The status of the Baltic Sea marine environment in terms of contamination by hazardous substances is assessed using several core indicators. Each indicator focuses on one important aspect of the complex issue. In addition to providing an indicator-based evaluation of the status of the Baltic Sea in terms of concentrations of perfluorooctane sulphonate (PFOS) in the marine environment, this indicator along with the other hazardous substances core indicators are used to achieve an overall assessment of hazardous substances.
The core indicator on PFOS concentrations addresses the Baltic Sea Action Plan's (BSAP) hazardous substances segment's ecological objectives 'Concentrations of hazardous substances close to natural levels' and 'All fish safe to eat'.
The core indicator is relevant to the following specific BSAP commitment:
PFOS is included in the HELCOM list of substances or substance groups of specific concern to the Baltic Sea which was adopted as part of the BSAP.
The core indicator also addresses the following qualitative descriptors of the MSFD for determining good environmental status (European Commission 2008b):
and the following criteria of the Commission Decision (European Commission 2010):
PFOS is included on the revised list of the EU Priority Substances (European Commission 2013) and in the Stockholm Convention list of persistent organic pollutants (POPs), Annex B, which requires the parties to the convention to restrict the production and use of the substance.
The production and use of perfluorooctane sulfonate (PFOS) has been regulated in some countries (e.g., US, Canada, and the EU), but large-scale PFOS production continues in other parts of the world, e.g. China. PFOS has been produced and used since the 1950s, but due to findings of detectable concentrations in human blood in the general population and negative health effects on living organisms, PFOS was phased out in 2002 by its main producer 3M.
Perfluorooctane sulphonate (PFOS), perfluoro octanoic acid (PFOA) and other perfluorinated compounds are considered global environmental contaminants. PFOS and PFOA are chemically and biologically inert and very stable (Poulsen et al. 2005). PFOS meets the P (Persistent) and vP (very Persistent) criteria due to slow degradation. PFOS is also bioaccumulative (B) and toxic (T) (OSPAR 2005). PFOA is considered as very persistent (vP) and toxic (T), but not bioaccumulative (Van der Putte et al. 2010). It has a capacity to undergo long-range transportation.
PFOS related substances and PFOA are members of the larger family of perfluoroalkylated substances (PFAS). Perfluorooctanyl sulfonate compounds are all derivatives of PFOS and can degrade to PFOS, also called as PFOS-related compounds. Some 100–200 PFOS-related compounds have been identified (KEMI 2006). PFOS binds to blood proteins and bioaccumulates in the liver, egg yolks, serum, and gall bladder unlike most persistent organic pollutant compounds that typically accumulate into fat (Renner 2001; Nordén et al. 2013; Goeritz et al. 2013; Shi et al. 2012).
PFOS has been shown to disturb the immune system, development and reproduction (endocrine disruption) of organisms and influence lipid metabolism. It is also suspected to induce liver necrosis. Falandysz et al. (2006) have suggested that the consumption of contaminated fish from the Baltic Sea contributes significantly to human blood levels of perfluoroalkyl compounds.
Marine mammals have considerably higher contamination levels of PFOS compared to marine and freshwater fish, and were found to be the most contaminated by PFOS of all Nordic biota studied (HELCOM 2010). Several hundreds to one thousand μg kg−1 ww of PFOS have been found in the livers of grey seals (in the southern Baltic Proper and Bothnian Sea; Nordic Council of Ministers 2004), harbour seals (Great Belt and the Sound; Nordic Council of Ministers 2004) as well as ringed seals (Bothnian Bay; Kannan et al. 2002). In the eggs of common guillemots (Western Gotland Basin), PFOS concentrations were greater than 1,000 μg kg−1 ww (Holmström et al. 2005). An OSPAR risk assessment (OSPAR 2005) on the marine environment concluded that the major area of concern for PFOS is the secondary poisoning of top predators, such as seals and predatory birds.
The evaluations in this core indicator are made based on concentrations mainly measured in fish, usually from reference areas with no specific local pollution load. The case studies and measurements from marine mammals in the Baltic Sea, highlight that PFOS may pose more severe contamination risks to the Baltic Sea than the current indicator evaluation would suggest.
