Perfluorinated surfactants contaminate German waters
Mislabeled waste in fertilizer leads to a water scandal.
When scientists in Germany reported high concentrations of perfluorinated surfactants in the Moehne River last summer (Environ. Sci. Pollut. Res. 2006, 13, 299–307), panic ensued. Those who obtain their drinking water from the river were up in arms, and authorities were eager to track down the source of contamination.
The saga began when Dirk Skutlarek and his colleagues at the Institute of Hygiene and Public Health at the University of Bonn (Germany) detected unexpectedly high concentrations of perfluorinated surfactants in the Ruhr River. Intrigued by the finding, they did a bit of detective work and eventually tracked down the source of the problem to an agricultural area close to one of the Ruhr’s tributaries, the Moehne River. There, they detected perfluorinated surfactants in concentrations of up to 4.39 micrograms/liter (µg/L).
When the scientists analyzed the local drinking water, taken from treated surface water, it showed concentrations of up to 0.60 µg/L of perfluorinated surfactants, with perfluorooctanoic acid (PFOA) the most abundant. Alarmed, local authorities distributed bottled drinking water to families with babies and pregnant women in the affected area and prompted the German Drinking Water Commission to recommend national guidelines for these so-far unregulated substances in drinking water. These new guidelines were indeed exceeded in the affected area. “These compounds don’t belong in drinking water, and as a consumer, I wish authorities would put more pressure on water suppliers,” Skutlarek says.
Used as stain-resistant coatings on textiles and papers, perfluorinated surfactants are also used to enhance firefighting foams and as ingredients in various consumer products. The end-stage metabolites and most important key compounds of this class of substances are perfluorooctane sulfonate (PFOS) and PFOA. Their persistence, tendency to bioaccumulate, and suspected carcinogenicity have prompted the EU to propose a substantial restriction on marketing and use of PFOS. The U.S. EPA has asked fluoropolymer and telomer manufacturers to participate in a global stewardship program on PFOA that aims to eliminate it from emissions and product content by 2015.
Waterworks often use costly activated-carbon filters to ensure the removal of anthropogenic pollutants, but Skutlarek is skeptical of their effectiveness for perfluorinated surfactants. “In some treatment plants with carbon filters, we have seen breakthrough of these compounds, so I doubt that they durably sorb to carbon,” he says. Poorly sorbing perfluorinated surfactants are not effectively removed in wastewater treatments plants either, says Jennifer Field of Oregon State University. On the contrary, such plants can even serve as point sources for carboxylic acids, such as PFOA, which are generated by the microbial degradation of other perfluorinated compounds, Field says.
European water companies have already recognized perfluorinated surfactants as potential contaminants in drinking-water sources, as highlighted in a review published by the Dutch Association of River Water Companies last June. Frank Thomas Lange, an author of the report and a chemist at the Water Technology Center (TZW) in Karlsruhe (Germany) points out that the first measurements for perfluorinated surfactants in German surface waters, conducted elsewhere by TZW in 2004, showed much lower concentrations. Falling in the low nanograms-per-liter range, these levels more accurately represent general background concentrations in German surface waters, Lange says.
He cautions that the discussion should not be limited to drinking water and that the various entrance paths into the human body need to be assessed. “I doubt that a major part of those substances enters the human body through drinking water, and I suspect that food, domestic dust, and clothing are important sources as well,” Lange says.
The contamination on the Moehne and Ruhr rivers turned out to originate from local fields treated with a fertilizer containing a mixture of food-industry sewage sludges. However, it is unlikely that the sewage sludges themselves were the source of the contamination. One explanation is that some mislabeled waste, possibly from tank-ship cleaning, was mixed with fertilizer during production, Skutlarek says. A lawsuit has since been filed by the local environment office and residents against the fertilizer’s German producer, which processes sludges from various European countries.
The polluted fertilizer was applied to several hundred fields in Germany, which also need to be checked for contamination, Skutlarek says. The soil could serve as a reservoir for these compounds, he says, which might eventually leach into groundwater.
