Whole effluent toxicity (WET) testing is commonly used to ensure that wastewater discharges do not pose an unacceptable risk to receiving environments. Traditional WET testing involves exposing animals to (waste)water samples to assess four major ecologically relevant apical endpoints: mortality, growth, development, and reproduction. Recently, with the widespread implementation of the 3Rs to replace, reduce and refine the use of animals in research and testing, there has been a global shift away from in vivo testing towards in vitro alternatives. However, prior to the inclusion of in vitro bioassays in regulatory frameworks, it is critical to establish their ecological relevance and technical suitability. This is part 1 of a two-part review that aims to identify in vitro bioassays that can be used in WET testing and relate them to ecologically relevant endpoints through toxicity pathways, providing the reader with a high-level overview of current capabilities. Part 1 of this review focuses on four apical endpoints currently included in WET testing: mortality, growth, development, and reproduction. For each endpoint, the link between responses at the molecular or cellular level, that can be measured in vitro, and the adverse outcome at the organism level were established through simplified toxicity pathways. Additionally, literature from 2015 to 2020 on the use of in vitro bioassays for water quality assessments was reviewed to identify a list of suitable bioassays for each endpoint. This review will enable the prioritization of relevant endpoints and bioassays for incorporation into WET testing.

整体污水毒性 (WET) 测试通常用于确保废水排放不会对接收环境构成不可接受的风险。传统的 WET 测试涉及将动物暴露于（废水）水样中，以评估四个主要的生态相关顶端终点：死亡率、生长、发育和繁殖。最近，随着 3Rs 的广泛实施，以替代、减少和改进动物在研究和测试中的使用，全球范围内发生了从体内测试向体外替代方案的转变。然而，在体外纳入之前在监管框架中进行生物测定，确定其生态相关性和技术适用性至关重要。这是两部分评论的第 1 部分，旨在确定可用于 WET 测试的体外生物测定，并通过毒性途径将它们与生态相关终点联系起来，为读者提供当前能力的高级概述。本综述的第 1 部分重点关注目前包含在 WET 测试中的四个顶端终点：死亡率、生长、发育和繁殖。对于每个终点，可以在体外测量的分子或细胞水平的反应与生物体水平的不良结果之间的联系是通过简化的毒性途径建立的。此外，2015 年至 2020 年有关使用审查了用于水质评估的体外生物测定，以确定每个终点的合适生物测定列表。该审查将使相关终点和生物测定的优先级能够纳入 WET 测试。