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.
Due to the fact that no commonly agreed monitoring strategy has been developed for pharmaceuticals, only data from screening studies, scientific literature and data compilations are currently considered.
A number of factors of potential importance with respect to establishing suitable assessment protocols for this indicator include: 1) developing and confirming the accurate usage and potential of sales statistics, 2) gaining a better understanding of the environmental cycle of diclofenac, 3) developing a clearer understanding of diclofenac transformations in the environment and WWTPs, 4) detailed monitoring of WWTP discharge rates and diclofenac concentrations, 5) clarification of the apparent rapid decrease in diclofenac concentration in rivers (fate and sediment status) 6) temporal monitoring to determine longer term environmental impacts, 7) greater spatial monitoring, 8) enhanced monitoring of all relevant compartments (e.g. water, sediment and biota), 9) potential designation of target organisms for monitoring effort (e.g. benthic feeders, sedentary filter feeders, or species that traverse the marine-freshwater boundary), 10) the role of WWTPs in close proximity to the Baltic Sea coast, and 11) agreement on suitable analytical methodologies. Many of these factors are discussed in Lehtonen et al., (2014), and as greater spatial and temporal data emerges clear progress will be possible.
The indicator is tentatively to be evaluated on the HELCOM assessment unit level 4 (http://www.helcom.fi/action-areas/monitoring-and-assessment/monitoring-and-assessment-strategy), as the status of the marine environment is presumed to be affected mainly from WWTP related point sources. In screening studies, water concentrations failing to achieve good status have generally been found to drop over a distance of a few kilometres. As knowledge on the spatial extent of diclofenac dispersal, its fate, and its impact increases it may be possible to apply a more suitable assessment strategy. The indicator is in theory applicable in all assessment units throughout the Baltic Sea, as diclofenac is used in all HELCOM regions.