We try to be as environmentally friendly as possible when manufacturing our pens. The packaging is made from 100% recycled materials, which is why you can still see tiny coloured dot remains from recycled printed paper. The plastic barrell is currently made from #5 plastic while we develop a way to produce pens with biodegradable plastic. #5 plastic can normally be recycled in your local curbside program so please contact your local council or community recyclers for more information regarding that (such as using the UK Gov's website at https://www.gov.uk/recycling-collections). Else, mail in programs are also gaining popularity such as Preserve and you can find some more from below online resources:

#5 plastic can be recycled into: signal lights, battery cables, brooms, brushes, auto battery cases, ice scrapers, landscape borders, bicycle racks, rakes, bins, pallets, trays. In case you don’t want to recycle, we strongly recommend you reuse the pens and turn them into a colourful, non ageing plant! 

PP (polypropylene) has a high melting point, and so is often chosen for containers that must accept hot liquid. It is gradually becoming more accepted by recyclers.