Nine Things to Know About Microplastics
1. What are microplastics?
Microplastics come in all sizes, shapes and colors. Some particles are so small that they’re invisible without a microscope, while others are perceptible as grains or fibers of different sizes. Microplastics are defined as plastic pieces that are between one micrometer (one millionth of a meter) and five millimeters in size. Nanoplastics are particles that are smaller than one micrometer.
All plastics are manufactured industrially. There is no such thing as “natural” plastic. Plastic consists mainly of carbon and hydrogen, which are bound together in long chains called polymers. The length of the chains, how they’re woven together and what other substances are included (e.g. chlorine) determine the properties of different plastic types.
Plastics also contain chemical additives that give the plastic certain properties. Phthalates are chemicals that make hard plastic soft and pliable in products like garden hoses and vinyl floor coverings, for example.
2. Where do microplastics come from?
Scientists distinguish between primary and secondary microplastics. Primary microplastics are small plastic particles that are intentionally manufactured in this size for use in cosmetic products or as abrasives. Secondary microplastics result when larger plastic products – such as plastic bags, bottles or fishing nets – break down into smaller plastic pieces.
Microplastics originate from a variety of sources. Car tire treads, made of a mixture of rubber and plastic, are a major land source. Studies have shown that an average car tire loses about 1.5 kilograms (3.3 pounds) over its lifetime from normal wear and tear, dispersing millions of microplastic particles into the environment.
Paint from buildings, roads and ships, and fibers from synthetic fabrics are additional sources of microplastics. Sportswear and fleece clothing release large amounts of fiber when washed and end up being flushed out with the wastewater. In modern water treatment plants, a lot of this material is filtered out and discharged into the collected sludge, but some still gets through. When the sludge from wastewater treatment plants is used as agricultural fertilizer, farmland becomes the recipient of large quantities of plastic fibers.
About 75 percent of all plastics that wind up in the ocean originate on land and are transported via rivers. Insufficient garbage handling makes rivers in Asia and Africa particularly vulnerable. Trash from ocean vessels – either lost or tossed from ships – accounts for the rest of the plastic debris in the ocean. Rubbish, and especially plastic, is piling up in five huge ocean gyres. The effects of the sun, wind and waves, coupled with abrasion from sand and stone, break down the plastics into smaller fragments and create huge amounts of microplastics and nanoplastics.
3. Why should we be concerned about microplastics?
Three attributes of microplastics in particular give cause for concern:
a) Plastics are difficult or impossible to get rid of.
b) Microplastics can harm aquatic organisms and animals.
c) We don’t know enough about how microplastics can affect people.
continua em inglês aqui