for Environmental Research show that the concentrations of fluoroalkylated compounds are growing in seals from Greenland – one of the primary preys of the polar bear. Fluoroalkylated compounds are also wide-spread in the Danish environment, which has been shown in a recent study carried out by DMU (Strand et al., 2007).

1.1.4 Known polyfluorinated substances

OECD has during the past years prepared a list of PFOA, PFOS and PFOS-related as well as polyfluorinated substances. This list has continuously been updated. Today the list contains nearly 1,000 different substances covering PFOS-substances, PFAS, PFOA and other PFCAs, fluorotelomers and other substances that may degrade to PFCAs (OECD, 2007).

The list used in this survey was the OECD 2006-list which was available at the start of the project (OECD, 2006). The OECD 2006-list divides the different fluorinated compounds in different categories as listed below. Some overlap exists between the different categories (e.g. PFOS compounds are also PFAS compounds etc.), why the list contains less than 1,000 unique CAS numbers. The OECD grouping is used in throughout this report. See Table 1.1:

Table 1.1: Categories of perfluorinated and polyfluorinated substances according to OECD 2006-list (OECD, 2006).

1.1.5 Projects on perfluorinated substances carried out previously in Denmark

1.1.5.1 2001/2002: Use of PFOS and related compounds in Denmark

A survey of perfluorooctane sulfonate (PFOS) and related compounds in consumer products carried out by COWI for the Danish EPA in 2001 and 2002 revealed that PFOS-related compounds were used in numerous products in Denmark (Havelund 2001, 2002). The survey showed that 75 of the 175 identified PFOS and PFOS-related compounds on OECD’s list at that time were registered in the Danish Product Register. A total consumption of 8-16 tonnes PFOS-compounds annually was registered. A market survey was carried out in order to quantify the non-registered amount of PFOS-compounds in products. This survey concluded that the total Danish consumption of PFOS-compounds in products probably was between 5 and 50 tonnes per year.

The 2001 search in the Danish Product Register showed that the PFOS-related compounds were mostly present in the following types of products:

• Impregnation agents for textiles, leather and paper
• Wax and other polishes
• Paint, varnish and reprographic agents
• Cleaning products (general cleaning products and cleaning products used for cleaning of metal surfaces or carpets).

1.1.5.2 2002: Use of PFOS and related compounds in impregnating agents, wax and floor polish.

As a follow-up, the Danish EPA initiated another survey of the use of PFOS-related compounds in impregnating agents, wax and floor polish products (Vejrup et al. 2002). In that project PFOS was detected in 3 out of 21 purchased consumer products. Two impregnating agents contained 212 mg perfluorodecane sulfonate/ml and 3.5 mg perfluorooctane sulfonamide/ml, respectively. One of the wax and polish products contained 9 mg N-ethyl-perfluorooctane sulfonamide/ml.

1.1.5.3 2004: Survey of alternatives to PFOS and PFOS-related compounds

In 2004 the Danish EPA initiated a survey with the aim to collect the know-how about the existing technical alternatives to PFOS/PFOS-related compounds and PFOA/PFOA-related compounds. This project also carried out an environmental and health assessment of PFOS/PFOA-related substances and of the possible alternatives to PFOS/PFOA-related compounds (Poulsen et al., 2005).

1.1.5.4 2005: Chemicals used in shoe care products – PFOS discovered

In 2005 the Danish EPA carried out a survey of the use of various chemicals in shoe care products (Engelund and Sørensen, 2005). In 1 out of 4 analysed samples very small amounts (1.1 and 0.36 mg/kg, respectively) of PFOS-related compounds were found. The PFOS-compounds were believed to be present in the product as impurities in a fluoropolymer that was added due to its water and dirt repelling properties.

1.2 Purpose

The former projects carried out for the Danish EPA have mainly covered PFOS and PFOS-related compounds in consumer products; this project is concerned by both perfluorinated and polyfluorinated compounds and includes e.g. fluorotelomers.

The purpose of this project was to

• Estimate the use of fluorotelomers and short-chained perfluorinated compounds in impregnating agents for textiles, carpets, leather, paper and cardboard, cleaning agents for glass, wax, floor polish, paint and other consumer related products in Denmark.
• Update the former environmental and health assessment of the perfluorinated substances and their decomposition products carried out in the previous project for the Danish EPA (Poulsen et al. 2005).
• Assess the need for further investigation and measurements of fluorotelomers in and from consumer products.

Estimation of use of fluorinated compounds within the area of foods is not included in this project, as this product area is not the responsibility of the Danish EPA.

1.3 Methods applied for the survey

Information about the use of fluorinated substances in products in Denmark has been obtained in different ways. A search has been performed in the Danish Product Register of the use of fluorinated compounds in Denmark. Additional information was obtained by contacting stores, suppliers, importers and producers of fluorinated substances and products containing fluorinated substances. However, this approach only gave sparse information, since the companies contacted either did not know about the chemical content of their products or did not want to give away any information about the use of fluorinated substances. Information found on the Internet about the content of fluorinated substances in different products was combined with official statistics of sales of different products in Denmark in order to estimate the use of fluorinated substances in Denmark in different product categories.

Fodnoter

[2] ”Poly” means that many of the hydrogen atoms have been replaced with fluor; ”per” means that all hydrogen atoms in the alkyl chain have been replaced with fluor.

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Version 1.0 October 2008, © Danish Environmental Protection Agency