Recently, the Dutch Board for the Authorisation of Plant Protection Products and Biocides (Ctgb) announced that starting from January 2026, the assessment of plant protection products (pesticides) and biocides regarding drinking water standards will officially utilize surface water monitoring data from 2020 to 2024. According to the latest report submitted by the Association of Dutch Water Companies (Vewin), substances including Glyphosate, 2,4-D, and various metabolites have been included in the latest list of substances of concern due to detection concentrations exceeding limits at surface water intake points.

According to the latest data published by Vewin, the following active substances and metabolites were detected at concentrations exceeding limits in surface water during the 2020-2024 period. Applications involving products containing these substances will be subject to intensified scrutiny.

List of Substances of Concern (in alphabetical order):

· 2,4-D

· Aminomethylphosphonic acid (AMPA) (Note: Human toxicologically non-relevant metabolite)

· Cyprodinil

· DEET

· Dicamba

· Dimethenamid

· Dimethomorph

· Flonicamid

· Fluopyram

· Fluroxypyr (Note: Human toxicologically relevant metabolite)

· Fosthiazate

· Glyphosate

· Iodopropynyl butylcarbamate (IPBC)

· MCPA

· Metamitron

· Metribuzin

· Monobromoacetic acid

· Monochloroacetic acid (Note: Human toxicologically relevant metabolite)

· N,N-dimethylsulfamide (Note: Human toxicologically relevant metabolite)

· Propamocarb

· Propyzamide

· Prosulfocarb

· Pyridate

· Pyrimethanil

· Tolclofos-methyl

· Trifluoroacetic acid (TFA) (Note: Human toxicologically relevant metabolite)

The Ctgb explicitly pointed out that not all exceedances will impact pesticide registration. The following two categories are excluded from the restricted list:

1. Non-agricultural sources or naturally occurring substances: Such as carbon dioxide, salicylic acid, paraffin oil, fatty acids, inorganic compounds (e.g., copper, silver), plant extracts, micro-organisms, and signaling substances (e.g., pheromones).

2. Temporary exceedances caused by accidents or disasters: For example, the Propamocarb exceedance caused by an accident in 2025, and the Prosulfocarb contamination incident in 2019. Data flagged as incidental events will be excluded from the assessment baseline.

In response to this new regulation by the Ctgb, it is recommended that relevant agrochemical and biocide companies take the following measures:

· Verify Product Composition: Immediately check whether the active substances and major metabolites in your products appear on the aforementioned “List of Substances of Concern.”

· Obtain Raw Data: If listed substances are involved, applicants should contact Vewin to obtain raw monitoring data for each intake point before submitting the dossier.

· Perform Pre-assessment: According to the “Working Instructions” (Werkinstructies) available on the Ctgb website, use the obtained raw data to calculate the 90th percentile concentration. If the calculation exceeds the limit, a scientific justification for this situation or an adjustment to the product label (GAP) must be prepared in advance.

· Focus on Metabolite Toxicological Properties: For metabolites, confirm their classification on the RIVM website. If classified as a “toxicologically non-relevant” metabolite, a more lenient standard of 1 µg/L may apply, which could be a key point for compliance defense.