Assessing the impact of waterborne and dietborne cadmium toxicity on susceptibility risk for rainbow trout

Cadmium impacts on calcium mineralization of zebrafish skeletal development and behavioral impairment

Cadmium (Cd) poses significant risks to aquatic organisms due to its toxicity and ability to disrupt the cellular processes. Given the similar atomic radius of Cd and calcium (Ca), Cd may potentially affect the Ca homeostasis, which can lead to impaired mineralization of skeletal structures and behavioral abnormalities. The formation of the spinal skeleton involves Ca transport and mineralization. In this study, we conducted an in-depth investigation on the effects of Cd at environmental concentrations on zebrafish (Danio rerio) skeletal development and the underlying molecular mechanisms. As the concentration of Cd increased, the accumulation of Cd in zebrafish larvae also rose, while the Ca content decreased significantly by 3.0 %-57.3 %, and vertebral deformities were observed. Transcriptomics analysis revealed that sixteen genes involved in metal absorption were affected. Exposure to 2 µg/L Cd significantly upregulated the expression of these genes, whereas exposure to 10 µg/L resulted in their downregulation. Consequently, exposure of zebrafish larvae to 10 µg/L of Cd inhibited the body segmentation growth and skeletal mineralization development by 29.1 %-56.7 %. This inhibition was evidenced by the downregulation of mineral absorption genes and decreased Ca accumulation. The findings of this study suggested that the inhibition of skeletal mineralization was likely attributed to the disruption of mineral absorption, thus providing novel insights into the mechanisms by which metal pollutants inhibit the skeletal development of fish.

Exposure to a sublethal concentration of CdO nanoparticles impairs the vision of the fruit fly (Drosophila melanogaster) by disrupting histamine synthesis and recycling mechanisms

While there is substantial literature on potential risks associated with exposure to emerging nanomaterials, less is known about the potential effects of hazardous metallic nanoparticles on vision, as well as the mechanisms that underpin them. The fruit fly (Drosophila melanogaster) was used as an in vivo model organism to investigate the effects of exposure to a sublethal concentration (0.03 mg CdO NPs/mL, which was 20% of the LC₅₀) on fly vision and compound eye ultrastructure. First, we observed a reduction in phototaxis response in treated flies but no change in locomotor activity. Because histamine (HA) has been linked to arthropod vision, we investigated HA synthesis, uptake, and recycling as a possible underlying mechanism for the observed adverse effect of CdO NPs on fly vision. This was accomplished by measuring the expression of the histamine decarboxylase (hdc) gene, which encodes the enzyme that converts the amino acid histidine to histamine (HA), as well as the expression of some genes involved in HA-recycling pathways (tan, ebony, Balat, CarT, and Lovit). The results showed that CdO NPs changed the expression levels of hdc, Lovit, tan, and eboney, indicating that HA synthesis, transport, and recycling were disrupted. Furthermore, less histamine immunolabeling was found in the head tissues of CdO NP-treated flies, particularly in the optic lobes. We also observed and quantified CdO NP bioaccumulation in compound eye tissues, which resulted in a number of cytological changes. Phenotypic effects (undersized eyes) have also been observed in the compound eyes of F1 flies. Considering the significance of vision in an organism's survival, the findings of this study are extremely crucial, as long-term exposure to CdO NPs may result in blindness.

Dependence of the artificial reservoir pollution with heavy metals on anthropogenic factors

The article presents the research results of the heavy metals content in artificial reservoirs located at different distances from a number of pollutants of anthropogenic origin. The manuscript provides data on the dependence of the concentration of copper, zinc, lead, iron, cadmium in pond water on their location on highways and arable land. The location near these anthropogenic factors of artificial reservoirs pollution causes the accumulation of heavy metals in the water leading to significant exceedances of permissible levels for the catch of commercial fish, poses a significant threat to the environmental situation and safety of aquaculture. Research has also revealed that fish farming technology used in the farm also determines the ingress and accumulation of heavy metals in the reservoir. In particular, it was found that the operation of non-letting ponds, the use of cascades near the highway and arable land increases the accumulation of heavy metals. According to the results of our research, the content of heavy metals in a pond located at a short distance from the road and agricultural land indicate a high increase in the concentration of toxicants in water. It was established that the concentration of Kuprum was in the water thickness – 0.085 mg/dm3, and at the bottom of the reservoir 0.095 mg/dm3 at MPC 0.001 mg/dm3. The Zn content in the water thickness was 0.119 mg/dm3, in the deep layers of the reservoir – 0.127 mg/dm3, exceeding the maximum allowable concentrations of 11.9 and 12.7 times, respectively. Mangan in the water thickness of the reservoir located near anthropogenic polutantes was 0.091 mg/dm3, and near the bottom of the reservoir – 0.034 mg/dm3 at the MPC – 0.01 mg/dm3. Fe in the water of an artificial reservoir located near the field and road exceeded the maximum allowable concentrations for this chemical element by 20 times regardless of the layer of its selection

