Growth of the aquaculture industry has triggered the need for research into the potential environmental impact of chemicals used by salmon farms to control diseases. In this study, the antiparasitic pesticides emamectin benzoate (EB), diflubenzuron (DI), teflubenzuron (TE), and cypermethrin (CP) were measured in sediments near salmon cages in southern Chile. Concentrations for EB were between 2.2 and 14.6ngg−1, while the benzoylphenyl ureas DI and TE were detected in the ranges of 0.1 to 1.2ngg−1 and 0.8 to 123.3ngg−1, respectively. These results were similar to data reported for the Northern Hemisphere. On the other hand, the pyrethroid CP was detected in higher concentrations, ranging from 18.0 to 1323.7ngg−1. According to reported toxicity data, this range represents a potential risk for benthic invertebrates. This report is the first baseline attempt at assessing antiparasitic pesticide levels in the Chilean Patagonia.

Diflubenzuron (DFB) is a larvicide widely used to control Aedes aegypti populations as an alternative to organophosphates (OPs), with a specific mechanism of action for insects by inhibiting their chitin synthesis. However, DFB is used extensively in urban and rural environments, having the aquatic environment as the major receptor. Thus, the present study aimed to investigate the toxicity of DFB-based formulation and compare it with the toxicity of the OP temephos (TMP)-based formulation, a larvicide still used to control A. aegypti, on freshwater fishes Oreochromis niloticus and Hyphessobrycon eques. Organisms were submitted to acute (48 h) and prolonged (7 days) exposures, in the presence and absence of organic sediment, seeking interactions between chemical and sediment. Histopathological analyses were performed on O. niloticus gills and liver. According to 48-h median lethal concentration (LC₅₀), DFB- and TMP-based formulations were classified as harmful and toxic to fish, respectively, following the Globally Harmonized System of Classification (GHS). After prolonged exposure to sublethal concentrations, DFB-based formulation decreased H. eques body weight at concentrations 272-fold lower than its LC₅₀. Ultrastructural responses of O. niloticus indicated edemas and aneurisms on gills, and hepatocyte hypertrophy and vascular congestion of the liver. TMP-based formulation also induced pyknotic nuclei, which may lead to irreversible necrosis. The addition of organic sediment did not alter the larvicide toxicity, suggesting that larvicides remained available to the organisms. Altogether, these results suggest that as an insect-specific pesticide, DFB still induces mortality and tissue damage in fishes; thus, both larvicides pose risks to fishes.

Diflubenzuron (DFB) is a widely used insecticide to control ectoparasites in fish farming. Although therapeutic concentrations (i.e., 50 to 100 mg/L) are safe as they fail to induce mortality, they can promote tissue changes. In Brazil, Pacu (Piaractus mesopotamicus) is a native species used for commercial production, and it remains crucial to determine underlying mechanisms to mitigate the potential effects of pathogens on productivity. The aim of this study was to analyze the transaminase profile and histopathological changes in the liver of P. mesopotamicus exposed to a DFB bath. Hence, the fish were exposed to an immersion bath containing a 70 mg/L nominal concentration of Difluchem 240 SC® (24% (m/m) DFB) for 30 (n = 10), 60 (n = 10), and 120 min (n = 10), every 24 h for 3 days. Following exposure, plasma transaminases and liver histology were analyzed. In DFB-exposed fish, levels of aspartate transaminase (AST) and alanine transaminase (ALT) were elevated when compared with the control at 30 and 60 min. Furthermore, liver morphology was altered based on exposure times. Compared with controls, the degree of reversible damage (degree of tissue change (DTC)) demonstrated high scores for all exposure times, with no difference between individual groups. Irreversible changes were increased in the 60 and 120-min baths. These findings highlight the impact of the therapeutic DFB concentration (i.e., 70 mg/L), revealing that 60-min and 120-min bathing induces irreversible and progressive hepatic changes.

