Biocide Runoff from Building Facades: Degradation Kinetics in Soil

Remediation of isoproturon-contaminated soil by Sphingobium sp. strain YBL2: Bioaugmentation, detoxification and community structure

The widely used phenylurea herbicide isoproturon (IPU) and its residues can inhibit the growth of subsequently planted crops. However, reports on bioremediation of IPU-contaminated soil are scarce. In this study, Sphingobium sp. strain YBL2-gfp (a derivative of the IPU-degrading Sphingobium sp. strain YBL2 isolated by our lab) was constructed to bioremediate IPU-contaminated soil. In pot experiments, strain YBL2-gfp colonized the roots of wheat and eliminated IPU residues in the soil within 21 d, effectively alleviating its toxicity and restoring wheat growth. IPU treatment reduced the richness and diversity of soil bacteria, while inoculation YBL2-gfp mainly affected richness with less impact on diversity. The high concentrations of IPU and inoculation of YBL2-gfp alone reduced the soil microbial community connections, while bioaugmentation treatment enhanced the soil microbial community connections. Additionally, strain YBL2-gfp stimulated the metabolic capacity of the indigenous microbes, promoting the degradation of IPU and reducing the negative impact of high concentrations of IPU on microbial community. Taken together, this study offers relatively comprehensive insights into the practical application of bioaugmentation, demonstrating that strain YBL2 has the potential to remediate IPU-contaminated soils.

Exposure levels and health implications of fungicides, neonicotinoid insecticides, triazine herbicides and their associated metabolites in pregnant women and men

Exposure to pesticides can pose a series of advance effects on human health. However, the exposure levels and health implications of the current use pesticides and their metabolites in both men and pregnant women remain unclear. In this study, an analytical method was developed to quantify fungicides, neonicotinoid insecticides, triazine herbicides, and their metabolites in the human serum. Fifty of the 73 target pesticides and metabolites were detected in the human serum of men and pregnant women from Wuxi, China, which included 11 triazine herbicides and metabolites, 17 neonicotinoid insecticides and metabolites, and 22 fungicides. Fungicides had the highest cumulative concentration (49.5 ng/mL), followed by neonicotinoid insecticides and metabolites (6.38 ng/mL), and triazine herbicides and metabolites (5.10 ng/mL). Moreover, the estimated daily intake (EDI) of fungicides was 10.4 and 12.7 times higher than that of triazine herbicides (included their metabolites) and neonicotinoid insecticides (included their metabolites), respectively. Of the three categories of pesticides, exposure to fungicides contributed to the highest exposure risk within the hazard quotient in the range of 5.1 × 10-3-0.17. Correlation analysis revealed that the pesticide exposure levels in human serum were correlated with their maximum residue levels in vegetables and fruits. Pesticide exposure has also been correlated with the weight and Body Mass Index (BMI) of humans based on structural equation modeling. This study provides new insights into the exposure of men and pregnant women to a cocktail of fungicides, neonicotinoid insecticides, triazine herbicides and their metabolites.

Photodegradation of typical pharmaceuticals changes toxicity to algae in estuarine water: A metabolomic insight

The ubiquitous existence of various pharmaceuticals in the marine environment has received global attention for their risk assessment. However, rather little is known thus far regarding the natural attenuation (e.g., photolysis)-induced product/mixture toxicity of these pharmaceuticals on marine organisms. In this study, the photodegradation behavior, product formation, and risks of two representative pharmaceuticals (i.e., ciprofloxacin, CIP; diclofenac, DCF) were explored in the simulated estuary water. It was noted that both pharmaceuticals can be completely photolyzed within 1 h, and five products of CIP and three products of DCF were identified by a high-resolution liquid chromatography-mass spectrometer. Accordingly, their photodecomposition pathways were tentatively proposed. The in silico prediction suggested that the formed transformation products maintained the persistence, bioaccumulation potential, and multi-endpoint toxic effects such as genotoxicity, developmental toxicity, and acute/chronic toxicity on different aquatic species. Particularly, the non-targeted metabolomics first elucidated that DCF and its photolytic mixtures can significantly affect the antioxidant status of marine algae (Heterosigma akashiwo), triggering oxidative stress and damage to cellular components. It is very alarming that the complete photolyzed DCF sample induced more serious oxidative stress than DCF itself, which called for more concern about the photolysis-driven ecological risks. Overall, this investigation first uncovered the overlooked but serious toxicity of the transformation products of prevalent pharmaceuticals during natural attenuation on marine species.

Eluates from façades at the beginning of their service time affect aquatic and sediment organisms

Biocides are used in building materials to prevent microbial growth during storage (in-can preservatives) as well as after application (film preservatives). These compounds can leach out from the material into the environment and harm non-target organisms. In this study, the ecotoxicological effect of leachates at the beginning of a façade lifetime, on sediment and aquatic organisms was examined. For this purpose, leaching tests were carried out in the setting of a natural weathering experiment and a laboratory immersion with façade samples consisting of render/paint systems. The leaching experiments were performed with three different formulations, namely no biocides containing control, a formulation containing only in-can preservatives (benzisothiazolinone (BIT), methylchloroisothiazolinone (CMIT), and methylisothiazolinone (MIT)), and, as is common in organic building materials, containing both in-can and film preservatives (octylisothiazolinone (OIT) and terbutryn (TB)). In order to elucidate the effects of in-can and film preservative-containing eluates the toxicity of the generated leachables was evaluated on the model of several aquatic and sediment organisms, namely luminescent bacteria (Vibrio fischeri), green algae (Scenedesmus subspicatus), Salmonella typhimurium TA1535/pSK1002 (umu-test), fish-egg (Danio rerio), Chironomus riparius, and Lumbriculus variegatus. It was demonstrated that in-can preservatives leach out rapidly at the beginning of a façade lifetime and despite the short half-life of these compounds in aqueous solutions, they could be detected at high concentrations in the eluates. Furthermore, eluates from early sampling times, predominantly containing in-can preservatives, were found to cause toxic effects on sediment and aquatic organisms. The results demonstrate that in-can preservatives can impose a significant stress factor on the environment.

