1, 4 - Dioxane:
An AEG Virtual Environmental Symposium

Friday, October 22, 2021
1:00-5:00pm (Eastern Time Zone)

Register Now
Sponsored By

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Free for all AEG 2021 Annual Meeting Registrants 

$75 for Members

$100 Non-members

$25 Students


PDHs and Continuing Education Units will be available.

If you have any questions, please contact Heather Clark, AEG Meetings Manager, at 303-518-0618 or heather@aegweb.org


1,4-Dioxane (DXA) is a manufacturing impurity still found in many shampoos, personal care products and food containers; it is also a legacy contaminant closely associated with TCA at many old solvent spills, and due to groundwater contamination, it has impacted millions of people’s drinking water.  


AEG’s cross-section of experts will trace the origin of this widespread and notoriously difficult to remove Emerging Contaminant. Current EPA and State regulatory approaches will be examined, and the groundbreaking citizens’ action on Long Island that resulted in the nation’s strictest drinking water standard for dioxane at 1 ppb will be highlighted. 


Dioxane remediation technologies around the globe will be surveyed, and an innovative new dioxane biofilter for onsite wastewater treatment will be introduced. The solution to the Dioxane problem is not yet apparent, but AEG’s Dioxane Symposium will cover everything that savvy environmental practitioners need to know about dioxane in 2021.

Conveners: Patricia Bryan and Loren Lasky

Patty Bryan is President and Principal Geologist at Bryan Environmental Consultants, Inc. in the Chicago area, a remediation-oriented, woman-owned business.  A graduate of Binghamton University (SUNY Binghamton), she serves on the Board for Professional Geologist in Illinois.  She is past Chairman of the Chicago Chapter of AEG and served as President (2010 to 2014) and Executive Director (2015-2016) of the AEG Foundation.

Loren Lasky, PG, has 35 years of experience as an environmental consultant and regulator in the New York, New Jersey and Pennsylvania area.  She has a Masters degree in Geology from the Colorado School of Mines and served as chairman of the New York/Philadelphia Chapter of AEG. Now, she helps promote the education of geology students as a Director of the AEG Foundation, and plans annual Environmental Symposia as co-chair of AEG’s Environmental TWG.  


1:00-1:50pm     Joan Smyth                 Keynote: 1,4 Dioxane – In Consumer Products, Landfill Leachate and Surface Water

2:00-2:25pm     Kyla Bennett               Just Because It’s Legal Doesn’t Mean It’s Safe: The Case of 1,4-Dioxane

2:30-2:55pm     Adrienne Esposito     Long Island Citizens React to Nation’s Highest Level of Dioxane in Drinking Water Wells

3:00-3:15pm                                          Break

3:15-3:40pm     Gary Smith                 1,4-Dioxane in Groundwater: Emerging Contaminant Concerns

3:45-4:10pm     Gary Smith                 1,4-Dioxane Remediation in Groundwater: A Worldwide Remediation Technology Survey

4:15-4:40pm     Arjun Venkatesan      Innovative and Alternative Treatment Technologies to Mitigate 1,4-Dioxane Contamination in the Long Island, New York Water Cycle

4:45-5:00pm                                          Discussion




Senior Hydrogeologist and Vice President, Smyth Gardner, Inc., joan@smithgardnerinc.com











1,4 Dioxane – In Consumer Products, Landfill Leachate and Surface Water

This presentation will follow the path of 1,4 Dioxane in our environment from initial synthesis to post-disposal. Details will be presented of synthesis and usage of 1,4 dioxane during consumer product production and will summarize concentrations in consumer products over time and regulations limiting 1,4 D in consumer products. The presentation will follow the disposal of consumer products in landfills and will summarize concentrations of 1,4 dioxane in landfill leachates in the United States and globally. Since most landfill leachates are disposed at wastewater treatment plants, this presentation will also summarize data from surface water studies pf 1,4 dioxane in wastewater treatment plant discharges as well as surface water sampling locations to evaluate the potential impact of landfill leachates on surface water. As a point of comparison, limited information regarding concentrations of 1,4 D in septic system effluent will also be presented to give a more comprehensive picture of how 1,4 D is entering our environment from consumer product usage and disposal.


