Pesticide metabolites
Breakdown products of pesticides, which frequently outlast and out-travel the parent compound. Several are detected in groundwater decades after the parent pesticide was withdrawn.
Key facts
- Contaminant group
- Agricultural
- European Union — legal limit
- 0.1 µg/l for relevant metabolitesNon-relevant metabolites are assessed against health-based values, which are typically far higher.
- United Kingdom — legal limit
- 0.1 µg/l for relevant metabolites
Where it comes from
- Degradation of applied pesticides in soil and water
- Legacy compounds whose parent products were banned decades ago
- Metabolites of currently approved products
How it behaves in water
Often more mobile and more persistent than the parent compound, because degradation typically increases polarity and therefore water solubility. This is why a metabolite can be the compound actually found in an aquifer while the parent is undetectable.
How it is measured
Micrograms per litre. Regulatory treatment depends on whether a metabolite is classified as relevant — meaning it retains the parent’s pesticidal activity or toxicity — which determines whether the strict pesticide limit applies to it.
Regulatory position
| Jurisdiction | Value | Status | Notes |
|---|---|---|---|
| European Union | 0.1 µg/l for relevant metabolites | legal limit | Non-relevant metabolites are assessed against health-based values, which are typically far higher. |
| United Kingdom | 0.1 µg/l for relevant metabolites | legal 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
The relevance classification is the operative question. A non-relevant metabolite exceeding 0.1 µg/l is a regulatory matter rather than a health one; a relevant metabolite is treated as the parent compound would be.
What removes it
| Row | Effective | Not reliably effective |
|---|---|---|
| 1 | Granular activated carbon, though performance varies more than for parent compounds | Boiling |
| 2 | Reverse osmosis and nanofiltration | Sediment filtration |
| 3 | Blending with an uncontaminated source | Water softening |
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