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To investigate the formation and leaching potential of degradation products N,N -dimethylsulfamide (DMS) and dimethylsulfamic acid (DMSA) from cyazofamid under real-world agricultural conditions, the fungicide cyazofamid was applied in a potato crop as part of the Danish Pesticide Leaching Assessment Programme (PLAP). Leaching of DMS, DMSA, 4-chloro-5-(4-methylphenyl)-1 H -imidazole-2-carbonitrile (CCIM), and 4-chloro-5-(4-methylphenyl)-1 H -imidazole-2-carboxylicacid (CTCA) was monitored in water from the variably saturated zone (suction cups) and groundwater for more than two years following the applications. In total, 424 samples were analyzed for the content of the four degradation products. An additional laboratory study was executed in parallel with the field monitoring study. Here, cyazofamid was applied to soil columns and leaching of the four degradation products was studied under controlled conditions. In the EFSA conclusion on cyazofamid, CCIM and CTCA are mentioned as major relevant metabolites ; DMS is not mentioned in the risk assessment and DMSA is only included in acute oral toxicity studies and an in vitro bacterial mutation assay. In contrast to the EFSA conclusion on cyazofamid, our studies showed no leaching of the two major metabolites , CTCA and CCIM, but instead, major leaching of DMS and DMSA in both the field and laboratory studies was observed. That is, both DMS and DMSA leached to the groundwater in concentrations >0.1 μg/L for more than half a year. Based on this, we suggest improvements to the current pesticide risk assessment. [Display omitted] • Previously unknown cyazofamid degradation products leached into the groundwater. • Combined real-world field- and lab study expose shortcomings in the risk assessment. • If 14C-labelling is used in risk assessment all carbon atoms needs to be labelled. [ABSTRACT FROM AUTHOR]

Abstract Biocides – added to facade coatings like paints and renders to reduce microbial growth on the outer surfaces of buildings – are known to leach into the environment, when the facades are getting in contact with rainwater. The leaching process is described as diffusion controlled process. Nevertheless, no comprehensive data on diffusion coefficients is available so far. The present study aimed for determining the diffusion coefficients in paint of eight biocides, applying an easy, reproducible method. The study was performed using a paint closely related to commercially available paints. It suggests a new method to determine diffusion coefficients in paint films by submerging paint films consisting of several layers with water for 1 h intervals over a period of 30 h. By determining the biocide concentrations in the water after the contacting time, the mass flow of biocides across the paint film was calculated. The resulting diffusion coefficients varied from (0.27 ± 0.07) · 10−15 m2 s−1 for Cybutryn to (11.97 ± 3.14) · 10−15 m2 s−1 for Diuron. Graphical abstract Image 1 Highlights • An easy, reproducible method for determination of diffusion of biocides is proposed. • Diffusion coefficients were determined for eight biocides. • Diffusion coefficients can partially be related to molecular volume and logK OW. [ABSTRACT FROM AUTHOR]

The use of biocides as additives for building materials has gained importance in the recent years. These biocides are applied, e.g., to renders and paints to prevent them from microbial spoilage. However, these biocides can leach out into the environment. In order to better understand this leaching, the partition of biocides between water and inorganic phases of render with organic binder was investigated. The partition constants of carbendazim, diuron, iodocarb, isoproturon, cybutryn (irgarol), octylisothiazolinone, terbutryn, and tebuconazole towards minerals typically used in renders, e.g. barite, calcium carbonate, marble, kaolinite, and talc were determined. Partition constants for calcium carbonate varied between 0.2 mL g − 1 (diuron) and 5.2 mL g − 1 (iodocarb), respectively. The results for barite and kaolinite were in a similar range and usually the compounds with high partition constants for one mineral also had high values for the other mineral. No sorption to marble at all was found. From all minerals investigated, only talc showed high partition for all studied biocides. Partition constants for talc varied from 21.3 mL g − 1 (iodocarb) to 683.7 mL g − 1 (tebuconazole), respectively. The comparison with render-water distribution constants of two artificially made renders showed that the distribution constants can be estimated based on partition constants of compounds for individual components of the render. [ABSTRACT FROM AUTHOR]

Terbutryn is a commonly used biocide in construction materials. Especially polymer-resin-based renders and paints, used in external thermal insulation composite systems, are very susceptible to microbial deterioration. Previous studies have shown that biocides leach out of the material when contacted with rainwater; thus, they reach surface waters where they might have adverse effects on aquatic organisms. The knowledge on the long-term leaching performance and especially the formation and fate of degradation products is rare. In the present study, the leaching of terbutryn from artificial walls equipped with two types of render was observed for 19 months. In addition to concentration and mass load determinations for terbutryn, photodegradation products were identified and studied in the leachate and render. The results show that terbutryn leached mainly within the first 6-12 months. During the exposure, only 3% of the initial terbutryn was emitted to the runoff, while 64-80% remained in the coating. The overall mass balance could be closed by including several degradation products. Contrary to expectations, the major fraction of transformation products remained in the material and was not washed off immediately, which is of high importance for the long-term assessment of biocides in coating materials. [ABSTRACT FROM AUTHOR]

In this study it was tested, which mechanism for the transport of biocides in polymeric renders is more relevant: (1) evaporative transports (meaning there is a flow of water through the material due to evaporation on the surface), which transports also the biocides to the surface, (2) transport through the polymer and (3) transport through water filled pores. It turned out that under the experimental conditions evaporative transport was not relevant, while transport through soaked (constantly wetted) renders was considerably faster than by other means. Additionally it turned out that also the equilibria were influenced by the water content. Differences in equilibria can be up to factor 10 between constantly wetted (soaked) and un-wetted materials. The two tested materials (one silicone and one acrylate render) had significantly different leaching behavior concerning equilibria and dynamics of mass flows, but for both the pre-wetted materials leached most. [ABSTRACT FROM AUTHOR]

Highlights: [•] Partitioning of biocides between polymeric renders and water is described. [•] The partitioning constants are correlating to the K ow in some cases. [•] For triazines the fraction of polymer in the render influences the partitioning. [•] The render fraction also influences carbamates and isothiazolinones. [•] For the phenylureas the partitioning is not influenced by the polymer content. [ABSTRACT FROM AUTHOR]