Ms. Smyth is a Senior Hydrogeologist and Vice President at Smith Gardner, Inc., an engineering and environmental consulting firm in North Carolina.  She has 32 years’ experience primarily serving the solid waste industry.  She also works with the Solid Waste Association of North America aggregating emerging contaminant information for their website and membership.


Northeast and Mid-Atlantic Director and Director of Science Policy, Public Employees for Environmental Responsibility (PEER), kbennett@peer.org


Just Because It’s Legal Doesn’t Mean It’s Safe: The Case of 1,4-Dioxane

The chemical 1,4-dioxane is a likely human carcinogen, and has contaminated the drinking water of roughly 88 million Americans in 45 states. The toxicity of 1,4-dioxane has been acknowledged for decades, yet it is still largely unregulated. Specifically, the US Environmental Protection Agency (EPA) does not have a regulatory limit for 1,4-dioxane in drinking water, and a patchwork of state regulations do not protect human health. This presentation will explore the long- term failure of EPA to act on 1,4-dioxane, and the devastating effects this has on New York and California water supplies. We will also examine how the industry is fighting any regulation of 1,4-dioxane in drinking water, and how industry influence is preventing regulators from protecting the public from this, and other, carcinogens.


Kyla Bennett is PEER's Northeast and Mid-Atlantic Director and Director of Science Policy. Kyla previously worked at EPA Region 1 for ten years as a wetland permit reviewer and as the Region’s Wetlands Enforcement Coordinator.  Kyla has a Ph.D. in Ecology and Evolutionary Biology from the University of Connecticut and a JD from Lewis and Clark Law School in Portland, Oregon.


Executive Director, Citizens Campaign for the Environment, aesposito@citizenscampaign.org












Long Island Citizens React to Nation’s Highest Level of Dioxane in Drinking Water Wells

1,4-dioxane is considered a “likely human carcinogen” which has been found in drinking water wells throughout the nation. Out of 4,400 wells tested by the EPA, Long Island was home to the highest levels in the country. Long Island is a sole source aquifer, which means we are 100% dependent on groundwater for drinking water. To better understand 1,4-dioxane contamination in LI water supply wells, Citizens Campaign for the Environment (CCE) compiled drinking water quality reports from the EPA and local water suppliers and created an interactive map of 1,4-dioxane contamination for each water district on Long Island. Thirty-nine water districts had 1,4-dioxane detections and some wells contained levels over 100 times higher than the EPA’s cancer risk guideline for the chemical (.35 ppb). Many of these high detections are likely legacy contamination from past industrial practices, however there were 1,4-dioxane detections in areas with no history of heavy industry or manufacturing. CCE theorized that small levels of 1,4 Dioxane were likely from household products, which can contain 1,4-dioxane as a bi-product of manufacturing but do not list the chem- ical on the label. Unfortunately, we still have approximately 400,000 septic systems on Long Island. What washes down the drain, ends up in the aquifer system. CCE conducted first-of-its-kind testing on 80 popular household products, including shampoo, body washes and soaps, laundry detergent, and even baby products, and found that 80% of these products contained detectable levels of 1,4-dioxane. From this data, we created a consumer guide to help residents avoid products with high levels of 1,4-dioxane, conducted an extensive community outreach program, and lobbied for a 1,4-dioxane ban in household products in New York State. We successfully passed this landmark bill and in 2019, NY became the first state to pass legislation mandating the removal of 1,4-dioxane in products. In 2020, NY approved the strongest drinking water standard for 1,4-dioxane in the nation at 1 ppb. We believe that the extensive work done to combat 1,4-dioxane contamination in NY can serve as a guide for other states and federal regulators seeking to address this emerging contaminant.


