The Delano Guardians hosted a community meeting on April 21 to inform residents about potential health risks associated with indoor air exposure to chemicals from an underground tetrachloroethylene (PCE) plume in downtown Delano. Environmental scientists presented their report, which indicates that indoor air quality in certain buildings is a concern.
The Agency for Toxic Substances and Disease Registry (ATSDR) and the Department of Toxic Substances Control (DTSC) have identified several dry cleaners on Main Street as the source of the underground water plume and contaminated soil. These include Oak Lane Dry Cleaners, Oasis Dry Cleaners, and the former National Cleaners.
Although Delano’s drinking water is sourced from groundwater wells that are not affected by the contaminated plume, chemicals from the plume may still enter nearby buildings through vapors seeping from contaminated soil or groundwater.
DTSC has been investigating this contamination for about 10 years and has taken measures to clean up the affected sites and reduce exposure. The most recent step occurred in 2023, when DTSC began operating two soil vapor extraction (SVE) systems in the downtown area. These systems act like vacuums to remove PCE vapors from the soil and help reduce vapor intrusion into buildings.
In 2022, the Delano Guardians and other community groups requested a report from ATSDR to understand how these chemicals might affect the health of local residents after community members began raising concerns.
“We had several people who had either worked at the well, worked within the vicinity, and we were hearing that there were several people that either recently been diagnosed—or throughout the years as they worked—they’re diagnosed with some kind of cancer,” said Yolanda Vega, President of the Delano Guardians.
Using environmental data collected by DTSC between 2011 and 2024, ATSDR concluded that the former Quality Appliances Building, labeled as Building 36, has elevated levels of chloroform in indoor air. Long-term exposure to chloroform in this building, specifically over 20 years or more, could increase the lifetime cancer risk for full-time workers.
“Breathing chloroform for 20 years or more may increase lifetime cancer risks among full-time workers,” explained Ben Gerhardstein, an environmental scientist with ATSDR. “If somebody worked in that building for 20 years or more and breathed the chloroform that was in the building, it could increase their cancer risk.”
Gerhardstein also noted that indoor air samples from Building 36 were only collected in 2015 and 2016, and chloroform levels may have changed since then.
In a residential building, labeled Building 17, exposure to chloroform and 1,2-dichloroethane (1,2 DCA) may slightly increase the lifetime cancer risk. However, this risk is considered low. ATSDR’s toxicological evaluation found that exposure to the combination of chemicals in indoor air poses a low concern for increased cancer risks for people exposed for more than 33 years and children exposed for 21 years.
“ATSDR performed an in-depth toxicological evaluation and estimated cancer risks for children and adults,” Gerhardstein said. “That assessment found that exposure to the combination of chemicals in indoor air is a low concern for increased cancer risks for two groups of people: people exposed for more than 33 years and children exposed for 21 years.”
ATSDR determined that the chloroform in Building 17 likely comes from indoor sources, such as vaporized drinking water or cleaning products. However, the source of 1,2-dichloroethane remains unknown.
“In that building, we were able to determine that chloroform likely comes from an indoor source,” Gerhardstein said. “Sometimes chloroform comes from drinking water—it can be vaporized into the air—or from cleaning products. Those are possibilities. But we don’t know the source of the 1,2-DCA.”
In Oak Lane Cleaners, labeled Building 22, the indoor air chemical levels are currently below thresholds that would cause health problems. However, a sample taken in November 2023 showed a significant increase compared to a previous sample from 2018.
“If Trichloroethylene, TCE, levels keep rising, it could become a health concern in the future,” Gerhardstein warned.
ATSDR also assessed four homes and 27 commercial buildings in downtown Delano and found no current health concerns. Despite this, Gerhardstein noted that 317 buildings could not be assessed due to certain limitations in data availability.
To improve indoor air quality, ATSDR recommends that residents reduce their use of harmful chemicals by removing or using fewer products that emit vapors. They should also increase ventilation by letting more outdoor air into their buildings and consider using air purifiers. Building owners are advised to take steps to lower chemical levels indoors, seal cracks or holes in floors or foundations to prevent vapor intrusion, make necessary building modifications, and cooperate with DTSC by allowing access for air sampling.
The full report is available at https://www.atsdr.cdc.gov/HAC/pha/Delano/Delano-HC-508.pdf.