Detection of Cladosporium spinulosum on an engraving by Rembrandt and susceptibility profile to eco-friendly antifungal treatments

Interdisciplinary studies on cultural heritage artworks provide efficient solutions to control fungal growth and the negative effects of biodeterioration. In this study, we aimed to identify the population of filamentous fungi colonizing an engraving by the Dutch painter Rembrandt, whose conservation status was compromised and showed visible stains of biodeterioration. Microbiological techniques, such as cultivation-dependent approaches and molecular biology, have been used to identify fungal populations. In addition, the anaerobic atmosphere technique and eco-friendly antifungal agents, such as essential oils (EOs) of Curcuma longa, Thymus vulgaris, and Melaleuca alternifolia, were tested against the metabolically active fungal population Cladoposporium spinulosum. Furthermore, in vitro assays revealed that the interaction between the fungal strains and EO was positive, inhibiting the growth of these fungi, and the EOs from T. vulgaris and M. alternifolia showed low minimum inhibitory concentration values. Exposure to anaerobic conditions for 35 days was effective in the total elimination of isolated fungal strains. In conclusion, this study demonstrated the effectiveness of a nondestructive technique for artwork on engraving colonized by fungal strains and using EO as an alternative to toxic antifungals used in conventional treatments in artworks. Thus, this interdisciplinary study involving applied microbiology and botanical and preventive conservation presents a tool to control microbial growth while maintaining artwork integrity.

Emissions of the Urban Biocide Terbutryn from Facades: The Contribution of Transformation Products

Biocides are added to facade paints and renders to prevent algal and fungal growth. The emissions of biocides and their transformation products from building facades during wind-driven rain can contaminate surface waters, soil, and groundwater. Although the emissions of biocide transformation products may be higher than those of the parent biocide, knowledge of the emissions of transformation products over time is scarce. Combining field- and lab-scale experiments, we showed that solar irradiation on facades controls the formation of transformation products and can be used with runoff volume to estimate the long-term emissions of terbutryn transformation products from facades. The slow (t1/2 > 90 d) photodegradation of terbutryn in paint under environmental conditions was associated with insignificant carbon isotope fractionation (Δδ13C < 2 ‰) and caused 20% higher emission of terbutryn-sulfoxide than terbutryn in leachates from facades. This indicated continuous terbutryn diffusion toward the paint surface, which favored terbutryn photodegradation and the concomitant formation of transformation products over time. The emissions of terbutryn transformation products (77 mg m-2) in facade leachates, modeled based on irradiation and facade runoff, were predicted to exceed those of terbutryn (42 mg m-2) by nearly 2-fold after eight years. Overall, this study provides a framework to estimate and account for the long-term emissions of biocide transformation products from building facades to improve the assessment of environmental risks.

Science for art: multi-years' evaluations of biocidal efficacy in support of artwork conservation

In recent decades, the relationship between Science and Art has been gradually strengthened through the use of diagnostic, conservation, and valorization technologies. New technologies can also be used to support the creation and durability of bio-artworks. Within such a context, starting from the Spring of 2014, we performed in situ experimentations to eventually increase the durability of the graphical artwork of William Kentridge on the Lungotevere embankments, whose creation was scheduled in the following years. We applied various combinations and concentrations of three different biocides (Algophase, Biotin R, and Preventol R80) and two water repellents (Hydrophase surfaces and Silo 111) on 34 test areas. However, the artist preferred to leave his artwork to a natural fading. Right before the realization of the graphical artwork "Triumph and Laments of Rome" in 2016, just the black biological colonizations mainly composed of cyanobacteria were removed through pressurized water. We monitored the artist's work through analyses of images and colorimetric variations and such drawings showed a duration of 4 years in the natural conditions of recolonization. Here we show how the recolonization of treated and control areas, analyzed with the same methods, showed an increased duration, 3 years longer than under natural conditions in the case of Preventol R80^® and Biotin R^® plus Silo 111^®. The tested solutions showed differential effectiveness and multiple possibilities of use to support the maintenance of the artwork if the artist wanted to preserve his artwork for a longer period.

Tuning the sensitivity of cell-based biosensors for the detection of biocides

The presence of biocides in wastewater can negatively impact the efficiency of wastewater treatment processes, particular the process of nitrification. In this paper, we describe the development of cell-based biosensors (CBBs) with tunable levels of sensitivity for rapidly detecting the presence and predicting the type and concentration of biocides. The CBB assay developed is performed by first exposing a panel of bacterial strains (E. coli, B. subtilis, B. cereus) to the sample being tested and to the control sample without biocide, and then adding a fluorescent dye (LIVE/DEAD BacLight). We then compare the fluorescence signals generated by the two samples, and the differences in the signals indicate the presence of a biocide, as previously reported in the literature. We found that the sensitivity of the CBB assay can be improved by tuning the type/salinity of the buffer used to suspend the cells, and by changing the number of cells used in the assay. These changes improved the level of detection (LOD) of the biocide Cetyltrimethylammonium bromide (CTAB) from 10 ppm to 0.625 ppm and the biocide Grotan® BK from 500 ppm to 7.8 ppm. With the optimized conditions for each strain, we also establish that the combined response from the panel of bacterial strains can be used to predict the type and concentration of biocide sample tested. Additionally, we provide evidence that the response of the tunable CBB assay can be quantitatively measured using a compact, commercially available fluorometer. Overall, the significance of this work will improve point-of-use testing and enable the discrimination between biocide-containing samples of similar toxicity and detection of lower toxicity samples, thereby improving the accuracy of the CBB assay.