Assessment of trace inorganic contaminates in water and sediment to address its impact on common fish varieties along Kuwait Bay

The impact of the trace elements on selected marine fishes/crustacean in Kuwait (Sheam, Lobster, Speatty, and Nagroor) were investigated (As, Cd, Ni, Pb, and V) using the element concentrations in marine water and sediments. The toxic elements concentrations were measured in water samples (As, Cd, Cr, Cu, Hg, Ni, Pb, V, and Zn) for estimation of toxic levels, heavy metal evaluation index (84-360), and the degree of contamination (77-353). Similarly, sediment samples were analyzed for As, Cd, Cr, Cu, Ni, Pb, V and estimated for contamination factor, I_geo index, and ecological risk factor with respect to each element analyzed in the sample. The modified degree of contamination (0.25-3.67), risk index (6.5-282.27), metal pollution index (5.95-18.21), and pollution load index (0.27-1.2) were calculated for the samples. This study demonstrated that the water was medium to high contaminated with Cd, Hg, Pb, and V. The sediment analyses showed that most of the metals were within the toxic limits except for Cd, Cu, and Pb in few samples. Most samples were in between the effect range low-effect range medium and threshold effect level-probable effect level range of most metals, except for Cr, Cu, and Ni. Average trace elements concentration in fishes varieties investigated in this study indicated high As in all varieties irrespective of the season and high Ni in all fish during summer. The bioaccumulation factor showed that the trace elements in sediments contributed more to the fish than water. Concentrations of trace elements were greater in fish sampled in winter than that sampled in summer due to variations in the planktonic population in the sea. The estimated daily intake and the chronic daily intake for the Kuwaiti male and female were calculated. The hazards studied revealed that the consumption of Lobster and Speatty may lead to cancer and non-cancer hazards, in both male and female, Speatty having higher probability. The major sources of toxic elements contamination of Kuwait Bay water and sediment appear to be oil-based contamination, urban sewage, brine from desalination, and the trace elements released due to the natural oxidation-reduction processes.

Bioaccumulation of trace elements in tissues of Indian oil sardine (Sardinella longiceps) from the northern United Arab Emirates

Small, partially enclosed gulfs are especially vulnerable to coastal pollution. The Arabian Gulf is a shallow, hypersaline, warm gulf with rising levels of pollution caused by rapid development and industrialization. We measured 19 trace elements in the gastrointestinal tract, liver and muscle of Indian oil sardines (Sardinella longiceps) from three sites from the United Arab Emirates in the southern Arabian Gulf. Concentrations of cadmium, chromium, copper and zinc exceeded international maximum permissible limits (MPL) in all three tissues in most sites. High concentrations in muscle raises concerns about the risk to humans, as muscles are widely consumed by humans. Discriminant Function Analysis showed that the three study sites (Sharjah, Ajman and Umm Al Quwain) could be discriminated based on a combination of elements. Improved monitoring of pollutants is needed to ascertain the concentration of pollutants in species at different trophic levels. We recommend better control measures to reduce the discharge of pollutants into this fragile marine ecosystem.

Protection of Danio rerio from cadmium (Cd2+) toxicity using biological iron sulfide composites

Cadmium (Cd²⁺) pollution has become a global environmental problem. This study is the first to demonstrate the feasibility and effects of applying biological iron sulfide composites (BISC) for the protection of Cd²⁺ exposed fish, aiming at remediation of Cd²⁺ polluted waters during emergency pollution events. Experimental results indicate that BISC can remove Cd²⁺ efficiently and significantly protect Cd²⁺ exposed Danio rerio, by increasing its overall survival rates. Meanwhile, the protective effect of BISC is significantly enhanced with optimized BISC dosing ratios of 2.4 or more, as well as with more rapid onset of BISC dosing following Cd²⁺ exposure and in water with higher pH levels in the range of 6-8, with D. rerio survival rates increased by more than 90% (P = 0.05). Additionally, BISC confers advantages over SRB and combinations of its constituents, with effective removal of Cd²⁺ and increasing survival rates of Cd²⁺ exposed D. rerio.

