Associations of exposure to blood and urinary heavy metal mixtures with psoriasis risk among U.S. adults: A cross-sectional study

Accumulating evidence showed that environmental exposure to toxic metals was harmful to human health. However, information about the effects of exposure to metal mixtures on psoriasis was scarce. To investigate the independent and comprehensive associations between heavy metal co-exposure and psoriasis in adults, data of 6534 adults aged 20–80 years from the National Health and Nutrition Examination Survey (NHANES) were used. Among them, 187 (2.86 %) were diagnosed with psoriasis and the rest were participants without psoriasis. We examined the independent and combined associations of 3 blood metals and 11 urinary metals with psoriasis risk. In the single-metal analyses, urinary barium (Ba), cesium (Cs), antimony (Sb), uranium (Ur), and cadmium (Cd) were positively correlated with psoriasis risk, while urinary molybdenum (Mo) was identified as a protective factor for psoriasis. Moreover, weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models consistently revealed the positive effect of urinary metal co-exposure on psoriasis risk. The associations were more evident in the young and middle-aged group than the elderly group. In the urinary mixtures, Ba was the highest weighted metal in the whole population and the young and middle-aged people, whereas Sb was the top weighted metal in the elderly group. Additionally, BKMR analysis revealed the potential interaction between certain components of urinary metal mixtures in psoriasis. The results of quantile-based g computation (qgcomp) model further proved the toxic effect of urinary metal mixtures on psoriasis, and the positive linear relationship between urinary Ba and psoriasis risk was identified by restricted cubic splines (RCS) regression. We concluded that co-exposure to multiple heavy metals was associated with psoriasis risk. Given the limitations of the NHANES study, further prospective designed studies are warranted.