fluoxastrobin and azoxystrobin

Strobilurin fungicides are used primarily in fruits and vegetables, but recently, a patent was issued for one strobilurin fungicide, azoxystrobin, in mold-resistant wallboard. This raises concerns about the potential presence of these chemicals in house dust and potential exposure indoors, particularly in young children. Furthermore, recent toxicological studies have suggested that strobilurins may cause neurotoxicity. Currently, it is not clear whether or not azoxystrobin applications in wallboard lead to exposures in the indoor environments. The purpose of this study was to determine if azoxystrobin, and related strobilurins, could be detected in house dust. We also sought to characterize the concentrations of azoxystrobin in new wallboard samples. To support this study, we collected and analyzed 16 new dry wall samples intentionally marketed for use in bathrooms to inhibit mold. We then analyzed 188 house dust samples collected from North Carolina homes in 2014-2016 for azoxystrobin and related strobilurins, including pyraclostrobin, trifloxystrobin, and fluoxastrobin using liquid chromatography tandem mass spectrometry. Detection frequencies for azoxystrobin, pyraclostrobin, trifloxystrobin, and fluoxastrobin ranged from 34-87%, with azoxystrobin being detected most frequently and at the highest concentrations (geometric mean = 3.5 ng/g; maximum = 10,590 ng/g). Azoxystrobin was also detected in mold-resistant wallboard samples, primarily in the paper covering where it was found at concentrations up to 88.5 µg/g. Cumulatively, these results suggest that fungicides present in wallboard may be migrating to the indoor environment, leading to exposure in the residences that would constitute a separate exposure pathway independent of dietary exposures.

Topics: Acetates; Air Pollution, Indoor; Chromatography, Liquid; Construction Industry; Dust; Fungicides, Industrial; Imines; North Carolina; Pyrimidines; Strobilurins

Fusarium head blight is a very important disease of small grain cereals with F. graminearum as one of the most important causal agents. It not only causes reduction in yield and quality but from a human and animal healthcare point of view, it produces mycotoxins such as deoxynivalenol (DON) which can accumulate to toxic levels. Little is known about external triggers influencing DON production.. In the present work, a combined in vivo/in vitro approach was used to test the effect of sub lethal fungicide treatments on DON production. Using a dilution series of prothioconazole, azoxystrobin and prothioconazole + fluoxastrobin, we demonstrated that sub lethal doses of prothioconazole coincide with an increase in DON production 48 h after fungicide treatment. In an artificial infection trial using wheat plants, the in vitro results of increased DON levels upon sub lethal prothioconazole application were confirmed illustrating the significance of these results from a practical point of view. In addition, further in vitro experiments revealed a timely hyperinduction of H2O2 production as fast as 4 h after amending cultures with prothioconazole. When applying H2O2 directly to germinating conidia, a similar induction of DON-production by F. graminearum was observed. The effect of sub lethal prothioconazole concentrations on DON production completely disappeared when applying catalase together with the fungicide.. These cumulative results suggest that H2O2 induced by sub lethal doses of the triazole fungicide prothioconazole acts as a trigger of DON biosynthesis. In a broader framework, this work clearly shows that DON production by the plant pathogen F. graminearum is the result of the interaction of fungal genomics and external environmental triggers.

Topics: Biomass; Catalase; Fungicides, Industrial; Fusarium; Hydrogen Peroxide; Methacrylates; Oxidative Stress; Oximes; Pyrimidines; Spores, Fungal; Statistics, Nonparametric; Strobilurins; Triazoles; Trichothecenes; Triticum