SummaryAs an assignment from the Swedish Environmental Protection Agency, IVL has during 2006/2007performed a "Screening Study" of 1,5,9-cyclododecatriene. The screening programme includedmeasurements in background areas and in the vicinity of potential point sources. Measurements werealso done in urban areas reflecting diffuse emission pathways from society. Sample types were air, soil,sediment, sludge and biota (fish). A total of 55 samples were included. CDDT was not found in any ofthe samples. The reported detection limits were 0.04 - 0.05 ng/m3 in air, 10 ng/g DW in sediment andsoil, 20 ng/g DW in sludge and 1-4 ng/g WW in fish. The overall conclusion is that 1,5,9-cyclododecatriene is generally not present in the Swedish environment in concentration that is ofenvironmental concern. The substance is thus not recommended as a candidate to be included inregular monitoring.