Variation of Tolerance to Isothiazolinones Among Daphnia pulex Clones

Isothiazolinones are a family of broad-spectrum biocides widely used in industry and consumer products. Chloro- and methyl-isothiazolinones (CMIT and MIT) are documented as strong irritants, yet they are still used in a wide variety of applications, including cosmetics, cleansers, hygienic products, and various industrial applications. The subsequent substantial release of these molecules from urban sources into freshwater environments, and their potential impacts on aquatic species, have nevertheless received little attention so far, with few studies reporting on the toxicity of either CMIT or MIT to nontarget organisms. The present study addresses this current knowledge gap by evaluating the acute toxicity to Daphnia pulex (Cladocera) of CMIT/MIT (3:1) and MIT, the two formulations most commonly used by manufacturers. In addition, genetic diversity is known to be a major component of variability in phenotypic responses, although it is largely overlooked in typical toxicity tests. Thus the potential range of responses inherent to genetic diversity is rarely considered. Therefore, to account for intraspecific variations in sensitivity, our design involved eight clonal lines of D. pulex stemming from distinct natural populations or commercial strains. Clones exhibited strong variation in their responses, with median lethal concentration (LC50) values ranging from 0.10 to 1.84 mg/L for the mixture CMIT/MIT, and from 0.68 to 2.84 mg/L for MIT alone. These intraspecific ranges of LC50 values challenge the use of single clones of daphnids in standard ecotoxicological tests and the predictions based on their results. The present study brings new evidence that assessing ecological risk of chemicals while ignoring genotype diversity is neither ecologically relevant, nor a representative evaluation of the diversity of potential adverse outcomes. Environ Toxicol Chem 2023;42:805-814. © 2023 SETAC.

Disposition of Aerosols of Isothiazolinone-Biocides: BIT, MIT and OIT

Biocides are widely used in everyday life, and accordingly, human exposure to them is inevitable. Especially, the inhalational exposure of humans to biocides and resultant respiratory toxicity are gaining public interest due to the recent catastrophe associated with humidifier disinfectants. Aerosolized chemicals are subject to gravitational deposition and chemical degradation. Therefore, the characterization of the disposition of aerosols is essential to estimate the inhalational exposure to biocides. Here, we compared the disposition of aerosols of one of the commonly used biocide classes, isothiazolinone-based biocides, BIT, MIT, and OIT. An acrylic chamber (40 cm × 40 cm × 50 cm) was created to simulate the indoor environment, and a vacuum pump was used to create airflow (1 LPM). Biocides were sprayed from a vertical nebulizer placed on the ceiling of the chamber, and the distribution of particle sizes and volume was measured using the Optical Particle Sizer (OPS) 3330 device. During and after the aerosol spraying, airborne biocides and those deposited on the surface of the chamber were sampled to measure the deposition using LC-MS/MS. As a result, the broad particle size distribution was observed ranging from 0.3 to 8 μm during the nebulization. The inhalable particle faction (>2 μm) of the isothiazolinones was 32−67.9% in number but 1.2 to 6.4% in volume. Most of the aerosolized biocides were deposited on the chamber’s surface while only a minimal portion was airborne (<1%) after the nebulization. More importantly, significant amounts of MIT and OIT were degraded during aerosolization, resulting in poor total recovery compared to BIT (31%, 71% vs. 97% BIT). This result suggests that some isothiazolinones may become unstable during nebulization, affecting their disposition and human exposure significantly.

Rapid plant uptake of isothiazolinone biocides and formation of metabolites by hydroponic Arabidopsis

Isothiazolinones biocides are water-soluble, low molecular weight, nitrogenous compounds widely used to prevent microbial growth in a variety of applications including personal care products and building façade materials. Because isothiazolinones from buildings wash off and enter stormwater, interactions with terrestrial plants may represent an important part of the environmental fate of these compounds (e.g., in green stormwater infrastructure). Using the model plant Arabidopsis thaliana grown hydroponically, we observed rapid (≥99% within 24 hours), plant-driven removal of four commonly used isothiazolinones: benzisothiazolinone (BIT), chloromethylisothiazolinone, methylisothiazolinone, and octylisothiazolinone. No significant differences in uptake rate occurred between the four compounds; therefore, BIT was used for further detailed investigation. BIT uptake by Arabidopsis was concentration-dependent in a manner that implicates transporter-mediated substrate inhibition. BIT uptake was also minimally impacted by multiple BIT spikes, suggesting constituently active uptake. BIT plant uptake rate was robust, unaffected by multiple inhibitors. We investigated plant metabolism as a relevant removal process. Proposed major metabolites that significantly increased in the BIT-exposure treatment compared to the control included: endogenous plant compounds nicotinic acid (confirmed with a reference standard) and phenylthioacetohydroximic acid, a possible amino acid-BIT conjugate, and two accurate masses of interest. Two of the compounds (phenylthioacetohydroximic acid and TP 470) were also present in increased amounts in the hydroponic medium after BIT exposure, possibly via plant excretion. Upregulation of endogenous plant compounds is environmentally significant because it demonstrates that BIT impacts plant biology. The rapid plant-driven isothiazolinone removal observed here indicates that plant-isothiazolinone processes could be relevant to the environmental fate of these stormwater compounds.

