The abundance of metal pollutants in freshwater habitats poses serious threats to the survival and biodiversity of aquatic organisms and human beings. This study intends for the first time to assess the pernicious influences of heavy metals in Al Marioteya canal freshwater in Egypt, compared to Al Mansoureya canal as a reference site utilizing the creeping water bug (Ilyocoris cimicoides) as an ecotoxicological model. The elemental analysis of the water showed a significantly higher incidence of heavy metals, including cadmium (Cd), cobalt (Co), chromium (Cr), nickel (Ni), and lead (Pb), in addition to the calcium (Ca) element than the World Health Organization’s (WHO) permitted levels. The Ca element was measured in the water samples to determine whether exposure to heavy metals-induced oxidative stress engendered Ca deregulation in the midgut tissues of the creeping water bug. Remarkably, increased levels of these heavy metals were linked to an increase in chemical oxygen demand (COD) at the polluted site. Notably, the accumulation of these heavy metals in the midgut tissues resulted in a substantial reduction in antioxidant parameters, including superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and ascorbate peroxidase (APOX), along with a marked rise in malondialdehyde (MDA), cytochrome P450, and protein carbonyl levels. These results clearly indicate a noticeable disturbance in the antioxidant defense system due to uncontrollable reactive oxygen species (ROS). Notably, the results demonstrated that oxidative stress caused disturbances in Ca levels in the midgut tissue of I. cimicoides from polluted sites. Furthermore, the comet and flow cytometry analyses showed considerable proliferations of comet cells and apoptotic cells in midgut tissues, respectively, exhibiting prominent correlations, with pathophysiological deregulation. Interestingly, histopathological and ultrastructural examinations exposed noticeable anomalies in the midgut, Malpighian tubules, and ovarioles of I. cimicoides, emphasizing our findings. Overall, our findings emphasize the potential use of I. cimicoides as a bioindicator of heavy metal pollution in freshwater to improve sustainable water management in Egypt.

Nano zinc oxide has the potency to be harmful, so it is important to assess its effects on the human health and biological system. In the current study, vitamin E (100 mg/kg) was used to explore its antioxidant role in mitigating the potential toxicity of ZnO NPs (50 and 200 mg/kg) in male albino rats tissues. Sixty adult male albino rats weighing 180–200 g were arbitrarily divided into six groups: G1:control group,G2: vita E (100 mg/kgb.w) group, G3: Zn NPs (50 mg/kg b.w) group, G4: Zn NPs (200 mg/kg b.w), G5: vita E + Zn NPs(50 mg/kg b.w) group and G6:Vita E + Zn NPs (200 mg/kg b.w) group. Giving both Vita and ZnNPs daily by oral gavage for 4 weeks. The results revealed that exposure to the structure of the liver and testicular tissues was examined by light microscopy, DNA damage by the comet assay, metallothionein levels and sex hormones evaluation by ELISA, and several stress markers by spectrophotometric methods. Sperm count and motility were assessed by optical microscopy. Detailed analysis of the liver and testicular tissue of rats treated with 50 and 200 mg/kg ZnO NPs revealed many adverse effects of nanoscale particles in tissues structure, accompanied by focal necrosis, inflammatory cellular infiltration in liver tissues and distorted seminiferous tubules with disorganized germ cells in tests tissues, increased lipid peroxidation, DNA damage, and reduced levels of antioxidant enzymes. Due to their tiny size that allow them to penetrate physiological barriers, ZnO NPs can enter, translocate within, and damage living organisms. Nevertheless, co-administration of ZnO NPs with Vita E significantly (p < 0.05) reversed the biochemical alterations associated with ZnO NPs administration and lead to improvement of the histopathological picture of hepatic and testicular tissues. Findings related to Vita E may either inhibit the activity of (ROS) molecules and prevent their binding to the DNA structure and /or scavenging peroxyl lipid radicals inducing DNA-damaging products. So, the present results indicated that Vita E effectively attenuates the adverse effects of ZnO NPs and could mitigate or prevent its toxicity which lead finally to healthy tissues of liver and testes.