Studies have shown that washing textiles releases microfibres into the wash water, which cannot be sufficiently retained by wastewater treatment plants. Synthetic fibres pose the greatest risk to the environment because of their longevity and inability to biodegrade. However, Hohenstein project manager Juliane Alberts does not give the all-clear for biodegradable fibres and natural fibres: "Biodegradability alone does not mean that pure natural fibres, for example, are completely harmless to the environment. They, too, remain in ecosystems until they completely degrade and can also have a negative impact. In addition, additives, auxiliaries or finishes used in textile production can further slow the degradation process and leach into the environment."