Return human waste to the soil is a key sustainability practice. But it has to be done properly if it's not to spread pathogens. If you're doing composting toilets, use care.
On the surface of their bodies, the Romans appear to have hosted fleas, bedbugs and three varieties of lice. Excavation of a site in York, England, showed that despite all the time they spent in public baths, "the Romans had just as many body lice and fleas as the Vikings, who are regarded as fairly smelly, unclean people," Mitchell says.
The load of pests likely affected Roman health....
With all their body oils and bath rituals, Mitchell says, "they would have smelled clean, but they would have had infectious disease nonetheless."
He thinks the Romans' unexpected infestations might have been because of a major flaw in their cleanliness habits. Human waste hauled out of town was sometimes dumped onto food crops. Waste collectors called stercorarii would haul solid waste out of town and sell it to farmers as fertilizer. Without prolonged composting, Mitchell explains, parasite eggs could have gotten onto the plants and later reinfected the people who ate them, possibly canceling out the benefits of the Romans' more hygienic practices.