Transformation and stable isotope fractionation of the urban biocide terbutryn during biodegradation, photodegradation and abiotic hydrolysis

Terbutryn is a widely used biocide in construction materials like paint and render to prevent the growth of microorganisms, algae and fungi. Terbutryn is released from the facades into the environment during rainfall, contaminating surface waters, soil and groundwater. Knowledge of terbutryn dissipation from the facades to aquatic ecosystems is scarce. Here, we examined in laboratory microcosms degradation half-lives, formation of transformation products and carbon and nitrogen isotope fractionation during terbutryn direct (UV light with λ = 254 nm and simulated sunlight) and indirect (simulated sunlight with nitrate) photodegradation, abiotic hydrolysis (pH = 1, 7 and 13), and aerobic biodegradation (stormwater pond sediment, soil and activated sludge). Biodegradation half-lives of terbutryn were high (>80 d). Photodegradation under simulated sunlight and hydrolysis at extreme pH values indicated slow degradability and accumulation in the environment. Photodegradation resulted in a variety of transformation products, whereas abiotic hydrolysis lead solely to terbutryn-2-hydroxy in acidic and basic conditions. Biodegradation indicates degradation to terbutryn-2-hydroxy through terbutryn-sulfoxide. Compound-specific isotope analysis (CSIA) of terbutryn holds potential to differentiate degradation pathways. Carbon isotope fractionation values (ε_C) ranged from -3.4 ± 0.3‰ (hydrolysis pH 1) to +0.8 ± 0.1‰ (photodegradation under UV light), while nitrogen isotope fractionation values ranged from -1.0 ± 0.4‰ (simulated sunlight photodegradation with nitrate) to +3.4 ± 0.2‰ (hydrolysis at pH 1). In contrast, isotope fractionation during biodegradation was insignificant. Λ^N/C values ranged from -1.0 ± 0.1 (hydrolysis at pH 1) to 2.8 ± 0.3 (photodegradation under UV light), allowing to differentiate degradation pathways. Combining the formation of transformation products and stable isotope fractionation enabled identifying distinct degradation pathways. Altogether, this study highlights the potential of CSIA to follow terbutryn degradation in situ and differentiate prevailing degradation pathways, which may help to monitor urban biocide remediation and mitigation strategies.

Removal of methylisothiazolinone biocide from wastewater by VUV/UV advanced oxidation process: Kinetics, mechanisms and toxicity

Methylisothiazolinone (MIT) is frequently used as antimicrobial in household and industrial products, and poses ecological and health risks to aquatic organisms and humans. In this study, vacuum ultraviolet (VUV)/ultraviolet (UV) irradiation was found highly efficient for removal of MIT. The rate constant of MIT degradation (k_obs) under VUV/UV irradiation was 3.75 μEinstein^-1 cm², which was around 12.5 times higher than that under UV irradiation. The •OH concentration during the VUV/UV process was 1.0 × 10^-12 M. The contributions of UV photolysis and •OH oxidation to MIT degradation under VUV/UV irradiation were 7.3% and 92.7%, respectively. The optimum solution pH (6.0-7.1) gave k_obs 33%-39% higher than those at pH 3.9 and 9.3. CO₃^2-/HCO₃^- inhibited MIT degradation and the k_obs decreased by 74% when the concentration of CO₃^2-/HCO₃^- was increased to 1 mM. The order of MIT removal efficiency under VUV/UV irradiation was ultrapure water > secondary effluent > reverse osmosis (RO) concentrate, because of the light screening and •OH quenching effect of actual wastewater. In RO concentrate, the rate constant of MIT degradation under VUV/UV irradiation was 22% higher than that obtained under UV irradiation. The reduction of TOC, UV₂₅₄, and total fluorescence regional integration of the RO concentrate during VUV/UV process were 7.2%, 34.9%, and 52.3%, respectively. Twelve main transformation products of MIT were identified after VUV/UV degradation. The main degradation mechanisms of MIT were sulfur atom oxidation and hydroxyl addition. Quantitative structure-activity relationship analysis showed that VUV/UV degradation was an efficient method to remove the toxicity of MIT.

Degradation of isoproturon in vitro by a mix of bacterial strains isolated from arable soil

Isoproturon (IPU) is widely used to control annual grasses and broad leaf weeds in cereal crops. In this study, four IPU-degrading bacterial strains, i.e., Sphingomonas sp. ISP1, Arthrobacter sp. ISP2, Acinetobacter baumannii 4IA and Pseudomonas sp. ISP3, were isolated from agricultural soil. The mixed culture of four isolates completely degraded the herbicide at 100 mg/L within 10 days. During IPU degradation, several transient accumulations of the metabolites, including 3-(4-isopropylphenyl)-1-methylurea, 3-(4-isopropylphenyl)-urea, 4-isopropylaniline, and 4-toluidine, were also identified. Moreover, the inoculation of the isolated mixed culture into the soil from a mountain with no previous herbicide application increased the degradation rate by 51% of the herbicide on average. Furthermore, bioaugmentation with isolated bacteria in the soil resulted in short term variations in bacterial structure compared to the unaugmented soil. The findings of this study were instrumental in understanding the mechanisms of pesticide breakdown and bioremediation in liquid media and soil.

Lessening the toxic effect of the methylisothiazolinone via vermicompost tea on Pisum sativum

Biocides, which are found in nature as persistent pollutants, pose a great danger to the ecosystem. Methylisothiazolinone (MIT), a widely used biocide, reaches plants by mixing with water and soil. Vermicompost tea (VCT), which strengthens the plant defence mechanism and increases its growth and development, is a liquid fertiliser consisting of the cooperation of worms with microbes. In the present study, after applying 0.4 g/L (EC50/2), 0.8 g/L (EC50), and 1.6 g/L (EC50 × 2) MIT concentrations without and with VCT on forage pea (Pisum sativum), root lengths, mitotic index data, chromosome and nuclei abnormalities, and DNA damage level were determined. When VCT applied and non-applied groups were compared, it was found that, especially in the VCT applied group, they cope with the stress conditions created by MIT. In addition, positive effects were observed in root lengths, mitotic index data, and amount of cell nuclei abnormalities. In line with other study results, VCT reduces cellular damage by regulating the normal life cycle disrupted in the cell due to mutagens using the curative-regulatory feature.

