Association between blood heavy metal levels and subtypes of steatotic liver disease: A nationally representative cross-sectional analysis in South Korea.

Most prior studies have investigated the association between heavy metals and nonalcoholic fatty liver disease as a single entity; however, there is limited evidence regarding subtype-specific associations with steatotic liver disease (SLD) as defined by the new criteria. Thus, this study investigates associations between blood levels of heavy metals and SLD subtypes using nationally representative data from South Korea. Data were obtained from the Korea National Health and Nutrition Examination Survey between 2005 and 2017, including adults aged 19 years and older. Blood levels of heavy metals, including lead (Pb), mercury (Hg), and cadmium (Cd), were examined. SLD, estimated using the hepatic steatosis index with alcohol consumption, was categorized into metabolic dysfunction-associated SLD (MASLD), metabolic alcohol-related liver disease (MetALD), and alcohol-related liver disease (ALD). Weighted logistic regression was used to assess the association between blood concentrations of Pb, Hg, and Cd and the prevalence of each SLD subtype. The associations with metabolic biomarkers were evaluated using a weighted generalized linear model, and subgroup analyses were conducted by sex. A total of 18,871 adults (9117 males [48.31%]) with available heavy metal-related data were included in the analysis. Blood Pb levels were associated with a decreased risk of MASLD (adjusted odds ratio [aOR], 0.90 [95% CI: 0.86-0.95]) but an increased risk of ALD (1.21 [1.15-1.27]). Blood Hg level was associated with MASLD (1.03 [95% CI: 1.01-1.04]), MetALD (1.07 [1.05-1.09]), and ALD (1.02 [1.01-1.03]), with a linear trend in disease risk across quartiles. Blood Cd level showed no associations overall but was significantly associated with MetALD (1.59 [95% CI: 1.11-2.27]) and ALD (1.52 [1.24-1.85]) in male only. Both blood Hg and Cd levels were positively associated with liver enzymes and metabolic parameters. This first nationally representative study using the new classification highlights the subtype-specific impact of heavy metals on SLD. The findings suggest Hg and Cd link metabolic dysfunction to liver disease, underscoring the need for subtype-tailored environmental risk assessments and precision public health strategies.