Zombie Pharm: Bugs Bring PPCPs Back From The Dead

Like a water-industry version of The Walking Dead, trace chemicals and pharmaceuticals are given new life when exposed to microbes in the wastewater treatment process.

“The dose makes the poison” is an old axiom referring to toxicity thresholds, and it has stood the test of time and scientific scrutiny. This ‘basic’ concept is also the foundation for the decision to regulate or not regulate. For the most part, pharmaceuticals and personal care products (PPCPs) pass through the water cycle in such small measures, parts per billion (ppb) or trillion (ppt), that toxicologists and regulators have considered them benign. But a new study challenges the notion that trace contaminants can do no harm — at least not when they can be brought back to life.(!)

Benjamin Blair, a postdoctoral fellow at the University of Colorado Denver, has discovered that the microbes used during biological wastewater treatment are reanimating Frankenstein’s monster — taking the elements of broken-down pharmaceuticals and making them whole again. As a result, some PPCP levels are higher coming out of the wastewater treatment plant than they were going in.

The phenomenon, as reported by Environmental Health News, was recently discovered at the South Shore Water Reclamation Facility near Milwaukee, WI. Similar findings were recorded years before in Ontario, Canada, according to the article, but were attributed to sampling errors. This new evidence suggests that the initial Ontario data was true, and also that the reconstruction of pharmaceuticals could take place in the natural environment following effluent discharge.

Now that the existence of “zombie” PPCPs has seemingly been confirmed, should it change what some might call a nonchalant approach to trace contaminants among regulators?

More research needs to be done to determine exactly how and why the strange occurrence takes place. It was only triggered in two out of 48 pharmaceuticals that were successfully tracked at the Wisconsin plant — those being carbamazepine (an anti-epileptic drug) and ofloxacin (an antibiotic). It should also be noted that the higher, post-treatment levels were far below the toxicity threshold for humans. Still, the discovery adds a new layer of concern for an increasingly worrisome issue.

Chemical Concerns

While “the dose makes the poison” axiom holds true for individual constituents, the cumulative effect of the more than 70,000 PPCPs manufactured in the U.S. remains unresolved. However, if fish can be considered a “canary in the coalmine” — harbingers of dangerous side-effects — then the accounts of gender-altered species in PPCP-laden waters and fish with cancer are disturbing.

In the absence of a scientific consensus linking cause and effect, and with plenty of debate over impact and accountability in the public sphere (the typical wrangling common to industrial/environmental issues), there is at least enough common ground, and alarm, to result in a bipartisan chemical safety bill in Congress.

The rare political cooperation may be due to the fact that there is little comfort in the details that we actually know for sure. We know that there are scores of unmonitored chemicals produced, and we know that many slip past wastewater treatment plants, into our environment, and likely back into drinking water.

It doesn't portend a zombie apocalypse, but the chemicals in our water can certainly be scary.