Effect of surfactant in mitigating cadmium oxide nanoparticle toxicity: Implications for mitigating cadmium toxicity in environment

Cadmium (Cd), classified as human carcinogen, is an extremely toxic heavy metal pollutant, and there is an increasing environmental concern for cadmium exposure through anthropogenic sources including cigarette smoke. Though Cd based nanoparticles such as cadmium oxide (CdO) are being widely used in a variety of clinical and industrial applications, the toxicity of CdO nanoparticles has not been well characterized. Herein we report the toxicity of CdO nanoparticles employing zebrafish as a model. Two different CdO nanoparticles were prepared, calcination of Cd(OH)₂ without any organic molecule (CdO-1) and calcination of Cd-citrate coordination polymer (CdO-2), to evaluate and compare the toxicity of these two different CdO nanoparticles. Results show that zebrafish exposed to CdO-2 nanoparticles expressed reduced toxicity as judged by lower oxidative stress levels, rescue of liver carboxylesterases and reduction in metallothionein activity compared to CdO-1 nanoparticles. Histopathological observations also support our contention that CdO-1 nanoparticles showed higher toxicity relative to CdO-2 nanoparticles. The organic unit of Cd-citrate coordination polymer might have converted into carbon during calcination that might have covered the surface of CdO nanoparticles. This carbon surface coverage can control the release of Cd²⁺ ions in CdO-2 compared to non-covered CdO-1 nanoparticles and hence mitigate the toxicity in the case of CdO-2. This was supported by atomic absorption spectrophotometer analyses of Cd²⁺ ions release from CdO-1 and CdO-2 nanoparticles. Thus the present study clearly demonstrates the toxicity of CdO nanoparticles in an aquatic animal and also indicates that the toxicity could be substantially reduced by carbon coverage. This could have important implications in terms of anthropogenic release and environmental pollution caused by Cd and human exposure to Cd²⁺ from sources such as cigarette smoke.

A new and highly selective turn-on fluorescent sensor with fast response time for the monitoring of cadmium ions in cosmetic, and health product samples

Cadmium (Cd) which is an extremely toxic could be found in many products like plastics, fossil fuel combustion, cosmetics, water resources, and wastewaters. It is capable of causing serious environmental and health problems such as lung, prostate, renal cancers and the other disorders. So, the development of a sensor to continually monitor cadmium is considerably demanding. Tetrakis(4-nitrophenyl)porphyrin, T(4-NO2-P)P, was synthesized and used as a new and highly selective fluorescent probe for monitoring cadmium ions in the "turn-on" mode. There was a linear relationship between fluorescence intensity and the concentration of Cd(II) in the range of 1.0×10(-6) to 1.0×10(-5)molL(-1) with a detection limit of 0.276μM. To examine the most important parameters involved and their interactions in the sensor optimization procedure, a four-factor central composite design (CCD) combined with response surface modeling (RSM) was implemented. The practical applicability of the developed sensor was investigated using real cosmetic, and personal care samples.

Effect of heavy metals on fish larvae deformities: A review

Heavy metals have been associated with many fish deformities in natural populations and in laboratory produced specimens as well. Deformities in general have devastating effects on fish populations since they affect the survival, the growth rates, the welfare and their external image. Although the embryonic stage in respect to heavy metal exposure has been extensively studied, there is not much information available as to what happens in fish larvae and adults. In the present article, we present the available information on the effect of heavy metals on fish larvae deformities. We also address the need for more research towards the effects of metals on the subsequent life stages in order to assess the long-term consequences of heavy metal poisoning on fish organisms and possibly correlate these consequences with the environmental contamination (use as biomarkers).

Trade-offs between elimination and detoxification in rainbow trout and common bivalve molluscs exposed to metal stressors

The purpose of this paper was to examine trade-offs between elimination and detoxification in rainbow trout and three common bivalve molluscs (clam, oyster, and scallop) exposed to cadmium (Cd), copper (Cu), and zinc (Zn) based on recent reported experimental data. We incorporated metal influx threshold with subcellular partitioning to estimate rate constants of detoxification (k(d)) and elimination (k₂). We found that the relationships between k₂ and k(d) were negative for rainbow trout and positive for bivalve molluscs. However, the relationships between k(d) and % metal in metabolically detoxified pool were found positive for rainbow trout and negative for bivalve molluscs. Our results also indicated that rainbow trout had higher accumulation (~60-90%) in metabolically active pool when exposed to essential metals of Cu and Zn and had only 10-50% accumulation in response to non-essential metal of Cd. Based on a cluster analysis, this study indicated that similarity of physiological regulations among study species was found between Cd and Zn. Our study suggested that detoxification can be predicted by an elimination-detoxification scheme with the known elimination rate constant. We concluded that quantification of trade-offs between subcellular partitioning and detoxification provides valuable insights into the ecotoxicology of aquatic organisms and enhances our understanding of the subcellular biology of trace metals.