Key Message

This pre-core test indicator and its threshold values are yet to be commonly agreed in HELCOM and the presented thresholds are furthermore not currently approved EQS values, but provisional proposals. 

The indictor is included as a test indicator for the purposes of the 'State of the Baltic Sea' report, and the results are to be considered as intermediate.

Pharmaceuticals represent a major group of substances of emerging concern and it is vital that a detailed understanding of their distribution, role and fate in the environment is determined. This pre-core indicator targets the development of a status evaluation of the occurrence and concentrations of diclofenac in the Baltic Sea marine environment. Currently the distribution, role and fate of diclofenac in the Baltic Sea is not clearly understood, with limited information from few monitoring and screening studies available. Thus, while an initial overview is possible, accurate evaluations of the status of the environment cannot be made at this time. Defining trends and environmental status will only be possible after monitoring has been carried out to encompass the required spatial distribution and temporal periods. Furthermore, diclofenac was included in the EU first watch list under the Environmental Quality Standards Directive, requiring those HELCOM Contracting Parties who are also EU member states, to gather suitable monitoring data for the purpose of facilitating the development of appropriate methods and addressing any risk posed. It has recently been proposed that diclofenac be removed from this watch list since sufficient data has been collected and it remains to be clarified if diclofenac will be added to the list of priority substances. 

Diclofenac_in water_detected_NEW.pngDiclofenac_in water_below detecteion limit_NEW.pngDiclofenac_biota_NEW_frame.png

Key message figure 1. Overview of sample location in Baltic Sea water (left) and biota (right). Samples in which diclofenac were detected are indicated by squares, with colours indicating good (green) and not good (red) status. Circles indicate samples in which diclofenac was not detected, with colours indicating the analytical limit* certainty, green having analytical limits below the set threshold value (i.e. reliable) and yellow having analytical limits above the set threshold value or unknown (i.e. uncertain reliability).

*The term "analytical limit" is used in this report as no differentiation between LOD and LOQ could be assigned to the reported values in all cases.

Available data have indicated that the diclofenac concentration can be high close to waste water treatment plants (WWTPs, these often being the major point of entry to the Baltic Sea), of which a large number can be found situated in coastal regions (<20 km from the coast). High concentrations of diclofenac may also be detected in rivers draining into the Baltic Sea. Moreover, concentrations of diclofenac have been detected in water, sediments and biota in the Baltic Sea. Further data and analyses to determine the environmental effects of increased diclofenac concentrations, the dispersal from source, and the spatial distribution in water, sediments and biota are required to guide status evaluation.

The indicator is applicable in the waters of all countries bordering the Baltic Sea. The indicator is established and further monitoring data is currently being gathered. The current data coverage (temporal and spatial) is low and thus the results and confidence in the indicator evaluation are considered as intermediate.

Relevance of the core indicator

Pharmaceuticals represent a major group of substances of emerging concern and diclofenac, categorised in the therapeutic group of anti-inflammatory and analgesics, is both a widely used pharmaceutical in the Baltic Sea region and one of the most common pharmaceuticals currently detected in the environment (Unesco and HELCOM, 2017). Diclofenac remains one of the most used and most widely sold anti-inflammatory and analgesics in the region and it has been utilised for an extended period of time. It has been widely detected in aquatic environments (e.g. 50 countries) and at concentrations that can be indicative of detrimental environmental effects (Weber et al., 2014, Zang et al. 2008). In addition to its inclusion on the EU first watch list a recent data analysis indicated that diclofenac was among the 20 most sold pharmaceuticals in the Baltic Sea catchment area. Furthermore, it was also among the 20 pharmaceuticals with the highest concentrations in WWTP influent and effluent, showed very low levels of removal in conventional WWTP systems (circa 1%), and was among the 20 highest concentrations of measured pharmaceuticals detected in river water (Unesco and HELCOM, 2017). It has also been detected in Baltic Sea biota at levels above threshold values (e.g. in Perch, Hallgren and Wallenberg, 2015; Karlsson and Viktor, 2014) and previous studies have linked toxic effects in marine organisms to high concentrations of diclofenac.

Policy relevance of the core indicator

BSAP segment and objectivesMSFD Descriptor and criteria
Primary link

Hazardous substances

  • Concentration of hazardous substances close to natural levels
  • Healthy wildlife

D8 Concentrations of contaminants

D8C1 Within coastal and territorial and beyond territorial waters, the concentration of contaminants do not exceed the threshold values.

Secondary link

Hazardous substances

  • Fish safe to eat

D9 Contaminants in fish and seafood

D9C1 The level of contaminants in edible tissues (muscle, liver, roe, flesh or other soft parts, as appropriate) of seafood (including fish, crustaceans, molluscs, echinoderms, seaweed and other marine plants) caught or harvested in the wild (excluding fin-fish from mariculture) does not exceed the threshold values.

Other relevant legislation: For some Contracting Parties the Water Framework Directive will be relevant and Diclofenac was added to the EU watch list. It is currently being reviewed to determine if it will be added to the priority list. ‚Äč


Cite this indicator

HELCOM (2018) Diclofenac. HELCOM pre-core indicator report. Online. [Date Viewed], [Web link].

ISSN: 2343-2543


Download full indicator report

Diclofenac HELCOM pre-core indicator 2018 (pdf)