Twenty types of perfluorinated compounds, commonly known as PFAS, were detected in compost produced at the McGill facility in Sampson County, but the sources of the contamination have not been identified.
The North Carolina Department of Environmental Quality sampled the compost, as well as wastewater residuals — sludge — from DAK Americas, a plastics manufacturing plant, after a Policy Watch investigation found high levels of a different toxic compound, 1,4-Dioxane, in the sludge entering the McGill facility.
In the most recent tests, high levels of 1,4-Dioxane were detected in the DAK sludge, but none was found in the compost, according to DEQ.
However, a wide range of PFAS were detected in the compost. Of the 33 types of PFAS sampled for, 20 were detected, with concentrations as high as 54.8 parts per trillion. (Scroll to bottom of story for a chart of the results.)
North Carolina has adopted the EPA’s voluntary drinking water advisory of 70 parts per trillion for PFOA and PFOS combined. The state has also recommended that people shouldn’t drink water containing more than 10 ppt of any single perfluorinated compound.
There is no state or federal standard for PFAS in compost and sludge.
The EPA doesn’t regulate PFAS individually — there are an estimated 4,700 — or as a class, although several states have passed their own legally enforceable contaminant limits.
Exposure to PFAS has been linked to a variety of health disorders: a depressed immune response, thyroid disease, high cholesterol, high blood pressure during pregnancy — known as preeclampsia — hormonal disruption, developmental problems, and even cancer.
At a US House subcommittee on PFAS hearing earlier this month, Jamie DeWitt, a toxicologist from East Carolina University, told lawmakers the compounds should be regulated as a whole. “PFAS don’t break down and they like water. PFAS move, they’re persistent, and they’re toxic.”
McGill receives a variety of materials that are turned into compost: peanut shells, animal bedding, chicken manure, swine waste and sludge from municipal wastewater treatment plants, as well as DAK. This makes it difficult to pinpoint the source of the contamination.
Wastewater can be contaminated by industrial processes, but also by polluted rivers and lakes. In a vicious cycle, water treatment plants withdraw contaminated water from rivers and streams. PFAS can’t be removed through traditional treatment, so they are present in water flowing from the tap. In turn, that contaminated water — through faucets, dishwashers, toilets — goes to the wastewater treatment plant, which also can’t remove it without special equipment.
The US Composting Council knows PFAS is a problem for the industry. Earlier this year a council spokeswoman told Policy Watch that the industry is urging the EPA to regulate perfluorinated compounds, especially in material being shipped to compost facilities.
The state’s compost rules are up for readoption this year by the Environmental Management Commission. Draft rules don’t require that compost facilities test for PFAS and 1,4-Dioxane. However, public comment could influence the final rule language. The public comment period begins June 17.
1,4-Dioxane: High in wet sludge, absent in compost
DEQ samples also showed wet sludge from DAK contained 1,4-Dioxane levels as high as 138,000 parts per billion. 1,4-Dioxane clings to water, which could explain why concentrations were elevated in wet sludge, which had a moisture content of 97 percent. A second sludge sample, which contained 94 percent moisture, had lower levels of 1,4-Dioxane: 37,800 ppb.
No 1,4-Dioxane was detected in dried sludge or in the McGill compost.
The EPA classifies 1,4-Dioxane as a likely carcinogen, but doesn’t regulate it.
DEQ’s findings are similar to those revealed in a Policy Watch investigation earlier this year. The investigation, published in April, found that one sample taken from a seven-ton shipment of sludge from DAK to McGill contained 20,400 parts per billion of 1,4-Dioxane. Policy Watch also tested compost for 1,4-Dioxane; none was detected.
After Policy Watch alerted DEQ to the sampling results, environmental regulators conducted their own independent sampling of the compost and the sludge.
1,4-Dioxane is produced as a byproduct of manufacturing processes, including plastics. DAK legally discharges 1,4-Dioxane into the Cape Fear River, which, with its tributaries, the Deep River and the Haw River, is a hotspot for the compound, not just in North Carolina but nationwide.
In the past four years, Fayetteville, Pittsboro and Wilmington, all in the Cape Fear River Basin, have reported concentrations of 1,4-Dioxane in drinking water above the EPA’s voluntary health advisory goal of 0.35 parts per billion. North Carolina has also adopted the EPA drinking water recommendation, as well as the federal agency’s goal of 3 ppb for groundwater. There are no regulations for 1,4-Dioxane in sludge and compost.
Drinking water can become contaminated with 1,4-Dioxane in two main ways: If the solvent is spilled or otherwise enters the groundwater, such as through the land application of wet sludge, it can migrate to private drinking water wells. Or municipal plants withdraw water from contaminated rivers and lakes; traditional water treatment methods can’t remove 1,4-Dioxane, so the compound passes through, into water flowing from the tap.
|Material||Sampling results (ppb) DEQ*||Moisture content (%)||Sampling results (ppb) Policy Watch||Moisture content (%)|
In the samples above, as moisture content drops, so do the concentrations of 1,4-Dioxane.
ND = non-detect Sources: DEQ (Gel labs), Policy Watch (Pace Analytical)
|Compound Name||Concentration (ppt) 30-60 day||Concentration (ppt) 90-180-day|
|Perfluoro- 2-methoxyacetic acid||1.59||ND|
The results were divided into two batches: When the compost was analyzed after 30 to 60 days, and had a moisture content of nearly 50 percent; and after 90 to 180 days, when the compost was slightly drier. Concentrations of seven types of PFAS increased over time.
ND = non-detect Source: DEQ (Gel labs)