Another thing that worries me is the vast quantity of polyester and other 'plastic' fibres that are 'washed' out of modern clothing and thereby fed into our waterways and thence into the sea. Whereas cotton, wool, linen, silk and other natural fibres like hemp fibre will degrade harmlessly and fairly rapidly in rubbish tips, rivers and oceans, artificial fibres are generally much more persistent and add to the already huge quantities of microplastics accumulating on earth!