A new device developed at Eawag now allows Scientists to determine whether, and to what extent, fragrances in the environment are absorbed in fish without using animals. This is possible thanks to the use of a mirror-polished stainless steel chamber and a permeable membrane with a layer of intestinal fish cells.
Fragrances are added in a wide variety of consumer products – cosmetics, detergents, cleaning agents, and air fresheners. If incompletely eliminated in wastewater treatment plants, they can end up in rivers and lakes. Companies are therefore required to perform an environmental risk assessment before fragrance compounds are used in final products. One important test parameter is the accumulation of substances in fish. However, the properties of fragrances make them difficult to test: some may readily stick to surfaces and they are by design volatile so that we can smell them. “This means,” says biologist Hannah Schug, PhD student in the Environmental Toxicology department led by Kristin Schirmer, “that, during the experiments, fragrances virtually dissipate.”
An intestinal epithelial cell line serving as a barrier
For this reason, Hannah Schug designed a novel test system in collaboration with a leading fragrance company. The device – the size of a small Rubik’s cube – has an inner surface made of polished-mirror stainless steel to reduce losses due to the compounds’ stickiness, and an air-tight lid to minimize evaporation. The system, called TransFEr chamber, consists of an upper and a lower compartment separated by a cellular barrier. This barrier is comprised of fish intestinal epithelial cells representing the intestinal epithelium as a “gatekeeper” in fish. The exposure solution is added to the upper compartment, and measurements are made in the lower compartment to determine the rate of transfer across the intestinal cells. The results indicate to what extent compounds – in this case fragrances – can be absorbed by the intestine to be accumulated or to be transformed in fish.