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.
Of the total 56 samples taken at the 6 different sites from April to October 2012, eight had a calculated RQMEC/PNEC>1; two samples from Hotranelva (Nord-Trøndelag county), four samples from Mørdrebekken (Akershus county), one sample from Skuterudbekken (Akershus county) and one sample from Vasshaglona (Aust-Agder county). These samples were typically collected from late June to mid-August. The cumulative risk was lowest at Timebekken (Rogaland county, RQMEC/PNEC of less than 0.121) and highest at Skuterudbekken (RQMEC/PNEC of up to 32.5).
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.