Flush by Bryn Nelson
Written March 10th, 2025 for History of Technology 2901 taught by Dr. Peter Denton at the University of Winnipeg.
Bryn Nelson’s book Flush: The Remarkable Science of an Unlikely Treasure, is as interesting as it momentarily grotesque. This comes with the territory as Bryn discusses several ways to use human feces as a useless tool rather than simply a human biproduct. Nelson makes an array of arguments which establishes his overall idea that we need to reassess our perspective of human waste. The frequent use of humour in the initial chapters makes the ideas more approachable than they may have been had they been presented in a dry, matter of fact way.
While Nelson is a microbiologist by profession he makes complicated matters palatable for common readers, an important feature when describing these often complex ideas. Nelson narrates his own learning as he writes, describing himself meeting experts in the field and being taught their methods throughout the book which allows the reader a seat at the table with impactful, forward-thinking people. The concepts described are at times complicated and without a background in science it can be difficult to grasp the potential for such developments as are discussed in his book. By breaking down these complicated matters into digestible chapters Nelson has created an accessible way for readers to think differently about how we handle our waste, how we can better insulate our communities against the spread of disease, and how we can mitigate the destruction of the environment as a result of human made chemicals and practices which poison our waterways and destroy ecosystems.
Chapter Three
Nelson states the obvious here: Human poop is inherently disgusting. Despite this, it has unique qualities which make it an irreplicable medical asset for fecal microbiota transplants, FMTs. Heavy regulations pertaining to FMT donation make it inherently difficult to work with and creating a reliable dosage system can often times be a complicated headache. Each person’s excrement is different than the next. What we eat, our genetics, our lifestyle choices all impact the viability of our excrement from being a priceless medical resource or just another pile of crap.
When a viable candidate is selected to donate their poop for medical purposes their waste is used to essentially reseed the intestinal tract of a compromised individual. While it may seem off putting at a glance, FMTs have a tremendous high rate of success. Centuries of medical research and innovation have brought us medicines bordering on magic, but there is nothing that compares to a human stool sample when it comes to managing cases of C. diff infections or other bacterial imbalances in an individuals gut which can lead to substantial harm for the affected person. A Dutch study once found a success rate of 94 per cent against C. diff using FMT versus the traditional medication referred to as “the antibiotic of last resort” which had a success rate of 31 per cent in that study.1
Despite this success, FMTs are still highly contested and regulations often complicate the process because of the inherent fear of inserting feces from one person into another. Physicians were often more repulsed by the idea than patients themselves, while data indicates it is a valid and effective means of overcoming otherwise arduous gut related ailments.
The argument of effectiveness that Nelson puts forward for FMTs is persuasive and to a certain degree undeniable. There is no substitute for the authentic microbiome of a human being or their feces. Nelson describes how stringent the process is when it comes to deciding whether individuals are capable of donating their own samples. With such a tight leash on who is eligible to donate stool samples, it is difficult to argue against the practice. This is no longer a shoot from the hip situation. Those who are willing to donate are few and those who are accepted are even 1Bryn Nelson, Flush (Grand Central Publishing, 2022), 55. fewer. Nelson refers to several published studies on the effectiveness of FMTs and at the very least opens the mental door to further consider the practical application of using feces as a micro bacterial instigator in affected individuals.
Chapter Five
What was found by researchers at the time of the COVID-19 pandemic, and has since been well documented, is the most effective way to restrict a highly contagious virus is to trace the excrement of communities in order to identify the presence of the virus among otherwise asymptomatic individuals. COVID outbreaks were not recognized until large segments of communities, dormitories, or other high population areas displayed indications they had been infected. By collectively examining the excrement of groups of people in precise locations, the illness could be identified as being present before a massive outbreak occurred. By identifying that the infection existed in sewage waste, dormant cases of COVID could be rooted out before more people were infected.
What made COVID-19 such a rampant illness was the segment of the population whose showed no symptoms of the virus but were capable of spreading it. If Joe Citizen is asymptomatic but the sewage channel his waste goes through is identified as being contaminated with COVID, everyone in his dormitory can be tested for the virus, and Joe Citizen can be isolated after having tested positive. Without this preventative step, as we saw on countless occasions, mass infection of a large population will occur.
This practice brought to mind such a practice being used in a halfway house to identify whether or not individuals within are consuming illegal substances is also intriguing. Nelson described remnants of narcotics to be traceable in fecal matter and a rigorous testing system could identify when such narcotics enter the sewage system. The cost/benefit of such a system may make it too costly to implement but the consideration that substances can be identified accordingly is at the very least interesting, if not slightly concerning. We as individuals are entitled to consent to whether or not our body is measured and examined, but it can be argued a social contract exists when our excrement is evacuated from our property into a publicly funded sewage system.