Adrienne holds a degree in Geology and Environmental Science from CW Post University.  She is a co-founder of CCE and has worked on numerous environmental campaigns for over 30 years.  Adrienne has crafted campaigns to engage the public on environmental protection issues including but not limited to upgrading failing sewage treatment systems, protection of drinking and surface water, remediation of toxic plumes, stewardship of land and water, support for large scale renewable energy projects, reduced pesticide application, and more. Link to full Bio


WGS Consulting, wgsconsulting@hotmail.com


1,4-Dioxane in Groundwater: Emerging Contaminant Concerns

1,4-Dioxane (DXA) is a likely human carcinogen and has been found in groundwater at sites throughout the United States (US) and worldwide. The physical and chemical properties and behavior of DXA create challenges for characterization and treatment in the environment. It is highly mobile, does not readily biodegrade, and is completely miscible in water. It is unstable at elevated temperatures and pressures and may form explosive mixtures with prolonged exposure to light or air.  DXA is a likely contaminant at many sites contaminated with chlorinated solvents because of its widespread use historically as a stabilizer for those compounds (particularly 1,1,1- trichloroethane [TCA]). DXA is a by-product present in many goods, including paint strippers, dyes, greases, antifreeze and aircraft deicing fluids, and in some consumer products (deodorants, shampoos and cosmetics), and as a purifying agent in manufacture of pharmaceuticals. It is a by-product in the manufacture of polyethylene terephthalate (PET) plastic. Traces may be present in some food supplements, food residues from packaging adhesives, or on DXA-containing pesticides applied to food crops. (1)  DXA is considered an emerging organic contaminant in the environment due to the above widespread uses, and investigative difficulty in detecting low DXA concentrations in groundwater plumes. It is typically found at low ppm or ppb concentrations in groundwater, but may be found at high ppm concentrations at DXA manufacturing sites. One of the last US manufacturers of DXA shut down in 2019 and moved production to European operations due to increasing regulatory scrutiny and perceived environmental risk.(2) DXA remediation has become a priority at many sites in the USA due to status as a likely human carcinogen. As of 2016, DXA had been identified at more than 34 USEPA National Priorities List (NPL) sites; it is likely present at many other USA governmental and industrial sites. (3) Remediation focus on DXA is typically on groundwater that may be used as a potable source, and ongoing risk assessments by federal and state agencies have increasingly lowered the acceptable risk level to low ppb concentrations (typically <5 ug/L). (1,4) This presents an issue for both remediation technology efficiency, and the ability to detect DXA at allowable groundwater concentrations in groundwater. DXA does not bind to soils and migrates preferably to groundwater pore spaces where it may migrate much more rapidly than co-contaminants such as chlorinated solvents. Thus, it is often found at the leading edge of groundwater plumes that exhibit multiple co-contaminants. (3,4)  This presentation summarizes the state of the art in DXA remediation of contaminated groundwater, including references to several ongoing successful remedial sites around the world.  
(1) US Environmental Protection Agency (USEPA), Office of Land and Emergency Management (Nov 2017) Technical Fact Sheet – 1,4-Dioxane, EPA 505-F-17-011, 8 p.  
(2) Editorial Staff, WAFB Television Baton Rouge Louisiana Video News (15 January 2019) BASF Chemical Plant in Zachary, LA to Shut Down in April 2019, TV Video.  
(3) Agency for Toxic Substances and Disease Registry (ATSDR) (2012. “Toxicological Profile for 1,4-Dioxane.” www.atsdr.cdc.gov/toxprofiles  
(4) USEPA (2006) Treatment Technologies for 1,4-Dioxane: Fundamentals and Field Applications, EPA 542-R-06-009, web address: clu-in.org/download/542r06009/pdf. 