An Ecotoxicological Evaluation of Four Fungal Metabolites with Potential Application as Biocides for the Conservation of Cultural Heritage

Biocides based on chemical synthetic compounds have been commonly used to counteract damages caused by microorganisms on stone cultural heritage. However, in the last few years, the use of commercial and traditional biocides has been banned and/or limited due to their dangerous profile for the environment, as well as human and animal health. Natural products could be used as suitable alternatives for cultural heritage purposes, as they have low toxicity and stability compared with synthetic pesticides. Even if most of the investigated solutions have already shown promising results, their efficiency, ecotoxicological, and chemical features are poorly investigated. In this manuscript, we aimed to evaluate the ecotoxicological profile of four fungal metabolites-namely, cavoxin, epi-epoformin, seiridin, and sphaeropsidone-with potential antimicrobial properties for monumental artworks. A battery of ecotoxicological tests using Aliivibrio fischeri (bacterium), Raphidocelis subcapitata (alga), Raphanus sativus L. (macrophyte), Daphnia magna (crustacean), and Caenorhabditis elegans (nematode) revealed a relative lower toxicity of these compounds, especially when compared with Preventol^® and Rocima^®, commercial biocides mainly used for the conservation of cultural heritage.

Degradation of a non-oxidizing biocide in circulating cooling water using UV/persulfate: Kinetics, pathways, and cytotoxicity

In industry, isothiazolinone (a mixture containing 5-chloro-2-methyl-4-isothiazolin-3-one (CMIT) and 2-methyl-4-isothiazolin-3-one (MIT), CMIT-MIT) as a non-oxidizing biocide is extensively used to control the growth of microorganisms in the circulating cooling water system, which potentially threatens the ecological environment and human health. In this work, the oxidative degradation of CMIT-MIT by UV/persulfate (PS) technology on a laboratory-scale was systematically investigated. The degradation of CMIT-MIT was greatly improved by UV/PS compared with only UV or oxidant. During the photolysis of 60 mg/L PS, the degradation rate and TOC mineralization rate of CMIT-MIT were 91% and 34.7%, respectively. The contributions of ^.OH and SO₄·^- to CMIT-MIT degradation in the UV/PS system were estimated to be 0.93% and 32.12% respectively. The degradation rate of CMIT-MIT decreased slightly with the increase of pH. The presence of SO₄^2- and NO₃^- had no significant effect on the degradation of CMIT-MIT, while the presence of Cl^- and CO₃^2- inhibited the CMIT-MIT removal rate. The degradation pathways and three possible intermediates of CMIT-MIT were obtained. After degradation of CMIT-MIT by UV/PS process, the cytotoxicity decreased within 20 min, effectively indicating that UV/PS could be as a potential technology to remove the CMIT-MIT in water treatment.

Current and future chemical treatments to fight biodeterioration of outdoor building materials and associated biofilms: Moving away from ecotoxic and towards efficient, sustainable solutions

All types of building materials are rapidly colonized by microorganisms, initially through an invisible and then later a visible biofilm that leads to their biodeterioration. Over centuries, this natural phenomenon has been managed using mechanical procedures, oils, or even wax. In modern history, many treatments such as high-pressure cleaners, biocides (mainly isothiazolinones and quaternary ammonium compounds) are commercially available, as well as preventive ones, such as the use of water-repellent coatings in the fabrication process. While all these cleaning techniques offer excellent cost-benefit ratios, their limitations are numerous. Indeed, building materials are often quickly recolonized after application, and microorganisms are increasingly reported as resistant to chemical treatments. Furthermore, many antifouling compounds are ecotoxic, harmful to human health and the environment, and new regulations tend to limit their use and constrain their commercialization. The current state-of-the-art highlights an urgent need to develop innovative antifouling strategies and the widespread use of safe and eco-friendly solutions to biodeterioration. Interestingly, innovative approaches and compounds have recently been identified, including the use of photocatalysts or natural compounds such as essential oils or quorum sensing inhibitors. Most of these solutions developed in laboratory settings appear very promising, although their efficiency and ecotoxicological features remain to be further tested before being widely marketed. This review highlights the complexity of choosing the adequate antifouling compounds when fighting biodeterioration and proposes developing case-to-case innovative strategies to raise this challenge, relying on integrative and multidisciplinary approaches.

Sol-gel-derived hard coatings from tetraethoxysilane and organoalkoxysilanes bearing zwitterionic and isothiazolinone groups and their antifouling behaviors

Current environmentally friendly marine antifouling (AF) coatings are mainly polymeric with a relatively low hardness. Hard sol-gel-derived AF coatings for underwater robot-cleaning are seldom used. In this work, two new organoalkoxysilanes, i.e., (N-methoxyacylethyl)-3-aminopropyltriethoxysilane and 2-(2-hydroxy-3-(3-(trimethoxysilyl)propoxy)propyl)benzo[d]isothiazol-3(2H)-one, were synthesized by a facile method. These two precursors were used with tetraethoxysilane (TEOS) to produce three series of hybrid AF coatings with zwitterionic group (Z-χ), antibacterial group (1,2-benzisothiazolin-3-one) (A-χ) and zwitterionic and antibacterial groups (S-χ) by a sol-gel process. The hardness of the coatings was measured using a pencil hardness tester and the AF behaviors of the coatings were examined by laboratory and field assays. A pencil hardness up to 5 H was achieved and slight deterioration was observed after 9 months of immersion in artificial seawater for the A-χ and S-χ coatings at a sufficiently high TEOS content. A synergistic effect between the zwitterion and antimicrobial agents existed but was not obvious. A higher TEOS content led to a higher hardness and better AF performance regardless of the type of AF group. Even with the same biofilm formation after field assay, coatings with a higher TEOS content exhibited a better resistance to mussel settlement.

