Higher levels of methyl mercury—above 5.75 µg/L—may be significantly associated with an increased risk of latent tuberculosis infection, according to a recent study.

The cross-sectional study aimed to evaluate the impact of methyl mercury (MeHg) levels on latent tuberculosis infection (LTBI) risk. The study included 5,243 participants and utilized data from the National Health and Nutrition Examination Survey 2011–2012.

The participant subgroups were divided based on LTBI status. In the non-LTBI group (n = 4,722), 48.6% of participants were male and 51.4% were female, while in the LTBI group (n = 521), 57.6% were male and 42.4% were female, with a statistically significant difference (P < 0.001). Regarding age, 66.9% of those in the non-LTBI group were 55 years old or younger, while 33.1% were older than 55; in contrast, within the LTBI group, 44.3% were 55 years old or younger, and 55.7% were older than 55, also showing a significant difference (P < 0.001).

The median MeHg level in the non-LTBI group was 0.64 µg/L (interquartile range [IQR] = 0.27–1.61 µg/L), while in the LTBI group, it was 0.95 µg/L (IQR = 0.37–2.86 µg/L), showing a statistically significant difference (P < 0.001).

The researchers employed advanced statistical techniques, including XGBoost and Random Forest, to rank variables influencing TB infection risk, identifying MeHg as an important factor. Subsequent analysis using restricted cubic splines demonstrated a nonlinear relationship between MeHg levels and LTBI risk, with a significant increase in risk observed at MeHg levels greater than 5.75 µg/L.

Participants with LTBI exhibited higher MeHg levels compared to those without LTBI, with the risk of infection escalating as MeHg levels increased. Additionally, a history of asthma was associated with lower MeHg levels and reduced LTBI risk. Mediation analysis revealed that MeHg partially mediated the relationship between asthma and LTBI risk.

The study, which was published in BMC Pulmonary Medicine, suggested MeHg may be associated with increased LTBI risk. While further research is necessary to establish causality, the findings also indicated that reducing environmental exposure to MeHg might help in managing LTBI risk.

The authors declared no competing interests.