An official website of the United States government.

This is not the current EPA website. To navigate to the current EPA website, please go to This website is historical material reflecting the EPA website as it existed on January 19, 2021. This website is no longer updated and links to external websites and some internal pages may not work. More information »

EPA in Missouri

Syntex National Priorities List (NPL) Superfund Site, Verona, Lawrence County, Missouri - Fact Sheet, April 2019

Site Update


The Syntex National Priorities List Superfund Site (site) covers approximately 180 acres and is located on 1st Street in Verona, Lawrence County, Missouri. The site is currently divided into two areas, the East Area and the West Area, which are divided by the Spring River. In the past, Syntex and several companies produced Agent Orange or hexachlorophene at the site, contaminating groundwater and soil with dioxin and volatile organic compounds (VOCs). Ongoing federal and Potentially Responsible Party actions have been taken to address and monitor contamination at the site. The former Syntex facility is now occupied by BCP Products.


The U.S. Environmental Protection Agency (EPA) Region 7 plans to host a Public Availability Session soon to provide a site update with information about ongoing and current activities at the site. After an EPA presentation, federal and state agency representatives will be available to discuss the site and answer questions from the public. To notify the public about the upcoming Public Availability Session, EPA will send postcards by mail, publish a public notice in the local newspaper, and notify community groups to ensure the local community has access to updates about the site’s progress.


Before industrial operations, the site was used for agricultural and recreational purposes. In the 1960s, Hoffman-Taff, Inc., owned and operated the facility. Hoffman-Taff produced 2,4,5-trichlorophenoxy-acetic acid (2,4,5-T) for the U.S. Army as part of the production of the defoliant commonly referred to as Agent Orange. In 1969, Hoffman-Taff leased a portion of the facility to Northeastern Pharmaceutical and Chemical Company (NEPACCO) for the production of hexachlorophene. Between 1969 and 1972, NEPACCO operated a soap production facility on site.

In 1969, Syntex Agribusiness, Inc. (Syntex) purchased the facility from Hoffman-Taff for chemical manufacturing and allowed NEPACCO’s lease to remain in effect. Dioxin (2,3,7,8-tetrachlorodibenzo-p-dioxin), also known as or 2,3,7,8-TCDD, was created as an unwanted byproduct in the production of 2,4,5-T and hexachlorophene, and dioxin residues were disposed of in several areas at the facility, contaminating soil and groundwater with dioxin and VOCs. Fish in the downstream Spring River were also contaminated.

Dioxin, a persistent organic pollutant, is considered by EPA to be an extremely toxic contaminant. Chlorinated dibenzo-p-dioxins (CDDs) are a family of 75 chemically-related compounds commonly known as chlorinated dioxins. One of these compounds is 2,3,7,8-TCDD. It is one of the most toxic of the CDDs and is the one most studied.


EPA added the Syntex facility to the Superfund program’s National Priorities List (NPL) in 1983. The NPL is a list of the nation’s hazardous waste sites with the highest priority for cleanup.

In 1988, EPA selected the remedy for dioxin-contaminated soils and equipment. The remedy included excavation and off-site thermal treatment of dioxin-contaminated soil; dismantling and decontamination of equipment; capping and covering of the trench area; and backfilling and vegetating of contaminated areas. EPA removed contaminated soil and equipment, and capped and revegetated excavated areas.

In 1993, EPA selected a remedy of “no further remedial action” for groundwater at the site, as off-site contamination was within the range of acceptable health-based standards. The groundwater assessment was based on water quality sampling from monitoring wells installed on the site. The remedy included continued groundwater monitoring and surface water sampling of the Spring River.

Additional information about the site, including site background, human and ecological impacts, and information on the contaminants of concern, is referenced in the Additional Information and About the Contamination sections below.


EPA conducts regular checkups, called Five-Year Reviews (FYRs), on certain Superfund sites where cleanups have been completed. FYRs are required by the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), or Superfund Law, when hazardous substances remain on site above levels that permit unrestricted use and unlimited exposure. FYRs provide an opportunity to evaluate the site remedy to determine whether it remains protective of human health and the environment. FYRs also include an examination of relevant site documents since the last FYR and a site inspection.

EPA has conducted five FYRs of the site’s selected remedy. The most recent was completed in 2017. The review summarized field data collected since the last FYR and assessed its impact on the protectiveness of the remedy. The FYR found that, at the time the Remedial Actions for soils, groundwater and surface water were implemented, they were protective of human health and the environment. However, the FYR concluded that the overall protectiveness of the remedy cannot be determined until further information is obtained. This is due to changes in the methodology, assumptions and toxicity values used for risk assessments that occurred after the remedies were selected. During the FYR, EPA sampled two, nearby private groundwater wells.

The FYR reported that one well had no detections of site-related compounds. In the second well, the only site-related compound detected was 1,4-dioxane at 0.11 micrograms/liter (µg/L), which is below EPA’s Regional Screening Level of 0.46 µg/L.


To address the issues identified in the Fourth FYR, EPA completed an Administrative Order on Consent (AOC) with Syntex Agribusiness LLC in September 2016. The purpose of the AOC is to facilitate additional investigation of the site and determine whether the remedy implemented at the site remains protective.

The Potentially Responsible Party (PRP), under the terms of the AOC, has submitted several workplans and received EPA approval to perform additional characterization of soil, sediment and groundwater at the site. This includes the following:
  • Installation of new sampling wells
  • Groundwater sampling in the East and West Areas
  • Soil sampling in the East Area for dioxin and dioxin-like compounds
  • Sediment sampling of the Spring River

The workplans also include a reassessment of human health and ecological risk using current methodology, assumptions and toxicity values. In 2017, with oversight from EPA, the PRP began conducting the characterization described in the workplans. EPA will provide updates regarding the work being performed in subsequent fact sheets as more information becomes available.

On Jan. 9, 2019, an Environmental Covenant covering the East Area went into effect. The Covenant assures that any future construction or repair activities will be conducted in a manner that is protective of human health and the environment.

The Covenant also requires the property owner to sample and assess the soils for dioxin and dioxin-related compounds, as well as polychlorinated biphenols (also known as PCBs), prior to excavation or disturbance. It requires proper maintenance of asphalt and concrete-covered areas. Additionally, it prevents groundwater use.


In an effort to help affected communities understand the technical information related to a Superfund site, EPA has established a Technical Assistance Grant (TAG) Program. The program provides up to $50,000 for a qualified citizens’ group to hire an independent technical advisor. The advisor can assist citizens in their interpretation of technical data, site hazards, and the different scientific technologies used to support site actions. (For more information, see EPA Contact Information.)


EPA has assessed the ability of the public to access the Administrative Record file and FYRs through an internet‐based repository and has determined that the local community has this ability. As a result, site information is available on EPA’s website.


  • For more information about Dioxin Health Risks, visit the CDC/ATSDR ToxFAQs™.
  • To learn more about dioxin, visit EPA’s website.


EPA and the state encourage members of the community to ask questions and report any concerns about the site. If you have questions about this fact sheet, need additional information about the site, and/or would like to receive site updates, please contact EPA:

Brian Zurbuchen, Ph.D.
Remedial Project Manager
Superfund Division
U.S. EPA Region 7
11201 Renner Boulevard
Lenexa, KS 66219
Phone: 913-551-7101
Toll-free: 1-800-223-0425
Elizabeth Kramer
Community Engagement Specialist
Enforcement Coordination Office, Environmental Justice Program
U.S. EPA Region 7
11201 Renner Boulevard
Lenexa, KS 66219
Phone: 913-551-7186
Toll-free: 1-800-223-0425