Plastics in the pasture: tracing microplastics in livestock dung from rural communities

Abstract

Microplastics are a pervasive environmental pollutant originating from diverse sources and comprising a wide range of polymer types. Their persistence and widespread release have raised global concern about ecological and animal health risks. (Micro)Plastics are ingested by livestock and excreted in dung, making dung analysis a useful approach for assessing environmental contamination. However, detailed characterisation of microplastics in livestock dung remains limited. This study investigated the abundance and characteristics of microplastics in 499 dung samples collected from chickens, goats, and cattle across 29 farms in rural South Africa. Microplastics were extracted through dung digestion using 30% hydrogen peroxide followed by density separation with zinc chloride, and characterised by counts, colour, shape, and polymer type. Chickens exhibited the highest microplastic loads, followed by goats and cows. Fragments were the dominant form, with beads being the least common type of microplastic found in goats, chickens, and cows. Transparent microplastics were the most common colour overall, whereas yellow particles were the least common in chickens and cattle, and green in the case of goats. Polychloroprene was the most frequently detected polymer, comprising 35.0% in goats, 14.1% in chickens, and 16.4% in cattle. These findings highlight that livestock dung is a significant pathway through which microplastics may enter agricultural soils, with potential implications for soil quality and sustainable food production. Future research should investigate the environmental fate and ecological impacts of these microplastics to better inform management strategies for agroecosystems. The study does not include any clinical data nor is it a clinical study.