UC Irvine study finds dangerous lead levels at LA homes declared clean after remediation

• Even after one of California's largest cleanup efforts, nearly 70 percent of remediated homes near the former Exide battery smelter in Southeast L.A. still exceeded the state's soil lead threshold.
• Continued contamination disproportionately affects low-income, predominantly Latino families with young children.
• Community-driven research by UC Irvine helped expose ongoing contamination, prompting expanded testing, blood lead screening and stricter remediation oversight.

Irvine, Calif., April 6, 2026 - Even after one of the largest environmental remediation efforts in California history, dangerous levels of lead persist in residential neighborhoods surrounding a former battery smelter in Southeast Los Angeles, according to a new study from the University of California, Irvine's Joe C. Wen School of Population & Public Health.

The findings reveal a serious public health failure while also highlighting the power of community-driven research to hold institutions accountable and drive meaningful change.

A 15-acre smelting facility operated in Vernon, California, from 1922 to 2015 by Exide Technologies processed up to 40,000 lead-acid batteries per day, releasing an estimated 3,500 tons of lead over its final three decades. After a 2015 U.S. Department of Justice action forced the plant's closure, the state of California declared the contamination an environmental disaster and allocated $176.6 million to clean up residential homes within a 1.7-mile radius around the site.

The cleanup plan involved removing contaminated soil exceeding California's safety threshold of 80 parts per million - without requiring verification testing after remediation, which is ongoing.

To investigate whether the cleanup was effective, researchers at Wen Public Health partnered with East Yard Communities for Environmental Justice to launch the Get the Lead Out! study. Between October 2021 and September 2024, the team collected 1,128 soil samples from 373 residential properties.

The results, published recently in Environmental Science & Technology, are striking:

• 70 percent of remediated homes yielded samples that exceeded 80 ppm.
• Contamination extended beyond the state's 1.7-mile cleanup boundary.
• 89 percent of samples from homes outside that boundary exceeded safe levels.
• Average soil lead levels measured 215 ppm - nearly three times the state limit.

Researchers also found that contamination spread primarily north and northeast of the site - with some of the highest levels detected outside the official cleanup zone.

"These neighborhoods are predominantly low-income, largely Latino and home to more young children than the county average, yet more than a third of yards the state declared 'clean' still exceed its own safety threshold," said Jill Johnston, UC Irvine associate professor of environmental and occupational health and the study's corresponding author. "That's a systemic failure in how this cleanup was designed and verified. The community knew something was wrong - and the data proved it."

Lead exposure is especially dangerous for children, in whom it can cause irreversible damage, including learning disabilities, behavioral challenges and reduced lifetime earnings potential. Among adults, it's linked to cardiovascular disease, including heart disease and stroke. In California alone, the economic burden of lead exposure is estimated at $8 billion to $11 billion annually.

In addition, the study highlights the outsized impact on vulnerable communities. The affected neighborhoods are more than 90 percent Hispanic, with a high proportion of renters and families with young children. These populations often face barriers to environmental protections and healthcare access.

Community leadership played a central role in translating preliminary Get the Lead Out! findings into policy change. Local advocates, including residents who first raised concerns about ongoing exposure, helped push for expanded testing, stronger oversight and greater transparency. Their efforts, combined with the study's findings, have already led to measurable changes:

• Creation of a biweekly Exide working group comprising regulators, public health officials and community leaders
• New requirements for post-cleanup verification testing at all properties
• Deployment of a state-funded third-party monitor to oversee remediation work
• Expansion of free blood lead testing through the Los Angeles County Department of Public Health
• Secured funding to clean contaminated parkways
• Public access to cleanup data through an interactive mapping tool

"This is what community-based participatory research can do," Johnston said. "When communities are true partners in generating evidence, that evidence drives real change. New safeguards, new oversight and greater accountability are put in place. But rebuilding trust in communities that have been failed for decades will take sustained commitment."

The researchers also found evidence of recontamination, suggesting that current cleanup strategies may not be sufficient to prevent ongoing exposure, particularly as contaminated dust continues to move through the environment.

While soil removal can reduce future exposure, the study's authors emphasize that cleanup alone does not address decades of harm or ongoing health risks. They urge decision-makers to go further - ensuring cleanup plans are enforced, understanding how recontamination occurs, and committing to neighborhood-scale remediation that keeps residents at the center of decision-making.

The study was supported in part by the Robert Wood Johnson Foundation Interdisciplinary Research Leaders program and the National Institutes of Health.

Co-authors included researchers from UC Irvine, UC Santa Barbara and East Yard Communities for Environmental Justice.

About the University of California, Irvine: Founded in 1965, UC Irvine is a member of the prestigious Association of American Universities and is ranked among the nation's top 10 public universities by U.S. News & World Report. The campus has produced five Nobel laureates and is known for its academic achievement, premier research, innovation and anteater mascot. Led by Chancellor Howard Gillman, UC Irvine has more than 36,000 students and offers 224 degree programs. It's located in one of the world's safest and most economically vibrant communities and is Orange County's second-largest employer, contributing $7 billion annually to the local economy and $8 billion statewide. For more on UC Irvine, visit www.uci.edu.

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