The rural areas of Bangladesh are quilted with verdant rice paddies nestled between glittering, blue river tributaries. Women wrapped in fuchsia, pomegranate-red and tangerine-orange saris walk among tan-and-brown cows. Market stalls are piled high with multicolored produce and spices. It is a country of vibrant colors.
This is where Jenna Forsyth landed in 2015, during the first summer of her PhD program with the Emmett Interdisciplinary Program in Environment and Resources at Stanford University. Armed with data that showed surprisingly high levels of lead in pregnant women in rural Bangladesh, her mission was to figure out where it was coming from and how to get rid of it.
At the start, there weren’t any obvious answers. There were no lead-belching factories in the area. Leaded gasoline had been banned for years. And it couldn’t be lead-based paint because few residents could afford to paint their homes. Her adviser thought the source could be lead-arsenate pesticides, but after spending days wading in muddy rice paddies, she ruled that out. She had hit a scientific dead end.
Undaunted, she returned to Stanford University and joined an interdisciplinary team of researchers to look at the problem anew. Ultimately, using old-fashioned detective work and high-tech chemical analysis, the team identified the source and joined government officials in getting the lead out. Now, they hope to use the same approach to reduce lead exposure throughout the world.
A heavy metal
Forsyth’s main PhD adviser was Stephen Luby, MD, an epidemiologist who had been tackling the global lead problem since the early 1990s. His work began in Pakistan, where his research contributed to banning leaded gasoline in that country. But after he read a study (Bergkvist et al., 2010, in Environmental Research) about unexpectedly high levels of lead in pregnant women in rural Bangladesh, he knew his work wasn’t done.
“There is no safe level for lead exposure,” said Luby, a Stanford School of Medicine professor of medicine and the director of research for the Stanford Center for Innovation in Global Health. Early in his career, Luby spent eight years focused on improving public health in Bangladesh, so this was personal.
Lead is a toxic heavy metal that can seriously damage reproductive, neurological and cardiovascular systems. Exposure to it is a global problem, with an estimated 1 in 3 children with blood lead levels at or above 5 micrograms per deciliter, the level considered unacceptable by the World Health Organization. (In October 2021, the U.S. Centers for Disease Control and Prevention lowered this level to 3.5 micrograms per deciliter.)
“There is no safe level for lead exposure.”
Stephen Luby, MD, director of research for the Stanford Center for Innovation in Global Health
Between 24 million and 46 million children and teenagers in Bangladesh are estimated to have lead levels above this threshold, the fourth highest number in this age group behind India, Nigeria and Pakistan. Lead poisoning has lifelong, irreversible effects on the cognitive abilities of children, and the social and economic impacts to a country can be devastating.
Children with blood lead levels above 5 micrograms per deciliter may score 3 to 5 points lower on intelligence tests than unaffected peers, limiting their potential. In addition, preschool lead exposure is often associated with juvenile delinquency, violence and crime. In Bangladesh alone, the lower IQ levels caused by lead poisoning are estimated to cost $16 billion annually in lost lifetime productivity, 6% of gross domestic product.
After Forsyth returned from Bangladesh, she reviewed her disappointing findings with Luby. But she had a hunch. She’d recently read a lead study from that region (Gleason et al., 2014 in Journal of Environmental and Public Health) hypothesizing turmeric as a potential source of lead. Could it be the powdery, orange-yellow spice that permeates daily life in Bangladesh? Turmeric is used in curries, as a clothing dye, in cosmetics, in medicines and as an insect repellent. Luby was skeptical, but he let her run with it. “Show me the evidence,” he said.
So, she analyzed 17 turmeric samples from her Bangladesh trip, and one had exceedingly high levels of lead and chromium. It was a start, and like any good medical detective, she began gathering more clues.
The golden spice
Forsyth is an environmental scientist with wanderlust. She’s spent nearly 15 years studying health problems in Bangladesh, Kenya, Tanzania, Costa Rica and Australia, looking for ways to reduce contaminants in air, water, soil and food.
When she was growing up in Logan, Utah, she loved mysteries. Early on, she decided to become a detective, and for her eighth-grade science fair project she went undercover to swab bathroom doorknobs at local restaurants, culturing bacterial samples to evaluate sanitation levels.
This love of evidence-driven puzzles set her on a course to carry on her detective work and, after studying bi
