Associations between lead, cadmium, mercury, and arsenic exposure and alanine aminotransferase elevation in the general adult population: an exposure-response analysis

Cadmium, lead, mercury, and arsenic are among the most toxic environmental contaminants. Serum alanine aminotransferase (ALT) is the most common liver biomarker. This analysis aimed to explore the associations between blood cadmium, lead, mercury, urinary total arsenic, and dimethylarsinic acid and ALT elevation in adults. Data were extracted from 5 National Health and Nutrition Examination Survey cycles (NHANES) 2007-2016. Patients with chronic viral hepatitis and excessive alcohol consumption were excluded. ALT elevation was defined according to the 2017 American College of Gastroenterology Clinical Guideline. Logistic models and restricted cubic splines were adopted to assess the exposure-response relationships. Comparing the highest to lowest quintile of exposure, the multivariable-adjusted odds ratios (95% confidence intervals) of ALT elevation were 1.38 (1.07-1.78) for blood lead (P_{for trend} = 0.01), 1.37 (1.16-1.62) for blood mercury (P_{for trend} < 0.01), 0.94 (0.78-1.14) for blood cadmium (P_{for trend} = 0.64), 1.07 (0.79-1.45) for urinary total arsenic (P_{for trend} = 0.81), and 1.25 (0.94-1.66) for urinary dimethylarsinic acid (P_{for trend} = 0.18). The associations between blood lead and mercury and ALT elevation were only observed in women. In addition, the associations between urinary total arsenic [1.53 (1.02-2.29), P_{for trend} = 0.02] and dimethylarsinic acid [2.17 (1.05-4.49), P_{for trend} = 0.02] and ALT elevation were also observed in women. Dose-response analysis showed that there was no safe exposure threshold of blood lead and mercury's toxic effect on ALT elevation, respectively. In conclusion, lead, mercury and arsenic were associated with ALT elevation in adults, and the associations were mainly observed in women.