BACKGROUND AND OBJECTIVES: Pb (lead) is a heavy metal, its carcinogenicity for bladder cancer is still debated, the link between blood lead levels (BLLs) and bladder cancer was investigated in this study. METHODS: This cross-sectional study, using the NHANES (1999-2018) database, explored the relationship between BLLs and bladder cancer among Americans aged 20-85. It employed weighted multivariable logistic regression for analysis. Additionally, subgroup analyses and smoothed curve fitting were also performed. RESULTS: This study included a total of 40,486 participants, the body mass index (BMI) of the participants is 28.71 ± 6.68 kg/m CONCLUSION: In this cross-sectional study, we found that the degree of correlation between BLLs and the risk of bladder cancer may vary among people with different BMIs. In people with BMI <
28 kg/m