Researchers find microplastics in 100 per cent of donkey faecal samples tested

(Press-News.org) A study by the University of Portsmouth has revealed for the first time the extent of the devastating impact of plastic pollution on livestock, humans and the wider environment on the Kenyan island of Lamu.  

The study was carried out by members of the Revolution Plastics Institute at The University of Portsmouth, in collaboration with The Donkey Sanctuary, The Flop Flopi Project and the Kenyan Marine and Fisheries Research Institute.  

Until now the impact of plastic waste on terrestrial working animals has been largely overlooked with most of the focus being on marine animals.  Professor Cressida Bowyer, Deputy Director of the Revolution Plastics Institute at the University of Portsmouth explains: “Most plastic pollution originates on land, yet its impacts on land-based animals remain chronically understudied. Our findings show how urgently this knowledge gap needs to be addressed.”  

Researchers took a multi-disciplinary approach, quantifying the amount of microplastics in donkey and cattle faeces, observing their natural feeding behaviour and surveying residents and visitors to understand their attitudes towards plastic pollution and donkey welfare. 

Alarmingly, they found microplastics in 100 per cent of donkey (and cattle) faecal samples analysed. Vets at The Donkey Sanctuary’s clinic in Lamu have long been calling for action due to the volume of donkey fatalities they see each year caused by plastic-induced colic, however this is the first published evidence of its complete and widespread impact.

In 2024, a total of 108 cases of colic were seen at the clinic, an average of 8 donkeys per month, with 14 of those subsequent fatalities. So far, in 2025, numbers are similar; clinic vets have seen 91 donkeys with colic, of which 16 have died.

Half of donkey owners surveyed admitted that with fluctuating feed prices, they could not consistently provide enough food for their animals who instead were left to roam in search of some. Analysing the animal foraging behaviours primarily at waste sites and in rural areas, researchers found at least one in every 10-20 items ingested was plastic.

As well as posing a serious risk to donkeys and livestock, a major food security concern is the potential for microplastic transfer to humans through consumption of contaminated animal products or crops fertilised with animal manure containing tiny plastic particles. Microplastics in humans has been linked to inflammation, cancer, reproductive disorders and other serious health issues.

Free-roaming donkeys are both culturally significant and a major tourist attraction on Lamu, and yet a lack of grass or edible vegetation is forcing many to forage for food at waste sites.

Rather than restricting the movement of donkeys, researchers and residents are calling for community clean-ups, better waste disposal systems, and government investment in recycling and plastic alternatives.

Dr Obadiah Sing’Oei, Programme Manager at The Donkey Sanctuary’s clinic in Lamu, said: “This study is a wake-up call for collective action to end the plastics crisis here in Lamu. Time and time again we see firsthand the terrible – and preventable - suffering caused to donkeys who have ingested plastics. This study provides hard evidence of the true scale of the problem and its widespread impact. Together with our partners we will not rest until we have a joined-up solution to create a safer environment for all.”

Dr Sing’Oei has been invited to present a paper called, “Plastics and One Health in Agrifood Systems: Understanding and Managing Risks” during a special Food and Agricultural Organisation (FAO) event (18-21 Nov) at its headquarters in Rome, Italy.

Leanne Proops, Professor in Animal Behaviour and Welfare at The University of Portsmouth, said: “This study demonstrates the interconnectedness of animal, human and environmental health. Pollution is placing severe pressure on the environment, harming donkeys and other livestock, which in turn affects human health and livelihoods. Here we have clear evidence that microplastics are present across an entire animal population which has serious implications for the whole ecosystem. This problem extends far beyond Lamu -underscoring the urgent need for a holistic approach to mitigate the global plastic crisis.” 

This first of its kind, peer-reviewed research demonstrates how deeply plastic pollution affects animals, people, and ecosystems - and highlights the urgent need for coordinated global and local action.  

END