This study presents a complementary approach for the evaluation of water quality in a river basin by employing active and passive sampling. Thirty-eight hydrophilic organic compounds (HpOCs) (organohalogen herbicides, organophosphorous pesticides, carbamate, triazine, urea, pharmaceuticals, phenols, and industrial chemicals) were studied in grab water samples and in passive samplers POCIS collected along Strymonas River, Northern Greece, at three sampling campaigns during the year 2013. Almost all the target compounds were detected at the periods of high rainfall intensity and/or low flow rate. The most frequently detected compounds were aminocarb, carbaryl, chlorfenviphos, chloropropham, 2,4-D, diflubenzuron, diuron, isoproturon, metolachlor, and salicylic acid. Bisphenol A and nonylphenol were also occasionally detected. The use of POCIS allowed the detection of more micropollutants than active sampling. Low discrepancy between the concentrations obtained from both samplings was observed, at least for compounds with >50 % detection frequency; thus, POCIS could be a valuable tool for the selection and monitoring of the most relevant HpOCs in the river basin. Results showed relatively low risk from the presence of HpOCs; however, the potential risk associated with micropollutants such as carbaryl, dinoseb, diuron, fenthion, isoproturon, metolachlor, nonylphenol, and salicylic acid should not be neglected.

Pesticide residue in mushrooms is less known. In this study, the risks of beta-cypermethrin, pyriproxyfen, avermectin, and diflubenzuron in oyster and shiitake mushrooms were evaluated using two different treatments: substrate mixture and surface spraying. Almost all the concentrations of these pesticides at day 90 were higher than 80% of the initial concentrations, while it was less than 45% for all cases within 35 days by spraying. For surface spraying, the residues of beta-cypermethrin were 0.0843–1.22 mg kg⁻¹ in shiitake mushrooms and below 0.005 mg kg⁻¹ in oyster mushrooms; the residues of pyriproxyfen, avermectin, and diflubenzuron were 0.122–4.84, 0.00501–0.111, and 0.0681–1.91 mg kg⁻¹, respectively. The residues of beta-cypermethrin, pyriproxyfen, and diflubenzuron in oyster mushrooms (in shiitake mushrooms) at interval of 0, 3, 5 days (1, 5, 7 days) were below their MRLs in China or Japan. The residue of avermectin in both mushrooms was lower than its limit of detection. These results provide information to safe and proper use of the pesticides in oyster and shiitake mushrooms.

A multi-residue method, based on gas chromatography coupled to tandem mass spectrometry (GC-MS/MS), has been developed for the determination of 70 organic micropollutants from various chemical classes (organochlorinated, organophosphorous, triazines, carbamate and urea, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, pharmaceuticals, phenols, etc.) in surface waters. A single-step SPE extraction using OASIS HLB cartridges was employed for the recovery of target micropollutants. The method has been validated according to monitoring performance criteria of the Water Framework Directive, taking into account the approved guidelines on quality assurance and quality control. The recoveries ranged from 60 to 110 %, the coefficient of variation from 0.84 to 27.4 %, and the uncertainty from 6 to 37 %. The LOD varied from 6.0 to 40 ng/L. The limits of quantification for the priority pollutants anthracene, alachlor, atrazine, benzo(a)pyrene, chlorfenvinphos, diuron, isoproturon, nonylphenol, simazine, and terbutryn fulfill the criterion of <30 % of the relevant environmental standards. The method was employed to investigate the water quality in the basin of a transboundary river, Strymonas, in NE Greece during three sampling campaigns conducted in the year 2013. Thirty-nine compounds were detected in the river water. Metolachlor, diuron, isoproturon, salicylic acid, chlorfenvinphos, 1,2-benzanthracene, pyrene, diflubenzuron, and carbaryl exhibited the highest detection frequencies.

Diflubenzuron (DFB) is an insecticide commonly used to control forest pests. The objectives of this study were to assess the effect of diflubenzuron on the development of Pinus pinaster seedlings and Pisolithus tinctorius under laboratory conditions and to study the possible protective role of this ectomycorrhizal fungus against the effects of diflubenzuron. In vitro experiments revealed that diflubenzuron inhibited fungal growth at all tested concentrations (0.01, 0.1, 1, 10 and 100 mg L⁻¹). Root growth was inhibited at the two highest diflubenzuron concentrations. The activity of the antioxidant defence system of non-inoculated P. pinaster increased at 1 and 10 mg DFB kg⁻¹ substrate, and inoculation increased the threshold to the highest concentration. The protective role of the ectomycorrhizal fungus was seen in the increase of CAT activity. This study revealed that despite causing no mortality, diflubenzuron has the ability to cause sub-lethal damage to P. pinaster. The disproportionate use of this insecticide may lead to higher amounts of its residues in soil and the biosphere, endangering trees, fungi and their symbiosis.