Associations between microplastics in human feces and colorectal cancer risk.

Microplastics (MPs) are widely detected in water, air, and food, raising increasing concerns about human exposure. Although growing toxicological evidence suggests that MPs can disrupt gastrointestinal function, their association with colorectal cancer (CRC) risk in humans remains underexplored. This case-control study examined the relationship between fecal MP concentrations and CRC risk in a Chinese population. A total of 258 CRC patients and 493 healthy controls were recruited from the Environmental Exposure and Human Health cohort at Quzhou People's Hospital. Fecal MP concentrations were quantified using Laser Infrared Imaging Spectrometer. The median MP concentration was significantly higher in CRC cases than in controls (62 vs. 43 items/g dry weight, p < 0.05). Multivariable logistic regression showed that individuals in the highest exposure quartile had an adjusted odds ratio of 11.3 (95 % CI: 6.77-19.5, p for trend < 0.01) compared to those in the lowest quartile. Restricted cubic spline analysis indicated a nonlinear dose-response relationship. Stratified analyses indicated that this association was particularly pronounced among females and individuals who frequently consumed spicy or high-fat foods. These findings provide first epidemiological evidence of a potential link between elevated MP exposure and CRC risk.