Air quality technicians hired by the Los Angeles County Department of Public Health have tested the air and dust in 100 Porter Ranch homes and found what they describe as low levels of a number of metals that should not be in the homes.
Despite the low levels, public health officials say certain metals may be the reason for the nosebleeds, headaches, nausea and other symptoms residents have complained about in the nearly three months since crews capped the natural gas leak at the Aliso Canyon Storage Facility adjacent to the community.
Here are answers to some of the questions raised by the tests.
Which metals were found?
County health officials say a number of metals were discovered, but they focused on five that showed up most frequently in their salt forms: barium, manganese, vanadium, aluminum and iron. The metals did not turn up in the tests of a control group of 11 homes located outside the zone affected by the gas well blowout.
Are officials certain that these metals are behind the headaches, nausea and other symptoms Porter Ranch residents are still reporting?
No. Cyrus Rangan, the head of Public Health's bureau of toxicology and environmental assessment, says "we're not saying we've found the canary [in the coal mine], so to speak." He says these metals "have the potential to cause some of these symptoms," but he cannot say that they are "definitely causing all the symptoms."
Rangan notes that the county's tests were only spot checks of 100 homes, so there could be higher concentrations of these metals in other parts of the homes.
Where do the metals come from and how did they get into homes at Porter Ranch?
Public Health says the metals were "consistent with those found in well drilling fluid which suggests they originated from" the storage facility.
Barium is added to the heavy drilling muds and fluids used during well drilling and in efforts to plug leaking wells. In the days following the initial well blowout last fall, Southern California Gas Co. workers made several attempts to plug the well by forcing heavy mud and fluid into it. But the pressure of the gas field was so high that it kept blowing the mud and fluids out of the well. Outdoor surfaces around homes, schools and parks were speckled with an oily black residue.
Were these metals part of the fluids and drilling muds used in the early attempts to seal the well?
L.A. County officials have been asking SoCal Gas to identify the content of the muds and fluids it used at the Aliso Canyon rupture well, but the gas company has declined to provide that information, saying it is proprietary.
What were the levels of the metals that were found?
The specific levels are detailed in this report from Public Health.
Interim County Health Officer Jeffrey Gunzenhauser says the levels were "at a very low level, below the levels we would normally consider to pose any kind of health risk for individuals."
What is known about the short and long-term health effects of these metals?
Barium sulfate is not considered to pose a long-term health threat, according to the Centers for Disease Control & Prevention's Agency for Toxic Substances & Disease Registry. It can cause redness and itching in the eyes and nose, and a scratchy throat.
Nausea, mild diarrhea and stomach cramps have been reported in people who have been exposed to some vanadium compounds.
Aluminum and manganese can create health problems (lung problems with aluminum dust, nervous system issues with manganese), but only if they are ingested in amounts far greater than what Public Health has reported finding.
Ferrous sulfate (iron) can cause constipation and an upset stomach.
How can these metals be removed from homes?
Public Health has devised a protocol for cleaning homes that includes a variety of measures, including comprehensive cleaning of surfaces and thorough ventilation to flush out residual contaminants. The full cleaning guidelines can be found here.
What about the air outside or on surfaces at my kids' schools?
In addition to home testing, the county tested the two public schools at Porter Ranch. The county tested for a total of 250 contaminants and found none of them in the air. It's unknown the extent of dust contamination from the metals beyond the homes tested.
Is there a test to determine whether I’ve been exposed to these metals?
There is no routine test for barium exposure. There are complex instruments that can be used to measure it in bones, blood, urine and feces, but those measurements cannot predict the extent of exposure or potential health effects. This is typically done only in cases of severe barium poisoning and for medical research.
Vanadium can be measured in blood and urine. These tests cannot determine if harmful health effects will occur from exposure to vanadium.
Aluminum can be measured in blood, bones, feces or urine. Urine and blood measurements can tell you whether you have been exposed to larger-than-normal amounts of aluminum.
Several tests are available to measure manganese in blood, urine, hair or feces. Manganese is normally present in the body, so some is always in tissues or fluids. Excess manganese is usually removed from the body within a few days, so past exposures are difficult to measure with common laboratory tests.
This story has been updated.