TEXAS — A new study published in the journal Biological Trace Element Research links secondhand smoke exposure to higher blood cadmium levels in adults.

Researchers analyzed national health data from 2015 to 2020 to assess cadmium levels in the blood and urine of 1,380 children and teenagers and 3,686 adults.

The study found that adults with heavy secondhand smoke exposure had approximately 1.5 times more cadmium in their blood compared to adults in smoke-free environments. Active adult smokers exhibited over three times more cadmium in their blood than adult nonsmokers. Cadmium levels in children and teenagers showed no measurable change based on tobacco smoke exposure.

"We knew that cigarette smoke exposes people to cadmium, but until now, we didn't know about the association with secondhand smoke," said Nandita Sarker, a doctoral student involved in the research. "This is important information because cadmium builds up in the body over time and is a factor in kidney, lung and prostate cancers," she said.

"Our findings suggest that secondhand smoke may contribute to the long-term accumulation of cadmium, a metal associated with cancer and other chronic diseases," said Taehyun Roh. "These results highlight the importance of protecting people from tobacco smoke exposure not only for respiratory health, but also for reducing exposure to harmful environmental contaminants that can accumulate in the body over time," he said.

The study also observed that women had higher cadmium levels than men across all age groups. Additionally, participants from racial minority groups, or those with lower income or less education, experienced higher exposure to cadmium. "This disparity cannot be explained by smoking habits alone, but likely is the result of broader social, environmental and financial inequalities," Sarker said.

Researchers measured both cadmium and cotinine levels in subjects to categorize tobacco smoke exposure. Cotinine remains in the human body for approximately 15 to 20 hours. "Cotinine only stays in the human body for about 15 to 20 hours, and this short window means a single lab test cannot distinguish between someone who just walked out of a heavily smoke-filled room and an occasional active smoker, nor can it track dietary cadmium intake over several decades," she said. "Follow-up studies that track people over longer periods will provide more insight into cause and effect," she said.

The research team included Garett Sansom, Nusrat Fahmida Trisha, and Nishat Tasnim Hasan, alongside Sarker and Roh. The study is available under DOI 10.1007/s12011-026-05102-9.