Application, release, ecotoxicological assessment of biocide in building materials and its soil microbial response

Biocides are used in building materials to protect the building against microbial colonization and biodeterioration. However, these biocides are introduced by gradual leaching into soils in proximity of the buildings. This review discusses the aspects and characteristics of biocides from building materials in terms of (i) in-situ leaching and simulation thereof in-vitro and in-field tests, (ii) persistence, as well as photolytic and biodegradation, and its influence on toxicological evaluation, and (iii) evaluation of terrestrial toxicity by conventional ecotoxicological tests and novel holistic testing approaches. These aspects are influenced by multiple parameters, out of which water availability, physicochemical properties of microhabitats, combination of biocidal building materials, soil parameters, and composition of the soil microbiome are of utmost relevance. Deeper understanding of this multiparametric system and development of comprehensive characterization methodologies remains crucial, as to facilitate realistic assessment of the environmental impact of biocides used in construction materials and the corresponding degradation byproducts.

Urban storm water infiltration systems are not reliable sinks for biocides: evidence from column experiments

Groundwater quality in urban catchments is endangered by the input of biocides, such as those used in facade paints to suppress algae and fungal growth and washed off by heavy rainfall. Their retention in storm water infiltration systems (SIS) depends, in addition to their molecular properties, on chemical properties and structure of the integrated soil layer. These soil properties change over time and thus possibly also the relevance of preferential flow paths, e.g. due to ongoing biological activity. To investigate the mobility of biocides in SIS, we analyzed the breakthrough of differently adsorbing tracers (bromide, uranine, sulforhodamine B) and commonly used biocides (diuron, terbutryn, octhilinone) in laboratory column experiments of undisturbed soil cores of SIS, covering ages from 3 to 18 years. Despite similar soil texture and chemical soil properties, retention of tracers and biocides differed distinctly between SIS. Tracer and biocide breakthrough ranged from 54% and 5%, to 96% and 54%, respectively. We related the reduced solute retention to preferential transport in macropores as could be confirmed by brilliant blue staining. Our results suggest an increasing risk of groundwater pollution with increasing number of macropores related to biological activity and the age of SIS.

Photochemical fate of medetomidine in coastal and marine environments

Medetomidine has been authorized in ship hull paints as an antifouling biocide under the biocidal product regulation in Europe since 2016. Its release into marine systems causes concerns over persistence and toxicity. However, the environmental fate of medetomidine has not been fully investigated. In this study, the photodegradation of medetomidine under natural sunlight conditions was investigated using collected coastal and sea waters. In addition, the phototransformation of medetomidine with reactive species (i.e., singlet oxygen, excited triplet state organic matter, and hydroxyl radicals) under UVA light was examined. Photoproducts were isolated by high-performance liquid chromatography (HPLC), identified by a combination of nuclear magnetic resonance (NMR) spectroscopy and time-of-flight mass spectrometry (qTOF), and reaction mechanisms were proposed. The results show that medetomidine is a neutral base (pKa of protonated form = 7.2) that leads to two different protonation states in the aquatic environment. Photodegradation of neutral medetomidine was dominated by reaction with singlet oxygen, while protonated medetomidine was relatively photostable. The contribution of reactive species to the overall photodegradation of neutral medetomidine was calculated to provide an assessment of phototransformation of medetomidine. The half-live of medetomidine was < 1.5 days in natural waters (pH_coastal = 8.3; pH_sea = 8.1) under sunlit near-surface conditions, suggesting that it is not persistent in the aquatic environment. Because medetomidine has a relatively short half-life in sunlit aquatic ecosystems, a number of products, such as 2-(2,3-dimethylphenyl)propanamide, can be formed by photochemical reactions of medetomidine, with unknown consequences for marine and coastal waters.

High-performance liquid chromatography-tandem mass spectrometry with post-column pH modification: Independent pH optimization for chromatographic separation and electrospray ionization

RATIONALE

In recent environmental research, multi-methods using high-performance liquid chromatography-mass spectrometry (HPLC/MS/MS) have become more and more important for the analysis of organic micropollutants in environmental matrices. As the targeted compounds usually have different physicochemical properties, the optimization of these methods is challenging.

METHODS

The pH in the electrospray of the mass spectrometer ion source was modified independently of the one used for the HPLC separation, using a post-column HPLC flow to make the spray acidic or alkaline. The method development was carried out manually in a systematic multistep way.

RESULTS

The method used for the analysis of organic biocides (e.g., terbutryn, propiconazole, and isothiazolinones) was optimized. It was shown that the use of a neutral as well as an acidified gradient could not be optimized for all target compounds, whereas a neutral gradient with post-column acidification was optimum for all target compounds.

CONCLUSIONS

Acidic or alkaline post-column infusion allows pH optimization for ionization conditions, independent of the pH optimization for chromatographic separation. The introduction of an additional modifier might also allow the minimization of matrix effects or directed formation of sodium adducts, without affecting the chromatographic separation.

Influence of façade orientation on the leaching of biocides from building façades covered with mortars and plasters

Biocides used in building façades to prevent potential growth of algae, fungi and bacteria are of major concern regarding the quality of stormwater runoff. The aim of the study was to analyze the influence of the façade orientation on the biocide release under real weather conditions to gain information for the development of on-site treatment systems. Field tests with model houses containing two different plaster compositions were carried out over a period of 18 months. The results of the analyzed rain events demonstrate that façade orientation plays an important role in the leaching loads of biocides. Biocide loads in the runoff decreased corresponding to the wind direction. High cumulated active substance discharges of diuron (149 mg/m²), carbendazim (43.5 mg/m²), terbutryn (9.3 mg/m²) and octylisothiazolinone (OIT) (31.9 mg/m²) were found in the runoff of the façades facing the predominant weather orientation. Meanwhile, the highest concentrations of diuron (2.8 mg/L) and OIT (0.7 mg/L) were observed in the runoff from façades with smaller runoff volumes. The obtained results demonstrate that treatment facilities have to be installed at all building sides. The hydraulic and the substance load is highest at the weather side, which has a strong influence on the dimension and the lifetime of the treatment system.

