The current vision proposes a new framework which is expected to advance the ecotoxicity testing in the 21 st century (Figure 1). As illustrated in Figure 1, sensitive species should be initially identified through published individual ecotoxicity data analysis. Biological responses are significantly altered by both chemicals and species, which lead to the diversity of species sensitivity [4]. Each species may display a high susceptibility to certain chemicals. Matching up pairs of \"sensitive species-chemicals\" provides a basis for the next step of ecotoxicity testing. Preliminary trials were initiated in this field [5; 6; 7; 8; 9; 10]. The in vivo exposure data of chemical are obtained from various database (e.g., ECOTOX) and other published literatures. Then, based on the data, species sensitivity distribution (SSD) was applied to find the sensitive species to a certain chemical. With results of ecotoxicity data analysis at the individual level, Chinese researchers compiled an extensive list of native sensitive species. Such list has been issued by the Ministry of Environmental Protection of China as an appendix of the Technical Guideline for Deriving Water Quality Criteria [11]. Secondly, species with established cell lines, such as mice, rats, insects, and fish, can be selected for high-throughput assays. With the existing cell lines, the ecotoxicity testing and risk evaluation can be processed according to the strategy envisaged in the NRC report [1]. For species without available cell lines, a crucial step is to check if artificial cultivation techniques are established for the species. Embryos of species that can be artificially cultivated, such as shellfish, crab, and shrimp, would permit the embryo-based medium throughput toxicity tests. Embryo-based toxicity testing is slightly more expensive than the pathway-based method, yet considerably reduces the time and costs compared to the conventional testing. Through the embryo-based assays, animals are not suffering from unpleasant states, such as pain and distress. Species that cannot be artificially bred pose a major challenge facing the high-throughput tests. Unfortunately, it is a commonly encountered scenario that a large number of species, including endangered communities, cannot be artificially produced. Those challenges may be addressed based on characteristics of different compounds. For example, for endocrine disruptors that induce interference effects by binding to receptors, it is possible to set up regression analysis between the binding affinity and interference effects. In this case, the binding affinity of chemicals acts as an indicator to clarify the toxicity of endocrine disruptors. For another example, [PERSON] et al. [12] derived a water quality threshold for ammonia using an eco-genomic approach. This approach based on the change of zooplankton's genetic diversity along with concentrations of ammonia, provided insight into the deployment of bioinformatics techniques in chemical risk assessment. In summary, for sensitive taxa that cannot be artificially cultivated, high-content experimental and computing methodologies  
Figure 1: A framework for ecotoxicity testing in the 21 st century. such as molecular toxicology, systems biology, and bioinformatics, can be combined to meaningfully extrapolate ecotoxicological outcomes and devise more effective testing strategies. Ecotoxicity data from pathway-based tests, embryo-based tests, or toxicity prediction and extrapolation modeling will ultimately be analyzed together with physicochemical properties, environmental fate, and in vivo and in vitro exposure data of chemicals. This procedure would allow a comprehensive assessment of the environmental risks posed by chemicals. The main limitation of high-throughput assay is that endpoints measured in high-throughput assay and the assessment endpoints considered in risk assessments are not connected. Also, new tools and models are restricted by regulatory structures change [13].