Monday numbers: A closer look at 1,4-Dioxane levels in the Cape Fear

Levels of 1,4-Dioxane, which the EPA has linked to cancer, increased for a fourth straight month in raw water entering the Cape Fear River Authority’s Sweeney plant in Wilmington, according to the utility.

Although the plant’s advanced treatment techniques, including granulated activated charcoal, remove much of the chemical, the amount in finished water also increased to levels above the EPA’s health advisory goal of 0.35 parts per trillion. 

The concentration was 0.54 ppt on July 2, according to CPFUA, which announced the results last week.

There is no enforceable EPA or state drinking water standard for 1,4-Dioxane.

Monthly sampling usually occurs at the beginning of each month.

The chemical is used by the pharmaceutical and plastics industries. Pinpointing the contaminant source is difficult, because many manufacturers discharge into the Cape Fear River, the drinking water supply for most of Wilmington. 

The headwaters of the Cape Fear begin more than 100 miles upstream, at the Haw River in Reidsville, in Rockingham County, one of the 1,4-Dioxane hotspots, according to DEQ sampling from 2014-2016. Other areas in the Cape Fear River Basin with elevated results include McCleansville (Guilford County), Asheboro (Randolph County) and Bynum (Chatham County).

DEQ studies conducted in 2018 showed that high levels of the chemical also were found in Randleman Lake, which spans Guilford and Randolph County. 

Another waterbody, Buckhorn Reservoir, the drinking water supply for Wilson, also had elevated levels. The reservoir is in the Neuse River Basin.

According to the EPA’s Toxics Release Inventory, there are four known dischargers of 1,4-Dioxane in North Carolina: DAK Americas in Fayetteville, Invista in Wilmington, and Starpet in Asheboro — all in the Cape Fear River Basin.

The fourth facility is CNA Holdings in Cleveland County.

However, since TRI information is voluntarily self-reported, there are likely data gaps.

1,4-Dioxane (parts per billion)

0.35  — EPA health advisory goal for drinking water

2.2  — Level, pre-treated water, July 1

0.54   — In finished water

1.5 — Level, pre-treated water, June 3

0.35 — In finished water

GenX, July 2 results (parts per trillion)

8.61 parts per trillion— Level, finished water

42 — Level on Jan 22, 2018, the highest level since testing began

70 — State health advisory goal for drinking water

Perfluorinated compounds, July 2 results (parts per trillion)

70 — EPA health advisory goal for drinking water, PFOA and PFOS combined

3.67 — Combined level of PFOA and PFOS, finished water

300 — Total level of all perfluorinated compounds, pre-treated water

116 — Total, finished water

10 — DEQ maximum recommended level of any individual perfluorinated compound in drinking water

11.9 – 22.6 — Range in levels of compounds above the DEQ recommendation

4— Number of compounds that exceeded 10ppt in drinking water

41 — Number of compounds tested for

27 — Number of compounds that were non-detects

14 — Number that were hits