Low birth weight rates rose nearly 50% around Aliso Canyon gas leak, UCLA study finds

New research is showing that the effects of one of the largest methane gas leaks in U.S. history could reverberate for generations.

Nearly 10 years ago, a Southern California Gas Company storage facility in Aliso Canyon leaked methane for almost four months, spewing years’ worth of planet-heating carbon emissions into the atmosphere and dangerous chemicals into nearby San Fernando Valley communities, including Porter Ranch, Granada Hills and Chatsworth.

A study published Friday in the journal Science Advances found that women who were pregnant at the time of the leak had babies with low birth weights at rates almost 50% higher than normal.

“There are risks to having these large natural gas storage facilities close to major urban populations,” said Michael Jerrett, principal investigator of the UCLA Aliso Canyon Disaster Health Research Study team. “It can translate into substantial health effects that could have lifelong effects.”

Not only did the Aliso Canyon gas storage facility leak the superheating greenhouse gas methane, but it also released chemicals such as benzene, a known carcinogen, and hexanes, which have been linked to low birth weight in other studies, Jerrett said. Heavy metals were also found in some homes downwind.

Research has linked low birth weight to developmental disorders, such as autism and  attention deficit hyperactivity disorder, as well as chronic diseases in adulthood, including diabetes, high blood pressure and some heart diseases, Jerrett said.

The researchers emphasized the low birth weight is not a guarantee of these long-term effects, but that it is “an important overall indicator in public health,” said Kimberly Paul, lead author of the study and assistant professor-in-residence in the department of neurology in the David Geffen School of Medicine at UCLA.

Paul and her team analyzed birth records within and downwind of the leak’s plume and compared them to similar communities in L.A. County during the period of the leak. They found that pregnant women living closest to the leak were more likely to have adverse birth outcomes, but pregnant women living as far as 9 miles downwind also had higher rates of low birth weight.

Researchers grouped study subjects by their distance from the leak. Adverse effects were found up to 9 miles downwind.

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The study also found a likely increase in miscarriages during the leak.

“No matter who we compared the Aliso community to — whether it was these other communities or even women who lived in Aliso before the blowout — we found that the prevalence of low birth weight and term low birth weight was almost 50% higher than expected,” Paul said.

Since the leak, community members near the Aliso Canyon gas storage facility have called for the facility to be shut down, but state officials have pushed a shutdown timeline back, citing the state’s energy needs.

Activists called for the total shutdown of Aliso Canyon after the leak, but it remains open nearly 10 years later.

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“It's important for studies like this to continue so that we better understand what all the risks and benefits of continued reliance on natural gas are for local communities, but also for the broader region of Los Angeles,” Jerrett said.

He and Paul hope the study will help inform policy to better protect public health as the state transitions to cleaner energy sources.