Blood lead levels and bladder cancer among US participants: NHANES 1999-2018

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(2). The average BLL is 0.0858 mu mol/L (range: 0-2.96 mu mol/L). A fully adjusted model showed that the BLL was associated with bladder cancer (odds ratio [OR] = 2.946, 95% confidence interval [CI] = 1.025 to 8.465, P = 0.047) in people with BMI < 28 kg/m(2). However, no difference was found in the BMI >= 28 kg/m(2) subgroup or in the general population. According to the subgroup analysis of participants with a BMI < 28 kg/m(2), blood lead was associated with bladder cancer in the male, nonhypertensive, and < 70-year-old subgroups (p < 0.05) but no significantly different is observed in other subgroups. In addition, we discovered a nonlinear association between the BLLs and bladder cancer risk using a linear regression model. 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(2), a higher BLL was independently associated with bladder cancer. However, more experiments are needed to confirm this finding.