Perfluorinated tensides (PFTs) are organic surface-active compounds in which the hydrogen atoms on the carbon skeleton have been completely replaced by fluorine atoms. Perfluorinated tensides have no natural source. Because of their special physicochemical properties, they are industrially produced and used in a variety of products. They accumulate in the environment as well as in human and animal tissues. PFT are suspected to be carcinogenic.
98% of all agricultural land is contaminated with PFT
THE PERFLUORIZED TENSIDES
Environmental poison in German drinking water
The slightly different tensid
Perfluorinated tensides have a high thermal and chemical stability. The carbon chain of the compound is hydrophobic, while the head group has hydrophilic properties. This amphiphilic character results in its use as a surfactant.
In contrast to the usual surfactants, the perfluorinated carbon chain also has a lipophobic character. In addition to water, it also rejects oil, grease and other non-polar compounds as well as dirt particles.
LIMIT VALUE OVERRUNS FROM PFT
PFT content in sewage sludge
THE SUBSTANCE GROUPS
Assignment of PFT
- the perfluorinated alkyl sulfonates (PFAS) with the best known representative perfluorooctanesulfonate (PFOS)
- the perfluorocarboxylic acids (PFCA) with the best known representative perfluorooctanoic acid (PFOA)
MANUFACTURE AND USE
The all-purpose poison
For the production of perfluorinated surfactants, industrial synthesization usually uses the methods of electrochemical fluorination (ECF) according to Simons (1941) or fluorotelomerization. Every year, several thousand tons of PFT are produced, the country with the largest production volume being the USA.
The compounds are mainly used in the textile industry for the production of breathable jackets and in the paper industry for the production of dirt, grease and water repellent papers. Other areas of application include the photographic industry, the manufacture of fire-extinguishing agents, aviation and the galvanic industry. They can also be part of lubricants and impregnating agents. In the production of fluoropolymers PTFE (polytetrafluoroethylene, “Teflon”) and PVDF (polyvinylidene fluoride) PFOA is used as an emulsifier. In this application, PFOA occurs as a process emission and as a contaminant in end products.
ENVIRONMENTAL AND HEALTH ASPECTS
Carcinogenic and Toxic
PFTs are considered non-biodegradable in nature. They are therefore classified as long-lived organic pollutants. Meanwhile, the chemicals of this group are distributed worldwide; They have already been detected in liver samples of polar bears.
The Demminer Gesundheits- und Lebensmittelüberwachungsamt warned in February 2008 against the consumption of regional wild boar liver: In the liver of examined animals, which were killed in the district Demmin, increased levels of perfluorinated surfactants were found. The Federal Institute for Risk Assessment estimates an amount of 0.1 micrograms per kilogram of body weight as “tolerable daily intake”. In the investigated boar organs, an average of 122 micrograms per kilogram of liver was found, which means “when consuming 65 grams of such contaminated liver, the tolerable daily amount of 8 micrograms has already been reached,” calculated the head of the Demminer Veterinary and Health Office. According to the report, PFT is deposited in the blood and liver of the animals and degrades only slowly.
Perfluorinated tensides are toxic to humans and animals and are suspected of causing cancer. In the body perfluorinated surfactants accumulate in the blood and organ tissue and are excreted only slowly (in humans in 4.4 years about half in PFOA, in PFOS in about 8.7 years). Initial evidence in the blood of chemical workers was provided in the 1960s. Sensitive measurement methods were published only in 2001, which also enabled the detection of PFT exposure in the general population. In 2006, PFT was also detected in lower concentrations in breast milk in Lower Saxony.
PFT IN GERMAN WATERS
In March 2006, a study by the Institute for Hygiene and Public Health (IHÖG) at the University of Bonn on the presence of PFT in different surface waters in Germany increased concentrations in the Ruhr and then also in the Möhne demonstrated Test series on high PFT levels in US waters, German researchers also wanted to study German soils for the carcinogen to check drinking water quality. In the district of Arnsberg-Neheim, a concentration of 0.56 μg / L was found in drinking water, and the Federal Environmental Agency’s Drinking Water Commission is aiming for a value of 0.1 μg / L.It turns out that the burden of manure derived from industrial waste originated from which was applied to fields located in the catchment area of the rivers. Some areas were rebuilt in the sequence. Depending on the degree of contamination and geology of the subsoil, it was decided to drain with subsequent activated carbon treatment of the leachate or for the removal and dumping of the topsoil.
In November 2006, investigations at the wastewater treatment plant in Rhede showed that high levels of PFT are present in the sewage in the inflow of the wastewater treatment plant. Even in the course of the treatment plant significantly higher concentrations were measured. These studies suggest that PFT accumulates in sewage sludge.
Due to their broad application, perfluorinated surfactants are also released into the environment via municipal sewage treatment plants and can be traced, especially below settlements, to comparatively low-flow waters. An example of this is the Itter below Solingen, where up to 0.7 μg / l PFT has been detected.
Harald Friedrich, at that time head of department in the Ministry of the Environment, suggested that the treatment of the drinking water obtained in the Ruhr waterworks should be fundamentally improved by further measures.
The PFT freight of the Ruhr near Essen was determined to be only 0.044 micrograms per liter for the sum of PFOA and PFOS in the annual mean 2009. Compared to 2007, the average daily freight at the mouth of the Ruhr decreased by a total of 59 percent.
NUMBER OF ALL PFT INTOXICATIONS THAT ARE FATAL
Conspicuous PFT values were in 2006 below the water legally approved transmission from the industrial park Gendorf also measured in Southeast Upper Bavaria in the Alz (sum PFT about 8 g / L, of which PFOA 7.5 micrograms / L). According to the further dilution, concentrations of 0.1 and 0.05 μg / L were measured for PFOA downstream on the Inn and on the Danube.
For the construction of the Nord connection of the Nuremberg airport to the A3 motorway (federal highway 4f) with a tunnel under the runway has made the government of Middle Franconia in their plan approval of 15 February 2012 on the condition that the construction will not affect the found in the airport sector PFT residues has. The planned lowering of the groundwater level by 22 meters during tunneling requires extensive water diversion measures. This means that it is not possible to rule out a shipment of PFT residues in the soil. These were created by infiltration of extinguishing foam during firefighting exercises on the airport grounds. Since it is first necessary to find and test methods for removing the PFT in the soil, the start of construction can be delayed by many years.
In 2012, elevated levels of PFT were also detected in the lake Stoibermühle north of Munich Airport and in Lindacher See north of the air base Ingolstadt / Manching.