Background: Lead is a toxic metal for human health, but its carcinogenicity is controversial, and the effect on bladder cancer is still unknown. The object of this study was to demonstrate the link between blood lead and bladder cancer. Objectives: We investigated associations of lead exposures with bladder cancer. Methods: We used the database from the National Health and Nutrition Examination Survey (NHANES, 1999-2018) to perform a cross-sectional study. We performed Weighted multivariate logistic regression to examine the association between blood lead level with bladder cancer, and then a subgroup analysis was performed. The nonlinear association between BLL and bladder cancer was described using fitted smoothing curves. Results: A total of 40,486 participants were included in this study, the mean (SD) BMI was 28.71 ± 6.68 kg/m2. A fully adjusted model showed that BLL was parallel 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 < 28kg/m2. However, no difference was found in BMI≥28kg/m2 subgroup and in General population. In subgroup analysis of participants with BMI < 28kg/m2, blood lead was associated with bladder cancer in the male, non-hypertensive, < 70 year old subgroup (p < 0.05), but was not significantly different from the other subgroups. Additionally, we discovered a non-linear association between BLL and bladder cancer using a linear regression model. Discussion: In this cross-sectional study, we identified higher BLL level was independently associated with Bladder cancer in People with BMI<28kg/m2.The results compensated for earlier investigations, but more large-scale prospective cohorts were required for validation. Keywords: Blood lead level (BLL), Bladder cancer, NHANES (National Health and Nutrition Examination Survey)

The authors have declared no competing interest.

Guangzhou Science and Technology Plan Project (Project No. 202201010834); Natural Science Foundation of Guangdong Province (Project No. 2021A1515010065); Guangzhou Health Science and Technology Project (Project No. 20211A011103); The Ministry of Education's Industry-University Cooperative Education Project in 2022 (220904082210823); Guangzhou Medical University Student Innovation Ability Improvement Plan in 2022 (106); Doctoral Program of Guangdong Nature Foundation (2017A030310148)

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