Cadmium probably manifests their toxic effects by eliminating some species and not affecting others in natural aquatic systems, which seems important to determine which species are most likely to be eliminated. Those species are the useful indicators of cadmium effects and the drivers of how ecosystems will change in response to cadmium contamination. Such information is urgently needed with regard to studies of differences among taxa in toxicity, detoxification, and the resulting responses to cadmium hereafter.
Aquatic organisms are exposed to many different cadmium forms or species such as waterborne and particle-associated cadmium in natural aquatic systems, but WQC assumes that cadmium toxicity primarily occurs via the dissolved phase and no WQC are available for particulate cadmium (in mg/kg) currently. So in future, the importance of considering not only water chemistry but also dietary chemistry in devising environmental regulations for cadmium should be emphasized and the cadmium WQC and guidelines are suggested to be reconsidered.
Toxicity and mechanisms of waterborne and dietary cadmium to saltwater aquatic organisms has been addressed in this topic based on laboratory controlled experiments of single species populations, which maybe have limitations from an ecological or ecotoxicological perspective, because extrapolation from laboratory to field is difficult and risky. More investigations of population, community, and ecosystem level effects and pathways of cadmium are needed, and risk assessments of cadmium should always include bioassay or investigations of in-situ or field community condition in future.
Furthermore, cadmium as the one of the most widely used constituent metal in Quantum dots (QD) core metalloid complexes of Nanoparticles, are known to cause acute and chronic toxicities in organisms and pose environmental and human health risks, but information on routes of exposure and the environmental transport and fate of cadmium QD materials is scarce. The potential risks by which to the environment should be seriously considered.
