TABLE 5.
Studies linking exposure to triclosan and parabens and microbiome changes.
| References | Animal model | Triclosan and Paraben dose | Microbiota changes | Health effects |
| Studies in animals | ||||
| Gaulke et al. (2016) | Zebrafish | TCS (100 μg/g) | • Exposure to TCS led to a slight reduction in diversity, with significant decreases in α-diversity between days 4 and 7 in exposed fish. • Reduced abundance of Enterobacteriaceae and increased abundance of Pseudomonas. |
_ |
| Narrowe et al. (2015) | Fathead minnow | TCS (100 and 1,000 ng/L) | • Increase in α-diversity associated with TCS exposure. | • Exposure to TCS may induce long-term effects on the host organism. |
| Hu et al. (2016) | Sprague-Dawley rats | MPB (0.105 mg/kg) and TCS (0.05 mg/kg) | • The abundance of Bacteroidetes (Prevotella) and Elusimicrobia increases in both groups. • Firmicutes (Bacilli) abundance decreased in both groups. • Betaproteobacteria abundance increased in the group exposed to MPB. • Deltaproteobacteria increased in the group exposed to TCS. |
• A subtle but constant reduction in body weight was observed in the young rats. |
| Yang et al. (2018) | C57BL/6 male mice | TCS (5–80 mg/kg) | • Beneficial bacteria like Bifidobacterium were reduced. | • Exposure to TCS led to low-grade colon inflammation and colitis and increased risk of colon cancer related to the presence of colitis. |
| Gao et al. (2017) | C57BL/6 mice | TCS (2 mg/L) | • After 4 weeks of exposure, α-diversity increased but it subsequently decreased after 9 weeks of exposure. | • The bacterial genes involved in stress response showed significant enrichment after exposure to TCS. • High enrichment of metal resistome in the gut microbiota, which is related to a reduced effectiveness of infection treatment. |
| Studies in humans | ||||
| Bever et al. (2018) | Infants | TCS (exposure through breast milk) | • Significant increases in the genus Dermabacter, order Rhodospirillales, and family Rhodospirillaceae were found in babies exposed to TCS through breast milk. | _ |
| Ribado et al. (2017) | Infants and their mothers | TCS (environmental exposure and through breast milk) | • Enrichment of the phylum Proteobacteria in mothers exposed to TCS-containing toothpaste. • Enrichment of Proteobacteria in infants with higher TCS levels. |
_ |
TCS, triclosan; MPB, methylparaben.