Research Could Lead To Cheaper, Better Testing For 'Forever Chemicals' In US Drinking Water

Lawrence — A new investigation from the University of Kansas improves detection of PFAS, a family of so-called “forever chemicals” in drinking water supplies. The method, which can measure trace pollution levels of PFAS in water more quickly and inexpensively than current techniques, recently was detailed in the open-source journal PLOS Water.

PFAS chemicals, marketed for decades in products like nonstick cookware and fire- and stain-resistant fabrics, linger in the environment and the human body, and they can cause cancers, immune system problems and developmental issues.

“These are man-made synthetic chemicals that contain poly- or perfluorinated carbons,” said study co-author Michael Zhuo Wang, professor of pharmaceutical chemistry at the University of Kansas. “They’re used in industry to make products like Teflon, anti-water coatings and firefighting foams. They have wide industrial applications. The problem is they don’t break down very easily in the environment.”

Wang said these chemicals stay in the environment, move around in soil and water, and eventually end up in drinking water.

“Our body can absorb these compounds into the blood and tissues, and we don’t have the capacity to break them down either,” he said. “So, they accumulate in the body. Some studies show half-lives in the range of five to eight years in blood. More and more epidemiological studies suggest they may be associated with health issues, including developmental issues and certain cancers. Kidney cancer and testicular cancer in men are two that have been mentioned in recent studies.”

Because of these serious health concerns, there’s a move among U.S. lawmakers to tighten regulations of PFAS in drinking water. However, to comply, private and municipal labs will need to be able to economically and effectively detect PFAS compounds in ultra-trace amounts.

“The current EPA regulation limits some PFAS in drinking water to about 4 parts per trillion. Depending on the compound, regulated levels range roughly from 4 to 10 parts per trillion,” Wang said. “They also have maximum contaminant level goals, which suggest ideally there should be zero. So, the target is essentially no detectable PFAS.”

Yet to determine whether PFAS are below the 4 parts-per-trillion level, labs need extremely sensitive tests beyond what’s capable at typical labs that analyze municipal drinking water.

“The biggest challenge is sensitivity — how to go down to sub-part-per-trillion levels. Detecting PFAS at this low level is like finding a few grains of sand in an Olympic-size swimming pool,” Wang said. “The most sensitive instrument is LC-MS (liquid chromatography-mass spectrometry). But without sample pre-concentration, it only reaches parts per billion, which is about a thousand times higher than the parts-per-trillion level.”

The KU researcher said current EPA methods require concentrating the water sample first, a time-consuming process.

“Typically, you start with 500 milliliters of water and use solid phase extraction to concentrate it before analysis,” Wang said. “That concentration step is what drives time and cost. It requires large sample volumes, and the process is slow.”

The KU researcher and his lab members, doctoral student Deepak Timalsina, who served as lead author of the study, and co-author Bhargavi Srija Ramisetty, a recent doctoral student, sought to develop more practical, economic and time-saving approaches to detecting PFAS that are accurate and scalable.

To do so, they combined fast-flow solid-phase extraction (SPE) for concentrating PFAS from water samples with UPLC-MS/MS (Ultra Performance Liquid Chromatography–Tandem Mass Spectrometry) for very sensitive chemical analysis.

“The biggest improvement in our method is time reduction in sample concentration,” he said. “We reduced the time from hours to minutes. For a 500 milliliter sample, it used to take about 100 minutes to load. Now it takes about 6 to 8 minutes, about a 20-fold reduction. To push detection even lower, you need larger volumes — up to 4 liters instead of 500 milliliters. That’s an eightfold increase in volume.”

With the original method, the same process would take about eight times longer, more than a half-day just for loading sample onto SPE cartridge.

“With the fast-flow approach, we can do that in about 60 minutes,” Wang said.

In addition to cutting the time involved in preparing samples, the KU process for fast-flow solid-phase extraction slashes the price of PFAS analysis.

“What worried me most is the cost of current methods,” Wang said. “Today, each sample can cost at least $400 to $500 for analysis in the marketplace. That’s too expensive to fully implement EPA regulations across all water treatment plants. The goal is to reduce that cost so water bills don’t increase significantly due to monitoring requirements.”

One impediment to broader, more rigorous PFAS sampling is the complexity and expense of sending heavy volumes of water from drinking-water processing plants to testing labs.

“One challenge is logistics, shipping large water samples from the field to labs,” Wang said. “Samples can be 500 milliliters or even 4 liters. That’s heavy and inconvenient to transport.”

To address the problem, today Wang’s team is collaborating with InnovaPrep, a company based at KU Innovation Park with funding from an NIH Small Business Technology Transfer grant.

“The idea is to develop a concentrating device, like a pipette-based system, that absorbs PFAS from water,” Wang said. “Instead of shipping large water volumes, you would ship a small, pencil-sized device to the lab. That would greatly reduce shipping cost and complexity.”

Wang said currently it’s too expensive to fully implement EPA regulations across all water treatment plants. He believes the expense of shipping and testing will continue to be a chief hurdle to detecting PFAS compounds.

“Our goal is to reduce that cost so water bills don’t increase significantly due to monitoring requirements,” he said.