Systemic drivers of toxic food adulteration: lead chromate in turmeric across eastern India.

Food adulteration poses a growing threat to the integrity of food systems and public health globally. This study investigated turmeric adulteration with lead chromate across five eastern Indian states through a combination of sample analysis and qualitative supply chain assessments. We collected 503 turmeric samples from 34 cities and conducted 128 stakeholder interviews between 2021-2023. In total, 30% of turmeric samples exceeded India's permissible lead limit of 10 µg g⁻¹, with the highest levels in the state of Bihar (geometric mean: 48 µg g⁻¹, maximum: 6,416 µg g⁻¹). Adulteration primarily served to enhance turmeric root color and extend shelf life. Although regulations prohibit lead in turmeric, enforcement has been inconsistent-hindered by limited capacity and the prioritization of more immediate or visible issues. Using population-level exposure modeling, we estimate that halting the practice of turmeric adulteration with lead chromate could increase child IQ by up to 2.3 points, resulting in future income gains of US$ 239 million to 1.6 billion annually in Bihar alone. If cardiovascular disease mortality reductions are included, there would be an additional benefit of approximately US$ 430 million to 2.8 billion per year. Our findings underscore the urgent need for strengthened governance and targeted supply chain interventions.