Steel wools microfibers causes iron overload and induces biochemical changes in Gallus gallus domesticus chicks (Galliformes: Phasianidae).

Steel wool (SW) has a broad-spectrum of applicability, particularly as abrasives, cleaning household utensils and surfaces in general. However, when present in the natural environment, they can be ingested by animals, such as birds, and may represent a risk to the survival of individuals. Accordingly, in this study, we attempted the hypothesis that the ingestion of SW microfibers (SWMs) by Gallus gallus domesticus chicks (model system used) alters growth/development, induces redox imbalance and cholinesterasic effect, as well as promotes iron overload in different organs. For this, the animals received SWMs twice (within a 24-h interval) in an amount corresponding to 12% of their total stomach volume. At the end of the experiment, we observed less weight gain and less head growth, increased production of hydrogen peroxide (in the brain, liver, crop, and gizzard), nitrite (liver, crop, proventriculus and gizzard), malondialdehyde (brain, liver, muscle, proventriculus, and gizzard), along with increased superoxide dismutase activity in the liver, muscle and crop of animals exposed to SWMs. Such results were associated with iron overload observed in different organs, especially in liver, crop, and gizzard. Furthermore, we evidenced an anti-cholinesterasic effect in birds that ingested the SWMs, marked by a reduction in the acetylcholinesterase activity (in brain). Thus, our study sheds light on the (eco)toxicological potential of SWMs in avifauna, conceding us to associate their ingestion (despite ephemeral and occasional) with damage to the health of individuals, requiring a greater attention spotted to disposal of these materials in ecosystems.

Green toxicology approach involving polylactic acid biomicroplastics and neotropical tadpoles: (Eco)toxicological safety or environmental hazard?

Different and alternative renewable-source materials, commonly called bioplastics, have been proposed due to the high production and consumption of petroleum-derived plastics and to their high toxicity in the biota. However, their toxicological safety has not yet been assessed in a comprehensive way; therefore, their effects on several animal groups remain completely unknown. Thus, we aimed at testing the following hypothesis: the exposure of Physalaemus cuvieri tadpoles to polylaic acid biomicroplastic (PLA BioMP) at environmentally relevant concentrations (760 and 15,020 µg/L) induces physiological changes in them. Based on the collected data, biopolymer uptake changed tadpoles' growth and development features, reduced their lipid reserves (it was inferred by decreased triglyceride levels), as well as increased reactive oxygen and nitric oxide species production after 14-day exposure. The proportional increase in total glutathione levels, and in superoxide dismutase and catalase activity, was not enough to counterbalance the production of reactive species. In addition, the two tested concentrations caused cholinesterase effect, which was marked by increased acetylcholinesterase and butyrylcholinesterase. This finding is indicative of the neurotoxic action of PLA BioMP. To the best of our knowledge, this is the first report on the harmful consequences of exposing amphibian representatives to the herein tested biopolymers. Therefore, this finding encourages further studies and contributes to demystify the idea that bioplastics are "harmless" to the aquatic biota in freshwater environments.

Polyethylene glycol acute and sub-lethal toxicity in neotropical Physalaemus cuvieri tadpoles (Anura, Leptodactylidae).

Although many polymers are known by their toxicity, we know nothing about the impact of polyethylene glycol (PEG) on anurofauna. Its presence in different products and disposal in aquatic environments turn assessments about its impact on amphibians an urgent matter. Accordingly, we tested the hypothesis that short-time exposure (72 h) of tadpoles belonging to the species Physalaemus cuvieri (Anura, Leptodactylidae) to PEG induces oxidative stress and neurotoxicity on them. We observed that polymer uptake in P. cuvieri occurred after exposure to 5 and 10 mg/L of PEG without inducing changes in their nitrite levels neither at the levels of substances reactive to thiobarbituric acid. However, hydrogen peroxide and reactive oxygen species production was higher in animals exposed to PEG, whose catalase and superoxide dismutase levels were not enough to counterbalance the production of these reactive species. Therefore, this finding suggests physiological changes altering REDOX homeostasis into oxidative stress. In addition, the increased activity of acetylcholinesterase and butyrylcholinesterase, and reduction in superficial neuromasts, confirmed PEG's neurotoxic potential. To the best of our knowledge, this is the first report on PEG's biological impact on a particular amphibian species. The study has broadened the understanding about ecotoxicological risks associated with water pollution by these polymers, as well as motivated further investigations on its impacts on amphibians' health and on the dynamics of their natural populations.