Recently, agricultural land in the rural area Sauerland in North Rhine-Westphalia, Germany, has been contaminated with perfluorinated compounds (PFC) (Kraft et al. 2007). Industrial waste containing mainly perfluorooctanoic acid (PFOA) has been illegally manufactured into a so-called “soil improver” by a recycling company and disseminated by farmers, leading to increased levels of PFOA after leaching into surface raw water for drinking water production (Fig. 1). Irrespective of this headline-catching incident PFC represent a group of emerging chemicals of concern (Table 1). An increasing number of studies show that humans are exposed to a large number of PFCs (Kärrman et al. 2007; So et al. 2007). PFOA and PFOS, the two most important PFCs in the environment, are auxiliary substances for the industrial production of perfluorinated polymers. These are widely used for non-stick coatings for instance on cooking pans and stain repellent coatings on items such as fast-food packaging, furniture and carpets. The major source of PFOA and PFOS in the environment seems to be their dissemination with waste water and their release in traces from consumer products.

Fig. 1
figure 1

The Möhne Lake: recreation area and drinking water source highly contaminated by perfluorinated compounds

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Table 1 Perfluorinated compounds (PFCs): facts and terminology
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In order to achieve a realistic risk assessment an expert panel met during the Annual Meeting of the German Society of Toxicology. Detlef Wölfle (Federal Institute for Risk Assessment, BfR, Berlin) reported on the persistence and toxicology of PFCs. Some compounds, e.g. PFOA and PFOS, are resistant to biotransformation and were ubiquitously found in human blood with half-lives of several years. Oral toxicity studies in rats and monkeys showed that liver is the primary target organ. While PFCs were not considered to be genotoxic, PFOA and PFOS are tumor promoters in rats (COT 2006a, b). Following in utero exposure in rodents PFOA (Hernderson and Smith 2007; Wolf et al. 2007) and PFOS produced reduced viability, body weights deficits and other postnatal effect on pups (Fig. 2).

Fig. 2
figure 2

Chemical structure of perfluorooctane sulfonate (PFOS) as an example of a PFC

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Jürgen Angerer (University of Erlangen) presented epidemiological data. Several studies have reported an increase in PFC concentrations in humans up to the late 1990s. Recent efforts have not yet resulted in declining environmental concentrations. In two independent studies, median values of blood plasma concentrations of PFOS and PFOA were determined. They amount to 12–22 μg/l and 5–7 μg/l, respectively. Blood levels did not correlate with age. Interestingly, the levels were higher in male compared to female individuals. Importantly, lactation is a considerable source of exposure for infants (Kärrman et al. 2007). Furthermore, PFCs undergo trans-placental transfer (Midasch et al. 2007). The total amount of PFCs transferred to a breast fed infant is approximately 200 ng/day. Michael Wilhelm (University of Bochum) presented brand-new data on individuals exposed to PFOA-contaminated drinking water as a consequence of the “Sauerland-soil-improver scandal”. Compared to controls 4–8-fold increased levels of PFOA in plasma have been observed in children, women and men. In contrast to PFOA, plasma concentrations of PFOS did not differ from controls. Therefore, individuals exposed to PFOA- contaminated drinking water could be clearly identified by an increased PFOA/PFOS ratio. Additionally, there was a clear positive association between consumption of drinking water and PFOA concentrations in plasma. Hermann Dieter (Federal Environmental Agency, Berlin) addressed regulatory aspects of PFCs. Recently, criteria have been proposed that allow differentiation between specific and non-specific genotoxicity (Dorn et al. 2007). Based on this classification PFCs can be categorized as weakly non-specific genotoxic. The Federal Environmental Agency recommends for drinking water a precautionary value of 0.10 μg/l and a long-term toxicological threshold value of 0.30 μg/l. A tolerable daily intake (TDI) of 0.10 μg PFT/(kg/day) was proposed (Dieter 2007).

Finally, the expert panel addressed regulatory consequences of the “Sauerland-soil-improver scandal” in Germany. Further placement of PFC contaminated soil improver must be prohibited. Fortunately, PFOA plasma concentrations were considered to be too low to cause overt adverse health effects in the exposed population.