Preliminary results show that 4 out of 6 sampling sites had concentrations of PPPs that potentially pose a risk for aquatic organisms in the environment.
Figure 1. Contribution plot of the individual (blue column) and cumulative (value on the y-axis) MEC/PNEC ratios for the PPPs detected in, Hotranelva (01.07.12- 15.07.12), Mørdrebekken (26.06.12- 10.07.12), Skuterudbekken (10.08.12-28.08.12) and Vasshaglona (11.06.12-25.06.12). The individual MEC/PNEC equal to or larger than 0.01 arge given above each column (figure taken from Petersen, K., Steinrød, M. and Tollefsen, KE. (2013): Initial environmental risk assessment of combined effects of plant protection products in six different areas in Norway.
The identified risk scenarios based on RQMEC/PNEC were confirmed by RQSTU values above 1 for aquatic plants based on the samples from Hotranelva, Mørdrebekken and Vasshaglona, and for algae based on samples from Skuterudbekken and Vasshaglona.
The risk at each site appeared to be driven by a few compounds and these toxicity drivers for the risk of combined toxicity of PPPs were identified for future consideration of mitigation measures. As risk assessment of combined toxicity of complex mixtures is still in early phases of development, a need for indepth experimental and theoretical effort to improve both the data to support and verify the predictive modelling approaches were identified.
More information and details can be found in Petersen, K. (NIVA), Steinrød, M. (BioForsk) and Tollefsen, KE. (NIVA) (2013): Initial environmental risk assessment of combined effects of plant protection products in six different areas in Norway.