Cancer Cluster Rene Long, left, Richard Hudson, Sandra Edwards and Mary Hutchins stand in front of an abandoned home in their Fifth Ward neighborhood on Thursday, Dec. 5, 2019, in Houston. A cancer cluster was identified in the the historically black north Houston neighborhoods of the Fifth Ward and Kashmere Gardens, near a site of legacy contamination from rail yard operations. Creosote was used for decades to treat wooden railroad ties in the yard. Though wood treatment has ceased for many years, the creosote sunk deep into the ground, creating a plume that has moved beneath an estimated 110 homes. The cancers identified in the cluster are associated with the contaminants found in creosote. (Brett Coomer/Houston Chronicle via AP)

HOUSTON — Texas health officials identified a cancer cluster in a north Houston neighborhood polluted by the wood preservative creosote from a nearby railroad operation, prompting calls from residents and the city for a more in-depth investigation of potential ongoing risks.

An assessment by the Department of State Health Services didn't attempt to determine whether the cancers were linked to chemicals beneath homes in the city's Fifth Ward and Kashmere Gardens. But the Texas Commission on Environmental Quality requested the assessment because of residents' concerns that a plume of polluted groundwater from the Union Pacific site had made some of them sick, and city health officials said it underscored the need for a closer examination.

"I was crying and frustrated," after learning about the cancer cluster, resident Leisa Glenn told the Houston Chronicle.

Creosote, deemed a probable human carcinogen, was used for more than 80 years in a rail yard in the historically black area, until the 1980s, the Chronicle reported.

The assessment found that the number of lung and bronchus cancers was, on average, 36% higher than would be expected, esophagus cancers almost 63% higher and larynx cancers 90% higher.

But the study cautioned that lifestyle and other factors also could be a cause, and it did not account for how long residents had lived in the area.

Still, "the contaminants in the plume are linked to those specific cancers," found in the assessment, said Loren Hopkins, chief environmental science officer at the Houston Health Department.

For example, arsenic is found in creosote and linked to lung cancer.

Union Pacific told the Houston Chronicle that it is reviewing the study, which it said it just received.

The study was completed in August but the city and residents were never notified by the state. The city health department learned about it at the end of November, officials said.

"The fact that there has been shockingly little communication between the state and community is astounding," said Elena Craft, a toxicologist and senior director of climate and health at the Environmental Defense Fund.

Union Pacific bought the site from Southern Pacific in 1996, and in 2014 warned residents against drinking water from wells because of contamination that had moved off-site.

It also has been using wells to extract contamination from the plume, and is testing the air in homes for harmful vapors.

The state environment agency said in a statement that it "continues to oversee cleanup activities being performed at the site."

Hopkins said city health officials have asked the state for additional studies to determine if there is an environmental link, and to consider liver cancer and non-cancer health effects, which she said also can be caused by chemicals in the plume.

In addition, the city health department will conduct a door-to-door health survey, and gather information about people who might have moved away before they were diagnosed with cancer, she said.

Hopkins said even if an environmental link were proven, it likely would have been caused by exposure when pollution levels were higher, because it takes a long time for cancer to develop.

Still, she said she was "very surprised" by the findings because it's often difficult to detect cancer clusters.

"I just feel the anxiety the citizens are suffering from living over this and finding out about the cancer cluster," she said. "It is tragic, and they are frustrated that things aren't moving faster."