Microplastics detected in wild animal stool in landmark discovery

14 Nov 2018 --- In a landmark discovery, scientists have for the first time detected plastic microfibers in the stool of wild animals. A team of Morris Animal Foundation-funded researchers at the University of Georgia found this form of microplastics in the stool of South American fur seals by examining droppings from pinnipeds. The team believes that this form of examination is an efficient way to monitor environmental levels of microfiber and microplastic in the environment. The study was published in the Marine Pollution Bulletin.

“It's no secret that plastic pollution is one of the major threats to marine ecosystems, but we're learning now just how widespread that problem is," says Dr. Mauricio Seguel, a research fellow at the University of Georgia. “These samples are invisible to the naked eye. We want to understand factors that are driving their distribution and what this means for animals in the Southern Hemisphere.”

The team examined the dropppings of 51 female South American fur seals on the remote Guafo Island, in southwestern Chile, from December 2015 to March 2016. Each sample's inorganic material was dissolved in a solution in a lab, leaving only the microscopic, plastic particles to be analyzed. Researchers then found that 67 percent of the samples contained a remarkable abundance of microfibers, which until now had only been reported in animals fed in captivity.

Microplastics are plastic fragments smaller than 5 millimeters. Microfibers are the least studied form of microplastic. They are small “hairs” of plastic, less than 1 millimeter in size, from materials such as polyester or nylon and can end up in the ocean through wastewater, no matter how thorough the cleaning treatment. They can also absorb a wide array of pollutants.

The researchers believe the microfibers arrived at Guafo Island through changing ocean currents, before being consumed by plankton and continuing up the food chain through fish and, finally, to the seals. There isn't enough evidence to determine if microfibers have any adverse effects on mammals, but some studies have indicated morphological changes in fish.

Seguel tells PackagingInsights that several studies are being conducted in different places throughout the world to understand the potential health threats of microplastics on wild animals.

“Most of these studies are performed in in vitro systems and some preliminary results show that there are morphological changes in the tissues of invertebrates and fishes as a consequence of the interaction with microplastics. Direct effects on mammals remain to be elucidated but indirect effects occur because microplastics can adsorb and serve as a vehicle for pollutants into mammals.”

He also explains that the Morris Animal Foundation experiment did not identify the source of the microplastics found in the seal stool, and that in general, this is “very difficult” to determine. “Other research groups are trying to standardize methods to determine the potential source of a microplastics,” he says.

Stool analysis, the team noted, could be a good tool to monitor the exposure of marine mammals to plastics as it's effective and non-invasive, poses no danger to either the researcher or the animal, and it's easy to identify both fur seals and their feces. Seguel says his colleagues are conducting similar, follow-up tests in other parts of South America.

“It's not too late to act to heal our oceans, but one of the first steps is determining how much we have damaged the ecosystem through our activities, like producing and disposing of plastic,” says Dr. Kelly Diehl, Morris Animal Foundation Interim Vice President of Scientific Programs. “Studies like these will help us learn those answers so we can begin to make better decisions for the health of marine life.”

Seguel is less optimistic about the future health of the ocean, stating that, “Microplastics in the ecosystems will probably remain for hundreds of years.”

He does concede, however, that, “changes in manufacturing and plastic use practices can contribute to diminishing the volume of microplastic release into aquatic systems.” He gives the example of California banning the use of microplastic beads in cosmetics which is due to come into effect in 2020.

In October, new research from Medical University of Vienna and the Environment Agency Austria found particles made of polypropylene (PP), polyethylene-terephthalate (PET) and other microplastics in human stools.

Also in October, a new investigation into the published literature on microplastics found “significant gaps in our understanding of the effects” of the less than 5mm size plastic particles on the environment. The study authors Emily Burns and Alistair Boxall are calling for “better quality and more holistic monitoring studies alongside more environmentally realistic effects studies on the particle sizes and material types that are actually in the environment.”

In April, the highest amounts of microplastics ever recorded were discovered in the Arctic Sea ice. On average, 12,000 pieces of microscopic particles were detected per liter of ice across five sample locations, with the research team identifying plastic packaging and increased shipping and fishing in the Arctic as the primary causes.

By Joshua Poole