Overview
Large cross-sectional study using six NHANES cycles from 2005 to 2016 (n=7,719 adults) to examine associations between urinary concentrations of five metals (cadmium, cobalt, lead, antimony, barium) and overactive bladder (OAB) risk. WQS, BKMR, and quantile g-computation were applied for mixture analysis.
Overactive bladder was defined as urinary urgency often with increased frequency and nocturia, with or without urgency urinary incontinence, in the absence of infection or other pathology, following International Continence Society criteria. OAB prevalence in the sample: 1,574 of 7,719 participants (20.39%).
Key numbers
n=7,719 US adults; OAB prevalence 20.39% (1,574 of 7,719).
Single-metal associations (adjusted logistic regression):
- Cadmium: associated with increased OAB risk; highest quartile (Q4) versus lowest (Q1): OR=2.74 (95% CI: 1.94-3.87) among young and middle-aged individuals.
- Lead: OR=1.84 (95% CI: 1.35-2.52) for Q4 versus Q1 among young and middle-aged individuals.
- Cobalt: positively associated with OAB by restricted cubic spline.
- Antimony: positively associated.
- Barium: inverse (protective) association.
Mixture analysis: WQS and BKMR consistently showed positive association of combined urinary metal exposure with OAB risk. Quantile g-computation confirmed harmful effects of metal combinations. BKMR identified potential interactions among specific mixture components. Associations were more evident in young and middle-aged individuals and in alcohol consumers versus older adults and abstainers.
Evidence Fitness
Context only. Cross-sectional design; temporality not established. Urinary biomarkers reflect recent renal exposure. OAB is a functional urological outcome with subjective components. The large sample size (n=7,719, six NHANES cycles) is a strength for detecting mixture associations in a nationally representative US population.
Methods (brief)
NHANES 2005-2016 (six cycles: 2005-2006, 2007-2008, 2009-2010, 2011-2012, and others). Urine metals by ICP-MS, creatinine-adjusted. OAB defined per ICS criteria (self-report). Ln-transformed metal concentrations; all p-values remained below 0.05 for Ln-transformed concentrations. WQS, BKMR, restricted cubic splines, quantile g-computation.
Implications
Certification: Cadmium and lead as the dominant contributors to a urological outcome (OAB) in a large US adult population is consistent with their HMT&C Tier-1 status and their relevance to chronic low-dose dietary exposure.
Courses: Useful for demonstrating that heavy metal mixture effects extend to urological endpoints that are not conventionally attributed to metal exposure.
App: No food concentration data.
Microbiome: Not applicable.
Related evidence
- Cadmium
- Lead
- Single-metal regulatory limits systematically underprotect against dietary heavy-metal exposure
Update history
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