Climate Change and The Problem with Nephrology

Classically, nephrology isn’t about much more than problems of water and salt. The FFS part of nephrology is not so different than any other subspecialty. Except…

Dialysis. Let’s face it, dialysis is what separates nephrology from the rest. This is about dialysis for end-stage renal disease (ESRD) (also known as end-stage kidney disease (ESKD)).

There are currently about 808,000 persons in the US with ESRD, 69% of whom (~557,000) are on dialysis: 89% (719,000) on hem (HD), and 11% (89,000) on peritoneal (PD).

The average HD treatment is 4 hours, and with 3 treatments weekly, that’s 156 treatments. The flow rate of dialysis solution through the artificial kidney (AK) is about 400 ml/min (sometimes higher, in the recent past typically up to 600 ml/min). Before that solution gets to the AK, it goes through a series of purification steps, almost always including reverse osmosis, with an average rejection rate of 90%. That amounts to about 5,241,600,000,000 liters (L) of water per year for treatments. Add another liter of saline per treatment to prime the blood lines and dialyzer, and support BP during the treatment. That’s another 54,600,000 L/year, for a total of 5,241,654,600,000 L/year. But that is after the 90% rejection rate by RO, so multiply by 10, and our national water usage for HD is about 52,416,546,000,000 L/year. (This is more than four times the volume of Lake Superior! —and it doesn’t count hand washing—is anybody still washing hands?) The 90% of RO rejection water goes down the drain, although it is purer than anything that comes out of the taps from which we drink and bathe, even if we have the most efficient water filters in our homes (even home versions of RO), because of the earlier steps in the water purification process for HD. It is the purest of grey water, but it goes down the drain as wastewater.

PD is more efficient with respect to water usage. For those 62,000 patients, at about 10 L/treatment, 7 days/week, that’s about 225,680,000 L/year. Still a lot of water, but much more efficient.  

Then there’s the plastic. AKs are simple looking, but complex devices made from clever plastic and cellulosic compounds. At least 3 meters of plastic tubing are used for each treatment, not counting the plastic tubing and bags for saline, plus miscellaneous injectables (heparin, erythropoiesis-stimulating drugs, etc.). Costs or weights for this material are difficult to uncover. But the bottom line is it is all single-use, disposable, and has to find its way somewhere, to biohazard incinerators, or landfills, trash dumps, ending up as particulates in every breath we take, or nanoparticles in our beaches, oceans, everywhere we go, in everything we eat, and found in every organ of every species where we have looked.

So, water and plastic are the real paradigms of nephrology practice when we consider environmental impact, and they present monumental challenges to environmental stability. The challenges are incrementally subtle, but dangerous in the aggregate. Solutions are tough to concoct. Both of these problems are Gordian knots, and there is no sword of Alexander likely to split them in twain, not any time soon. Biodegradable “plastics” for this application are probably a chimera, and different technologies altogether will have to be brought to bear to solve this one.  

Regarding preservation and reclamation of water, I have personally discussed this issue with the chief engineer of Davita, one of the US two largest dialysis providers. He is sensitive to the problem, but says it is cost-prohibitive for the company alone, and really belongs to cities that provide the water. One might contend this is a matter for negotiation. In any case, one might envisage a cooperative arrangement between dialysis providers, water suppliers, cities and other interested private parties to reclaim grey water. It might even be looped back into the dialysis facilities’ own purification systems at night, while patients are not being treated, and sent back into the world afresh in the morning.

In an ideal future, no one will need dialysis. We will create new ways to protect the lives of our patients. Porcine xenotransplantation is on the near horizon, and there is no shortage of donors—although that presents its own challenges, both environmental and humane. The progress on implantable bioartificial kidneys has been slower, and is not yet at the human testing stage, but might present a more ecologically friendly alternative. Until then…  


Note: The views expressed in this article are the author’s own and do not necessarily represent the views of ACOI.