Project Unleaded takes on global lead poisoning crisis

Lead, one of the most toxic substances on Earth, has turned up recently in protein powders, applesauce, and other common food products. The discoveries are reminders that lead exposure remains a threat everywhere, not just in developing countries.

"Americans generally think we've solved the lead problem," said Stephen Luby, principal investigator for Project Unleaded, a Stanford University initiative based at the Center for Human and Planetary Health working to identify and eliminate major sources of lead poisoning worldwide. "This is fundamentally not true."

Lead exposure kills approximately 5 million people annually and causes permanent brain damage in 800 million children across the globe. It lowers IQ, impairs learning, and costs the world economy over $1 trillion each year. Yet until recently, the problem received less than 1% of the funding allocated to diseases like malaria or tuberculosis.

"When you find elevated blood lead levels in a population, it's a signal of recent or ongoing exposure which will cause long-term damage," said Jenna Forsyth, director of Project Unleaded. "That's why prevention—finding and eliminating sources before exposure happens—is so critical."

12 years of investigative research

Luby, the Lucy Becker Professor of Medicine at Stanford, began investigating lead exposure in Bangladesh in 2013. Working with colleagues at the International Center for Diarrheal Disease Research, Bangladesh, Luby found that more than 30% of pregnant women in rural areas had elevated blood lead levels—but the source remained a mystery.

"There weren't any obvious answers," Luby said. The countryside had no lead-belching factories. Leaded gasoline had been banned. Lead-based paint was uncommon because few residents painted their houses.

When Forsyth joined the project as a Ph.D. student in 2014, she brought training in environmental engineering and a detective's instinct for following clues. She ruled out lead-arsenate pesticides after collecting and testing hundreds of pesticide samples. Back at Stanford, working with soil chemist Scott Fendorf and other colleagues, the team took a different approach: they examined the food supply chain.

Testing turmeric samples from Bangladesh revealed the answer. Some contained lead levels up to 500 times the national standard. Interviews with farmers and processors traced the practice to economic incentives: processors could command higher prices for brighter yellow turmeric, so they added a powerful industrial pigment that contains lead. Most processors were unaware of the potential health effects.

"People are unknowingly consuming something that could cause major health issues," Forsyth said at the time.

Working with Bangladesh's government, the researchers helped implement stricter testing, quality control measures, and enforcement. Within a year, lead levels in turmeric dropped more than 90%. Within two years, contamination was eliminated entirely. The intervention is estimated to have saved approximately 20,000 lives for less than $100 per person. Luby and Forsyth are working toward similar outcomes in India, Pakistan, Nepal and other countries.

Following the evidence

Forsyth and Luby's more recent work examines the battery manufacturing and recycling industry in Dhaka, Bangladesh. A source attribution study revealed these industries are the largest contributors to childhood lead poisoning in the capital city, with an estimated 5.5 million children and adults acutely affected through inhaling lead particulates in the air.

Bangladesh has hundreds of informal battery recycling operations, many operating illegally near residential areas. Workers break down old batteries, extract lead, and melt it in open air, releasing toxic fumes that poison entire communities. The problem has intensified as Bangladesh pushes to electrify its four million rickshaws—a booming industry worth an estimated $870 million.

"The key hurdles include overcoming pushback from industries that, like tobacco companies, have a financial incentive in continuing to generate a product that kills millions of people every year," Luby said.

Expanding scope and impact

Success in identifying and eliminating the major source of lead exposure across Bangladesh has inspired increased attention to addressing lead exposures.

Stanford researchers and local collaborators aim to conduct population-level studies in various countries and develop affordable lead detection methods that span applications from contaminated spices to environmental media, such as soil, air, and industrial hotspots.

The team's priorities include careful attribution studies on multiple sites with elevated population lead levels to clarify and focus intervention efforts and the development and evaluation of interventions to reduce these exposures.

Forsyth, Luby and collaborators at Stanford and organizations including UNICEF, Pure Earth, the Lead Exposure Elimination Project, Center for Global Development and universities across South Asia, are working to identify contaminated products, eliminate exposure, and mainstream awareness of lead as a critical development issue.

The work requires navigating complex political and economic forces. In many countries, pollutive, informal industries persist and regulations go unenforced. Creating sustainable change will require shifting market incentives and building government capacity to regulate industries.

"We need more strategic research to advance solutions to reduce lead exposure globally even in the context of limited resources, and we are thrilled to base this effort at the new Center for Human and Planetary Health," Forsyth said.

"Lead contamination exerts an immense global health burden, but careful collaborative interdisciplinary research can make this invisible toxin visible and provide a pathway to a healthy future," Luby said.

Provided by Stanford University