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19 august 2021

The average human body contains more than a pound of only six individual elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Even the bulkiest of the rest run to only a few ounces apiece (potassium, sulfur, sodium, chlorine). Probably, unless you're a gardener, the one of those ten you think about least often is phosphorus. Who ever hears from their doctor that they're getting too much, or too little, phosphorus? Yet in their new book on the element, Jim Elser and Phil Haygarth quote from Isaac Asimov:

Life can multiply until all the phosphorus is gone, and then there is an inexorable halt which nothing can prevent. … For phosphorus there is neither substitute nor replacement. (106)
Of course, it's not like you can make substitutions for oxygen or nitrogen either, but our atmosphere is so plentiful in both that the idea of running out is absurd. Phosphorus, though, is in (relatively) limited supply; much of the phosphorus in our biosphere is locked in various minerals and hard to access for the purposes of life. Elser & Haygarth's book attempts to bring this element into our consciousness, and they certainly raised mine.

Phosphorus is an essential material in bones. Even in boneless creatures, it is central to the workings of DNA, RNA, and the universal bio-energy molecule adenosine triphosphate (ATP). We rarely worry about our phosphorus intake or levels because it's hard for a healthy person to take in too much (phosphorus regulation is a big deal in the human body's self-maintenance), and by the time you exhibit a phosphorus deficiency, you're probably fixing to die of something worse. Phosphorus is simply life itself, and if you eat at all, you tend to get enough.

Elser & Haygarth present a narrative of a fallen world, in phosphoric terms. In the natural condition, phosphorus weathers out of minerals like apatite into the soil, is taken up by plants, which are eaten by animals, which redeposit that phosphorus in the soil in the form of manure (and ultimately of their skeletons). Some leaches into the Earth's water system, where it follows an analogous cycle.

Premodern agriculture just kept the cycle going, taking manure from livestock (and from people) and using it to grow crops which livestock and people ate and so forth … but the scale and logistics of 21st-century agriculture prohibit such a circle-of-life approach. Elser & Haygarth vividly paint the picture (66, 172) of current practices that separate manure production from fertilizer use, with gigantic poultry and pork operations distant by thousands of miles from the arable farms that could use their phosphorus. And in any case, all the manure in the world couldn't support crop production at levels essential to maintain a skyrocketing human population.

As a result, the past half-century has seen an enormous expansion in the mining of phosphorus rock. Our ancestors sometimes stumbled on troves of fertilizer-grade phosphorus in arcane sources like mummies and guano, but efficient extraction of phosphorus from the Earth's crust had to wait for gargantuan bucket-wheel and dragline excavators which can scrape whole counties of Florida clean and send the good stuff where it needs to go.

And that, say Elser & Haygarth, is not sustainable. Staggering amounts of phosphorus are wasted in this postlapsarian economy. The plants we feed phosphorus to are lazy – not strictly the plants' fault, but we've bred cultivars that aren't good at taking up phosphorus themselves or at pairing with bacteria who can do it for them. Phosphorus leaches into lakes, polluting them; it accumulates in landfills and becomes inaccessible; the animals we eat in growing proportions excrete the element uselessly into the environs of their factory farms.

There have been some success stories along the way. Elser & Haygarth point to the late-20th-century campaign against phosphate detergents. Such activism brought Lake Erie, poisoned by suds, back to life – but relentless phosphorus runoff from agricultural uses, far more insidious, threatens to reverse these gains (101). Humans are of course better at dealing with attacks than infiltrations. When we suddenly started pumping detergent into our waterways within a few decades, we could react over a decade or two. But agricultural runoff is re-polluting water at climate-change pace, and by the time we wake up, we may be as doomed as the proverbial frog in the pot.

Elser & Haygarth are not pessimists, though. They imagine a much more recycling-conscious future, where current scales of production are maintained but waste is greatly curtailed. Genetic modification seems to offer the best promise. Both plants and animals can be engineered to use phosphorus more efficiently. Yet here, the green movement is at times its own worst enemy. Genetic change is the essence of life itself, but to suggest helping it along via gene editing provokes an almost faith-based revulsion from the environmentalist left.

Emblematic for the resistance that science runs up against is Enviropig (44). This superhero-sounding creature was designed by Canadian researchers to be able to digest phytate, a somewhat impenetrable phosphorus source that is available to cows and other ruminants but not to pigs (or to us). If Enviropig had taken hold, the efficiency of phosphorus processing would have increased manifold; but note my contrary-to-fact syntax. Fears of a Frankenswine led to the shutting down of Enviropig and the cessation of its gene line. I hope not the slaughtering, but I did not want to delve further into the fate of poor Enviropig.

Phosphorus is a lively, entertaining, and phosphorus-obsessed read that will get any reader more interested in ol' Number 15. It balances bad news with optimism. With scientists as devoted as Elser & Haygarth, perhaps we can think our way out of Asimov's bind after all.

Elser, Jim, and Phil Haygarth. Phosphorus: Past and Future. New York: Oxford University Press, 2021. QD 181 .P1E445