Frequently asked questions about source research dinoterb 2024

What is dinoterb?

Dinoterb is a crop protection product used to control weeds that has been in use since 1974. It has been banned for use in agriculture since July 1, 1998. The active ingredient dinoterb is poorly soluble in water, somewhat volatile (the substance can evaporate to some extent), reasonably degradable in soil, and not very mobile (the substance does not move easily with (moving) water and is not easily carried away with the water).

How does it end up in surface water?

It is not yet clear how, when, and why this substance ended up in surface water. What is clear, however, is that during sampling in 2021 and 2022, elevated concentrations were measured at more measuring points compared to previous years. The results can be viewed in the national Atlas of pesticides in surface water. The measurements are assessed each year by considering all measurements from the past year per measuring location, rather than looking at a single measurement value. 

What were Deltares' findings?

  • There is no clear evidence for a possible cause of elevated dinoterb levels.
  • There is no indication of a structural source or route.
  • The data analysis has been performed correctly.
  • No documentation has been found to indicate that dinoterb has been used as a herbicide in recent times.
  • Disturbance and agitation of the waterbed may cause any dinoterb present to re-enter the surface water and cause temporarily elevated concentrations of dinoterb.
  • It is unclear whether (urban and industrial) wastewater could be a possible source.
  • The method of analyzing dinoterb as part of a multi-component analysis affects the measurement accuracy.

Source investigation dinoterb (Deltares report)

Could this be illegal consumption?

Deltares investigated whether there are any indications that dinoterb continued to be used after the ban or that it is still in use today. The Deltares investigation shows that there are no concrete indications of illegal use. 

Deltares concludes that recent (illegal) use of dinoterb as a crop protection agent "is not a plausible cause for all concentrations of dinoterb exceeding the standard." This conclusion is based on a combination of literature research, information from the Netherlands Food and Consumer Product Safety Authority (NVWA), interviews with users in the region, and data analysis. 

Has HHNK tracked down the perpetrator?

HHNK conducted the source investigation due to its responsibility for water quality. It was primarily aimed at finding explanations for the high concentrations and was not a criminal investigation. 

Regardless of the investigation, HHNK always takes action when there are concrete indications of the use of dinoterb or other prohibited substances. Efforts are also being made to achieve more effective cooperation in the areas of licence, supervision enforcement. This involves collaboration between the NVWA, the Environmental Protection Agency, and HHNK.  

The NVWA is the competent authority responsible for authorisation supervision enforcement with regard to the possession and use of unauthorised plant protection products. 

HHNK is also responsible for supervision enforcing the correct use of crop protection products in matters relating to surface water. 

What does the next step look like?

Deltares recommends investigating three further possibilities: 

  • Investigate whether dinoterb that may have been stored in the waterbed in the past is released due to disturbance;
  • Taking samples to determine whether dinoterb from possible industrial or human use is entering the sewage treatment plant;
  • Additional analysis as soon as dinoterb is detected in regular measurements, in order to rule out possible variations in future measurements.  

HHNK will implement these recommendations and remain fully committed to improving water quality. 

Are you sure the measurements are correct?

The data analysis of dinoterb measurements in surface water reveals no errors in the analysis, but does indicate possible contamination and matrix effects, the influence of which on the reliability and accuracy of the measurements was not investigated further at the time. It is unclear what effect possible contamination of samples and matrix effects may have on the reliability and accuracy of measurements.

Work is currently underway on an automatic alert system for unusual measurement data.

Following the Dinoterb source study conducted by the Deltares research institute, further research into the Dinoterb analysis technique is being carried out at the Waterproef laboratory. Pending the results of this research, the Dinoterb measurement results will not be reported as of January 1, 2024, following consultation with HHNK.

Should I be concerned about my health? 

No. Research conducted by the National Institute for Public Health and the Environment (RIVM) on behalf of the Municipal Health Service (GGD) shows that there is no cause for concern. Dinoterb was measured during water quality monitoring. The water quality standard for this substance is based on preventing negative effects on aquatic organisms during prolonged 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 does not pose any health risks. 

The RIVM considered the worst-case scenario, namely daily swimming in water with the highest concentration of dinoterb found. The RIVM concluded that no health risks are to be expected in the assessed exposure scenario, i.e., daily exposure via swimming water, orally and dermally (skin). The RIVM also expects no health risks from diving, boating, playing, and watering the garden. Exposure to dinoterb in these cases will be lower than for daily swimming.

If you are concerned about the environmental impact of substances in your environment, please contact the GGD (see contact details at the bottom of this page).

Can I eat fish I have caught myself in places where dinoterb has been measured? 

The Netherlands Nutrition Center provides advice on eating fish from surface waters. As far as is known, there is no specific advice relating to dinoterb. In general, the Netherlands Nutrition Center advises against regularly eating freshwater fish caught in Dutch waters . 

Can I swim in places where dinoterb has been measured? 

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

Is it safe for my animal to swim in ditches and canals where dinoterb has been measured, or to drink the water from them? 

The water quality standard for dinoterb is based on negative effects on aquatic organisms. Exceedances of the water quality standard do not indicate any risks to human health or the health of your animal.  

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

The water quality standard for dinoterb is based on negative effects on aquatic organisms. Exceedances of the water quality standard do not indicate any risks to public health. If you are concerned about your health due to substances in your environment, you can contact the Municipal Health Service (GGD):

Reporting dinoterb