As an assignment from the Swedish Environmental Protection Agency, IVL has during 2006performed a "Screening Study" of zinc pyrithione and irgarol 1051. These substances are biocidesused as anti-fouling agents in products such as paints, anti-dandruff products and some medicalproducts. Because of their common appearance in consumer products, zinc pyrithione and irgarol1051 are likely to be emitted and distributed in the environment via a variety of sources, e.g. pointsources and via consumer use. Emissions in areas with boating activities are also likely to occur.The overall objectives of the screening were to determine the concentrations of the substances in avariety of media in the Swedish environment, to highlight important transport pathways, and toassess the possibility of current emissions in Sweden. A further aim was to investigate the likelihoodof uptake in biota and humans.The screening programme included measurements in background areas and in the vicinity ofpotential point sources and/or “affected areas”. Measurements were also carried out in urban areasreflecting diffuse emission pathways from the society. Sample types were water (surface water, inand outgoing sewage water, industrial effluents, drinking water and landfill leachate) sediment,sludge, biota (fish) and human urine. A total of 124 samples were included. 112 samples have beenanalysed with respect to zinc pyrithione, 115 samples have been analysed with respect to zinc andlead, and 118 samples have been analysed with respect to irgarol 1051.Zinc pyrithione (ZPT) was only detected in three water samples (representing ingoing water toSTPs and one industrial effluent) in concentrations of 1.9, 17 and 32 µg/l. All other samplesshowed ZPT levels below the detection limit. It was not possible to identify any correlation withzinc levels. Irgarol 1051 occurred to a larger extent; it was detected in 40 % of water samples(0.006-0.014 µg/l), 50 % of sludge samples (2.1-54 µg/kg dw) and in 70 % of sediment samples (2.5– 20 µg/kg dw). Neither zinc pyrithione nor irgarol 1051 was detected in human urine.Conclusively, zinc pyrithione was only detected in three environmental samples, thus it is notregarded as problematic substance; no further monitoring is necessary.¾ It was not possible to identify any correlation between zinc and zinc pyrithione.¾ The limited detection frequency despite extensive use indicate high degradation rate of zincpyrithione¾ Irgarol 1051 was detected in approximately 70 % of all sediment samples (from allsampling sites apart from the background sites). This is not surprising considering the useof the substance as an antifouling component in boat paints. However irgarol 1051 wasalso detected in approximately 50 % of the sludge samples, suggesting; 1) a wide use of thesubstance throughout Sweden, and 2) other sources and usage applications of thesubstance than previously reported.¾ Irgarol 1051 was more frequently occurring in STP effluent water, than in ingoing water.The reason for this is unclear.¾ Sludge and sediment seem to be appropriate matrices to analyse with regard to irgarol1051.¾ Neither irgarol 1051 nor zinc pyrithione occurred in humane urine