Cases / Chemical pollution · Switzerland · 1970–2020
Chlorothalonil metabolites in Swiss groundwater
Nature's voice · report
My groundwater under the Swiss Plateau carries R471811, a breakdown product of a fungicide used since the 1970s, above 0.1 µg/L at more than half of the monitoring points there.
Did nature suffer? Yes. Harm is on record.
Recorded
- The fungicide has been banned since 2020. Its breakdown products are very persistent, and they will affect me for many years. BAFU (Switzerland)
What the record lacks: 3 insufficient See the gaps
Breakdown products of the fungicide chlorothalonil, used in Switzerland since the 1970s, were found in groundwater in a 2017 pilot study. The substance has been banned since 2020.
more than 50%Swiss Plateau monitoring points where metabolite R471811 exceeds 0.1 µg/L
BAFU. Chlorothalonil was used from the 1970s and banned in 2020; more than a quarter of monitoring points nationwide are affected.
BAFU. Chlorothalonil was used from the 1970s and banned in 2020; more than a quarter of monitoring points nationwide are affected.
Status As of October 2026: groundwater contamination by chlorothalonil metabolites continues; the court record on Syngenta's challenge is reported only in secondary summaries.
What?
Metabolites of the fungicide chlorothalonil, including R471811, in Swiss groundwater: more than a quarter of monitoring points nationwide are affected, and more than 50% of Swiss Plateau points exceed 0.1 µg/L for R471811. BAFU (Switzerland)
Where?
Switzerland, with the heaviest reported contamination on the Swiss Plateau. BAFU (Switzerland)
When?
Fungicide in use since the 1970s; metabolites found in a 2017 pilot study; ban in 2020. BAFU (Switzerland)
Who?
Gained
None on recordLost
None on recordHarmed
- Swiss groundwater (Swiss Plateau) — R471811 above 0.1 µg/L at more than half of monitoring points; metabolites very persistent BAFU (Switzerland)
Why?
Not recorded in the sources reviewed.
How?
Metabolites of the fungicide, used since the 1970s, reached groundwater, where BAFU describes them as very persistent and expected to affect groundwater for many years. BAFU (Switzerland)
6 of 6 questions answered from the record
What happened
The record, in order.
Chlorothalonil is a fungicide that has been used in Switzerland since the 1970s. Its metabolites, including one called R471811, were found in groundwater in a pilot study in 2017, according to BAFU, the Swiss environment office.
BAFU reported that more than a quarter of monitoring points nationwide are affected. On the Swiss Plateau, R471811 exceeds 0.1 µg/L at more than 50% of monitoring points. The substance has been banned since 2020. BAFU described the metabolites as very persistent and expected them to affect groundwater for many years.
Syngenta is reported to have challenged the revocation of the approval in court. The account of that case comes only and is recorded under unverified items.
- 1970Use of chlorothalonil in Switzerland begins (1970s)
- 2017Metabolites found in groundwater in a pilot study
- 2020Chlorothalonil banned
How it looked
What was shown, beside what was recorded.
Shown
Recorded
- Chlorothalonil metabolites found in groundwater in a 2017 pilot study
- More than a quarter of monitoring points nationwide are affected
- On the Swiss Plateau, R471811 exceeds 0.1 µg/L at more than 50% of monitoring points
- Substance banned since 2020; metabolites very persistent and expected to affect groundwater for many years
In court and with insurers
Every proceeding and every insurer decision on record.
Lawsuits and rulings
No court case on record. No court has ruled on this case.
Insurers
No insurer decision on record.
What nature saw
Outcomes measured on the ground, and nature's note.
Nature's report opens this page. Below: further outcomes measured on the ground.
Monitoring points affected nationwide
more than 25%
Chlorothalonil metabolites in groundwater (BAFU)
Swiss Plateau points above 0.1 µg/L (R471811)
more than 50%
BAFU
Expected duration
many years
BAFU describes the metabolites as very persistent
What we don't know
Undisclosed, unproven, untried: recorded as data.
Record
- Insufficient Reported but not independently verified: secondary reports say Syngenta's court challenge to the revocation of the approval was dismissed, but that an interim decision in 2020 temporarily removed the words “probably carcinogenic” from the state website. The court files could not be checked.
- Insufficient Reported but not independently verified: that the ban was upheld in court, on a basis that was only partly read. The final ruling on the scientific basis was not checked.
- Insufficient Reported but not independently verified: a French study screening 157 transformation products reportedly measured R471811 in more than half of raw and drinking water samples.
Did the harm stop?
The fungicide has been banned since 2020, but BAFU describes its metabolites as very persistent and expected to affect groundwater for many years.
Who paid?
Not established in the record.
Sources
Voices on record: — Company or project✓ Government and regulators— Courts— Press and investigations— Communities and civil society✓ Researchers
Government and regulators
- Chlorothalonil in groundwaterBAFU (Switzerland) ·
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