Federal health officials are conducting a new study to determine whether veterans once stationed at a now-shuttered California military base were exposed to dangerously high levels of cancer-causing toxins.

The decision by the Centers for Disease Control and Prevention comes nine months after an Associated Press investigation found that drinking water at Fort Ord contained toxic chemicals and that hundreds of veterans who lived at the central California coast base in the 1980s and 1990s later developed rare and terminal blood cancers.

In a letter last Friday to Rep. Katie Porter, D-Calif., the director of the CDC’s Agency for Toxic Substances and Disease Registry, Patrick Breysse, wrote that “there are sufficient data and scientific reasons for ATSDR to re-evaluate health risks related to historical drinking water exposures at Fort Ord.” Porter had asked for a new study in February, two days after the AP published its story.

The agency did not immediately respond to a request seeking further details about the new study.

Army veteran Julie Akey, who lived at Fort Ord and was diagnosed in 2016 at the age of 46 with multiple myeloma, a rare blood cancer, said she is “confident that science will prove our high rate of cancers and illnesses are not a coincidence.”

Akey started a Facebook group for Fort Ord veterans with cancer. The number has grown to nearly 1,000.

In 1990, four years before it began the process of closing as an active military base, Fort Ord was added to the Environmental Protection Agency’s list of the most polluted places in the nation. Included in that pollution were dozens of chemicals, some now known to cause cancer, that were found in the base’s drinking water and soil.

The AP’s review of public documents showed the Army knew that chemicals had been improperly dumped at Fort Ord for decades. Even after the contamination was documented, the Army played down the risks.

One of those chemicals was trichloroethylene, or TCE, which was known as a miracle degreaser and was widely used at Fort Ord. The Army found TCE in Fort Ord’s wells 43 separate times from 1985 to 1994, and 18 of those tests showed TCE exceeded legal safety limits.

The new health study will update one conducted more than 25 years ago. The previous ATSDR public health study, published in 1996, found that toxins in the soil and in the aquifers below Fort Ord were not likely to pose a past, present or future threat to those living there.

But that conclusion was based on limited data supplied by the military and before medical science understood the relationship between some of the chemical exposures and cancer, particularly TCE. Four years after the ATSDR’s assessment, in 2000, the Department of Health and Human Services added TCE to its roster of chemicals known to cause cancer.

It’s unclear how long and at what concentrations TCE may have been in the water before 1985, when hundreds of thousands of people lived on the base. And TCE wasn’t the only problem. The EPA identified more than 40 “chemicals of concern” in soil and groundwater.

The Department of Veterans Affairs told the AP earlier this year that the contamination was “within the allowable safe range” in areas that provided drinking water.

Veterans who lived at Fort Ord and have since tried to get medical care or disability benefits through the VA based on their cancers have repeatedly been denied. Akey and others hope the new study will find a link between their cancers and their time at Fort Ord, allowing them to get care and benefits.