Study finds 70% of remediated Los Angeles yards still exceed lead limit

A comprehensive new study from the University of California, Irvine's Joe C. Wen School of Population & Public Health reveals that dangerous lead levels persist in residential neighborhoods surrounding a former battery smelter in Southeast Los Angeles, despite one of California's largest environmental remediation efforts. The research, published in Environmental Science & Technology, demonstrates how community-driven science can drive accountability and meaningful environmental policy change.

Background: Decades of Industrial Contamination

The Exide Technologies facility in Vernon, California, operated for 93 years before closing in 2015 following a U.S. Department of Justice enforcement action. During its final three decades, the 15-acre smelting operation processed up to 40,000 lead-acid batteries daily, releasing an estimated 3,500 tons of lead into the surrounding environment.

Following the plant's closure, California declared the contamination an environmental disaster and committed $176.6 million to remediate residential properties within a 1.7-mile radius of the site. The cleanup protocol involved removing soil that exceeded California's safety threshold of 80 parts per million (ppm) of lead, but notably did not require post-remediation verification testing.

Community Partnership Drives Research

Recognizing the need to assess cleanup effectiveness, UC Irvine researchers partnered with East Yard Communities for Environmental Justice to launch the Get the Lead Out! study. Between October 2021 and September 2024, the collaborative team systematically collected 1,128 soil samples from 373 residential properties across the affected area.

Significant Findings Reveal Ongoing Contamination

The study's results highlight substantial shortcomings in the remediation effort:

Remediated Properties:

• 70% of homes that underwent state cleanup still contained soil samples exceeding the 80 ppm safety limit
• More than one-third of properties declared "clean" by the state continue to pose health risks

Geographic Distribution:

• Contamination extends significantly beyond the official 1.7-mile cleanup boundary
• 89% of samples from properties outside the designated cleanup zone exceeded safe levels
• The highest contamination levels were detected north and northeast of the former facility

Contamination Severity:

• Average soil lead levels measured 215 ppm—nearly three times California's safety threshold
• Some areas showed evidence of recontamination, suggesting ongoing environmental exposure

Health and Social Justice Implications

Lead exposure poses particularly severe risks to children, causing irreversible neurological damage that can result in learning disabilities, behavioral challenges, and reduced lifetime earning potential. For adults, exposure is linked to cardiovascular disease, including heart disease and stroke. California estimates the annual economic burden of lead exposure at $8 billion to $11 billion.

The affected neighborhoods bear a disproportionate burden of this environmental hazard. The communities are more than 90% Hispanic, with high concentrations of renters and families with young children—populations that often face systemic barriers to environmental protection and healthcare access.

"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."

Community Advocacy Drives Policy Reform

The study exemplifies the power of community-based participatory research to generate evidence that drives policy change. Local advocates, including residents who initially raised concerns about ongoing exposure risks, worked alongside researchers to translate preliminary findings into concrete reforms.

Key Policy Achievements:

• Establishment of a biweekly Exide working group including regulators, public health officials, and community representatives
• Implementation of mandatory post-cleanup verification testing for all remediated properties
• Deployment of state-funded third-party monitoring to provide independent oversight of remediation activities
• Expansion of free blood lead testing services through the Los Angeles County Department of Public Health
• Secured funding for contaminated parkway cleanup
• Creation of an interactive public mapping tool providing transparent access to cleanup data

Implications for Future Environmental Remediation

The research underscores critical gaps in current environmental cleanup protocols and highlights the importance of community engagement in ensuring effective remediation. The evidence of recontamination suggests that soil removal alone may be insufficient to prevent ongoing exposure, particularly as contaminated dust continues to circulate through the environment.

"This is what community-based participatory research can do," Johnston emphasized. "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 study's authors advocate for comprehensive approaches to environmental remediation that go beyond soil removal to address decades of accumulated harm and prevent future exposure. They emphasize the need for robust enforcement of cleanup standards, improved understanding of recontamination mechanisms, and commitment to neighborhood-scale solutions that prioritize community input throughout the decision-making process.

This research demonstrates that effective environmental justice requires not only technical remediation but also sustained community partnership and systemic policy reform to address the root causes of environmental inequality.