Would you drink water that’s been purified from sewage? Bill Gates did:
“It’s water,” he says. “Having studied the engineering behind it… I would happily drink it every day. It’s that safe.” – Bill Gates
He’s talking about the Omniprocessor in Seattle, USA, which illustrates perfectly the prevalence of chemophobia in our society. The Omniprocessor takes sewage waste and purifies it into clean drinking water. The dried sewage is then combusted to power the plant, producing electricity that can be sold back to the grid. Essentially, it’s a free sewage disposal system that also gives you clean drinking water and a plentiful supply of electricity. Omniprocessors could be a huge income boost for farmers in developing countries.
The plant in Seattle was met with resistance. One study showed that 26% of survey participants were so disgusted by the idea of “toilet-to-tap” that they agreed with the statement: “sewage water could never be purified to such an extent that I would be willing to drink it”. Try it yourself: which glass of water would you rather drink?
If science tells us the purified sewage-water is perfectly clean, then why aren’t people comfortable with drinking it?
Instinct: Once contaminated, always contaminated
Paul Rozin at the University of Pennsylvania provides an explanation. He uses the term “contagion” to describe the perceived, permanent grossness that objects or substances acquire once they have touched something disgusting. No amount of purification can remove the ‘disgust factor’ that’s been acquired by the object. It’s purely psychological, and has no basis in science, but might have evolved as a useful behavioural adaptation that protects us from disease.
Mark Schaller at the University of British Colombia coined the phrase “behavioural immune system” to describe this phenomenon. It includes a suite of feelings and behaviours, including repulsion and disgust, that prevent us from eating contaminated food. It’s overly sensitive, and is at the root of many culinary taboos (e.g. don’t eat pork/prawn/insects).
All of this makes evolutionary sense: for millions of years of human evolution, we had no way of purifying food once it had become contaminated. We had no way of boiling water (and no fire) for 90% of human history. We had no modern medicines for 99% of human history, which made even small illnesses a horrifying, life-threatening prospect. Paranoia about cross-contamination has probably saved our species from extinction.
So why do some people see ‘synthetic chemicals’ as contaminants?
Science teachers are partly to blame. I tell my students never to eat in the lab because we’re fearful of contaminating the student’s food with lab chemicals, which might make them ill. I tell my students never to pour back into the stock solution because we might contaminate the stock solution, ruining future experiments. When an unidentified clear liquid (either pure water or a highly corrosive acid) splashes onto a student’s skin, I tell them to assume it’s the highly corrosive acid and wash immediately with copious amounts of water, just in case. Science teachers inadvertently instil in students a fear that laboratories are highly contaminating places. We do this with the absolute best of intentions.
Paranoia about contamination in laboratories has likely prevented countless accidents worldwide. It’s saved lives and limbs, too, and that’s why teachers must keep emphasising these safety messages. In doing so, however, do need to be mindful of the the unfortunate side-effect of ‘contagion’, which is the gut instinct that foods and lotions (or even water) created in a lab must be contaminated with something nasty. We need to counteract that notion in the following way.
We must emphasise purification techniques in school
When my students made aspirin last week (about 8 tablets’ worth), I told the students we cannot ingest the aspirin because “it’s contaminated: it contains unknown impurities”. Similarly, when we made esters last term (edible artificial flavourings), I told the students not to touch the esters or smell them too closely because they “contain contaminants such as highly corrosive sulfuric acid”. These safety warnings are valid and necessary – they’re actually a legal requirement of my job.
In industry, however, both aspirin and esters (and everything else) would be purified after production to a very high standard (usually 99.99%) before being certified safe for human consumption. Generally, however, high-school chemistry students don’t learn about purification techniques – not even in theory – so for them, the laboratory remains a dangerous place where dirty, contaminated things are created. Inadvertently, that’s become the take-home message from high-school science.
“…for [students], the laboratory remains a dangerous place where dirty, contaminated things are created.”
Purification techniques such as fractional distillation, centrifugation, recrystallisation, affinity purification and liquid-liquid extraction are all beyond the scope of a high-school chemistry course. Water purification and extraction of substances using supercritical carbon dioxide (scCO2) are in the Year 11 textbook, but these topics are not taught by many schools. Students don’t need to know the details – but they do need industrial relevance built into their course, and they need to be made aware that many of the products we use were made or designed in labs. Most importantly, they need to know that these products were purified to a high standard before being put to use.
People go for ‘natural’ products because they try to avoid potential contaminants from the laboratory
After years of hearing these messages in school, it’s no surprise that some people are so averse to eating foods or using products made in a lab. As one of my survey respondents put it so succinctly:
“If I can’t eat in a lab due to fear of contamination, how could food made in lab possibly be safe to eat? If I have been taught to treat every lab chemical that gets onto my skin as potentially corrosive, how could a moisturiser made in a lab from synthetic ingredients ever be good for my skin? This goes against what I’ve been taught throughout school!”
Science education in schools might just be one of the root causes – and one of the solutions – to the widespread prevalence of chemophobia. More next week.
This post is part of a weekly series on chemophobia. Read part 1 here.
James Kennedy 
Seattle, WA USA: Literally, turning $#!+ into sunshine. I have a friend who wrote most of Michigan’s DEQ standard processes for water purification systems in the State (not to be confused with the Flint mess – which creates an interesting problem). Needless to say, I’ve never worried about purified water but we’ve been shown that bureaucratic omissions in reporting can lead to catastrophic problems. Great post.
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