Abstract
Inappropriate processing and disposal of electronic waste contributes to the contamination of aquatic systems by various types of pollutants such as the rare-earth elements (REE) in which lanthanum (La) is included. Knowledge on the toxicity of these elements in marine organisms is still scarce when compared to other metals such as mercury (Hg) and arsenic (As). Therefore, this study aims to assess the toxicity of La on the mussel Mytilus galloprovincialis, considered a good bioindicator of aquatic pollution, through the analysis of metabolic, oxidative stress, neurotoxicity and histopathological markers. Organisms were exposed to different concentrations of La for a period of 28 days (0, 0.1, 1, 10 mg/L) under controlled temperature (18 °C ± 1.0) and salinity (30 ± 1) conditions. La concentrations in mussels increased in higher exposure concentrations. La exposure demonstrated a biochemical response in mussels, evidenced by lowered metabolism and accumulation of energy reserves, activation of the antioxidant defences SOD and GPx as well as the biotransformation enzymes GSTs, especially at intermediate concentrations. Despite oxidative stress being shown by a decrease in GSH/GSSG, oxidative damage was avoided as evidenced by lower LPO and PC levels. Inhibition of the enzyme AChE demonstrated the neurotoxicity of La in this species. Histopathological indices were significantly different from the control group, indicating impacts in gonads, gills and digestive glands of mussels due to La. These results show that La can be considered a risk for marine organisms and thus its discharge into the environment should be monitored.
Highlights
Nowadays, an emerging concern associated with anthropogenic activities is the disposal of electronic waste (e-waste), a consequence of the increasingly rapid technological evolution (Otsuka et al, 2012)
In the present study the impacts induced by La in the species Mytilus galloprovincialis were evaluated in terms of mussel’s histopathological alterations and biochemical effects, including impacts on organisms metabolism, oxidative and neurotoxic status
The present findings clearly revealed that organisms exposed to La decreased their metabolic capacity avoiding the consumption of GLY
Summary
An emerging concern associated with anthropogenic activities is the disposal of electronic waste (e-waste), a consequence of the increasingly rapid technological evolution (Otsuka et al, 2012). The groups of REEs encompasses the lanthanides as N well as Scandium (Sc) and Yttrium (Y) (IUPAC, 2005), and despite their rare-earth nomination, A they are rather abundant in the Earth’s crust, often less concentrated than other M elements (USEPA, 2012). Because of their unique physicochemical properties (e.g., naturally coherent behaviour, high lustre and electrical conductivity; Topp, 1965), REEs are widely and intensively applied in numerous high-tech, medical and agricultural products and processes
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