Ron Cox’s family lived in a mobile home park in El Cajon. Vapors from underground pollution have been found in several homes near where the Cox family lived. April 25, 2017. Brandon Quester, inewsource
Ron Cox’s family lived in a mobile home park in El Cajon. Vapors from underground pollution have been found in several homes near where the Cox family lived. April 25, 2017. Brandon Quester, inewsource

Vapors from a dangerous chemical that runs underground in El Cajon have seeped into people’s homes, new air testing shows, contrary to what some residents were led to expect when they learned of the plume last October. In some homes, people may have breathed the gas for years or even decades.


News in Numbers


State officials offered 19 households in the Starlight Mobile Home Park and Greenfield Mobile Home Estates air testing four days after inewsource reported the plume ran beneath their community, and 18 days after the Department of Toxic Substances Control issued a Proposition 65 hazard warning.

It is the first time anyone has assessed the air inside homes in the 30 years since a county employee discovered the contamination, despite the fact the community borders Magnolia Elementary School, which closed temporarily over the issue and is perforated with monitoring wells.

The gas is trichloroethylene, or TCE, a chemical commonly used for cleaning and degreasing. TCE is a strongly linked to kidney cancer, according John Budroe, senior toxicologist with the state environmental health agency. It may also cause liver cancer and malignant lymphoma. It is harmful to babies in utero and and can lower men’s hormone levels, sex drive and sperm quality, he said.

View larger map – click on a color in the plume to see approximate concentration

Specialists with ERM, a contractor for Ametek Inc., tested 18 of some 45 homes that sit atop the most potent part of the plume. In one, the air tested far above the level that calls for immediate action, according to Environmental Protection Agency guidelines. Three others homes tested above the “accelerated response action level.” Two had worrisome levels in the crawl space. Eight did not have significant amounts of the gas, two were slightly elevated, and the results for two more homes are not yet in.

“Nobody knows the effects of living over a house that has the minimum or acceptable amount of TCE seeping up into the air for 30 years,” said Ron Cox, who is suing Ametek and the company currently operating at the site, Senior Operations, for loss of home value. His family lived in a third mobile court, Villa Cajon Mobile Home Estates.

Cox’s mother, Arla JoDoell Cox, died at age 63 of kidney cancer. His brother, Adam Cox, is in hospice with a brain tumor.

“They failed to let me or my family know this is happening and this could affect their health, why haven’t they fixed it, why didn’t the notify they public?” he asked.

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Dr. Mary McDaniel, an environmental medicine physician consulting with Ametek, the legally responsible party, said the mobile home parks weren’t tested sooner because years of testing at the school indicated levels there were safe. Company officials and state officials with the San Diego Regional Water Quality Control Board believed the levels would be even lower inside the homes.

The company and its contractor have been expanding a system of groundwater treatment.

“In fact Ametek began environmental remediation on the site even before the water board order requiring them to. So there’s been pump-and-treat systems installed. There’s been a system installed in the classrooms at the school,” she said.

The fact that some houses did have actionable levels of the gas was a surprise, McDaniel said.

Ametek had air purifiers installed immediately in two homes.

The attorney for Cox, John Fiske, described a different history leading up to the discovery of the TCE inside people’s homes.

“Ametek and its top executive ignored notices of violation and abatement from the water board. The water board tried for ten years to get Ametek to clean this up and they refused to do it.”

The plume may originate from as many as seven places on the 17 acre former manufacturing site where chemical waste was thrown away in pits or sumps, said Sean McClain, an engineering geologist who has worked on the site for the Regional Water Quality Control Board. The practice continued into the 1980s, documents show.

From there, the chemicals flow down through broken rock into the shallow groundwater, under the densely populated mobile home parks, beneath Highway 67 and toward the Gillespie Field airport, where the plume loses steam 1.3 miles from its source.

How much liquid waste do you have to pour underground to get it to travel for 1.3 miles? State documents show one “collection tank” was meant to receive up to 7,000 gallons of used chemicals per month. The plume is notable for its length.

Three residents from Greenfield Mobile Home Estates have also filed a lawsuit in San Diego Superior Court. Ametek responded with a list of 39 defenses.

Earlier coverage:

Toxic plume in El Cajon reaches beneath mobile homes
October 20, 2016

El Cajon homes to be tested, and a new map of a toxic plume
October 31,2016

El Cajon meeting for residents concerned about toxic plume
November 15, 2016

El Cajon residents pack meeting on toxic plume
November 17, 2016

Correction: The Department of Toxic Substances Control said an earlier version of this story misstated its belief about levels of a toxic substance inside homes. That reference has been removed.

Ingrid Lobet is a reporter at inewsource specializing in the environment. To contact her with tips, suggestions or corrections, please email