Background and methodsWithin the screening program of 2007 SWECO Environment has had the assignmentfrom the Swedish Environmental Protection Agency to measure the occurrence of:• Tolylfluanid which is used as fungicide in fruit and flower cultivations,as a seed disinfectant and as a biocide in paint and wood oil products.• Chlorothalonil which is used as a biocide in wood preservationproducts and in boat paints.• Diuron which has been commonly used as a weed killer on railwayembankments, roads and parking lots. Today the substance is used as abiocide in water based paints and (outside of Sweden) in boat paints.• Cypermethrin which is used as an insecticide in forestry and forhousehold applications to control arthropods.• Kathon which is used as a preservative for the control ofmicroorganisms in aqueous-based industrial products such as cleaningagents and in cosmetics, toiletries and household products such asshampoos, other hair and skin care products, fabric softeners orpolishes. Kathon is also widely used as a slemicide in the pulp andpaper industry.• Propiconazole which is used as a fungicide in paint and wood oilproducts for exterior use to prevent the forming of mould duringstorage and underneath the painted surface. It is also used in cerealcrops and grass seed cultivations.These substances were measured in various matrices affected by different activitiesand in background areas in Sweden. The sampling was performed on a national levelwith sampling points chosen by SWECO and on a regional level with samplingpoints chosen by regional county boards. Results from the national and the regionalscreening were collectively evaluated.The objectives of the project were to elucidate the main sources of these substancesto the environment, to elucidate the levels of these substances in the environmentand if the substances are found briefly assess whether the levels constitute anenvironmental and/or health problem.A national sampling strategy was devised which included soil, groundwater, surfacewater, sediments, storm water, sediments from storm water manholes as well asincoming water, sludge and effluents from sewage treatment plants. SWECO ENVIRONMENTScreening of biocides and organic halogensSWECO Environment 6The major sources to the environment of the investigated substances were:• Forest seedling nurseries (tolylfluanid, cypermethrin).• Paint manufacturing industries.• Landfills receiving painted and impregnated building material (tolylfluanid,propikonazol, diuron, kathon, cypermethrin).• Agriculture (tolylfluanid, propiconazole).• Sites where painted and/or impregnated wood is stored (tolylfluanid,propikonazol, diuron, kathon)• Soils below outdoor building surfaces that had been recently painted(tolylfluanid)• Railway yards and railway embankments where diuron has been used as aweed killer.• Marinas (chlorthalonil)• Intermittent storage sites for timber (cypermethrin)• Storm water from detached houses and villa gardens (cypermethrin)• Waste water treatment plants (Kathon)• Pulp and paper industries (Kathon)• Single house sewage plants (Kathon)Swedish environmental background levels in surface water and sediments weredetermined in reference lakes and in soil in the vicinity of these lakes.Conclusions and recommendationsThere does not seem to be a relation between the amounts of biocides used and theoccurrence in the environment. This is exemplified by Kathon that is used in a largenumber of products but was never found in any sample. Diuron on the other hand isused in smaller amounts, in a few products, but was found at background lakes andin a number of samples at point sources, such as paint factories.Only Cypermethrin was found at levels (in soil) that could cause any immediateeffects. On a few occasions diuron and propiconazole were found at high levels(relative to effect concentrations) in incoming water, storm water, ground water andsludge. However, they were well below any effect levels in surface water, soils andsediments.Some main conclusions and recommendations are:• The screened biocides are not found at levels that give rive to any immediateenvironmental and/or health concern. SWECO ENVIRONMENTScreening of biocides and organic halogensSWECO Environment 7• Paint industries, storage sites for treated wood and/or landfills seem to be themost important sources of propiconazole, diuron and tolylfluanid to theenvironment.• Cypermethrin is a possible candidate for further screening. The substancewas detected in storm water from areas with detached houses and in thetopsoil at sites where timber is stored. Further screening should focus on theusage of cypermethrin in pesticides for villa gardens and for protection offelled timber.• Chlorothalonil and the kathon substances CMI and MI were not detected inany samples. There is no further need for screening of these substances.However, the need for screening of kathon biodegradation products can notbe excluded since the stability and ecotoxicity of these compounds is largelyunknown.• It may be pertinent to review German screening studies on the occurrence ofdegradation products of tolylfluanid before deciding if these should beinvestigated in the future.