In Louise Pennys engaging mystery series, chief inspector Armand Gamache often launches an investigation by asking his team, Tell me what you know. Its an effective strategy when assembling clues following a suspicious death. Its also a starting point when unearthing hazards that hide under the carpet or, in many cases, emanate from it. The soft pile beneath our feet is increasingly suspect: Lets review the evidence. We know that synthetic clothing, like nylon and polyester fleece, sheds microfibers in the wash, where a single load can release tens of thousands of miniscule plastic threads that pass through water treatment systems and enter waterways. Scientists are finding these pernicious microfibers throughout the oceans food chain, raising contamination concerns for marine organisms and for ourselves. We know that new carpet, most of it made from nylon or polyester (specifically polyethylene terephthalate, or PET), is a Vesuvius of volatile organic compounds. It off-gasses chemicals like formaldehyde, acetate and benzene, which can cause respiratory problems, headaches and worse. We know that older carpeting becomes a holding pond for particulates tracked in on shoes and pet paws, and for chemicals that settle out of the air (such as lead dust, flame retardants from appliances and furnishings, and cleaning chemicals). Mixed into that sludge are dust and the inescapable dust mites. We know, too, that spent carpets pose a major disposal problem, constituting at least 2 percent of municipal solid waste in the U.S. Fewer than 10 percent of carpets are recycled; the vast majority end up in a landfill. And now for the specifics of our case: a man seemingly poisoned (fortunately, not fatally) by a wall-to-wall carpet in a small apartment abroad. The carpet, probably two decades old, had begun to degrade, so he arranged to have contractors remove it. That precipitated what his doctors called an explosion of dust that left him coughing and in respiratory upset so severe, he recalls, it felt like nausea in my lungs. An accumulation of what he describes as fibrous grey dust, identical in colour to the carpet, settled on every exposed surface in the apartment. He abandoned the place temporarily and had contractors renovate with new plaster, paint and floor tiles no more carpet. Cleaners scoured his furniture and books before he moved back in. But his respiratory distress returned, with sneezing and a runny nose. The sparkling renovation was soon marred by an accumulation of the familiar fibrous grey dust. Could it be coming from outdoors, he wondered? (It wasnt heating season, and there was no air conditioner.) Before leaving the apartment for three weeks of travel, he sealed up the windows and balcony door with tape to restrict any air exchange. When he returned, more fibrous dust coated exposed surfaces. He had felt fine while traveling, but his respiratory problems resumed upon coming home. He has since moved, but is left with lingering questions about what irritated his lungs and what impact it might have long-term. His pneumologist warned him that problems from some health hazards like tobacco smoke, coal dust and asbestos may not manifest for years or decades. None of those triggers were in his small apartment, but was there another culprit? Plastic microfibers from a decomposing carpet? When I heard his story, I went in search of studies on airborne plastic microfibers. Nylon or PET carpets cover more than half of U.S. floors, many of them in settings where infants crawl and young children play. It doesnt take a detective to conclude that carpets shed. (Simply watch an online video of carpet manufacturing, and you can see loose fibres hanging off the yarns during the spooling and tufting processes; imagine how many more go airborne as the carpet breaks down over time with wear and vacuuming.)
I expected to find a whole body of research on the potential health effects of inhaled plastic microfibers. I was dead wrong. The U.S. Environmental Protection Agency reports that our health risks from indoor pollution often exceed those from outdoor air, yet few scientists are examining exposure risks of inhaled microfibers from the shedding carpets in our homes, schools and offices. What is known about how plastic microfibers behave in the body is not reassuring. In May 2017, British researchers Stephanie Wright and Frank J. Kelly described in the journal Environmental Science and Technology anticipated hazards from inhalation of plastic microfibers. Workers who process nylon and polyester fibres report symptoms of respiratory distress such as sneezing, breathlessness, coughing and wheezing. Long term, these microfibers appear to be biopersistent, able to resist innate respiratory defence systems and lodge deep in lung tissue, potentially causing chronic inflammation and fibrosis. Microfibers lingering within the lungs pose threats from two sources, the first of which is chemical leaching. The plastics themselves often include additives with known toxicity, as well as what Wright and Kelly called hazardous unreacted residual monomers (molecules), some of which are classified as carcinogenic, mutagenic or both. The surface of plastic microfibers can also attract and concentrate chemicals from their surroundings (a process known as adsorption). Once inhaled, the tainted microfibers could introduce those hazardous substances to lung tissue. Research done two decades ago found that inhaled cellulosic and plastic fibres like the mineral fibres of asbestos are candidate agents contributing to the risk of lung cancer. This case is not closed. One lingering mystery is why theres no focused study of a public health threat that could turn out to be as widespread, severe and costly as asbestos has proven to be. In fiction, what we do not know can make for a compelling thriller; but in real life, that same uncertainty can be deadly.
Portland Press Herald, 10 December 2018 ; https://www.pressherald.com