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Parabens are a family of endocrine-disrupting chemicals. Environmental estrogens may play a vital role in the development of lung cancer. To date, the association between parabens and lung cancer is unknown. Based on the 189 cases and 198 controls recruited between 2018 and 2021 in Quzhou, China, we measured 5 urinary parabens concentrations and examine the association between urinary concentrations of parabens and lung cancer risk. Cases showed significantly higher median concentrations of methyl-paraben (MeP) (2.1 vs 1.8 ng/mL), ethyl-paraben (0.98 vs 0.66 ng/mL), propyl-paraben (PrP) (2.2 vs 1.4 ng/mL), and butyl-paraben (0.33 vs 0.16 ng/mL) than controls. The significant association between urinary concentrations of PrP and the risk of lung cancer (odds ratio (OR)adjusted = 2.22, 95% confidence interval (CI): 1.76, 2.75; Ptrend < 0.001) was identified in the adjusted model. In the stratified analysis, we found that urinary concentrations of MeP were significantly associated with lung cancer risk (OR = 1.16, 95% CI: 1.01, 1.27 for the highest quartile group). Besides, comparing the second, third, and fourth quartile groups with the lowest group of PrP, the adjusted OR was 1.52 (95% CI: 1.29, 1.65, Ptrend = 0.007), 1.39 (95% CI: 1.15, 1.60, Ptrend = 0.010), and 1.85 (95% CI: 1.53, 2.30, Ptrend = 0.001), respectively. Parabens exposure, reflected in urinary concentrations of parabens, may be positively associated with the risk of lung cancer in adults.

Many studies have investigated the effect of bisphenol A (BPA) exposure on gut microbial community changes, while the influence of gut microbiota on metabolism of BPA in organisms remains not well known. To explore this, in this study, Sprague-Dawley rats were intermittently (a 7-day interval) or continuously dosed by oral gavage at 500 µg BPA/kg bw/day for 28 days. Under a 7-day interval BPA exposure, the metabolism of BPA in rats and gut microbiota structure did not change greatly with dosing time. In contrast, following continuous BPA exposure, the relative abundances of Firmicutes and Proteobacteria in rat gut were significantly increased, and the alpha diversity of rat gut bacteria was greatly reduced. Meanwhile, the mean proportion of BPA sulfate to total BPA in rat blood was gradually decreased from 30 (day 1) to 7.4% (day 28). After 28 days of continuous exposure, the mean proportion of BPA glucuronide to total BPA in rat urine elevated from 70 to 81%, and in rat feces the mean proportion of BPA gradually decreased from 83 to 65%. Under continuous BPA exposure, the abundances of 27, 25, and 24 gut microbial genera were significantly correlated with the proportion of BPA or its metabolites in rat blood, urine, and feces, respectively. Overall, this study first demonstrates that continuous BPA exposure disrupted the rat gut microbiota community, which in turn altered the metabolism of BPA in rats. This finding contributes to the better understanding of metabolism of BPA in humans.

Parabens are widely used in consumer products resulting in frequent exposure to humans and some toxic effects in humans. However, little is known about the association between human paraben exposure and rheumatoid arthritis (RA). In this study, a case-control cohort (n = 290) were established in Hangzhou, China, aiming to quantify the residues of MeP, EtP, PrP, and BuP in serum samples and to determine their associations with RA risks. MeP (mean 4.7 ng/mL, < LOD–20 ng/mL) was the predominant paraben in human serum, followed by PrP (1.9 ng/mL, < LOD–24 ng/mL), EtP (1.4 ng/mL, < LOD–10 ng/mL), and BuP (1.09 ng/mL, < LOD–10 ng/mL). Human serum concentrations of MeP were correlated with the levels of rheumatoid factors [adjusted β = 0.19, 95% confidence interval (CI): 0.12, 0.46], anti-cyclic citrullinated peptide antibody (adjusted β = 0.30, 95% CI: 0.26, 0.58), immunoglobulin G (adjusted β = 0.24, 95% CI: 0.21, 0.30). Significant associations between MeP (adjusted β = 0.15, 95% CI: 0.037, 0.28) and PrP (adjusted β = 0.23, 95% CI: 0.080, 0.38) exposure were correlated with C-reactive protein levels. In addtion, a correlation between MeP and odds ratios (OR) of RA (ORcrude = 1.337, CI: 1.110, 1.624, p = 0.03; ORadjusted = 1.866, CI: 1.321, 2.636, p = 0.02) was positive and significant. To our knowledge, this study first finds the significant associations among parabens exposure, change of specific immune marker, and RA risks, indicating that human exposure to parabens may increase the risk of RA.