1,4-Dioxane Remediation in Groundwater: A Worldwide Remediation Technology Survey

DXA remediation in groundwater may be designed for either ex situ or in situ application. In practice, in situ methods are typically designed to transport contaminated groundwater to the location of remedial technologies that are more typically used ex situ, such as funnel & gate or French drain extraction. With several US DXA remedial projects having now been operating for years, effective remedial technologies have increasingly been narrowed to those capable of destroying DXA, either chemically or thermally. For this reason, in situ chemical or biochemical remediation are much more difficult to design for low acceptable residual DXA concentrations in potable groundwater supplies. Currently, effective remedial technologies applied for DXA in the USA include 1) Advanced Oxidation Processes (AOP), or, 2) adsorption or ion exchange (IEX) materials (e.g., AmbersorbTM), used in combination with thermal regeneration of granular activated carbon (GAC). Treated groundwater can be reinjected, or directed for additional residual treatment in Wastewater Treatment Plants (WWTP), prior to surface water discharge. Because DXA and similar contaminants must be treated to essentially non-detect concentrations (<1 ug/L) in drinking water remedial scenarios or in many surface water quality discharge scenarios, proprietary AOP technologies have been developed specifically for DXA These include peroxide/ozone oxidation – prominent examples licensed as HiPOxTM technology by APTWater (5) and photocatalytic oxidation - licensed as PhotoCatTM technology by Purifics (6). These technologies have been proven to be effective for DXA remediation at multiple sites, down to low ppb or ppt levels, even from initial high ppm-level (>100 mg/L) concentrations using multiple pass technology. These technologies are typically applied for ex situ pumping and recovery of DXA contaminated groundwater, and treated groundwater can be reinjected to improve hydraulic transport and recovery efficiency of contaminated groundwater. Filtration or membrane technologies may be used ahead of AOP methods to avoid solids issues with AOP equipment when necessary. IEX methods for DXA remediation using AmbersorbTM or similar resins typically operate at lower contaminated groundwater influent concentrations (<1 mg/L) but can achieve non-detect levels (<1 ug/L) on a continuous basis. These methods depend on IEX regeneration, typically aligned with a second phase of concentrated DXA adsorption on GAC, followed by GAC thermal regeneration, that results in total DXA destruction. (7) Additional destruction technologies are being developed at demonstration levels currently, including electrochemical destruction at high temperatures for concentrated DXA or PFAS type emerging contaminants (8). Residual low ppb levels of DXA after remedial treatment can be reinjected, to assist in contaminated groundwater transport and recovery, or, discharged to WWTPs that achieve residual destruction by biochemical or physical/chemical methods. Traditional UV/peroxide technology is not likely to be effective for DXA in a low ppb or non-detect remedial setting.


(5) APTWater, Long Beach, CA (2009) HiPOx Case Study: US Air Force Plant 44, 2 p.

(6) Purifics, London, ON, Canada (2013) Groundwater Remediation Case History: Chemical Free 1,4-Dioxane

Purification, Sarasota Florida, 2 p.

(7) Woodard, S., ECT2, Whittier, CA (2016) Optimized Treatment of 1,4-Dioxane in Extracted Groundwater with Reinjection for Aquifer Replenishment, 2016 Emerging Contaminants Conference, Westminster, CO, PPT presentation, 21 p.

(8) Linked News - Australia, “AECOM announces first demonstration of DEFLUORO electrochemical remedial technology for emerging contaminants,” May/Jun 2021.


Mr. Smith has been a US registered professional engineer for more than 40 years, practicing in chemical and environmental engineering specialties with international experience in Australia, Asia, Europe, South America, Canada, Japan, and the Middle East as well as mainland USA, Hawaii & Alaska. He specializes in multidisciplinary environmental engineering roles including advanced/sustainable land and groundwater remediation, industrial and municipal water supply and wastewater treatment, industrial facility due diligence, EHS/PSM auditing, air quality studies and pollution control technologies, human health and ecological risk assessment, and environmental assessment of industrial facilities and properties.  Mr. Smith has worked with a wide range of industrial manufacturing clients, including petroleum and gas exploration, production & refining, petrochemicals, coal and mineral mining, pharmaceuticals, food processing, textiles, pulp & paper, organic and inorganic chemicals, commercial landfill industry, and the defense & aerospace industry.  Mr. Smith has also been employed as military petroleum fuels officer, chemical process engineer and regulatory agency administrator in Louisiana.


