Econyl™ is a fibre made from 100% recycled nylon waste such as industrial plastic, waste fabric, fishing nets etc. Made in Italy by Aquafil. Econyl™ is made in a closed-loop system, using less water and creates less waste than the similar nylon production. While more sustainable than nylon, Econyl™ can still shed plastic micro-particles that can end up in our water systems and oceans, therefore if choosing to buy/wear Econyl™, it is best to wash as little as possible, or wash in a Guppy Bag™ (the patented solution that filters out tiny micro-fibres released from textiles during washing for you to dispose of responsibly).
Further reading here