FRAM FORUM 2015
RESEARCH NOTES
Christine F. Solbakken // NILU – Norwegian Institute for Air Research
Record high levels of siloxanes released into Tromsøysund That nice, silky smooth feeling you get when you rub yourself with lotion after the shower comes from chemicals called siloxanes. Scientists find these same substances in hair shampoo, cleaning products, car wax – and in cod caught in Tromsøysund. “The siloxanes we found in cod collected outside Tromsø comes partly from soap, shampoo, skin creams, and various other personal care and cleaning products we use,” explains senior researcher Nicholas Warner at NILU – Norwegian Institute for Air Research at the Fram Centre. “We flush the substances down the drain,” Warner continues, “and although the water treatment plants capture some of it, significant amounts are still discharged into the aquatic environment. In Europe alone, siloxane emissions are estimated at over 20 kilotons per year.” The substances, with simple abbreviations and complicated names such as D4 (octamethylcyclotetrasiloxane), D5 (decamethylcyclopentasiloxane) and D6 (dodecamethylcyclotetrasiloxane), are used in cosmetics, personal care products and cleaning products that most of us have at home. D4 used to be an important ingredient in personal care products until a few years ago, when it was discovered that it induced toxic effects in several organisms. Therefore, production has shifted to use less D4 and more D5 in these products – and scientists are now finding very high concentrations of D5 in the aquatic environment.
RECORD-BREAKING LEVELS Collecting water and sediment samples from wastewater emission sites around Tromsøysund during the autumn of 2014, the NILU scientists have further investigated the siloxane exposure levels to the local aquatic environment. “We have found extremely high concentrations of siloxanes in wastewater effluent,” Nicholas Warner explains. “The concentrations ranged between 100 and 10 000 nanograms per litre in wastewater effluent collected from outlets in Tromsø. The highest concentrations were of D5, which is the dominant siloxane used in personal care product formulations.” D5 is also used in biomedical and cleaning products. Thus, it is not surprising that the levels observed in the outlet that receives waste from the local hospital were six to ten times higher than in other wastewater outlets. It was more surprising that the concentrations found were significantly higher in samples from Tromsø than in samples from British cities with much larger populations.
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