The Kansas Department of Health and Environment has provided inconsistent information on a health study it published two years ago about a chemical spill in northeast Wichita.
The spill near 29th and Grove happened decades ago, contaminating a long plume of groundwater. In 2023, the state published a health study looking into cancer rates and birth outcomes near the spill, following requests from residents.
The report ultimately found significantly high rates of liver cancer, especially among Black people. While the state emphasized that the study could not determine whether the chemical spill was responsible for the health disparities, the outcome alarmed residents and set into motion legislative and local efforts to provide health screenings for those impacted by the spill.
Two years later, though, the state says the physical area it analyzed to measure cancer rates was much larger than the groundwater plume itself and larger than what was originally reported.
Some community members now wonder how useful the study’s findings are in drawing conclusions about the health impact of the groundwater contamination.
“There may be higher incidences in that plume, but we can't know that because we're taking in this very large geographic area,” said Sedgwick County Commissioner Jim Howell. “… So we're left with a giant question mark. We don't really know what the data is telling us.”
The original health study said that the analysis focused on “2,793 addresses representing the area of interest where the contaminated groundwater plume has travelled.” Media outlets across Wichita and Kansas – including KMUW, the Wichita Eagle and the Associated Press – reported that cancer rates were higher above the chemical spill specifically.
But in recent emails with KMUW, KDHE revealed that the study actually analyzed cancer rates in two ZIP codes: 67219 and 67214. These ZIP codes contain the addresses above the groundwater plume – but they also contain thousands more that were not exposed to the 29th and Grove contamination site.
Meanwhile, KDHE wrote in a statement that the portion of the study that focused on birth outcomes did analyze addresses specifically in the plume area, as opposed to the two ZIP codes. KDHE wrote that the availability of more detailed birth outcome data allowed it to conduct the precise analysis. The study found that the rate of babies with low birthweights born to mothers living above the plume was significantly higher than the rate in Kansas.
Howell said KDHE needs to correct the report to clearly identify the area of interest that was studied for cancer rates. KDHE wrote to KMUW that the study was not incorrect, though acknowledged it may be “confusing.”
Why does it matter?
Clarity around where a health study is conducted is one of the key pieces of information that must be justified to the public, according to the Center for Disease Control’s 2013 recommendations into investigating cancer clusters.
“The definitions and the justification should be transparent to the community so that they understand the rationale behind the approach taken,” the recommendations read. “This means sharing information that is consistent, timely, and expressed in a manner that the lay public is able to understand. Otherwise, these decisions might be seen as arbitrary and thus be rejected by the community.”
State Rep. Ford Carr, whose district includes parts of the contaminated area, said the state should have been more transparent about the study.
“At a minimum, when they released that information, it should have came with that disclaimer” that the study looked at ZIP codes 67214 and 67219, Carr said.
The 2023 health study did reference the two ZIP codes once, saying KDHE used census data to count the number of people in 67214 and 67219. It did not define the two ZIP codes as the “area of interest,” which the study refers to throughout the study when discussing cancer rates.
Calls for a more specific study
Defining the boundaries of the area of interest is a key part of designing a health study.
That’s because it’s “possible to create or obscure a cluster inadvertently by modifying the area of interest,” according to 2022 guidelines for investigating unusual cancer patterns by the Centers for Diease Control and the Agency for Toxic Substances and Disease Registry.
Carr, Howell and Aujanae Bennett – a community activist focused on the contamination – all say they would like the state to analyze cancer rates above the 29th and Grove groundwater plume specifically.
“Much more detailed research is needed to determine the incidence among those who resided in the affected homes,” wrote Elizabeth Ablah, a professor in the Department of Population Health at the University of Kansas School of Medicine-Wichita, in a text to KMUW. Ablah has researched local groundwater contamination issues.
Without this analysis, Howell said there’s little information to understand how groundwater contamination impacted cancer rates.
“We maybe inadvertently have misled people to be seeing this report as a justification for their great fear,” said Howell. “I know there is a problem there, but … the magnitude may not be as great as what people thought because the report actually is misleading.”
State Epidemiologist and Environmental Health Officer Farah Ahmed told KMUW in December that KDHE has to measure cancer rates at the ZIP code level. That’s because a population estimate is needed to calculate the rates.
“We rely on census data for that,” Ahmed said. “And so there's no census data available at the neighborhood level, so I have to use census data for the ZIP codes.”
KDHE recently used ZIP codes to complete another health study in east Wichita at the request of the Forest Hills neighborhood, which has a contaminated groundwater plume beneath it. The study found no disproportionate cancer rates in the two ZIP codes encompassing the neighborhood.
Several neighbors complained that designing the study around the two ZIP codes, instead of the impacted neighborhood, could dilute the effect of the contamination.
What is the risk to residents?
It’s not clear when exactly the chemical spill near 29th and Grove took place, though experts have estimated it occurred in the 1970s or ’80s. City staff discovered it in 1994, and Union Pacific Railroad was identified as the source of the spill in 1998.
The chemical spilled – trichloroethylene – is often used in manufacturing. It’s also a carcinogen, with stong evidence linking it to kidney cancer and some evidence linking it to liver cancer. Some human studies indicate that trichloroethylene may cause small birth weight, though these people were also exposed to other chemicals. The Environmental Protection Agency announced in December that it was banning the chemical.
The largest risk to Wichita residents is if they drink the contaminated groundwater from a well, according to the KDHE.
The KDHE has said that City of Wichita public water – which is safe to drink – is available across the contamination area. One well used for water consumption was identified in the plume area in 2022, and bottled water was provided to the resident.
Anecdotally, some residents who live or have lived above the plume say that groundwater wells were common in the area decades ago.
Trichloroethylene also has the ability to evaporate from the groundwater into the air, and the KDHE has said there is potential for risk of residents inhaling contaminated vapors. Union Pacific conducted air quality testing in some homes and buildings above the plume in 2004, 2009, 2012 and 2013.
None of those tests found concentrations of trichloroethylene above the state’s indoor air quality standard for a residential setting, according to Sedgwick County.
However, the state’s air quality standard became more stringent between 2009 and 2012. Some air quality tests from three houses in 2004 showed TCE levels above KDHE’s current standard, but the levels fell within the standard at the time.