Mr. Smith has long term specialty experience with soil and groundwater remediation at a wide range of industrial, defense, and commercial sites worldwide.  He is expert in both traditional remediation technologies such as contaminated groundwater extraction/reinjection, pump & treat remedial systems, in situ treatment for petroleum hydrocarbon and chlorinated solvent wastes, and remediation of landfills with ongoing waste and landfill gas issues.  He is also expert in the application of air stripping and steam stripping technologies for liquid and vapor remediation, and currently practices in emerging contaminant remediation for compounds like 1,4-Dioxane & PFAS.


Associate Director, Center for Clean Water Technology, Stony Brook University, arjun.venkatesan@stonybrook.edu 












Innovative and Alternative Treatment Technologies to Mitigate 1,4-Dioxane Contamination in the Long Island, New York Water Cycle
1,4-Dioxane is a probable human carcinogen and a widespread contaminant in Long Island water supplies, with some of the nation’s highest concentrations detected (up to 34 μg/L). Analysis of the Unregulated Contaminant Monitoring Rule 3 data from the USEPA revealed that 39 water districts/distribution areas in Long Island had detections of 1,4- dioxane greater than the EPA’s cancer risk guideline level of 0.35 μg/L. Furthermore, recent studies have confirmed the presence of very high levels of 1,4-dioxane in several household products and thus domestic wastewater could potentially serve as an important and ongoing source of 1,4-dioxane pollution in the environment. Due to its environmental persistence, conventional water and wastewater treatment processes are not effective in removing 1,4-dioxane. A combination of concentrated onsite wastewater treatment systems, sole-source aquifer, and elevated background 1,4-dioxane levels in groundwater, as observed in Long Island, NY, presents a unique challenge to prevent further contamination via wastewater discharges. Research at the NYS Center for Clean Water Technology is focused on optimizing both drinking water treatment and onsite wastewater treatment to minimize 1,4-dioxane exposure and to control ongoing pollution of groundwater. This presentation will summarize i) recent data from a pilot-study of 1,4-dioxane treatment using four different Advanced Oxidation Process (AOP) technologies; ii) the performance of full-scale Nitrogen Removing Biofilters (NRBs) to remove 1,4-dioxane from onsite wastewater; and iii) treatment challenges and research needs. Results reveal that although all AOP systems are capable of removing 1,4-dioxane, UV/H2O2 and O3/H2O2 performed most efficiently with respect to cost and energy consumption. In NRBs, the majority of 1,4-dioxane removal (~80%) occurred in the top oxic layer, implying that the removal was likely driven by aerobic microbial degradation. The results also demonstrate that installation of NRBs can reduce 1,4-dioxane to levels even lower than the NY State drinking water standard of 1 μg/L.


Dr. Arjun Venkatesan is the Associate Director for the New York State Center for Clean Water Technology at Stony Brook University. Dr. Venkatesan has more than 13 years of experience studying the fate, transport, and treatment of emerging contaminants. His current research projects (funded by New York State, U.S. DOE, and industry partners) focus on the development and evaluation of novel water treatment technologies to remove emerging contaminants such as perfluoroalkyl substances and 1,4-dioxane. To date, Dr. Venkatesan has published 35 plus peer-reviewed journal articles and his work on emerging contaminants has been featured in several media including PBS News Hour, Royal Society in Chemistry, Environmental Factor (NIEHS), American Society of Agronomy, and American Chemical Society.

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