Bioconcentrations of herbicides used in sugarcane crops in tilapia (Oreochromis niloticus) and the risk for human consumption.

The practice of intensive herbicide use in the sugarcane industry has a high risk of compromising the quality of the water and the organisms that live there due to losses through runoff, leaching and other processes. In this work, the dynamics of four herbicides present in three different mixtures were evaluated through their incorporation and elimination in the muscle tissue of tilapia (Oreochromis niloticus). The highest mean values of bioconcentration factors were 1.730 for ametryn, 0.891 for tebuthiuron, 0.322 for hexazinone and 4.783 for diuron. Diuron presented the highest risk regarding the consumption of tilapia fillets by the population. However, considering that the fish would reach maximum levels of diuron when exposed to extremely high concentrations, an individual weighing 70 kg would need to ingest approximately 1.5 kg of this food product to surpass the acceptable daily intake of 0.007 mg kg-1 body weight. It was concluded that the risk of injury to the population consuming tilapia fillets from fish exposed to herbicides in water arising from sugarcane activities is very low. According to the risk estimation performed in this work, which is substantiated by the assumptions of the World Health Organization and the International Life Sciences Institute, there is a low risk of injury to the population consuming tilapia fillets from fish exposed to water containing herbicides in concentrations arising from sugarcane activities. However, as the risk was estimated from laboratory conditions, caution should be taken where herbicide applications are carried out with high frequency near water bodies, as the consumption of fish from these areas is quite common.

Depletion study, withdrawal period calculation and bioaccumulation of sulfamethazine in tilapia (Oreochromis niloticus) treated with medicated feed.

The residue depletion of sulfamethazine (SMZ) was evaluated in tilapia (Oreochromis niloticus) after 11 days of administration of medicated feed containing SMZ, at the dose of 422 mg/kg body weight (bw). The determination of SMZ in feed and tilapia fillet was carried out using the QuEChERS approach for sample preparation, and high performance liquid chromatography with diode array detector (HPLC-DAD) and ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QToF-MS) for quantitation, respectively. Both methods were validated based on international and Brazilian guidelines and shown to be suitable for the intended purposes. The withdrawal period to reach the maximum residue level (MRL) of 100 µg/kg, according to the European Union (EU) legislative framework to all substances belonging to the sulfonamide (SA) group (EU, 2010), was 10 days (260 °C-day). After treatment, the maximum level of SMZ accumulation in the tilapia muscle was 1.6 mg/kg. SMZ was shown to be quickly excreted by tilapia. Thus, considering the acceptable daily intake of SMZ established by the Codex Commission (0-0.05 mg/kg bw), and a factor of 5 times the upper amount of fish consumption in Brazil (38 kg/year), this study showed that there is a low risk of adverse effects to consumers. This study offers subsidies not only for the establishment of public policies with regard to the use of veterinary drugs currently not allowed in a country by their legal legislative framework for fish farming, but also to fish producers for the proper handling to ensure safe fish fillets.

Acute toxicity and bioconcentration of fungicide tebuconazole in zebrafish (Danio rerio).

This research work investigated the bioconcentration of tebuconazole [(±)-α-[2-(4-chlorophenyl)ethyl]-α-(1,1-dimethylethyl)-1H-1,2,4-triazole-1-ethanol] fungicide in zebrafish (Danio rerio) under laboratory conditions and a first-order kinetic pesticide dissipation in the water. The concentrations of tebuconazole fitted to an equivalent nonlinear kinetic type model which allowed the calculation of the following parameters: bioconcentration factor (38.80 L kg(-1) ), time to reach maximum fish concentration (6 days), maximum concentration in fish (0.0075 µg mg(-1) ), half-life in fish (24 days) and time needed for the fish to eliminate 95% of the maximum concentration (105 days). These calculations permitted the establishment of theoretical reference limit values for human consumption of fish and the establishment of safe limits for the water pesticide concentration. The data would also be useful in safe strategies associated with fishery activities that are conducted in aquatic regions close to crops using tebuconazole. The information will contribute to enlarge the tebuconazole toxicokinetics database of aquatic organisms.