In this bonus episode Chris and Xand continue to explore microplastics - an issue gaining a lot of media and academic interest. They are joined by Dr Stephanie Wright, a Senior Lecturer in Environmental Toxicology at Imperial College, London, whose work looks at the intersection between plastic pollution and human health.

If you’d like to share your thoughts on this or any other topic covered on the podcast, you email us at whatsupdocs@bbc.co.uk or Whatsapp on 08000 665 123.

Presenters: Drs Chris and Xand van Tulleken Guest: Dr Stephanie Wright Producer: Jo Rowntree Executive Producer: Rami Tzabar Editor: Kirsten Lass Assistant Producers: Maia Miller-Lewis and Mary Holditch Tech Lead: Reuben Huxtable Social Media: Leon Gower Digital Lead: Richard Berry Composer: Phoebe McFarlane Sound Design: Melvin Rickarby

At the BBC: Assistant Commissioner: Greg Smith Commissioning Editor: Rhian Roberts

A Loftus Media production for BBC Radio 4.

Christian News: Stamping on a Human Face