The Lead Poisoning Case: A Surprising Culprit

In Bangladesh, turmeric — sold as the root or in a powder form — is a popular spice. In the 1980s, some farmers began adding a dye to make the root more attractive to buyers. But there was a problem with the dye. It was a type of lead, and it was poisoning millions of people.

Jenna Forsyth, a Ph.D. student in California, and Paromita Hore, a New York City detective who looks into cases involving toxic elements such as lead, each investigated cases of lead poisoning that involved Bangladeshi children in New York City and pregnant women in Bangladesh. Every time you go on such a mission, “it is absolutely a lead detective mystery,” says Hore.

Forsyth became so curious that she got on a plane and went to Bangladesh, where she teamed up with a renowned health research institute based there called icddr,b — formerly the International Center for Diarrheal Disease Research, Bangladesh. Together, they interviewed the pregnant women with high lead levels and came up with a number of possible causes: Perhaps the lead came from agricultural pesticides? “We sampled hundreds of agrochemicals. Did not find lead in them,” Forsyth says. Could it be lead in paint? “These women were living in primarily unpainted tin homes,” she says. Perhaps it was lead-soldering on cans used to store food that can flake off into the food? It happens but it wasn’t common enough to explain the data. Soil? Rice? No evidence found. None of the investigative work led to a clue that would solve the puzzle. “So, we went back to square one,” Forsyth remembers.

She reviewed all the studies done on this population in case there was a hint that had been missed. Poring over scientific papers, she found one small study of 28 kids that looked at heavy metal exposure and found lead in turmeric, the bright yellow powder that’s used as a spice and is one of the most common ingredients in Bangladeshi cuisine. Forsyth’s team started doing a bunch of testing and found there was indeed lead in both turmeric powder and turmeric roots they’d obtained in local markets. What’s more, the chemical fingerprint of the lead they found in the turmeric matched the lead in the women’s blood. Since there are four different types of lead, that was a eureka moment. “It was like, ‘Okay! Yes! Now, we can focus [our attention],” Forsyth recalls. But there were lots more questions. One of their biggest: How could lead have gotten into the spice?

Forsyth and her colleagues set out to talk to turmeric farmers – including a man in his 70s. His ancestors were turmeric farmers and he’d been harvesting the root all his life. He knew the processing steps intimately – from the boiling and drying of the root to polishing off the outer layer and then eventually grinding, all to make a brilliantly yellow powdered spice. “I remember we were sitting in the car – there was monsoon rain, splashing outside – and that's when the person said, ‘Yeah, back in the 1980s, there was a huge flood,’ ” Forsyth remembers. With so much rain, the farmer told her, turmeric roots wouldn’t dry properly in the sun. Instead of turning their usual bright yellow, the roots became black-ish. The farmers were desperate to restore the color so they could sell their crop. They went in search of a solution. “They found the cheapest yellow pigment available at that time,” Forsyth says. The vibrant yellow pigment was lead chromate. It’s often used in industrial paints – think of the yellow of construction vehicles.

The farmers made a fateful decision: They started sprinkling lead chromate on the turmeric roots when it was being polished to make them look better. The lead chromate turned the roots a bright yellow. It worked so well it became common practice. The farmers kept using the lead chromate even after the flood waters receded since the lead-laced-roots were more appealing in the marketplace. “They don't know that this is harmful for human health,” says Musa Baker, Forsyth’s colleague and a research investigator at icddr,b. “Rather, they want to expand their business” since their turmeric could now fetch a higher price. This discovery that lead was routinely added to turmeric came as a shock, especially since the spice is part of daily fare for Bangladeshis, says Baker. “It was really alarming,” says Dr. Mahbubur Rahman, the project coordinator at icddr,b. Their team gathered all the data they could, published it and brought it to the authorities in 2019. “The chairman of the Bangladesh Food Safety Authority, she took it very seriously,” says Baker. What the chairman knew from their travels is that this issue wasn’t limited to Bangladesh. It had reached halfway across the world to New York as well.