When considering the value of testing communal waste to determine the bacterial contents developing nations requiring medical aid are key beneficiaries. If an organization is giving medical assistance to a community which cannot afford to sustain hospitals and doctors an investigation of the communal waste is a proactive way of determining on a large scale what viruses may be rampant in the community. Nelson describes throughout his book the complex and detailed data about an individual which is stored in fecal matter. By understanding the general health of a community one has a clearer resolution for what broad issues require immediate attention. Nelson describes the value of such practices in remote instances but the practice of examining communal sewers for viruses is broadly applicability.
Chapter Eleven
Chapter 11, Balm, takes a close look at the impact of human activity on the environment, how to curb the damage we have caused, and what we can continue to do to actively repair the ecosystems we have harmed since the beginning of the industrial revolution more than 100 years ago. The primary target of this chapter is sustainable farming, how we do it in the West, and what we can learn from Indigenous practices and those in Cuba who were forced to remodel their farming practices in the shadow of the US embargo set in the 1960s.
The chapter begins discussing the flourishing Cuban coral reefs which have been able to regrow like nowhere else in the world as a direct result of the Cuba embargo set against the island nation during the Cold War. When the Soviet Union fell Cuba was no longer on the receiving end of large quantities of gasoline, synthetic fertilizer and other harmful manmade chemicals which drastically alter aquatic ecosystems when they runoff into bodies of water. The lack of industrial ships coming through the area reduced the waste discharged by the ships and the ecological disturbances they create, allowing the region to flourish. The lack of manmade chemicals forced Cuban farmers to adapt to farming more organically. Nature, as it turns out, is stocked full of fertilizers if we know what we’re looking for.
The argument Nelson makes here is compelling and interesting. It rings similar to chapter three in that there is an organic option we need to consider implementing on a large scale in the farming industry. Agriculture and medicine are both based on naturally occurring ecosystems and growth patterns which we have replaced with lab made chemicals. The fallacy of being better off by swapping the terrestrial for the test tube has created unsustainable methods of caring for ourselves and the land.
Throughout this chapter Nelson provides examples of instances where the initiative to revitalize the natural order of ecosystems and alter industrial practices having real effects on the stability, health and longevity of a region. He describes the Sechelt Mine in British Columbia which has taken to countering the harms of residual dust, called fines, by using the fines as part of a biomass recipe to create healthy, sustainable fertilizer for poplar plantations.2 From this he describes Salish Soils, a company which focuses on creating natural compost from industry 2Nelson, 276-277. waste such as fish guts from a salmon fishery and even human biosolids. These examples of utilizing what would otherwise be waste, left for the land fill, paints a wonderful picture of what sort of impactful change is occurring in western society and what sort of expectations we as citizens should begin having for our government policies and local industries.
This point brought to mind the restaurant and grocery industries. Restaurants in the Western world waste untold millions of dollars and pounds worth of food every year as a result of unfinished plates, and spoiled and unappealing products. These industries also create literal tons of plastic waste as nearly every product sold in grocery stores or restaurants arrives in single use plastic packaging. In some small towns in Canada local grocers make deals that any food which has expired can be given away to farmers under the written promise none of the food will be consumed by humans. This system creates a cost relief for local farmers while also preventing landfill waste on behalf of the grocer. This practice is not mentioned by Nelson specifically but is in the same line of thinking about how we can intelligently use our waste.
This chapter lays into the idea that we are part of the ecosystem, something easily forgotten in cities. We therefore have a responsibility to help sustain this very ecosystem we exist within or will suffer the consequences of our inaction. As the ecosystem becomes poisoned by our collective unwillingness to adjust the practices of our agricultural and industrial enterprises, we will continue to poison the land, the water and ultimately ourselves. The basis of Western industry is not sustainability, rather it is maximizing profit potential. Changing this mindset is a large part of what Nelson writes throughout this book, but chapter 11 really digs into the idea while exploring the collective benefit of reconsidering our place in the natural world and our reliance on the stability of our environment.
Nelson’s book is as important as it is well written. He describes industries and practices that most people do not personally engage with yet are still impacted by directly. By writing a series of stories about situations and experts the way Nelson has he creates a single narrative from many voices. We as a society have much to gain from reconsidering how we clean up after ourselves and what we do with the waste we create. The natural response to feces is repulsion, understandably so, but in the modern era we have the information available to make better use of our waste, human, industrial and otherwise.