Vol. 13 Issue 2, Spring 2008
By Suzanne Snedeker, Ph.D., Associate Director for Translational Research, BCERF
Dr. Suzanne Snedeker recently presented a talk on chronic health effects associated with exposure to DDT, including the risk of diabetes and cancer, at an international conference on the health risks of DDT held at Alma College on March 14, 2008. Alma, Michigan (MI) is located a few miles from one of the largest Superfund sites for DDT contamination in the US, the former Velsicol Chemical Corporation plant in St. Louis, MI, located on the banks of the Pine River. This article describes Dr. Snedeker’s experiences visiting the Superfund site, topics discussed at the conference, and the struggles that the Community Advisory Group, the Pine River Superfund Citizen Task Force, has had in getting support for conducting health assessments of residents that live in close proximity to this still active Superfund site. Since the World Health Organization now supports the limited use of DDT to spray interior walls of dwellings in areas where malaria is endemic, it is critical to revisit the importance of continued research on the health effects of DDT and why alternatives to DDT are equally important to pursue.
In my many years in cancer risk assessment, I had never had an opportunity to visit a Superfund site. On March 14, 2008, I rode with others attending the Eugene Kenaga International DDT Conference on Health and the Environment, to the Velsicol Chemical Corporation site in St. Louis, MI. The conference was being held only a few miles away, at Alma College. As we drove through this middle class residential neighborhood, a chain link fence containing a large dirt hill, dotted with large plastic tanks and equipment came into view. As we drove along the fence, we passed a tombstone with the words “WARNING DO NOT ENTER.” The tombstone marked the former site of the Michigan Chemical Company plant, later owned by Velsicol Chemical Corporation, which manufactured DDT for global use from 1943 to 1963.
The bus drove over a bridge to get to the opposite bank of the Pine River. We exited the bus and walked along the side of a children’s playground, to a roofed picnic area. There, a state and a US Environmental Protection Agency (EPA) representative managing the Superfund site remediation efforts told us about the history of the site.
The Velsicol Chemical Corporation Superfund Site
None of the plant buildings stands on the site anymore. By the early 1980s, the manufacturing plant was torn down and, as part of the Consent Agreement, Velsicol was required to build a slurry wall around the site and bury the 54-acre manufacturing site under a clay cap. The original agreement with Velsicol did not require any remediation, since it was thought that the DDT in river sediment would degrade over time and contamination on the plant site would be contained within the slurry wall and clay cap.
But as water levels started to rise within the slurry wall and DDT was detected in Pine River fish, studies were initiated to sample river sediments. Hot spots of DDT up to 30,000 parts per million (ppm) were detected. Remediation was required wherever contamination exceeded 3,000 ppm. The goal was to remove sediments so DDT levels would not exceed 5 ppm. Steel girder pilings were driven along the riverbank, and water was pumped out to access river sediments. In 2002, a “dense non-aqueous phase liquid” (DNAPL), a slurry of chemicals from the plant, was found to be migrating from the main plant site to the underlying river sediment. During excavations, 256 pipes were located that had led from the manufacturing plant into the Pine River.
During remediation efforts that started in 1999, the EPA removed 640,000 cubic yards of river sediment, and pumped out 4,355 gallons of DNAPL from the river bottom. It is estimated these wastes contained 222 tons of DDT (EPA, 2008). However, during remediation efforts to remove river sediments, excavations indicated the 20-year-old slurry wall was starting to fail. In addition, the clay cap had started to form cracks and was leaking contaminates into the river.
In 2005, a new chemical that is an acidic byproduct of the manufacture of DDT, called para-chlorobenzene sulfonic acid (p-CBSA), was first detected in groundwater drinking wells in St. Louis, MI (Michigan DEQ, 2006). Unlike DNAPL, the p-CBSA does not cling to river sediments. P-CBSA is very water soluble, can be carried downriver, and can seep from contaminated soil into groundwater and drinking water wells. This chemical has only been found at DDT manufacturing or waste sites. Relatively little is known about its toxicology or possible health effects (Michigan DEQ, 2006). There is concern about its continued detection in groundwater drinking wells near contaminated DDT waste sites.
Currently, the EPA is developing feasibility studies to determine the best way to remediate the Velsicol Chemical Corporation Superfund site.
Eugene Kenaga International DDT Conference on Health and the Environment
Because of their own concerns about the health impacts of DDT and the changes internationally that have sanctioned limited use of DDT (the World Health Organization has sanctioned limited use of DDT for residual spraying of interior walls of dwellings) for malaria control, Alma College, the Pine River Superfund Citizen Task Force, the Society for Environmental Toxicology and Chemistry (SETAC), and the International Society of Environmental Epidemiology organized this international conference on the health effects of DDT. Their goal was to assemble an international panel of experts to dialogue with local citizens on what we know and what we need to know about the health impacts and policy implications of DDT’s use. I was honored to participate on the panel of experts, and gave a presentation on what is known about DDT and the risk of cancer and diabetes.
The conference was named for Dr. Eugene Kenaga, who had worked in an anti-malarial unit in the Pacific during World War II, and later worked as a research scientist for Dow Chemical. Dr. Kenaga became concerned about the use and impacts of DDT in the 1960s, worked to limit its use, and became a leader in environmental toxicology and risk assessment. He was the founder and first president of SETAC, and an active member of the Pine River Superfund Citizen Task Force. The Task Force was founded in 1998 to establish a forum to link government experts and local citizens, to secure appropriate environmental health policies.
