A: Microplastics are small plastic particles with a size of 5 millimeters (about the size of an eraser at the end of a pencil) or less. Microplastics either originate from primary or secondary sources. 

• Primary microplastics are intentionally manufactured at a small size. Self-care products such as exfoliants, cosmetics, and toothpaste often contain microplastics to increase viscosity or abrasiveness. Fibers often used in textile production, such as those in polyester fabrics, are another notable source of primary microplastics. 

• Secondary microplastics occur when larger plastic products break down over time. Common products that produce secondary microplastics include phone cases, plastic water bottles, and food packaging. Microplastics can originate from the everyday use of such products. Fragmentation and degradation of plastics can be accelerated by exposure to heat and sunlight.