An unidentified compound was detected in the River Meuse in 2015 which was later identified as pyrazole. This forced drinking water suppliers to use alternative sources due to contamination of their intake water and back-up supplies. In response, authorities assessed potential health impacts, set a drinking water quality standard of 3 μg/L based on limited toxicology and precaution, and improved communication between stakeholders. Lessons included increasing transparency, responsibility clarity, and information sharing between drinking water companies, government, industry and health institutes. Actions were taken to prevent future incidents by considering drinking water impacts in emission permits and formalizing provisional guideline procedures.

1. Policy responses to emerging
contaminants in drinking water
sources in the Netherlands
Julia Hartmann (RIVM), Ans Versteegh (RIVM) &
Tjalling Vlieg (Ministry of Infrastructure and Water
Management)

2. Content
• Overview of the case
• Immediate policy responses
• Lessons learned
• Actions taken
NL: Policy responses to ECs in drinking water resources

3. The incident of pyrazole in the River Meuse, 2015
● Unidentified compound detected by drinking
water supplier (DWS)
● Compound appeared to be pyrazole
– E.g. precursor in production acrylonitrile
● Emission due to a malfunction in WWTS
● DWS forced to use alternative source
● Critical situation!
– Low volume of back-up water supply
– Contamination of back-up water supply
NL: Policy responses to ECs in drinking water resources
Intake water for
drinking water
production
Discharge WWTS
Poussin, J.K. et al (2012). Potential of semi-structural and
non-structural adaptation strategies to reduce future flood
risk: Case study for the Meuse. Natural Hazards and Earth
System Sciences. 12. 3455-3471. 10.5194/nhess-12-3455-
2012.
Introduction

4. Assess potential human health impact
Pyrazole is a precursor  Limited toxicological information was
available
1. Provisional guideline value: 15 µg/L, based on
– subacute test in rats
– first accepted for 2 years due to hydrazine-group
– accepted for lifetime exposure after further testing
NL: Policy responses to ECs in drinking water resources
Immediate policy response
2. Drinking water quality standard: 3 µg/L, based on
– provisional guideline value
– precautionary principle
– water quality standards from transboundary countries

5. Lessons learned from the incident of pyrazole
NL: Policy responses to ECs in drinking water resources
1. To prevent future incidents:
More focus on the use of surface water as source for the production of
drinking water
2. To improve responses during future incidents:
Involved stakeholders:
• Increase transparency
• Clear distribution of responsibilities
• Share information
Drinking water
companies
National, regional &
local government
Industry
Public health
institute
Lessons learned

6. Actions taken to improve responses during incidents
NL: Policy responses to ECs in drinking water resources
Stakeholders
Actions to be taken
Actions taken

7. Actions taken to prevent future incidents
● Issuing process of emission permits: include effect on drinking
water production
NL: Policy responses to ECs in drinking water resources
● Formalize the procedure for setting provisional drinking water
guidelines and publish guidelines on a publicly accessible website
Emission
permits
Drinking
water
Actions taken

8. Thank you!
NL: Policy responses to ECs in drinking water resources
Questions?
+31 30 274 2913
julia.hartmann@rivm.nl