Would you eat food grown on human poo? UvA students investigated
What do people actually think about growing food on human poo? Undergraduate students from the bachelor Computational Social Science studied it. In doing so, they found differences between cultures and men and women. “Human manure is the future.”
Worldwide, humans produce a billion tonnes of poo a year. But the vast majority is still uselessly flushed down the toilet. And that while it could be used as a valuable resource to grow food on. But are people willing to eat food grown on human faeces? Undergraduate Computational Social Science students researched exactly this and recently published their results in Waste Management Bulletin.
Yuck factor
One of the reasons human manure is being investigated is because it could be a sustainable alternative to animal manure and artificial fertilisers. The production of these common soil enrichers releases greenhouse gases and uses fossil fuels.
The Netherlands is already experimenting with human manure on a small scale. For instance, there are several circular housing communities that compost their faeces for their vegetable garden. There are also companies that capture human faeces from portable toilets and convert it into odourless manure, resembling coffee grounds, through a complicated processing process. The idea of unpleasant odours being spread on farmland evokes a sense of disgust in most people. The ‘yuck factor’ the researchers call it. But large-scale research into the acceptance of human manure was still lacking, noted Markus Knell (23), one of the students involved in the study.
Japan and England
Knell investigated perceptions on human manure with four other students under the guidance of assistant professor Steve Pickering. Based on interviews they conducted in Noord-Holland, the students developed a survey. Due to lack of funding in the Netherlands, the survey was conducted elsewhere. “In England and Japan, I still had funding to do research,” Pickering says. “In addition, both countries have similar economies and a long democratic history which makes them comparable in the final analysis.”
The students found major differences between the two countries. For example, Japanese were more open to eating food grown using human manure but were reluctant when it came to using it in public parks. For the English, the exact opposite was true: they were more concerned about health risks related to the presence of traces of medicines, drugs or other harmful substances. In addition to the differences between the two countries, the students also found differences in perceptions between men and women. Japanese men generally seemed most positive about the use of human manure. English women were more often reluctant.
Difference in history
The students have not yet found a good explanation for these differences. They suspect it has something to do with the history of human manure use in both countries. “What not many people know is that the use of human faeces in agriculture was once the most normal thing,” Knell explains. “Around the industrialisation of Europe, we stopped using it. Many people moved to cities where there was no functioning sewerage system at that time. As a result, people in London, for instance, had to deal with “The Great stink of London” in 1858. This was simultaneously accompanied by the outbreak of diseases such as cholera, which made people link the use of human manure to diseases and poor hygiene. In Japan, the situation is different. Around 1950, human manure was still occasionally used, so it is still considered a possibility today.
Knell and Pickering hope to carry out the research in the Netherlands one day. “Interviews with people from Noord-Holland showed that they were generally very supportive of the use of human manure,” says Knell. “I’m curious to see what that’s like in the rest of the Netherlands, though.”
In any case, the researchers are convinced. “Human manure is the future! As long as it can be done safely and the food tastes good, why not?” continues Pickering. “But before fruit and vegetables will be grown on human manure, a lot has to happen. Besides changing public opinion, the biggest challenge is in logistics. Ideally, you want to collect urine and the rest of your faeces separately. How will you manage that with the current sewerage system? And how do you make sure traces of medicine, drugs and other harmful substances are rendered harmless? That is all a matter of research and time.”
