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Environmental fate & pathways

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A conclusion on the biotic degradation of 1H-Benzotriazole is difficult due to the quantity of different findings in the available information in guideline studies as well as the public domain. While the performed OECD studies in the dossier indicate a low potential for biodegradation only, several publications show significantly higher degradation rates of 1H-Benzotriazole in the environment. For the reasons of the precautionary principle, the findings in the OECD studies are given more weight and the substance is assumed to be low (non-)biodegradable in the environment using the presented half-lives for the assessment.

Additional information

In addition to the presented screening tests in water showing no or little degradation of the test substances under test conditions, several publications on biodegradation processes in the environment or by other organisms have been available.

Wu et al. have reported on readily degradation of Benzotriazoles by Fenton reaction in presence of peroxide and iron. In addition, white rot fungi Phanerochaete chrysosporium has shown in experiments effectively degradation of the test substances under several conditons. Fungi have been cultivated for three days at 39 °C and afterwards exposed to concentrations up to 0.2 mg/mL Benzotriazole. In a second experiment, a mixture of Benzotriazole and Tolyltriazole was used. Only in test series with low concentrations (0.05 mg/mL) of Tolyltriazole merely no degradation has been observed. Furthermore, tests with horseradish plants were conducted showing that these plants also can remove Benzotriazoles from the soil. In the experiments adverse effects on the growth of the plants have been observed. Nevertheless, sampling of soils after three months has shown reduced concentrations of Benzotriazole of about 95 %. An additional experiment with ground horseradish roots with and without addition of peroxide has shown a DT50 of two days at room temperature for Benzotriazole (Wu et al., 1998).

Llorca et al. (2017) also investigated the removal of 1H-Benzotriazol by fungal treatment of a reverse osmosis concentrate with Trametes versicolor. Under sterile conditions a removal of 58 % BTA, respectively 32 % removal under non-sterile conditions, was observed.

Huntscha et al. (2014) examined the degradation behaviour of 1H-Benzotriazole in batch experiments with activated sludge from a WWTP in Switzerland over a period of 13 days. A half-life of 1.0 days was found. The focus of the study was the identification of potential transformation products. As major products with environmental relevance 4- and 5-hydroxybenzotriazole in batch experiments and samples from the effluent of the WWTP were identified.

Trejo-Castillo et al. (2021) investigated the simultaneous oxidation of 1H-Benzotriazole and Ammonium in batch experiments over 49 days using sludge from steady-state nitrification process. Findings indicated that the biotransformation capacity of BTA increased with increasing Ammonium concentration. Results in additional experiments with allylthiourea showed that the co-metabolic degradation of BTA was related to the AMO activity.

Jog et al. (2021) studied the aerobic biodegradation of 1H-Benzotriazole with return activated sludge from a WWTP handling domestic wastewater. In batch experiments at 30 °C with and without addition of C- and N-sources (glucose and ammonium chloride) the substance was readily degraded. Without additional nutrients BTA was completely biotransformed after a lag phase of 9 days within three days. With additional nutrients no lag phase was observed, but the removal rate was slower and BTA was completely transformed within 14 days.

Sediment/ bank filtration:

Burke et al. (2014) investigated the behaviour of micropollutants in the hyporheic zone by laboratory experiments under two different temperatures. In the column experiment with sediment from a bank filtration site Benzotriazole showed persistent behaviour after approx. three weeks under test conditions.

Several studies investigated the removal, respectively the degradation, of 1H-Benzotriazole during the treatment in different STPs/WWTPs.

Molins-Delgado et al. (2015) investigated the removal rates (by meaning of transformation into another substance) of Benzotriazole in 20 wastewater treatment plants in Spain during summer in 2011 by monitoring the BTA concentrations in the influent and effluent of the plants by HPLC-MS/MS. The removal rates ranged from 36 to 95 % (calculated half-life times considering hydraulic retention times 0.3 – 17 days).

Mazioti et al. (2015) studied the degradation of different triazoles, inter alia 1H-Benzotriazole, in activated sludge experiments under aerobic and anaerobic conditions, in presence of organic substrate and different sludge residence times in the treatment plants. No significant differences in the degradation under various conditions were observed. Based on the findings the calculated half-life time ranged from 23-45 hours for Benzotriazole. In addition, Mazioti proposed biodegradation of Benzotriazole via co-metabolism of microorganisms using molecular oxygen or nitrates as electron donors.

Kowalska et al. (2015) identified specific microorganisms in activated sludge from MBRs which were capable to degrade 1H-Benzotriazole by using molecular techniques (PCR, DNA sequencing). The most common species were Rhodococcus sp., Enterobacter sp. and Arthrobacter sp.. In biodegradation testing these bacteria were incubated for two weeks with 1H-Benzotriazole as only carbon source. The overall removal was about 19 %.

Burke et al. (2014), Temperature dependent redox zonation and attenuation of wastewater-derived organic micropollutants in the hyporheic zone, Sci Total Env 482–483 (2014) 53–61

Huntscha et al. (2014), Biotransformation of Benzotriazoles: Insights from Transformation Product Identification and Compound-Specific Isotope Analysis, Environ. Sci. Technol. 2014, 48, 4435−4443

Jog et al. (2021), Aerobic biodegradation of emerging azole contaminants by return activated sludge and enrichment cultures, Journal of Hazardous Materials 417 (2021) 126151

Kowalska et al (2015), Identification of selected microorganisms from activated sludge capable of benzothiazole and benzotriazole transformation, ABP Biochimica Polonica, Vol. 62, No 4/2015, 935–939.

Llorca et al. (2017), Fungal treatment for the removal of endocrine disrupting compounds from reverse osmosis concentrate: Identification and monitoring of transformation products of benzotriazoles, Chemosphere. 2017 Oct;184:1054-1070

Mazioti et at. (2015), Sorption and biodegradation of selected benzotriazoles and hydroxybenzothiazole in activated sludge and estimation of their fate during wastewater treatment, Chemosphere 131 (2015) 117–123

Molins-Delgado et al. (2015), Removal of polar UV stabilizers in biological wastewater treatments and ecotoxicological implications, Chemosphere 119 (2015) S51–S57

Trejo-Castillo et al. (2021), Cometabolic biotransformation of benzotriazole in nitrifying batch cultures, Chemosphere, Volume 270, May 2021, 129461

Wu, X., Chou, N., Lupher, D., & Davis, L. C. (1998). Benzotriazoles: toxicity and degradation. Conference on Hazardous Waste Research (pp. 374–382).