Overview on microplastics sources

The following is a comprehensive list of the primary sources of microplastics, broken down into three categories: primary microplastics, secondary microplastics and atmospheric microplastics.

Primary Microplastics

These are intentionally manufactured in small sizes for industrial and consumer use.

1. Microbeads in Personal Care Products:
   • Exfoliating Scrubs: Microbeads are added to scrubs and exfoliants to provide a scrubbing effect.
   • Toothpaste: Some toothpastes contain microbeads for abrasiveness.
   • Facial Cleaners: Used for exfoliation in facial cleansers.
   • Shower Gels: Microbeads are added to create a textured feel.
   Key Study: The banning of microbeads in many countries, such as the U.S. in 2015 under the Microbead-Free Waters Act, came after studies showed they were a significant pollutant in water systems.
2. Pellets or Nurdles (Pre-Production Plastic Pellets):
   • Raw Material for Plastic Manufacturing: Nurdles are small plastic pellets used in plastic manufacturing, and many end up in oceans and rivers due to spills during transportation.
   • Packaging: Used as a raw form of plastic to create a wide variety of products.
   Key Fact: Nurdles are considered one of the most common forms of plastic pollution in oceans due to accidental spills during transportation.
3. Synthetic Fibers in Textiles:
   • Polyester, Nylon, Acrylic: Clothes made from synthetic fibers shed microplastic fibers during washing.
   • Fleece Materials: Fleece jackets and blankets made from synthetic materials are major contributors.
   • Carpets and Upholstery: Synthetic fibers used in home furnishings like rugs, curtains, and sofas.
   Key Study: Research published in Environmental Science & Technology found that a single synthetic garment can release over 1,900 fibers per wash.
4. Tire Wear and Road Dust:
   • Tire Abrasion: Tires made from synthetic rubber shed microplastic particles as they wear down through friction with roads.
   • Road Markings and Paint: Road paint, thermoplastics used for lane markings, and plastic debris from roads themselves contribute to microplastic pollution.
   Key Study: A 2017 study published in Nature Geoscience estimated that tire wear contributes up to 30% of the microplastic pollution in oceans.
5. Paints and Coatings:
   • Marine Paint: Ships and boats use plastic-based coatings that degrade and release microplastics into oceans.
   • Household Paint: Indoor and outdoor paints often contain plastic particles that wear off over time and contribute to airborne and waterborne microplastics.
   • Automotive Paint: Car paint chips and wears away, contributing to microplastic pollution on roads and in air.
6. 3D Printing Materials:
   • Plastic Filaments: During the 3D printing process, thermoplastic materials such as PLA, ABS, and PETG often produce waste and microplastic fragments.
   • Plastic Dust: The handling and post-processing of 3D-printed objects can generate microplastic dust and waste particles.

Secondary Microplastics

These are formed when larger plastic items break down due to environmental factors like UV light, heat, or mechanical wear. Over time, large plastic items fragment into smaller pieces, becoming secondary microplastics.

1. Plastic Packaging:
   • Plastic Bags: Disposable plastic bags fragment and release microplastics over time.
   • Plastic Bottles: Bottled water, soda bottles, and other plastic containers break down into microplastics.
   • Plastic Food Wrappers: Snack wrappers, cling film, and other thin plastic materials degrade over time, releasing microplastic particles.
   Key Study: A 2018 study published in Frontiers in Chemistry found that bottled water can contain double the amount of microplastics compared to tap water.
2. Litter and Debris from Disposable Plastics:
   • Plastic Straws, Utensils, and Cups: Frequently disposed of improperly, these items degrade and fragment into microplastics in the environment.
   • Cigarette Butts: The filters in cigarettes are made from plastic (cellulose acetate) and contribute significantly to microplastic pollution when discarded.
   • Plastic Toys: Discarded toys left outdoors fragment over time and release microplastic particles.
3. Fishing Gear:
   • Discarded Fishing Nets and Lines: Commonly known as “ghost gear,” these items are made from durable plastic materials like nylon and break down into microplastics over time.
   • Fishing Buoys and Floats: Plastic buoys and other equipment used in commercial and recreational fishing contribute to plastic pollution when they degrade.
   Key Study: According to the FAO, up to 640,000 tons of fishing gear is lost in oceans annually, making fishing gear a major source of marine plastic pollution.
4. Construction Materials:
   • PVC Pipes: Polyvinyl chloride (PVC) is used in pipes and building materials and can break down into microplastics over time.
   • Plastic Insulation and Foam: Building insulation materials like polystyrene foam are known to fragment and release microplastics into the air and surrounding environment.
5. Automotive Parts:
   • Plastic Car Parts: Bumpers, dashboards, and interior trims made of plastic eventually degrade and release microplastic particles.
   • Plastic Coatings: Car exteriors and interiors often have plastic coatings that wear down, contributing to microplastic shedding.
6. Plastic Marine Debris:
   • Plastic Bottles, Bags, and Other Waste: Plastics that end up in the ocean, such as water bottles, bags, and wrappers, degrade into microplastic particles due to UV exposure and wave action.
   • Plastic Fragments from Larger Debris: Over time, large plastic waste in the ocean breaks into smaller pieces, contributing to the accumulation of microplastics in marine ecosystems.
7. Household Products:
   • Sponges: Synthetic cleaning sponges shed microplastic particles when used.
   • Detergent Pods: Some pods used in laundry or dishwashing contain plastic casings that can release microplastics as they dissolve.
8. Wastewater Treatment Plants:
   • Effluent Water: Wastewater treatment plants are unable to fully filter out microplastics, so they are often released into rivers and oceans through treated water.
   • Sludge: Sewage sludge used as fertilizer in agriculture contains microplastics that can spread to soil.
   Key Study: A 2020 review published in Environmental Science: Processes & Impacts noted that wastewater treatment plants can be both sources and sinks of microplastics, depending on how effectively they capture particles.
9. Cosmetic and Hygiene Products:
   • Face Wash and Makeup: Even after microbeads were banned, many beauty products contain microplastic additives such as polymers used to create texture or enhance shine.
   • Wet Wipes and Sanitary Products: Many wipes, pads, and tampons contain synthetic materials like polypropylene and polyester, which contribute to microplastic shedding.
10. Food and Beverage Contamination:
    • Seafood: Fish and shellfish ingest microplastics from the ocean, which then enter the human food chain.
    • Tap Water and Bottled Water: Microplastics can be found in drinking water due to contamination from pipes and plastic containers.
    • Salt: Sea salt has been found to contain microplastics due to ocean contamination.
    Key Study: A 2018 study by the University of Newcastle found that the average person ingests around 5 grams of plastic per week, roughly equivalent to the weight of a credit card, mostly through contaminated water and food.

Atmospheric Microplastics:

Microplastics are also present in the air and can settle on surfaces, including food and drink.

1. Synthetic Fibers from Clothing:
   • Fibers shed from clothes (especially during drying or general wear) become airborne and contribute to indoor microplastic pollution.
2. Plastic Dust from Degrading Materials:
   • Dust from plastics in furniture, electronics, and building materials breaks down and becomes airborne, contributing to indoor air pollution.
   • Microplastics can also come from plastic packaging, insulation, and everyday wear and tear on household items.
   Key Study: A 2020 study published in Science found that microplastics can be transported through the atmosphere, with concentrations detected in even remote locations like the Arctic.