Occurrence of methylisothiazolinone in water and soil samples in Poland and its biodegradation by Phanerochaete chrysosporium

Methylisothiazolinone is a commonly used biocide that is released into natural environments. In this work, the ability of the fungal strain Phanerochaete chrysosporium DSM 1556 to biotransform this compound was evaluated. The tested strain was able to remove MIT (at concentrations 50 μg L^-1 and 30 mg L^-1) from the growth medium with the efficiency 90% after the first 6 h and 100% after 12 h of incubation. Moreover, for the first time, qualitative LC-MS/MS and GC-MS analysis showed monohydroxylated and dihydroxylated methylisothiazolinone and N-methylmalonamic acid as the main products of fungal biodegradation. The ecological toxicity of the tested biocide and its derivatives was also evaluated by using an acute toxicity test with Daphnia magna. An approximately 90% decrease in the toxicity of metabolites formed in the P. chrysosporium culture was noticed. The concentration of MIT in soil and water samples collected in Poland was assessed for the first time. The analysis showed that the selected locations in Poland are contaminated by MIT in the range from 1.04-10.08 μg L^-1.

A strategy for an initial assessment of the ecotoxicological effects of transformation products of pesticides in aquatic systems following a tiered approach

In order to conduct a fast and comprehensive toxicity screening of pesticide transformation products (TPs), this study used a tiered approach by a combination of in silico and experimental methods to determine the probability to be of relevance for risk assessment. The six pesticides Boscalid, Penconazole, Diuron, Terbutryn, Octhilinone (OIT), and Mecoprop were used as model compounds. Identification of corresponding environmental known and unknown TPs were done by literature analysis and photolysis experiments in combination. Aquatic solutions of the pesticides were photolysed to generate TPs which can be expected in the aquatic environment. The resulting mixtures were screened for TPs by high resolution LC-MS/MS. The herein developed approach was conducted at three different tiers: Literature review and in silico methods were used to predict exemplary the environmental bacterial toxicity and the genotoxicity of every single TP at tier I. In case of indications to be toxic, experiments at tier II were applied. Hereby, the photolytic mixtures containing parent compound and TPs were used for the consecutive toxicity test. Microtox assay for the parent compounds and the photolytic mixture was conducted to determine the acute and chronic toxicity and the growth inhibition of V. fischeri. Umu-tests were conducted to determine primary DNA damage. At tier III, single substance standards were used to conduct toxicity tests in case of toxic indication by previous tiers and availability of analytical standard. Identification of TPs revealed 45 known environmental TPs that originated from the six pesticides. The number of substances that need to be assessed was therefore more than sevenfold. By the tiered approach, it was possible to assess toxicological effects on environmental bacteria of 94% of the selected TPs. For 20% we found strong evidence to be toxic to environmental bacteria, as they were assessed at least at two tiers. For further 44% of the TPs we found slight evidence, as they could be assessed at one tier. Contrary, this approach turned out to be unsuitable to assess genotoxic effects of TPs neither by in silico tools nor by experiments. The number of substances that could probably pose a risk onto environment was quadrupled in comparison to the consideration of solely the parent compounds. Thus, this study demonstrates that the conducted screening approach allows for easy and fast identification of environmental relevant TPs. However, the study presented was a very first screening. Its applicability domain needs to be assessed further. For this purpose as a very next step the approach suggested here should be verified by applying additional endpoints and including additional parent compounds.

Isothiazolinone Biocides: Chemistry, Biological, and Toxicity Profiles

The importance of isothiazole and of compounds containing the isothiazole nucleus has been growing over the last few years. Isothiazolinones are used in cosmetic and as chemical additives for occupational and industrial usage due to their bacteriostatic and fungiostatic activity. Despite their effectiveness as biocides, isothiazolinones are strong sensitizers, producing skin irritations and allergies and may pose ecotoxicological hazards. Therefore, their use is restricted by EU legislation. Considering the relevance and importance of isothiazolinone biocides, the present review describes the state-of-the-art knowledge regarding their synthesis, antibacterial components, toxicity (including structure–activity–toxicity relationships) outlines, and (photo)chemical stability. Due to the increasing prevalence and impact of isothiazolinones in consumer’s health, analytical methods for the identification and determination of this type of biocides were also discussed.

Photodegradation of benzisothiazolinone: Identification and biological activity of degradation products

The photodegradation of benzisothiazolinone was studied in water under UV-Vis irradiation and led to fourteen photoproducts. Chemical structures of these compounds were elucidated using GC-MS, LCMS/MS, and FT-ICR-MS experiments. Based on the chemical structures determined and their appearance order, a photo induced-degradation mechanism of benzisothiazolinone has been proposed, which combines isomerization, oxidation, hydroxylation, hydrolysis, and elimination processes. In silico tests on mutagenicity, Fathead minnow LC50 and oral rat LD50 were carried out to estimate the toxicity of the photoproducts. Compared with experimental data, the calculated oral rat LD50 values were found to be the most relevant and thus used for toxicity estimation. The photoproducts including a phenolic or a sulfino group or both functions were found potentially more toxic than benzisothiazolinone.

Biocide emissions from building materials during wet weather: identification of substances, mechanism of release and transfer to the aquatic environment

Biocides are added to or applied on building materials to prevent microorganisms from growing on their surface or to treat them. They are leached into building runoff and contribute to diffuse contamination of receiving waters. This review aimed at summarizing the current state of knowledge concerning the impact of biocides from buildings on the aquatic environment. The objectives were (i) to assess the key parameters influencing the leaching of biocides and to quantify their emission from buildings, (ii) to determine the different pathways from urban sources into receiving waters and (iii) to assess the associated environmental risk. Based on consumption data and leaching studies, a list of substances to monitor in receiving water was established. Literature review of their concentrations in the urban water cycle showed evidences of contamination and risk for aquatic life, which should put them into consideration for inclusion to European or international monitoring programs. However, some biocide concentration data in urban and receiving waters is still missing to fully assess their environmental risk, especially for isothiazolinones, iodopropynyl carbamate, zinc pyrithione and quaternary ammonium compounds, and little is known about their transformation products. Although some models supported by actual data were developed to extrapolate emissions on larger scales (watershed or city scales), they are not sufficient to prioritize the pathways of biocides from urban sources into receiving waters during both dry and wet weathers. Our review highlights the need to reduce emissions and limit their transfer into rivers and reports several solutions to address these issues.

