Strung Out

What happens to all the plastic that spins off a line trimmer?

John Quinn

The scourge of single-use plastics is, at this point, well understood by most people. All of that food packaging, the lids on to-go coffee cups, straws, pens, disposable razors – the plastic from these sources and many others must go somewhere, that somewhere usually being the ocean. While enlightened companies adopt compostable packaging, consumers try their best to sort their trash appropriately and recycle as much as possible. Of course, some actors aren’t so responsible: From the standpoint of a retailer or manufacturer, the best possible kind of plastic item would be one that seems to disappear magically.

photo by Dave Bonta, on Flickr

The unsurpassed champion at such a sleight-of-hand has to be the weed whacker. During the course of normal operation, a weed whacker’s plastic line abrades into such small pieces that they become almost invisible. And this itself is part of the problem – because it’s hard to address an issue that you can’t see. But it’s time to start noticing line trimmers and the plastic pollution they routinely spew.

Also known as line trimmer or weed eaters (a brand name, but often used generically), these tools are used by landscapers, highway crews, homeowners, and almost anyone who wants to cut grass and weeds. They are handy machines, likely to be found in almost any suburban garage or tool shed. The actual number of string trimmers is hard to pin down, but one website puts the figure at 90 million worldwide. A 2004 article in Consumer Reports said the big box stores were selling 10 million string trimmers a year. Sales like this are not surprising, given how easy to use and inexpensive the machines are.

They are also multifaceted polluters by their very design. When they came on the market in the early 1970s, the pollution from their small engines was obvious. Since then the immediate air pollution has improved. But they are still significant sources of neighborhood noise pollution, a problem they share with their equally ubiquitous cousins, leaf blowers.

The most serious pollution problem associated with the string trimmer, however, may be the easiest to overlook – it has to do with the nylon string that gives the machine its name. This nylon is a synthetic polymer, a disposable plastic item, and string trimmers use prodigious amounts of the stuff. In the course of mowing, the string is worn away and is spewed into the environment as the line whirrs around at speeds up to 28,000 feet per minute.

As a source of plastic pollution, trimmer line lurks under the radar of most users, which makes it one of the most insidious examples of disposable plastic. It’s a single use plastic with a vengeance. Regardless of one’s level of environmental awareness, there’s no attempt to recycle the line, because doing so is virtually impossible. The mower scatters the tiny pieces of plastic in grasses, among trees, in the thickets of shrubbery; collecting them is unheard of.

Each day trimmers toss tiny bits of nylon into yards, gardens, golf courses, and roadsides. The plastic is mistaken as food by birds and animals, both domestic and wild. Many of the tiny bits will eventually migrate into streams, rivers, lakes, and oceans. Marieta Francis, executive director of California’s Algalita Marine Research Institute, estimated that 80 percent of all marine pollution is plastic and, of that, 70 to 80 percent is post-consumer waste from land, swept by storms into rivers or streams or directly into the sea. There is scant research on the contribution of trimmer string to the mass of plastic found in the world’s oceans. But David Jones, of the Plastic Oceans Foundation, ventured: “You could pretty safely hypothesize that the total production of nylon used for trimmers ends up in particulate size in the environment. Inevitably the nylon will end up on the ground … and then find its way into the waterways.”

Much of what ends up in the ocean garbage patches – there are several – is “microplastics.” They measure from smaller than 5 millimeters to smaller than 1 millimeter. According to Columbia University’s Earth Institute, “The majority of the plastic found in the ocean are tiny pieces less than 1 cm in size, with the mass of one-tenth of a paper clip.” Or about the size of the minuscule pieces of plastics that whiz off a weed whip.

Microplastics are so pervasive that investigators in one marine study referred to them as “plastic plankton,” a appropriate term considering a recent study on plastic ingestion by fin whales stated that all baleen whales were in jeopardy through ingestion of microlitter, mostly plastics. Once inside an organism (if the shape and mass of a particle doesn’t obstruct digestion or excretory functions), it poisons the organism because plastics in the water tend to absorb all kinds of toxic pollutants, including polychlorinated biphenyls, PCBs, and varieties of DDT. Waterborne plastics attract new toxins as it leaches out old ones.

Determining how much plastic pollution is caused by trimmer string is difficult, to say the least. When asked how many tons of plastic are used to make the nylon line, an executive who works for a major US line trimmer manufacturer said he didn’t have figures on how much string his own company produced. He did say the pelleted plastic resin used to make the line arrives at his factory by the semi load and that his company – one of many manufacturers globally —uses “millions and millions and millions” of pounds annually. This plant is only one of about 50 companies listed by its trade industry lobby. Nearly all of these companies make or sell trimmer line. One Chinese company claims to produce 200 tons of trimmer line monthly.

It all adds up – that is, until it disappears into the environment.