Attenuation of toxicity and occurrence of degradation products of the fungicide tebuconazole after combined vacuum UV and UVC treatment of drinking water

Abstract

Antifungal azoles are the most frequently used fungicides worldwide and occur as active ingredients in many antifungal pharmaceuticals, biocides, and pesticides. Azole fungicides are frequent environmental contaminants and can affect the quality of surface waters, groundwater, and drinking water. This study examined the potential of combined vacuum UV (185 nm) and UVC (254 nm) irradiation (VUV/UVC) of the azole fungicide tebuconazole and the transformation product 1,2,4-trizole on degradation and changes in ecotoxicity. In vivo ecotoxicity was examined before and after UV treatment using bioassays with test organisms from different trophic levels to integrate changes in biological effect of the parent compound and the degradation products. The test battery included the luminescent bacterium Aliivibrio fischeri, the Gram-positive bacterium Bacillus subtilis, the fungus Fusarium graminearum, the green microalga Raphidocelis subcapitata, and the crustacean Daphnia magna. The combined VUV/UVC treatment of tebuconazole in drinking water efficiently degraded the parent compound at the µg/L-mg/L level and resulted in transformation products with lower toxicity than the parent compound. A direct positive correlation was observed between the applied UV dose (fluence, J/cm2), the disappearance of tebuconazole, and the decrease in ecotoxicity. The combined VUV/UVC process does not require addition of supplementary oxidants or catalysts and our study suggests that VUV/UVC-mediated photolysis of azole fungicides in water can decrease the overall toxicity and represent a potentially environmentally friendly treatment method.

Assessment of Xenoestrogens in Jordanian Water System: Activity and Identification

“…Tebuconazole is an azole fungicide used in vegetables, citrus, and field crops [ 162 ]. Moreover, it has high photochemical stability, very slow photodegradation, and slow microbial-mediated degradation in soil [ 163 , 164 ].…”

“…Moreover, it has high photochemical stability, very slow photodegradation, and slow microbial-mediated degradation in soil [ 163 , 164 ]. Tebuconazole was detected in drinking water and groundwater [ 162 , 165 ]. Tebuconazole exhibits moderate estrogenic activity [ 166 ].…”

“…It has been reported that TCP can reach groundwater and surface water, and its half-life in the soil can reach 120 days [ 167 ]. Therefore, the direct application of TCP might be the source of contamination [ 142 , 143 , 144 , 153 , 154 , 155 , 156 , 157 , 158 , 159 , 160 , 161 , 162 , 163 , 164 , 165 , 166 , 167 ]. Moreover, it has weak estrogenic activity, being 2500 times less estrogenic than 17β-estradiol [ 104 ].…”

Comparative assessment of UV-C radiation and non-thermal plasma for inactivation of foodborne fungal spores suspension in vitro

“…In the case of F. graminearum, a signicant increase in metabolic activity was observed aer irradiation, surpassing the control at all radiation doses. Other studies also report increased resistance of F. graminearum to UV radiation, [44][45][46] even compared to F. culmorum. 47 For A. niger and F. culmorum exposed to 90 min UV treatment, the relative metabolic activities increased to 50% and 15%, respectively (Fig.…”

Evaluation of the Aquatic Toxicity of Several Triazole Fungicides

“…One of the most frequently used fungicide classes worldwide are azoles (imidazoles and triazoles), as they are the active ingredients in numerous pharmaceutical products and pesticides. They are recognized as environmental contaminants, and it has already been shown that they affect the quality of groundwater, surface waters and even drinking water [5]. The molecular properties of triazole fungicides used in agricultural practices reveal that they have low molecular weight and are moderately lipophilic, making them easily absorbable and persistent in sediments and organic surfaces in aquatic ecosystems [3,6].…”