Thursday, February 29, 2024

After 1,4-Dioxane spike, CFPUA asks state environmental agency for assistance

Concentrations of 1,4-Dioxane, a likely human carcinogen, have been detected at increasing levels in both finished and raw water tested at Cape Fear Public Utility Authority since June. (Port City Daily graphic/Courtesy CFPUA)

NEW HANOVER COUNTY — Levels of 1,4-Dioxane in treated Cape Fear Public Utility drinking water tested earlier this month are 3.7 times higher than the federally-recommended lifetime one in a million cancer rate.

1,4-Dioxane does not have a maximum contaminant level and remains mostly unregulated (the state recently required testing, but cannot yet set limits as the Environmental Protection Agency has not set its own).

Related: Concentration of 1,4-dioxane detected in water highest at Sweeney Treatment since 2015

The compound is used as a solvent in various industrial capacities, is a byproduct of the thermoplastic polymer resin PET, and can be found in a number of household products including shampoos and detergents.

The Environmental Protection Agency (EPA) established a risk assessment level for 1,4-Dioxane of 0.35 parts per billion (ppb) in 2013. This level represents the cancer risk level for one individual out of one million after a lifetime of drinking water containing the compound. The EPA describes 1,4-Dioxane as a likely human carcinogen that does not biodegrade.

In July, Cape Fear Public Utility Authority (CFPUA) shared 1,4-Dioxane was detected in finished drinking water at 0.54 ppb — the highest it has observed since 2015. This month’s results from samples collected on Sept. 9 show finished levels at 1.3 ppb, with raw water detected at a far higher magnitude compared to other readings this summer, at 6.3 ppb.


In July, the Department of Environmental Quality (DEQ) began requiring publicly-owned wastewater treatment facilities in the Cape Fear River basin to perform investigative monitoring of 1,4-Dioxane and total PFAS for three consecutive months. The DEQ has identified wastewater facilities as a potential conduit for releasing high concentrations of 1,4-Dioxane through the wastewater treatment processes. However, these facilities are not believed to be the original source of the compound.

Since 2014, the DEQ has monitored 1,4-Dioxane in the Cape Fear River basin. In May 2015, the DEQ collected sufficient data to establish monitoring stations where 1,4-Dioxane levels were elevated. This included a station located just below the Cape Fear Region’s raw water intake source at Kings Bluff.

Between October 2014 and September 2015, 1,4-Dioxane levels at this station reached as high as 31 times the EPA’s drinking water risk level, at an average of 11 times over the level, at 4 ppb. Over that time frame, the compound was detected at alarming rates upstream, as high as 1,030 ppb in Reidsville. No federally-recommended surface water levels for the compound have been determined.

According to a CFPUA news release Tuesday, the utility’s monitoring “has usually shown” 1,4-Dioxane in concentrations below the EPA’s drinking water risk level.

CFPUA upgrades

Though CFPUA approved a $107 million bond package to fund infrastructure upgrades, including adding new Granular Activated Carbon(GAC) filters, this investment won’t immediately result in a reduction of 1,4-Dioxane levels.

1,4-Dioxane is removed by CFPUA due to biofilm, which are microorganisms which clings onto compounds. Biofilm builds up over time on CFPUA’s existing filters and can reduce 1,4-Dioxane concentrations at a 67% removal rate, according to a 2015 N.C. State estimation.

According to Vaughn Hagerty, CFPUA’s spokesperson, it will take time for biofilm to grow on newly-replaced GAC filters.

CFPUA’s release on the Sept. 9 results credit to the utility’s existing technology which makes the Sweeney Water Treatment Plant “one of the few water utilities in North Carolina able to significantly reduce 1,4-dioxane in water.”

Send tips and comments to Johanna Ferebee at

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