Uncovering hidden β-adrenergic agonist exposure from meat consumption through nationally representative human biomonitoring in Taiwan

Background: Despite stringent bans on clenbuterol in livestock production, its prolonged half-life poses a potential risk for human bioaccumulation. Conversely, legally permitted additives like ractopamine undergo rapid metabolism. This study utilized human biomonitoring (HBM) to uncover hidden β-adrenergic agonist exposures in Taiwan, contrasting internal body burdens with traditional market surveillance data. Methods: We analyzed data from a nationally representative sample of 1554 participants in the 2019 Taiwan Human BioMonitoring Program. Spot urine samples were tested for eight β-adrenergic agonists using ultra-trace isotope dilution online SPE-LC-MS/MS. Dietary habits, including meat and egg consumption frequencies, were assessed via validated food frequency questionnaires. Associations were evaluated using survey-weighted logistic regression models. Results: Clenbuterol was the most frequently detected β-adrenergic agonist (31.4%), starkly contrasting with its zero-detection rate in recent official market surveillance. In contrast, the legally permitted ractopamine was detected in only 4.2% of samples. After adjusting for confounders, urinary clenbuterol detection showed a significant association with red meat consumption (adjusted odds ratio = 1.39, 95% CI: 1.08–1.79, p = 0.011). Conclusions: A significant portion of the Taiwanese general population experiences hidden, low-dose exposure to clenbuterol. This prevalence highlights a critical gap between routine regulatory testing limits and the bioaccumulation potential of clenbuterol from red meat consumption. HBM proves essential for uncovering these hidden exposures. Integrating ultra-trace HBM data into public health frameworks is necessary to accurately assess dietary risks and effectively manage food safety policies.