New research revealed higher past levels of PFAS. What does that mean for current – and future – water quality?

WILMINGTON — A recent study showed that earlier estimates of combined PFAS levels in the Cape Fear River were off by orders of magnitude; levels were likely nearly two hundred times the average level reported earlier. But what does that mean for current water quality levels — and future testing?

It’s important to note the study doesn’t mean current levels have also increased. Chemours, the major producer of GenX and other specific PFAS that are dumped into the Cape Fear River from the Fayetteville Works facility, was forced in 2017 to implement mitigation efforts. Since then, PFAS levels have been lower. But spikes continue and, generally, researchers continue to find new chemicals in the water.

Related: Taking a look at the latest PFAS levels in CFPUA drinking water from Sweeney Treatment Plant

The initial study of PFAS in the Cape Fear River — the one the brought widespread attention to GenX, and then other chemicals — was conducted between 2013 and 2015 by Detlef Knappe and others. That study put the mean level of PFAS in the Cape Fear River by Lock and Dam 1 at around 710 nanograms per liter (ng/L), also knows as parts per trillion. This is the raw water that the Lower Cape Fear Water and Sewer Authority, CFPUA, Brunswick County, and Pender County all use (you can find CFPUA’s full response to the new findings here).

Known unknowns

However, when the initial study was conducted, there were only “analytical standards” for some, but not every one of, the PFAS chemicals. Without going into the technical specifics, this essentially means the exact quantity of certain PFAS chemicals wasn’t know, so estimates were used to round out a study of a larger number of total chemicals.

The initial study knew which chemicals it was looking for, but didn’t have the ability to measure each one individually. Since then, researchers have developed an “expanded suite of fluoroether standards,” according to Knappe. In other words, researchers can directly measure the amount of each PFAS in the suite instead of estimating them.

Knappe and his team had saved water samples from 2014 and 2015 and, when they went back and retested them, found that estimations had been low. Way too low.

More accurate testing, higher levels

The maximum estimated total of PFAS in the original study was 4,696 ng/L and the average was 710 ng/L. When the team measured each ether, the total was around 130,000 ng/L for the Lock and Dam 1 water (and around 1,000,000 ng/L close to DuPont and Chemours’ Fayetteville Works location).

According to Knappe, the major contributor to this total were PFMOAA at around 110,000 ng/L. While GenX levels have dropped since Chemours began mitigating its outflow, PFMOAA (Perfluoro-2-methoxyacetic acid) is still present in higher levels in the water; recently, it was responsible for major spikes in PFAS levels noted by Brunswick County over the summer. State regulators have identified PFMOAA as originating at Chemours’ plant, according to the Cape Fear Public Utility Authority (CFPUA).

Other contributors include PFO2HxA (7,800 ng/L) and PFO3OA (6,300 ng/L) — both which occurred at higher levels than the earlier estimated maximum total PFAS level.

Knappe also noted that, perhaps oddly, levels of the Nafion byproduct 2 “seemed low,” perhaps “because the Nafion process was not operating at Chemours at the time of sample collection or because Nafion byproduct 2 slowly degraded during sample storage.” Knappe noted that the other chemicals seemed highly persistent.

So, what does this mean for our current water quality situation?

Unknown unknowns