Dear MARMAM community, My co-authors and I are pleased to share our new publication: Polychlorinated biphenyls are associated with reduced testes weights in harbour porpoises (Phocoena phocoena), which has been published in Environment International. The article is open access and is available to read here: https://doi.org/10.1016/j.envint.2020.106303 Williams, R.S., Curnick, D.J., Brownlow, A., Barber, J.L., Barnett, J., Davison, N.J., Deaville, R., Ten Doeschate, M., Perkins, M., Jepson, P.D. and Jobling, S., 2021. Polychlorinated biphenyls are associated with reduced testes weights in harbour porpoises (Phocoena phocoena). Environment International, p.106303. Abstract Polychlorinated biphenyls (PCBs) are highly toxic and persistent aquatic pollutants that are known to bioaccumulate in a variety of marine mammals. They have been associated with reduced recruitment rates and population declines in multiple species. Evidence to date documents effects of PCB exposures on female reproduction, but few studies have investigated whether PCB exposure impacts male fertility. Using blubber tissue samples of 99 adult and 168 juvenile UK-stranded harbour porpoises (Phocoena phocoena) collected between 1991 and 2017, here we show that PCBs exposures are associated with reduced testes weights in adults with good body condition. In animals with poor body condition, however, the impact of PCBs on testes weights was reduced, conceivably due to testes weights being limited by nutritional stress. This is the first study to investigate the relationship between PCB contaminant burden and testes weights in cetaceans and represents a substantial advance in our understanding of the relationship between PCB exposures and male reproductive biology in cetaceans. As testes weight is a strong indicator of male fertility in seasonally breeding mammals, we suggest the inclusion of such effects in population level impact assessments involving PCB exposures. Given the re-emergent PCB threat our findings are globally significant, with potentially serious implications for long-lived mammals. We show that more effective PCB controls could have a substantial impact on the reproductive health of coastal cetacean species and that management actions may need to be escalated to ensure adequate protection of the most vulnerable cetacean populations. Feel free to email me (rosie.williams@ioz.ac.uk<mailto:rosie.williams@ioz.ac.uk>) if you have any questions or if you would like to discuss our findings further. Also, if you are unable to access the article at the above link then I would be happy to send you a copy of the manuscript. Best, Rosie Rosie Williams Zoological Society of London & Brunel University London Twitter: @RosieSWilliams1 _________________________________________________________________________ The Zoological Society of London is incorporated by Royal Charter - Registered Charity in England and Wales no. 208728. Principal Office England - Company Number RC000749 - Registered address Regent's Park, London, England NW1 4RY _________________________________________________________________________ This e-mail has been sent in confidence to the named addressee(s). If you are not the intended recipient, you must not disclose or distribute it in any form, and you are asked to contact the sender immediately. Views or opinions expressed in this communication may not be those of The Zoological Society of London and, therefore, The Zoological Society of London does not accept legal responsibility for the contents of this message. The recipient(s) must be aware that e-mail is not a secure communication medium and that the contents of this mail may have been altered by a third party in transit. If you have any issues regarding this mail please visit: https://www.zsl.org/about-us/contact-us