Overview of the toxic effects of titanium dioxide nanoparticles in blood, liver, muscles, and brain of a Neotropical detritivorous fish

Abstract

The toxicity of titanium dioxide nanoparticles (TiO 2 -NP) in the blood, liver, muscle, and brain of a Neotropical detritivorous fish, Prochilodus lineatus, was tested. Juvenile fish were exposed to 0, 1, 5, 10, and 50 mg L −1 of TiO 2 -NP for 48 hours (acute exposure) or 14 days (subchronic exposure) to evaluate changes in hematology, red blood cell (RBC) genotoxicity/mutagenicity, liver function (reactive oxygen species (ROS) production, antioxidant responses, detoxification, and histopathology), acetylcholinesterase (AChE) activity in muscles and brain, and Ti bioaccumulation. TiO 2 -NP did not cause genetic damage to RBC, but acutely decreased white blood cells (WBC) and increased monocytes. Subchronically, RBC decreased, mean cell volume and hemoglobin increased, and WBC and lymphocytes decreased. Therefore, NP has the potential to affect immune system and increase energy expenditure, reducing the fish's ability to avoid predator and to resist pathogens. In the liver, acute exposure decreased ROS and increased glutathione (GSH) content, while subchronic exposure decreased superoxide dismutase activity and increased glutathione-S-transferase (GST) activity and GSH content. GSH and GST seem to play an essential role in metabolizing NP and ROS, likely increasing hepatocytes' metabolic rate, which may be the cause of observed cell hypertrophy, disarrangement of hepatic cords and degenerative morphological alterations. Although most studies indicate that the kidney is responsible for metabolizing and/or eliminating TiO 2 -NP, this study shows that the liver also has a main role in these processes. Nevertheless, Ti still accumulated in the liver, muscle, and brain and decreased muscular AChE activity after acute exposure, showing neurotoxic potential.More studies are needed to better understand the biochemical pathways TiO 2 -NP are metabolized and how its bioaccumulation may affect fish homeostasis and survival in the environment. K E Y W O R D S bioaccumulation, glutathione-S-transferase neurotoxicity, immune system, reactive oxygen species

Mild Effects of Sunscreen Agents on a Marine Flatfish: Oxidative Stress, Energetic Profiles, Neurotoxicity and Behaviour in Response to Titanium Dioxide Nanoparticles and Oxybenzone

“…In the present study, no neurological disturbances of the cholinergic system were found in the brain after IP injection of TiO 2 NPs and BP-3, isolated or in mixture, for 3 and 7 days. In the same direction, several studies with freshwater fish reported no alterations in the AChE activity in the brain after waterborne exposure to TiO 2 NPs [46,[80][81][82][83]. On the contrary, waterborne exposure of the freshwater fish Carassius auratus to 200 µg L −1 of BP-3 promoted the increase in the activity of AChE [84].…”

“…Interestingly, some authors found a reduction in AChE activity in fish muscle after exposure to TiO 2 NPs while no alteration was found in the brain [80,82]. This suggests that the neurotoxic action of TiO 2 NPs does not affect brain directly but may be related with alterations of the metabolic processes on which the nervous system is specifically dependent.…”

Revisiting an Old Friend Nano-TiO2: A Crucial Assessment of Its Current Safety

“…Carmo et al reported the reduction of hemoglobin content and white and red blood cells in freshwater fish after exposure to TiO 2 NPs [15]. They treated Juvenile fish with various amounts of TiO 2 NPs (1-50 mg/L) for 48 h or 14 days as acute and subchronic exposures, respectively.…”

“…It was also observed that the NPs demonstrated potential for increasing energy expenditure by affecting the immune system, thereby decreasing the ability of the fish to avoid predators and fight pathogens. In addition to the toxic effect of TiO 2 NPs on blood cells, they may also be distributed to several organs through the blood stream, thereby modifying cellular metabolism and could possibly lead to some form of physiological imbalance of these affected organs [5,15,113]. Furthermore, exposure to TiO 2 NPs may cause damages to liver tissues of aquatic species, such as the presence of disordered cells, apoptotic nuclei, and foci with lipid accumulation [114].…”

“…Owing to their excellent near infrared reflective and electrical properties, TiO 2 NPs have achieved a wide range of applications, necessitating an assessment of their current toxicity. TiO 2 -based NPs have been specifically used in cosmetics [7], phamaceutical products [8,9], food colouration [10], plastic products [11,12], antifouling agents marine paints [13], photocatalysis and microbial boosting for soil remediation [7,14], filters [15], bacterial treatment [16], and in the photothermal [17,18], photodynamic and sonodynamic ablation of cancers [19,20]. Many other new applications of TiO 2 NPs are underway or possibly in pilot production, making TiO 2 NPs and their derivatives to be ranked among the most commonly-produced nanomaterials world wide [7].…”