Scientists from the Chinese Academy of Sciences in Beijing have made an alarming discovery: After surveying parks across seven Chinese cities, they found that those watered with recycled waste water had higher counts of microbe genes for antibiotic-resistance than parks watered with fresh water. In fact, the antibiotic-resistance gene (ARG) levels were up to 8,655 times higher.
While measuring antibiotic-resistance genes is not the same as measuring the microbes themselves, it is an indicator of the microbes’ presence. The study’s abstract notes that “147 ARGs encoding for resistance to a broad-spectrum of antibiotics were detected among all park soil samples.” The resistance genes that were measured were also chiefly in defense of antibiotics used on humans. The study demonstrates the possibility that microbes, ARGs and antibiotics themselves could survive the water treatment process. The danger is that they could be spread back into the community via the high-use public spaces where we love to gather.
It’s worth noting though that the study only occurred in China, so it can’t be taken to reflect other countries’ reclaimed water since treatment systems and antibiotic consumption vary from country to country. It does give pause for thought, however, and indicates that further international studies should be undertaken to determine if the findings are replicated elsewhere. As drought bites deeply into many regions, reclaimed water is a natural solution for irrigating public spaces. But if reclaimed water could lead to a public health crisis through multiplying antibiotic-resistant germs, then stronger safeguards will need to be put in place.