South of downtown Los Angeles, residents of neighborhoods surrounding Exide Technologies battery recycling plant in Vernon have long worried about their exposure to lead and arsenic. The factory, which began operating in 1922, recycled 11 million auto batteries per year and released 3,500 tons of lead into the air. Regulators began to investigate the plant’s emissions in 2008, and it eventually closed in March 2015. Since then, state agencies have slowly begun to dig up soil from residents’ yards and dispose of it to clean up the area.
Now, a new study measures residents’ past exposure to lead using a new method: baby teeth. Researchers asked residents for baby teeth from children who grew up in the neighborhoods of Boyle Heights, Maywood, East L.A., Commerce and Huntington Park. They collected 50 teeth from 43 children and analyzed them for exposure to lead and arsenic.
The study, published this week in the journal Environmental Science and Technology, found that communities with the highest soil lead levels also had the highest lead levels in children’s teeth. Some of the highest exposures occurred when a baby was still in its mother’s womb, during the third trimester of gestation. “Babies are growing really fast at that point, and so a lot of really important infrastructure is being built,” says Jill Johnston, director of USC’s Environmental Health Centers Outreach Program. “A tiny dose that affects how the cells are building has a huge effect.”
As many as 250,000 residents, mostly working-class Latinos, face a chronic health hazard from exposure to airborne lead and arsenic that subsequently settles into the soil, according to a 2013 health risk assessment by the South Coast Air Quality Management District. There is no safe level of lead, which is a potent neurotoxin.
The resulting research is known as the Truth Fairy study, says Mark Lopez, executive director of the non-profit East Yard Communities for Environmental Justice. “Giving your kids’ teeth to people is weird,” Lopez acknowledges. “We know that folks are familiar with the tooth fairy so we’re not slipping them a dollar but what we can bring is truth. What we can bring is information.”
Johnston first came up with the idea of using baby teeth after she learned how they can provide insights into what exposures looked like five or 10 years – or even longer – ago in this community.
Teeth grow like tree rings and incorporate lead and other metals as they add layers of enamel and dentin. The researchers can analyze each layer of the tooth for lead levels, which gives information on fetal and early childhood exposure. Each layer represents about two weeks of exposure, so it’s possible to get a fine-grain sequence of exposure data from each tooth. To study the teeth, the researchers used a high-energy laser beam (1/3 the size of a human hair) that blasts a tiny hole in the tooth where the growth rings are to sample micron-level amounts of material with mass spectrometry.
Blood tests, on the other hand, only show lead exposure from the past 30 days – and the Exide plant had been shuttered for years. Plus, the largely Hispanic community living near the plant was leery of blood tests led by Los Angeles County.
Only a few studies have looked for lead in teeth, so there’s not much to compare the results to – though the researchers point out that the neighborhoods around the Exide plant had double the lead levels compared to similar urban neighborhoods in Boston.
“I think the study really confirms a lot of concerns the community had about long-term exposure and what it could mean for health because of the industrial activity in this community,” says Johnston. “Even though the facility is not operating, we have legacy exposure because of the lead in the soil and dust in the community.”
The community has pushed back against the Department of Toxic Substances Control has allocated more than $176 million in state funds earmarked for testing and cleanup. But those funds are tied up in environmental review, and only a few hundred houses have been remediated, Lopez says.
The Los Angeles County Board of Supervisors voted in April to start a lead-based paint cleanup program for residents in the area impacted by the Exide plant. A $5.2 million allocation from the county’s settlement with SoCalGas over the Aliso Canyon leak will fund the new program to clean up approximately 150-300 homes.
“We can clean up Exide, but this is continuing to be an intergenerational issue,” says Lopez, whose grandparents started working to stop the polluting plant in the 1990s. “I expect that my grandchildren are still going to be fighting this.”