Spatiotemporal trends and ecological risk assessment of volatile methylsiloxanes in Tokyo Bay catchment basin, Japan: River water and sewage treatment plant samples.

Summary

Across 2013–2021, volatile methylsiloxanes (D3–D6, L3–L6) were widespread in Tokyo Bay catchment waters, peaking downstream of sewage treatment discharges. Significant annual declines in D4–D6 (−7.7% to −6.4%) and a decreasing ecological risk profile suggest regulatory measures are effective, despite levels near predicted no-effect thresholds.

Key Findings

• VMSs (D3–D6, L3–L6) were widely detected in rivers (2.3–1190 ng/L), with highest levels downstream of STP discharges.
• No consistent elevation was found downstream of silicone-manufacturing facilities except for D3.
• Significant annual declines in D4–D6 (−7.7% to −6.4%) were observed between 2013 and 2021.
• Ecological risk for D4–D6 decreased over time; 95th percentile field concentrations did not overlap with 5th percentile chronic NOECs, though levels were near predicted NOECs.

Clinical Implications

While not a clinical trial, these findings support counseling patients on environmentally safer product choices and inform clinicians’ advocacy for regulations limiting high-risk VMSs to reduce population exposure.

Limitations

• Human exposure and health outcomes were not assessed directly
• Sampling intensity and exact sample counts were not specified in the abstract; potential spatial/temporal sampling variability

Future Directions

Integrate human biomonitoring and source apportionment to link environmental trends to exposure and health, and assess mixture toxicity and alternatives to high-risk cVMSs.