New study reveals extreme variability of harmful chemicals in smokeless tobacco products in India

In India, nearly 200 million adults regularly use smokeless tobacco (SLT) products such as chewing tobacco and snuff. Incidentally, India has one of the highest global rates of oral cancer. Although 90 percent of those cancers can be attributed to carcinogenic chemicals present in smokeless tobacco, little information exists about the levels of such chemicals across various smokeless tobacco brands and products sold in India.

Over the past decade, University of Minnesota investigators, including researchers from the Masonic Cancer Center (MCC), have been engaged in a research partnership with researchers at Tata Memorial Centre in Mumbai, India, to fill this gap and build local capacity for analysis of smokeless tobacco products and relevant biomarkers in users. This partnership culminated in a new study investigating how much the SLT products sold in Mumbai vary in nicotine (an addictive chemical in tobacco) and tobacco-specific nitrosamines (TSNA, which are cancer-causing chemicals). While prior limited publications reported on the levels of such chemicals in Indian SLT products that were shipped to laboratories in the U.S., this is a first-of-its-kind study to come out of a laboratory in India. 

The study, published in The Lancet, looked at 321 samples representing 57 different brands of SLT products. The study is the most extensive analysis of brand-specific nicotine and TSNA levels in SLT products marketed in India. Key findings from the report include:

• Extremely variable levels of nicotine and TSNA across SLT brands.
  • Levels of unprotonated nicotine—the most addictive form—varied more than 2,500-fold  across products, ranging from less than 1 percent to 100 percent of total nicotine content.
  • The levels of cancer-causing TSNAs also varied significantly, ranging more than 1,000-fold across different brands.
• Inconsistent product manufacturing. Even within the same brand, products bought from different vendors showed differences in nicotine and TSNA levels, likely due to inconsistent manufacturing and storage practices.

“While all smokeless tobacco products are harmful, these findings reveal that consumers of some brands are unknowingly exposed to extremely high levels of addictive and cancer-causing chemicals,” said SPH Professor Irina Stepanov. co-principal investigator on the study and MCC member. “These findings emphasize the critical need for educational and policy efforts in India to prevent smokeless tobacco use and encourage its cessation.”

Co-principal investigators on the study are MCC member Samir Khariwala from the U of M Medical School, Stepanov from the University of Minnesota School of Public Health, and Pankaj Chaturvedi from the Advanced Center for Training, Research, and Education in Cancer (ACTREC) in Mumbai. Stepanov is also U of M Distinguished McKnight University Professor, Mayo Professor in Public Health, and director of the Institute for Global Cancer Prevention Research.

The study was funded by a research grant from the National Institutes of Health. The research is a collaboration between the University of Minnesota, ACTREC, and the Healis Institute for Public Health in Mumbai, India.

This story was authored by Virgil McDill and was first published by the School of Public Health.