Microplastics
Plastic particles below five millimetres, now detected in tap water, bottled water and the wider environment. The exposure is real and well documented; the health significance is genuinely uncertain, and Hydrionis presents it that way rather than resolving the uncertainty in either direction.
Key facts
- Contaminant group
- Emerging contaminant
- World Health Organization — guideline
- No guideline valueWHO concluded in 2019 that the evidence did not support a health-based guideline value, while calling for better data and for continued action on plastic pollution.
- European Union — guideline
- Watch list monitoringIncluded for monitoring under the recast Drinking Water Directive rather than as a limit.
Where it comes from
- Breakdown of larger plastic litter
- Synthetic textile fibres released in laundry
- Tyre wear particles washed from roads
- Plastic packaging, including bottle caps and the bottles themselves
- Wastewater treatment discharge, which removes most but not all particles
How it behaves in water
Particles range across several orders of magnitude in size. Smaller particles are more numerous, harder to detect, and more likely to cross biological barriers. Sampling and identification methods differ so widely between studies that reported concentrations are frequently not comparable at all.
How it is measured
No standardised method exists. Counts depend heavily on the minimum particle size the method can detect, which is why published concentrations vary by orders of magnitude. Studies reporting higher counts often simply used a lower detection size.
Regulatory position
| Jurisdiction | Value | Status | Notes |
|---|---|---|---|
| World Health Organization | No guideline value | guideline | WHO concluded in 2019 that the evidence did not support a health-based guideline value, while calling for better data and for continued action on plastic pollution. |
| European Union | Watch list monitoring | guideline | Included for monitoring under the recast Drinking Water Directive rather than as a limit. |
Table sources
- World Health Organization — Guidelines for Drinking-water Quality. Public but restricted · CC BY-NC-SA 3.0 IGO
- European Commission — Drinking Water Directive (EU) 2020/2184 and reporting. Open — attribution required · European Commission reuse policy (Decision 2011/833/EU)
- Drinking Water Inspectorate — Drinking water quality in England and Wales. Open — attribution required · Open Government Licence v3.0
- United States Environmental Protection Agency — Safe Drinking Water Information System. Open · US Government work — public domain
Health context
No health-based guideline value has been established by any major regulator, because the toxicological evidence at realistic exposure levels is not sufficient to set one. That is a statement about the state of evidence, not a finding that exposure is harmless.
What removes it
| Row | Effective | Not reliably effective |
|---|---|---|
| 1 | Conventional coagulation and filtration, which removes a large majority of larger particles | Boiling |
| 2 | Membrane filtration, including reverse osmosis and ultrafiltration | Chlorination and other disinfection, which does not remove particles |
Related intelligence
Sources
- World Health Organization — Guidelines for Drinking-water Quality. Public but restricted · CC BY-NC-SA 3.0 IGO
- Peer-reviewed scientific literature — Open-access hydrology, water chemistry and water use research. Public but restricted · Publisher terms — public access, reuse not clearly granted