New research, “Microplastics in Marine Mammals: A One-Health Perspective to Inform Human Health and Environmental Risk Assessment” was presented at the Society of Environmental Toxicology and Chemistry (SETAC) North American 45th annual meeting. Due to their ubiquity and small size, microplastics have been documented to be ingested by hundreds of marine species, including marine mammals. Baleen whales filter plankton from large volumes of water and are thus exposed to high levels of microplastics. Toothed whales, such as dolphins, are of particular importance because they are exposed to microplastics by eating prey that have also ingested microplastics. Dolphins are a well-studied sentinel species, meaning they can provide an early indication of what’s going on in our environment and what it may mean for human health. Studying microplastic ingestion in dolphins can help inform human health risk assessments with environmentally-relevant exposure levels.
Researchers are still unraveling the consequences of microplastic ingestion. Studies have found that microplastics can cause inflammation, a false sense of feeling full, microbial imbalance, insufficient oxygen in their tissues, and fiber formation in formerly healthy tissue. Furthermore, microplastics can serve as a pathway for other bacteria growing on their surface, or contaminants (such as persistent organic pollutants) absorbed from their environment. While most microplastics are expected to pass through an organism, some particles may enter the circulatory system where they may have systemic effects on the body. The mechanism and effect of this is still being investigated.
Microplastics in the marine environment can come from a variety of sources, with the majority of microplastics coming from the breakdown of larger plastic items such as textiles/clothing, packaging, fishing gear, and tires. Some of these particles are shed during the everyday use, or are continuously degraded in the environment following improper disposal. Currently one of the main reduction strategies is litter pickups and debris removal- which are helpful to eliminate further microplastic production, as each piece of plastic in the environment is capable of producing hundreds of thousands of microplastics that continue to break down into smaller and smaller pieces. In the marine environment, microplastics persist indefinitely and are capable of being transported to all regions of our ocean ecosystem. The research was presented by Bonnie Ertel in Fort Worth, Texas from October 20th-24th.