Factors affecting coupled degradation and time-dependent sorption processes of tebuconazole in mineral soil profiles

This laboratory degradation and adsorption study aimed to determine the tebuconazole degradation parameters for 6 profiles of Polish mineral soils and to find links between the tebuconazole degradation rate, its adsorption, soil microbial activity and other significant soil properties. The values of the adsorption distribution coefficient K_d, obtained in batch experiments after 96 h of shaking were in the range of 6.2-34.6 mL g^-1. In both batch experiments and incubation experiments at 20 °C, the typical course of adsorption processes was observed, an initial rapid stage followed by a slow stage. In 3 of the 18 soils examined, adsorption was not reached within 51 days. The range of the half-life values was 201-433 days for the Ap horizon and up to 3904 days for subsoils, which were estimated using the two-site nonequilibrium adsorption model coupled with first-order degradation for dissolved and adsorbed pesticide. It was found that modeling the degradation of tebuconazole on the basis of the coefficients of microbial biomass activity for topsoil and two subsoils explained almost 96% of the variance of the estimated pore water degradation rate coefficients in examined soils. The degradation rate was also negatively correlated with the amount adsorbed in the time dependent adsorption sites. This fraction was the least available for soil microorganisms because it was strongly adsorbed in soil pores with a radius <2.5 nm, determined from the H₂O desorption isotherm. The degradation rate was also affected by the ratio of the water content in soil during degradation experiments to the water content at field capacity. The results indicated that degradation occurred in the soil liquid phase only.

Aerobic dissipation of the novel cyanoacrylate fungicide phenamacril in soil and sludge incubations

The cyanoacrylate ethyl (2Z)-3-amino-2-cyano-3-phenylacrylate (phenamacril), has been introduced as an effective agent against several fungi species belonging to the Fusarium genus. However, in current literature, knowledge about the environmental behavior of this fungicide is limited and there are no data on the degradation in the environment. By performing tests on inherent degradability as well as degradation studies in soils this study provides the only published information regarding the environmental stability and degradation kinetics of this compound. Tests for inherent/ready biodegradation revealed the phenamacril is inherently degradable with zero order kinetics, even though the degradation is comparatively slow. Degradation of phenamacril in soil was found to occur following first order kinetics with a final plateau with a half live of 17.1 days (i.e. more rapidly than tebuconazole but less rapidly than octylisothiazolinone).

Entry of biocides and their transformation products into groundwater via urban stormwater infiltration systems

Biocides are, inter alia, applied as preservatives on facades to prevent the growth of microorganisms. Their incomplete mineralization results in new compounds, so-called transformation products (TPs). Rain causes that both applied biocides and their TPs leach from facades with stormwater into the urban aquatic environment. This study is the first to investigate the introduction of the biocides Diuron, Terbutryn, and Octylisothiazolinone (OIT) and their TPs into the groundwater via urban stormwater infiltration systems. In this study, the TPs of these biocides were created by laboratory photolysis and elucidated using LC-HRMS. The results were then used to analyze TPs by LC-MS/MS in stormwater and groundwater samples, which were taken from an urban swale-trench system and from groundwater wells upgradient and downgradient of the infiltration system. A sprinkling experiment was conducted to evaluate facades as a contamination source. Biodegradation tests were conducted to determine bio-persistence of biocides and their TPs. Fourteen TPs were identified under laboratory photolysis. TP-186, TP-210, and TP-256 of Terbutryn were hitherto unknown. Nine TPs were qualitatively detected in environmental water samples. Parent compounds, TP-219 of Diuron and TP-212, TP-214, and TP-226 of Terbutryn were detected at a maximum concentration of 140 ng L^-1 during stormwater events. Concentrations in groundwater were considerably below German drinking water limits, but were higher in groundwater samples downgradient from the investigated swale-trench system than in those collected upgradient. Neither the biocides nor most of their TPs were readily biodegradable under simulated surface water conditions. The results show that entry of biocides and their TPs into groundwater is caused by infiltration of urban stormwater.

Inoculation of soil with an Isoproturon degrading microbial community reduced the pool of "real non-extractable" Isoproturon residues

During pesticides degradation, biogenic non-extractable residues ("apparent NER") may not share the same environmental fate and risks with the "real NER" that are bound to soil matrix. It is not clear how microbial community (MC) inoculation for pesticides degradation would influence the NER composition. To investigate degradation efficiency of pesticides Isoproturon (IPU) and NER composition following MC inoculation, clay particles harboring MC that contains the IPU degrading strain, Sphingomonas sp., were inoculated into soil receiving ¹⁴C-labeled IPU addition. Mineralization of IPU was greatly enhanced with MC inoculation that averagely 55.9% of the applied ¹⁴C-IPU was consumed up into ¹⁴CO₂ during 46 days soil incubation. Isoproturon degradation was more thorough with MC than that in the control: much less amount of metabolic products (4.6% of applied IPU) and NER (35.4%) formed in MC treatment, while the percentages were respectively 30.3% for metabolites and 49.8% for NER in the control. Composition of NER shifted with MC inoculation, that relatively larger amount of IPU was incorporated into the biogenic "apparent NER" in comparison with "real NER". Besides its well-recognized role on enhancing mineralization, MC inoculation with clay particles benefits soil pesticides remediation in term of reducing "real NER" formation, which has been previously underestimated.