Contra Costa Health (CCH) said Thursday a toxicologist determined that Martinez Refinery Company's (MRC) release of spent catalyst in November didn't increase public health risks from exposure of hazardous materials in nearby soil.
The assessment was done by the contractor TRC, which concluded metals detected in 14 soil samples didn't appear in similar ratios or quantities to spent-catalyst dust samples collected shortly after the release Nov. 24-25, 2022.
Metals detected in the soil samples were within an expected range of levels typically found in the state.
CCH said the primary health risk from the release occurred during the initial hours and days after the refinery accident when people may have breathed in dust particles.
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"Contra Costa County has taken all steps to determine whether residents suffered any health consequences from November's hazardous materials release," John Gioia, chair of the county Board of Supervisors, said in a statement. "We are committed to holding MRC responsible for any impacts to the community and to ensuring that this type of incident does not happen again."
The release of "spent catalyst" started around 9:30 p.m. on Thanksgiving, and continued into the next day, showering the surrounding community in the dust-like substance.
Initial samples of the dust showed elevated levels of aluminum, barium, chromium, nickel, vanadium, and zinc, all of which can cause respiratory problems.
Contra Costa County policy required MRC to alert the community via the county emergency system and to immediately notify the county health department, neither of which happened. County health officials say they learned about the release via media reports a day and a half later.
The Contra Costa County District Attorney's Office is still investigating MRC for failing to notify authorities when it released 20 to 24 tons of waste into the air.
The Board of Supervisors put together an oversight committee, including residents from affected areas, to investigate whether the release increased risk of health problems in the community due to environmental contamination. The panel is also looking at what caused the release.
CCH said county health officer Dr. Ori Tzvieli will lift a March health advisory that warned refinery neighbors not to eat produce grown in soil possibly contaminated by spent catalyst dust until environmental testing could be completed.
"Now that we have these results, I personally would have no issue eating fruits and vegetables grown in ground soil from one of the affected areas," Tzvieli said in a statement.
CCH said the soil testing underscored the fact that metals in the ground are "a fact of life in developed areas like Contra Costa with heavy industry and agriculture." Metals found in the samples included lead and arsenic, once commonly used in pesticides, but the measured amounts didn't suggest a link to the spent-catalyst release.
CCH also said, "It's important to note that there is no absolute safe amount of arsenic that humans and animals can ingest. But while most edible plants absorb some small amounts of arsenic, they usually do not contain enough to be a health concern."
Tzvieli said people who are worried they may have elevated levels of lead, arsenic or other metals on their property can grow produce in pots or raised garden beds using clean store-bought soil. He also recommends rinsing and/or scrubbing produce well and peeling root crops like potatoes and carrots.
