The Japanese medaka (Oryzias latipes) extended one-generation reproduction test (MEOGRT) (Test Guideline 890.2200) is a Tier 2 test within the Endocrine Disruptor Screening Program of the US Environmental Protection Agency (US EPA). A modified MEOGRT was used to evaluate multigenerational effects of 2-ethylhexyl 4-hydroxybenzoate (2-EHHB) under flow-through conditions starting with adults (parent generation, F0) through a 3-week reproductive phase of the second generation (F2). Fish were exposed to one of five 2-EHHB test concentrations or a dechlorinated tap water control. Fecundity was affected at the lowest exposure (5.32 μg/L) and greater sensitivity occurred in the F1 and F2 generations. Percent fertility was also diminished from no effect level observed in the F0 generation to 101 and 48.8 μg/L in the F1 and F2 generations, respectively. Growth indices were decreased for F0 adult females and F1 subadults and adults at 48.8 μg/L 2-EHHB. Histopathologic examination of gonads, liver, kidney, and thyroid yielded possible delayed reproductive tract development in F1 subadult males, masculinization of the renal phenotype in F1 adult females (renal tubular eosinophilia) and reduced hepatic energy storage (liver glycogen vacuoles) in F1 (11.3 and 48.8 μg/L) and F2 (48.8 and 101 μg/L) males and females, respectively. Endocrine-related findings included a decrease in anal fin papillae in F2 adult males at 101 μg/L. Results of this study demonstrate effects on growth, development, and reproduction that may be mediated by endocrine (weak estrogenic) and nonendocrine mechanisms. Duration of the MEOGRT should not be routinely extended beyond the OCSPP 890 guideline study design.

中文翻译：

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4-羟基苯甲酸2-乙基己酯对日本青鳉的多代效应评价

日本青鳉 ( Oryzias latipes ) 延长一代繁殖测试 (MEOGRT)（测试指南 890.2200）是美国环境保护署 (US EPA) 内分泌干扰物筛查计划中的第 2 级测试。使用改良的 MEOGRT 来评估 4-羟基苯甲酸 2-乙基己酯 (2-EHHB) 在流通条件下的多代效应，从成虫（亲代，F0）开始，到第二代（F2）的 3 周生殖阶段。将鱼暴露于五种 2-EHHB 测试浓度之一或脱氯自来水对照中。最低暴露量（5.32 μg/L）时繁殖力受到影响，并且 F1 和 F2 代的敏感性更高。生育率百分比也从 F0 代中观察到的无影响水平分别降低至 F1 和 F2 代中的 101 和 48.8 μg/L。F0 成年雌性、F1 亚成体和成体的生长指数在 48.8 μg/L 2-EHHB 下下降。性腺、肝脏、肾脏和甲状腺的组织病理学检查显示，F1 亚成年雄性的生殖道发育可能延迟，F1 成年雌性的肾脏表型男性化（肾小管嗜酸性粒细胞增多），F1 的肝脏能量储存减少（肝糖原空泡）（11.3）和 48.8 μg/L) 和 F2 (48.8 和 101 μg/L) 雄性和雌性分别。内分泌相关的发现包括 F2 成年雄性的肛鳍乳头减少至 101 μg/L。这项研究的结果表明，对生长、发育和生殖的影响可能是由内分泌（弱雌激素）和非内分泌机制介导的。MEOGRT 的持续时间不应常规延长超出 OCSPP 890 指南研究设计。