Dinoterb

To determine the state of water quality in our management area, HHNK regularly takes measurements in the surface water. These measurements show that the substance dinoterb has been detected at several measurement points in the area. In response to this finding, we commissioned the independent research institute Deltares to conduct a source study. The agency investigated what possible explanations there could be for the recently found elevated values of dinoterb and where exactly the contaminations come from.

What is dinoterb?

Dinoterb is a plant protection product to control weeds that was used from 1974. It has not been allowed to be used in agriculture since July 1, 1998. The active ingredient dinoterb is poorly soluble in water, somewhat volatile (the substance can evaporate to some extent), fairly degradable in soil and little mobile (the substance does not move easily with the (moving) water and is not easily carried away with the water).

Now how does it get into surface water?

It is as yet unclear how, when and why this substance entered surface water. What is clear is that increased concentrations were measured at more sampling points during the 2021 and 2022 samplings compared to previous years. The results can be viewed in the national Atlas pesticides in surface water. Testing of the measurements takes place every year by considering all measurements of the past year per measurement location and not by looking at a single measurement value. 

What were Deltares' findings?

  • There is no clear evidence for a possible cause of elevated levels of dinoterb.
  • There is no indication of a structural source or route.
  • The data analysis was done correctly.
  • No documentation was found that dinoterb has been used as a herbicide recently.
  • Through disturbance and upwelling of the water bottom, any dinoterb present may re-enter the surface water and cause temporarily elevated concentrations of dinoterb.
  • It is unclear whether (municipal and industrial) wastewater could be a possible source.
  • The method of analyzing dinoterb as part of a multi-component analysis affects measurement accuracy.

Source research dinoterb (Deltares report).

Could there be illegal consumption?

Deltares has investigated whether there are indications that dinoterb has been or is still being used after the ban. Deltares' research shows that there is no concrete evidence of illegal use. 

Deltares draws the conclusion that recent (illegal) use of dinoterb as a plant protection product "is not a plausible cause for all norm-exceeding concentrations of dinoterb." The reason for this conclusion is a sum of literature review, information from the Dutch Food and Consumer Product Safety Authority (NVWA), interviews with users in the region and data analysis. 

Has HHNK tracked down a culprit?

HHNK conducted the source investigation because of its responsibility for water quality. It was primarily aimed at finding explanations for the high concentrations and was not a detection investigation. 

Irrespective of the investigation, HHNK always takes action if there are concrete indications of the use of dinoterb or other prohibited substances. We are also working on more effective cooperation in the areas of licensing, supervision and enforcement. This is an interplay between NVWA, Omgevingsdienst and HHNK.  

The authority for supervision and enforcement of the possession and application of unauthorized plant protection products lies with the competent authority NVWA. 

The supervision and enforcement of the proper application of plant protection products in surface water-related matters also lies with HHNK. 

What does the follow-up process look like?

Deltares recommends investigating three more possibilities: 

  • Investigate whether past potentially stored dinoterb in the water bottom is released by stirring;
  • Sample whether dinoterb from possible industrial or human use inflows into the sewage treatment plant; 
  • Additional analysis once dinoterb is found in regular measurements to rule out possible variations in future measurements.  

HHNK is working on these recommendations and remains fully committed to improving water quality. 

Is it certain that the measurements are correct?

Data analysis of dinoterb measurements in surface water did not reveal any errors in the analysis, but did identify possible contamination and matrix effects whose impact on measurement reliability and accuracy was not further investigated at the time. It is unclear what possible sample contamination and matrix effects may have on measurement reliability and accuracy.

An automatic signaling system on salient readings is currently being developed.

As a result of the Dinoterb source study by research institute Deltares, further research into the analysis technique of dinoterb is being carried out at the Waterproef laboratory. Pending the results of the research, the measurement results of dinoterb will not be reported as of January 1, 2024 after coordination with HHNK.

Should I worry about my health? 

No. Research by the National Institute for Public Health and the Environment (RIVM) commissioned by the Municipal Health Service (GGD) shows no reason for Health. Dinoterb was measured during water quality monitoring. The water quality standard for this substance is based on the prevention of negative effects for aquatic organisms in case of long-term exposure. So not for humans. The GGD (Zaanstreek-Waterland, Hollands Noorden and Kennermerland) has informed us that exposure to dinoterb, as a result of recreation in surface water with a maximum concentration of 443.8 ng/l poses no health risks. 

RIVM looked at the only conceivable scenario. Namely daily swimming in water with the highest concentration of dinoterb detected. RIVM concluded that for the exposure scenario assessed, i.e. daily exposure via swimming water, oral and dermal (skin), no health risks are expected. The RIVM also expects no health risks for diving, boating, playing and garden watering. Exposure to dinoterb in these cases will be lower than for daily swimming.

If you are concerned about environmental effects of substances in your area, contact the Public Health Service (see contact information at the bottom of this page).

Can I eat self-caught fish in places where dinoterb has been measured? 

The Nutrition Center provides advice on eating fish from surface waters. As far as known, there are no advices specifically in relation to dinoterb. In general, the Nutrition Center advises against regularly eating self-caught freshwater fish from Dutch waters. 

Can I swim in places where dinoterb has been measured? 

There are no public health risks at a maximum concentration of 443.8 ng/l. It is always wise to check what advisory applies to a bathing water location. The province ensures the safety of bathing water and can issue a negative swimming advice or ban on swimming for official open water swimming locations based on the water quality data received. More information can be found at zwemwater.nl and on the province's website. 

Can my animal safely swim in ditches and canals where dinoterb has been measured or drink its water? 

The water quality standard for dinoterb is based on adverse effects to aquatic organisms. Exceedances of the water quality standard say nothing about any risks to public health or the health of your animal.  

Can I use water from a ditch where dinoterb was found for my vegetable garden?

The water quality standard for dinoterb is based on adverse effects to aquatic organisms. Exceedances of the water quality standard say nothing about any risks to human health. If you are concerned about your health due to substances in your environment, please contact the Public Health Service (GGD):

Announcement dinoterb