Microplastics: Macro pollution across the Food Planet

Images of turtles entangled in plastic often hit the headlines. When not directly killing marine animals, plastic debris breaks down into tiny pieces called microplastics. Now found in every corner of the planet, including some of the Earth's most remote places like Antarctica, seafloors, and groundwater, microplastics have turned into a plague that keeps on spreading. So, it's perhaps unsurprising that a recent study discovered plastic fragments in the air we breathe. We should nevertheless be alarmed by the news. 

While we use plastics in nearly all aspects of life, the way we produce, distribute, consume, and dispose of food notably fuels our global appetite for this petroleum byproduct. In fact, food and drink packaging alone accounts for 16% of all plastics ever produced. Microplastics have infested the entire food chain, polluting land, water, and atmosphere with disastrous environmental and public health consequences.

Land pollution – Microplastics flushed down the soil

The agricultural sector contributes greatly to the problem, using 6.5 million metric tons of plastic annually. Representing 40% of the total agriplastic market, mulching – covering soil with a plastic film – is a significant contamination source on farms. The practice helps prevent weeds, conserve water, control temperatures, accelerate growth and prolong seasons for certain vegetables. But it also causes widespread soil and crop contamination. Paradoxically, despite the existence of plastic-free alternatives such as wood chips, leaves, grass trimmings, or straw – which all have the added benefit of enhancing soil quality – organic farmers still favor mulching because it increases productivity without prohibited fertilizers and pesticides.

Beyond plastic mulch, tunnels, greenhouses, and seed coatings – yes, as crazy as it sounds, seeds are coated in plastic – sewage sludge is by far the largest source of microplastics on farmlands. Whether poured directly on soils or first processed as biosolids, this fertilizer resulting from sewage treatments accounts for 92% of microplastics contamination on farms. The impact of such large-scale use remains unknown. Still, a 2019 Kansas State University lab experiment showed that wheat grown with microplastics contained 1.5 times more cadmium, one of the most toxic components in sewage sludge. The experiment also found drainage problems in plastic-contaminated soils.

Water pollution – Plastics dumped into the ocean

Although microplastics "only" account for 8% of the total mass of debris found in the infamous Great Pacific Garbage Patch, they represent 94% of floating fragments. These very particles take off and travel in the atmosphere when powered by waves and wind. As if that wasn’t bad enough, a study from Australia's national science agency, CSIRO, estimates that there are 35 times more marine habitat-threatening microplastics buried in the depth of the seabed than floating on the surface. What's more, fishing nets make up the vast majority of larger debris in the oceans. Some of this plastic eventually enters our food chain, from the plankton that krill eat to the salmon fillet on your plate. Microplastics have even found their way into groundwater.

Air pollution – Microplastics dispersed into the atmosphere

We force-feed our lands and waters a colossal quantity of plastic, only for them to chew and spit it back out into the atmosphere. Once in the air, microplastics can travel for up to six and a half days, accumulating organic pollutants, exposing the ecosystems to additional air pollution, and posing risks of respiratory diseases for humans, according to a study conducted by researchers at Utah State University and Cornell University.

Not only do we breath plastic particles, but we also eat a credit card-sized amount of microplastics each week. This can affect our immune system and facilitate the transmission of toxic chemicals and pathogens. We ingest microplastics and related chemicals through seafood but also through direct transfers from food packages. Bisphenol A is one of such substances. It's a carcinogenic endocrine disruptor now banned in baby bottles in most industrialized countries but still allowed in most low-income countries as well as in water bottles and soda cans.

Yet, despite such alarming evidence, plastic production continues to rise. Researchers project it'll quadruple by 2050. By then, we will have generated 26 billion metric tons of plastic waste, further contaminating soils, waters and air. What is it going to take for our food systems to learn that what goes around comes around?