You wear them at work, you wear them at play, you wear them to relax. You may even get sweaty in them at the gym.

But an investigation into headphones has found every single pair tested contained substances hazardous to human health, including chemicals that can cause cancer, neurodevelopmental problems and the feminisation of males.

Even products by market-leading brands such as Bose, Panasonic, Samsung and Sennheiser were found to contain harmful chemicals in the formulation of the plastics from which they are made.

Campaigners condemned “a market-wide failure” as they called for broad bans on whole classes of endocrine-disrupting chemicals in consumer goods and greater transparency from manufacturers about what is in their products.