Frequently asked questions follow-up survey dinoterb 2025

What has been studied (four studies)? 

In 2024 a source and cause study of dinoterb was carried out by Deltares on behalf of HHNK. This was in response to high readings for dinoterb in measurements of surface water. This found no source or cause for the presence of dinoterb in surface water measurements. Since then, four different additional and in-depth investigations have been conducted: 

  1. The Deltares sources and causes study from 2024 prompted Waterproef to look further into possible contamination and so-called false positive measurements in analyses dinoterb. Commissioned by Waterproef, Deltares conducted a new study for this purpose (2024/25).
  2. Waterproef also had Deltares investigate whether the results of the contamination study could also play into the more than 200 crop protection agents (GBM) that Waterproef measures on behalf of HHNK.
  3. In addition, the Deltares study from 2024 prompted HHNK to conduct additional sampling for dinoterb compliance in the water bottom and
  4. Do additional sampling in wastewater from WWTPs. 

What came out of that?

The in-depth study by Deltares on the measurement data and analysis method dinoterb at Waterproef concludes that the concentration of dinoterb cannot always be reliably measured and that Waterproef does the measurements according to the accreditation rules for laboratories (NEN). These findings apply very specifically only to dinoterb and not to other crop protection products. In addition, the additional samples taken by HHNK in compliance from the water bottom and in samples in the wastewater do not show dinoterb.   

Is there or is there not dinoterb in the surface water? 

Since last year (2024), much new research has been conducted and new knowledge and insights have been gained. With this knowledge (of today) HHNK concludes that there is no dinoterb in the surface water.   

What will HHNK do next? 

  1. HHNK stops monitoring dinoterb immediately.  
  2. HHNK withdraws all published dinoterb data from 2020 to the present.
  3. HHNK is discontinuing the sampling for nalevering from the water bottom due to dredging and at the WWTPs.
  4. HHNK continues to monitor water quality and plant protection products, keeping a focus on four specific GBM identified by Deltares as substances of concern.
  5. HHNK remains committed to improving water quality together with others.