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Responding to Emerging Contaminants: 1,4-Dioxane

The New Jersey Department of Environmental Protection, a national leader on addressing emerging chemical contaminants, earlier this year organized an interstate working group to address the detection of the synthetic chemical 1,4-dioxane in the Delaware River. The working group consists of experts from NJDEP, the Pennsylvania Department of Environmental Protection and the Delaware River Basin Commission, as well as representatives from New Jersey American Water and other water system industry representatives.

This working group is collaboratively investigating potential sources of the chemical and possible remedies. This work includes enhanced sampling and assessment as well as sharing of data and information. As a potential source or sources are identified, the group will work to coordinate a course of action to quickly address any potential risks to the environment or public health.

New Jersey is committed to protecting our drinking water from chemical exposure risks and will continue to work together with our partners in the public and private sectors to address this issue. As an important part of the DEP’s efforts to protect public health, the New Jersey Drinking Water Quality Institute (DWQI), comprised of the state’s leading water quality experts, voted 12-0 to recommend establishing a health-based drinking water Maximum Contaminant Level (MCL) of 0.33 parts per billion. This recommendation by DWQI, was accepted by NJDEP Commissioner Shawn LaTourette on December 16, 2021.

About 1,4-Dioxane

1,4-dioxane is a synthetic chemical used as a solvent in products such as adhesives, resins, oils and waxes and wood pulping, and was formerly used as a stabilizer for chlorinated organic solvents. 1,4-dioxane is also used in the manufacture of pharmaceuticals, certain plastics and rubber, and other products.

The chemical also appears as a byproduct of surfactants used in personal care products, detergents and cosmetics. Significant exposure to 1,4-dioxane is not known to occur during showering or bathing, as the chemical is not absorbed through the skin and does not vaporize significantly into the air from drinking water. However, since scientific studies indicate that 1,4-dioxane may pose a threat to human health if ingested in sufficient amounts, the chemical is a concern for drinking water supplies.

Information on health effects of 1,4-dioxane comes primarily from studies of laboratory animals, which show that prolonged exposure to low levels of 1,4-dioxane may result in adverse health impacts. Research suggests lifelong exposure to 1,4-dioxane may be associated with an increased risk of cancer or damage to the kidneys or liver. The United States Environmental Protection Agency (EPA) has classified the chemical as “likely to be carcinogenic to humans” from long-term exposure.

1,4-Dioxane and the Delaware River

In response to the detection of the synthetic chemical 1,4-dioxane in the Delaware River, the New Jersey Department of Environmental Protection has convened an interstate task force to assess potential sources of the chemical and possible remedies.

The State has established a working group consisting of DEP experts, Pennsylvania regulators, the Delaware River Basin Commission, and industry representatives. The group is conducting enhanced sampling and assessment to identify potential source(s) of the contaminant and recommend a course of action to address risks to the environment or public health.

Three separate Sub-Committees were established to ensure the overall goals of the interstate task force are met; Monitoring, Mapping, and Communications.

  • The goal of the Monitoring Sub-Committee is to develop a synchronized monitoring strategy to ensure the quality and consistency of sampling results through a coordinated effort with all programs intending to implement 1,4-dioxane monitoring.
  • The Mapping Sub-Committee is working collaboratively with the programs sampling 1,4-dioxane to effectively share data that can be produced in a consistent, useable, and geo-spatial manner.
  • The Communications Sub Committee’s objective is to develop a coordinated outreach plan for the public about the 1,4, dioxane track down study that includes health, technical issues, and remediation options to protect public health and addresses the concerns of the partners organizations and the concerns and questions of the public.

Among issues the group is evaluating is the recent detection of 1,4-dioxane near the Delaware River Regional Water Treatment Plant in Delran, operated by New Jersey American Water. At the amounts presently detected, the chemical is unlikely to pose an immediate acute health risk. Nevertheless, New Jersey American Water has made operational changes to reduce 1,4-dioxane levels in drinking water distributed by the Delran plant and is designing and installing new treatment at the plant to be completed by the end of 2021. While there is no cause for alarm, the information shared by New Jersey American Water is an important preliminary data point in the evaluation of this emerging contaminant for all water systems that draw from the Delaware River.

Furthermore, the DEP is conducting a track down study in the Delaware River watershed. The objective of this project is to collect samples to identify potential sources of the 1,4 -dioxane in New Jersey tributaries of the Delaware River, tidal and non-tidal, that may impact water supply.

“While we take the detection of 1,4-dioxane in the Delaware River very seriously, it is important for the public to understand that DEP does not believe that the current results pose any immediate health risk,” DEP Commissioner Catherine R. McCabe said on December 2, 2020. “New Jersey has led the nation in protecting our drinking water from chemical exposure risks, and we will continue that tradition by responding to the challenge of 1,4-dioxane, working collaboratively with our partners in the public and private sectors. We encourage water purveyors throughout the state to share information about the presence or treatment of 1,4-dioxane in source water supplies with the DEP while regulations for this emerging contaminant are in development.”

Regulating 1,4-Dioxane

Ground Water:

The NJDEP has adopted a Ground Water Quality Standard (GWQS) of 0.4 µg/L. Of an estimated State population of 8.9 million, about 3 million people rely on ground water from public water supply wells and private domestic potable wells. The ground water quality standard for 1,4-dioxane ensures that a current and scientifically based standard to protect, maintain, and restore ground water quality is in place. The ground water quality standards also establish minimum standards for the remediation of contaminated ground water.

Drinking Water:

There are no current federal or New Jersey drinking water standards for 1,4-dioxane. The DEP and the New Jersey Drinking Water Quality Institute are in the process of developing a 1,4-dioxane drinking water standard. This process would establish a regulatory limit for 1,4-dioxane in drinking water that is based on potential health effects from long-term consumption of affected water. In August 2021, the DWQI met to finalize their recommendation of a health based Maximum Contaminant Level (MCL) for 1,4 Dioxane of 0.33 ug/L. The DWQI will forward a formal recommendation to the NJDEP Commissioner. If the Commissioner accepts the recommendation, stakeholder and formal rulemaking would be initiated.

Once formally regulated, water systems would be required to monitor for the presence of 1,4-dioxane and would be obligated to take remediation measures where the levels are detected above the MCL, including the potential installation of additional treatment technology. Presently, no home-treatment systems or filters have been certified to remove 1,4-dioxane.

Health-based drinking water standards are developed using conservative assessments that consider exposure to a chemical over an entire lifetime. The USEPA has estimated the concentration of 1,4-dioxane in water corresponding to an increased lifetime cancer risk of one-in-a-million is 0.35 parts per billion (ppb), assuming consumption of two liters of water contaminated with 1,4-dioxane every day for an entire lifetime. The New Jersey Drinking Water Quality Institute met in August 2021 to finalize their recommendation of a health based a MCL for 1,4 Dioxane of 0.33 ppb.

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