Microplastics

Background and Sources of Microplastics

Microplastics are an emerging environmental concern with potential human and ecological health effects. Microplastics are generally defined as plastic particles between 1 nanometer (nm) and 5 million nm (or 5 millimeters [mm]) in size. Particles larger than 5 mm are often referred to as macroplastics while particles less than 1 nm are considered nanoplastics, a subgroup of microplastics. Primary microplastics are intentionally manufactured at small sizes. Examples include cosmetic beads, glitter, seed coatings, and pellets or nurdles (small, round, lens or disc shaped plastic pieces between 2 and 5 mm). Raw plastic materials are often transported as pellets or nurdles before being melted and molded into other products. Various pathways in the environment lead to the fate of macro- and microplastics breaking down to form secondary microplastics. Secondary microplastics make up the majority of microplastics found in the natural environment.

Nurdles - plastic "gravel"

Image credit: Hockadilly

Some common sources of secondary microplastics are:

Degradation of plastic items, such as food containers, toys, packaging, cigarette filters, and other items
Fibers shed from synthetic textiles and clothing
Particles from the breakdown of tires on road surfaces

Size is the only common parameter for microplastics as chemical composition and shape differ extensively. The type of source material and synthesis method used to produce different types of plastic polymers result in a variety of additives, colorants, and other toxicants in a single piece of plastic. Plastic particles can take on countless shapes given their versatility of use: fibers, films, foams, beads or spheres, pellets, and fragments. The shape of secondary microplastics is influenced by its source material, the type of weathering, and time spent in the natural environment.

Figure 1. Examples of items comparable in size to microplastics.

Commercial production of plastics began almost a century ago and has been increasing ever since. Demand for plastic product variety and quantity increased during this time, and so did plastic waste. Plastic waste is estimated to have increased from 390,000 U.S. tons in 1960 to over 35 million U.S. tons in 2018. As a result, microplastics have been found across the globe in wildlife such as birds and fish, and in all environmental media.

Routes of Exposure

The wide use of plastics has increased human exposure to microplastics through ingestion, inhalation, and contact with skin. Microplastics may be consumed through the ingestion of particles in drinking water, food, or from accidental ingestion from soil. Both aquatic and land animals may ingest microplastics, which can transfer up the food chain to humans. When plastic food packaging degrades due to heat or other environmental conditions, microplastic particles may leach into the food and be ingested. The small size of microplastics allows plastic fragments to become airborne, which leads to an increased risk of exposure through inhalation. Contact with skin may also be a route of exposure to microplastics, as some nanoplastics are small enough to be absorbed by the skin.

Figure 2. Microplastics Sources, Pathways and Fate Conceptual Diagram.
Image credit: Jeffrey L. Corbett, USGS

Ecological Effects

Microplastics and nanoplastics are prevalent throughout the entire ecosystem including soil, water, sediment, air, and biota. Studies have shown that these plastic particles can be accidentally consumed by an individual or travel through the food web from primary producers to top consumers resulting in negative impacts to aquatic and terrestrial wildlife.

The toxicity of a plastic particle is largely dependent on its size, shape, composition, and ability to bind with other chemicals present in the ecosystem. The larger, more rigid particles can be lodged in the gut of consumers resulting in intestinal blockage whereas smaller (nano) particles and fibers can cause metabolic, behavioral, and developmental impacts following ingestion. Additionally, microbial communities (biofilms) can form on the surface of these particles. These biofilms may contain pathogens and other toxic substances such as PCBs, PFAS, and mercury, therefore increasing toxicity and adverse impacts to the ecosystem population.

Micro- and nanoplastic research is evolving rapidly to better define toxicological impacts to aquatic and terrestrial wildlife, as well as to determine reliable field and laboratory methods for measuring particle concentrations across all environmental media.

Human Health Effects

The health effects of microplastics are still being identified. The most consistently reported health effects in current scientific research include decreased immune response, increased inflammation and oxidative stress, and organ effects including changes in liver, kidney, and lung tissue. Research on long term health effects is ongoing.

Health effects from ingestion and inhalation of microplastics can vary greatly based on the physical and chemical composition of the microplastic particles. When ingested, smaller particles may be absorbed into the GI tract, and increased amounts can leave less room for nutrients and food to be absorbed. When inhaled, smaller particles are more likely to enter cells in the lungs and cause inflammation in the respiratory system.

The different shapes and sizes of microplastics influence the amount of toxins and microbes that can adhere to their surface. Fragment particles, for example, have greater surface area compared to pellets of similar size. This increased surface area provides more room for the formation of biofilms containing toxins as well as harmful bacteria and viruses. Low-density or rubbery plastics, such as polyethylene and propylene, have higher chemical absorption. Current research suggests that organic and chemical pollutants that adhere to microplastics may have an effect on human health. Consequently, the hazards associated with microplastics are broad because they are unique to the particle size, shape, and composition.

Common Items Containing Plastics	Ways to Reduce Exposure
Shopping and grocery bags, saran wraps, case wraps, and bubble wraps	Use reusable or cloth bags Opt for beeswax wraps Return plastic bags and wraps to certain retail stores for recycling
Single-use plastic tableware, lids, straws, and drink stirrers	Decline single-use plastic items Choose compostable or reusable materials
Clothing made with synthetic fabrics such as nylon, polyester, acrylic, and spandex	Choose untreated cotton, wool, or silk fabrics Wash full loads of laundry, use cold water, wash less often, and line dry Use microfiber filters or fiber catching devices when washing
Cosmetics, dental products, feminine hygiene products, diapers, and wipes	Choose plastic-free packaging such as shampoo bars and toothpaste tablets Avoid products containing plastic microbeads or glitters Use reusable feminine hygiene products and cloth diapers
Plastic bottles, tubs, and jars	Choose plastic-free packaging Recycle curbside
Litter	Pick up plastic waste and dispose of in proper receptacles

Inspect plastic products for wear regularly and properly discard or recycle when signs of wear are noticed. For more information on recycling and to find a local collection facility, please visit Illinois EPA’s Recycling page.

Regulatory Status

Illinois was one of the first states to take action against plastics in 2015, and has since joined 16 other states in urging the National Oceanic and Atmospheric Administration to regulate microfiber pollution. Illinois has passed the following legislation to further reduce plastic use in the state:

• Public Act 098-0638 - bans the manufacture and sale of microbeads in personal care products, such as cosmetics, toothpastes, and facial cleansers beginning in 2018
• Public Act 102-1081 - amends the Illinois Procurement Code to ensure State agencies are purchasing compostable or recyclable foodware instead of single-use plastic disposable foodware for use at State parks and natural areas
• Public Act 103-0470 – requires State agencies to track single-use plastic disposable foodware purchases and replace polystyrene foam disposable food service containers with compostable or recyclable options beginning in January 2025
• Public Act 103-0093 - mandates Illinois EPA to create a public website with information on microplastics, and to prepare report on the topic for the Illinois General Assembly

Federal programs such as the Federal Microbead Free Waters Act of 2015, Save Our Seas Act 2.0, and the Clean Water Act all take steps toward reducing plastic waste in waters. The 2022 bipartisan Infrastructure Investment and Jobs Act designated $50 billion toward drinking water and wastewater improvements, including emerging contaminants such as microplastics. In 2023, US EPA released a Draft National Strategy to Prevent Plastic Pollution outlining three primary objectives—reduce plastic pollution during production, increase reuse and composting of materials, and capture and remove plastic pollution from the environment to prevent it from entering waterways. Altogether, these measures provide innovative approaches to preventing and reducing plastic pollution.