“The Task Force is guided by a theory that assumes citizen involvement in technical decision making is essential in a democracy. The Task Force believes that such community groups can improve the effectiveness of any technical work, research about risks, and decisions about remediation. A failed remediation of the Velsicol site in the 1980s, done with conscious exclusion of the public by officials, seems to be proof of the validity of the Task Force's assumptions regarding citizen involvement. The Task Force and College are determined not to allow similar mistakes to occur today.” http://www.pinerivercag.org/About%20Us.php
The conference allowed me not only to interact with scientists in other disciplines who are investigating and interpreting new data on health risks associated with DDT, but also to talk with members of the Pine River Superfund Citizen Task Force and hear the stories of their dedication, accomplishments and frustrations. The conference they and Alma College organized was excellent. Speakers included historians, federal agency personal, and academics in various human and wildlife health areas from the US and South Africa.
Because many of the speakers presented new, unpublished data, the details of their talks cannot be shared at this time, but I can share the topics discussed at the conference. Many of these areas are relatively new, emerging areas of research, and underscore why additional support is needed investigate DDT’s impact on human and wildlife health. Topics discussed included the history of DDT use for malaria control and concern about effects on biodiversity and wildlife, including the possible effects on bird species. Most presentations focused on whether there was evidence for effects on human health, including: the risk of exposure with regard to different types of cancers; emerging evidence of an association the prevalence of Type II diabetes; evidence of effects on early neurological development and cognition; whether DDT use in areas of malaria control affects male reproductive function in adults (sperm indices); and possible impacts of DDT use on infant health, including decreased birth weight and lactation duration, and male offspring urogenital malformations. (See list of presenters on conference website at http://www.alma.edu/academics/ddt/presenters.)
The afternoon session was devoted to panel discussions between area residents, members of the Task Force, and the scientists. These discussions included summaries of what is known about health effects of DDT from the earlier scientific presentations, what we need to know, and policy implications of DDT’s past and current use.
Many of the scientific presenters from the conference and Alma College faculty are in the process of writing a review article on the health effects of DDT for peer-review publication, along with a consensus statement on policy implications. This includes the need for monitoring health effects in populations exposed to DDT, whether by living in the proximity of Superfund sites or through DDT use in malaria control. The confirmed and emerging health risks of DDT should form a firm basis for not only the urgent need to seek alternatives to DDT, but also the need to continue to monitor exposed populations and determine wildlife and human health impacts. There is much work to be done in seeking alternatives to DDT, on both the efficacy of the alternatives as means of malaria control, and the health implications of any alternatives.
Looking toward the future in DDT-contaminated areas and populations
At the end of day, I returned to the Velsicol Chemical Corporation Superfund site with Dr. Diane Henshel of Indiana University, who was gathering health effects information of residents that live in proximity of the site. Her preliminary investigations will focus on whether there are any associations with cancer incidence or birth defects that would require further study.
It was dusk when we arrived at the Pine River. A group of teenagers were on the playground equipment in the park across from the plant site. The sun was setting behind the steel girders sticking out of the river. A prominent bright red “No Swimming” sign stood on the riverbank. Diane and I took pictures of the site. You could hear children playing in surrounding yards. This community wants what every other community wants. They want to know that they and future generations will not be exposed to DDT. They want the river restored so they can enjoy it with family and friends.
Despite the events that have unfolded in the 25 years since the Velsicol Chemical Corporation plant was demolished, the residents involved in the Task Force have been unable to secure a firm commitment by state or federal agencies to initiate studies monitoring levels of DDT in residents or to investigate health outcomes.
“As in many older industrial regions of modest incomes, residents of the Pine River watershed in Michigan have experienced powerlessness periodically, powerlessness in the face of resource exhaustion, environmental contamination, corporate restructuring, and global economic trends. Perhaps the most extreme proof of this powerlessness is the willingness of many residents of the region to accept as inevitable the health problems which they believe grow from the contamination to which they have been repeatedly exposed.” Pine River Task Force, http://www.pinerivercag.org/About%20Us.php
At lunch, during panel discussions, and at dinner, I talked with the current Secretary of the Task Force, Dr. Melissa Strait, Chair and Professor of Chemistry at Alma College, about the desire of the Task Force to work with scientists in determining health effects of not only DDT contamination, but also of the many other chemicals that leaked from the Velsicol plant and other industries located on the Pine River.
It is important that there is recognition that regulation and remediation are only the first steps in addressing chemical contamination; there is still the obligation to determine health effects of chemicals in exposed populations. To this end, because many of our Ribbon readers are epidemiologists and risk assessors, I urge you to consider collaborations that may help Pine River Superfund Citizen Task Force conduct health assessments. Indeed, this information would not only be important to residents near other DDT Superfund sites, but would have important implications for design of studies globally, in areas where DDT is still actively being used.
MI-DEQ (2006) Toxicological Assessment, para-Chlorobenzenesulfonic Acid, CAS #98-66-B, January 2006, Michigan Department of Environmental Quality (DEQ), , http://www.deq.state.mi.us/documents/deq-rrd-p-CBSAToxAss.pdf
EPA (2008) Region 5 Superfund, Velsicol Chemical Corp. (Michigan) EPA ID #MID0002439, April 2008, http://www.epa.gov/region5superfund/npl/michigan/MID000722439.htm). cited May 11, 2008.