Only a few measurements of PFAS in the Baltic Sea surface water exist (Nordic Council of Ministers 2004; Theobald et al. 2007; Lilja et al. 2009) and they were mostly performed in potentially affected coastal areas. PFOA and PFOS dominated the water samples. Concentrations of PFOA were determined in the range 0.57-0.68 ng l−1 (Little Belt, Kiel Bight, Mecklenburg Bight, Arkona Basin) up to 4–7 ng l−1 (Little Belt, the Sound, coast of Poland, Gulf of Finland). PFOS was found at levels of 0.34-0.90 ng l−1 for all locations mentioned, with the exception of single measurements of 2.9 ng l−1 (coast of Poland) and 22 ng l−1 close to Helsinki (Gulf of Finland). Farther away from the coast, in the Arkona Basin, PFOA and PFOS levels were 0.35-0.40 ng l−1.
Limited data exist for PFAS concentrations in Baltic Sea sediments (Nordic Council of Ministers 2004; SEPA 2006; NERI 2007; Theobald et al. 2007). PFOS and/or PFOA were occasionally detected, but consistently at levels below 1 μg kg−1 dw or ww. The highest levels reported so far have been from the Gulf of Finland close to Helsinki (PFOS 0.9 μg kg−1 ww), close to Stockholm (PFOS 0.6 μg kg−1 ww) and along the coast of Poland (PFOS and PFOA both around 0.6 μg kg−1 dw). Along the German Baltic Sea coast, concentrations of PFOS in sediments were in the order of 0.02-0.67 μg kg-1 dw and those of PFOA 0.09-0.68 μg kg-1 dw (Theobald et al. 2007).
The most important route of exposure of PFOS for humans is uptake from food (especially fish), drinking water and exposure to indoor dust (FOI 2013).
Use of synthetic compounds to increase grease, oil and water resistance of materials
Use of firefighting foams
Substances, energy and litter- Input of other substances (e.g. synthetic substances, non-synthetic substances, radionuclides) – diffuse sources, point sources, atmospheric deposition, acute events
Substances, energy and litter
- Input of other substances (e.g. synthetic substances, non-synthetic substances, radionuclides) – diffuse sources, point sources, atmospheric deposition, acute events
PFOS is both intentionally produced as well as an unintended transformation product of related anthropogenic chemicals. PFOS is still produced in several countries, such as China. Some PFAS have been manufactured for more than five decades. They are applied in industrial processes (e.g., production of fluoropolymers) and in commercial products such as water- and stain-proofing agents and fire-fighting foams, electric and electronic parts, photo imaging, hydraulic fluids and textiles (Paul et al. 2009).
The American company 3M, was the main producer of PFOS and its related substances until 2002. They started the production of perfluorochemicals already in 1949. The production of PFOS increased between 1966 and 1990 and peaked between 1990 and 2000. In 2003, China started a large scale production of PFOS. Between 2003 and 2008 China was both the main global producer and user of PFOS substances. However, also Japan and Germany produced PFOS during the same time period, but after 2007 no PFOS production occurs in Germany (Carloni 2009).
The major transport ways of PFOS to the Baltic Sea has been shown to be rivers (77%) but also atmospheric deposition (20%). Waste water treatment plants on the other hand were shown to have a negligible contribution (less than 2%) (Filipovic et al. 2013). The sources of PFOS to the atmosphere are still not clear, but a major contributor is believed to be transformation of precursor compounds (FOSA (Perfluorooctane sulfonamide) and FOSE (Perfluorooctane sulfonamidoethanol)) that have been emitted from production facilities and fluorochemical products (Armitage et al. 2009). Seventy-eight percent of the total PFOS in the Baltic Sea was estimated to be stored in the water column (Filipovic et al. 2013).
PFAS can be introduced into the environment both from point sources (e.g. landfills, manufacturing plants, application of firefighting foam containing PFOS) and non-point sources such as atmospheric deposition and degradation of precursors (Ahrens & Bundschuh 2014). High amounts of PFOS have been found in both sludge and groundwater close to military air base sites and airports where firefighting foam has been used to prevent fires (FOI 2013; Arias et al. 2015). Furthermore high levels of PFAS, including PFOS, have been found close to industries producing fluortelomers (Wang et al. 2014; Shan et al. 2014).