The Power and Peril of Tiny Things
Puddock Hill Journal #83: It’s what we don’t see that will get us.
Out in rural America, a problem is brewing that may poison farmers, farm animals, and the crops farmers grow, not to mention the broader ecology.
In some parts of the country, farmers have been spreading a kind of fertilizer known as biosolids, which are produced from sewage. It turns out many of these products contain Per- and poly-fluoroalkyl substances (PFAS), which have come to be known as “forever chemicals” for their persistence in the environment. The movie Dark Waters, based on a New York Times article entitled "The Lawyer Who Became DuPont's Worst Nightmare,” dramatized the effects of these chemicals when released in concentration, where they entered the water table and severely poisoned one farmer’s cows.
In much smaller quantities, PFAS are ubiquitous, found on every continent, in the bodies of 98 percent of Americans, in water systems serving 200 million of our fellow citizens, and even in 20 percent of private wells, according to studies cited by John Hopkins Bloomberg School of Public Health.
No wonder they turn up in fertilizer made from biosolids, reinforcing a vicious cycle in which they enter our food supply, get consumed, end up in sewage, and return to the produce aisle.
PFAS also leach into the environment from landfills and sewer systems. They find their way into groundwater and water bodies. Fifty percent of rivers have measurable quantities of PFAS compounds. Some of the farmers who used PFAS-contaminated fertilizer are now suing the companies that provide it, although those companies are lobbying Congress to limit their liability.
According to the EPA, known health effects of PFAS include decreased fertility or increased high blood pressure in pregnant women; developmental effects or delays in children, including low birth weight, accelerated puberty, bone variations, or behavioral changes; increased risk of some cancers, including prostate, kidney, and testicular cancers; reduced ability of the body’s immune system to fight infections, including reduced vaccine response; interference with the body’s natural hormones; and increased cholesterol levels and/or risk of obesity.
If PFAS are ubiquitous, they’re probably in our backyards—and in every living thing that passes through our backyards. Last year, the Environmental Working Group collected data that showed PFAS were present in 330 wildlife species around the world. They published an interactive map that “plots a great variety of wildlife, including many types of fish, birds, reptiles, frogs and other amphibians, large mammals such as horses and polar bears, and small mammals such as cats. Some are already endangered or threatened.”
In Puddock Hill’s region, PFAS have been found in smallmouth bass and rock bass in the Brandywine Creek in Delaware; in largemouth bass, white perch, and channel catfish in the White Clay Creek in Delaware; and in channel catfish and smallmouth bass in the Schuylkill River of Pennsylvania.
What strikes me is that these chemicals—indeed most chemicals—are for the most part invisible in our environment. Yet, when researchers look, they find them. Since being invisible doesn’t mean not being present, I think of how carelessly so many of us spread herbicides, pesticides, and fungicides around our yards with no concept of the consequences.
In April, an essay published in the journal Environmental Science & Policy called attention to something I learned in graduate school: that under E.U. and U.S. law, only the active ingredients in pesticides are disclosed to the public, even though “additional chemicals like solvents and surfactants (co-formulants)” contained in the products “can be toxicologically relevant, and some are even more toxic than the active ingredient in the formulation.”
Yet another invisible harm comes from nanoplastics. Admittedly, it is difficult, if not impossible, to eliminate all plastic use, even in the garden. What’s the harm, we may tell ourselves, of one more plastic pot, a few yards of garden fabric, or that plastic-coated wire holding up our dahlias?
Studying the effects of microplastics and nanoplastics in the environment—even in the human body—is a fairly new pursuit. A series of scientific experiments reported this year in the journal Environmental Science: Nano found that nanoplastics can alter the physiological functioning of trees, “causing, for example, oxidative stress or reducing photosynthesis.” The researchers had assumed nanoplastics would travel through fissures in root tissue but instead found that they are transported up into the tree after absorption into the plant’s cells, a more profound invasion.
Our wholesale pollution of the environment amounts to a staggering uncontrolled experiment, as we have so much to learn not only about the interactions of manmade substances with plants but about the inner workings of the plants themselves.
Much as biologists have only begun to appreciate the microbiome in the human body, botanists are still discovering what makes plants function at the microscopic level. A preprint study (that is, not yet peer reviewed) in the publication bioRxiv claims to demonstrate that
…a single tree can host approximately a trillion microbes in its aboveground internal tissues, with microbial communities partitioned between heartwood and sapwood, each maintaining a distinct microbiome with minimal similarity to other plant tissues or nearby ecosystem components. Notably, the heartwood microbiome emerges as a unique ecological niche, distinguished in part by endemic archaea and anaerobic bacteria that drive consequential biogeochemical processes. Our research supports the emerging idea of a plant as a “holobiont”—a single ecological unit comprising host and associated microorganisms—and parallels human microbiome research in its implications for host health, disease, and functionality.
Imagine how much damage a single manmade chemical can do to this delicate dance of life that appears, to the naked eye, as a sturdy trunk and limbs.
Similarly, the dirt beneath our feet—or more important, beneath our flora—contains multitudes that we’re only beginning to understand. Brian Darby, associate professor of biology at The University of North Dakota, writing for kids in The Conversation, wrote an explanation of the life in soil that can be edifying for all of us:
To get a sense of just how many creatures are there [in the soil], picture this: The zoo in Omaha, Nebraska, boasts over 1,000 animal species. But if you scooped up a small spoonful of soil in your backyard, it would likely contain at least 10,000 species and around a billion living microscopic cells.
Most of those species are still largely a mystery. Scientists don’t know much about them or what they do in soil. In fact, most species in soil don’t even have a formal scientific name. But each plays some kind of role in the vast soil ecosystem, including generating the nutrients that plants need to grow.
Soil, in fact, contains sixty percent of global biodiversity. How troubling then that, as the authors of a study entitled “Global changes and their environmental stressors have a significant impact on soil biodiversity” write in the journal iScience, “Many previous meta-analyses investigating the impact of different global changes on biodiversity have omitted soil fauna or are limited by the [changes] studied.” The authors’ broad-scale meta-analysis found: “Unexpectedly, pollution caused the largest negative impact on soil biodiversity — particularly worrying due to continually increasing levels of pollution and poor mechanistic understanding of impacts…”
Again, the unseen has outsized impacts on our increasingly compromised environment.
Many of these pollutants are beyond our control, except maybe in the voting booth or with the choices we make while shopping. But we do control what we put into our own backyards, where we can pledge right now to limit the use of poisons.
Winter scenes at Puddock Hill…
Looking down from the tenant house toward the small pond:
The small pond viewed from the bench on a cold day: