BACKGROUND Fluorochloridone (FLC) is a widely used herbicide, and its target organs are testes and epididymides. The Globally Harmonized System of Classification and Labelling of Chemicals classified FLC as Level 2-possibly cause fertility or fetal damage (no relevant data support). The maximum residue levels of FLC in processed crops have been reviewed in the latest European Food Safety Authority (EFSA) report in 2018. However, the toxic effect of FLC on fertility and early embryonic development is limited, and the health risk assessment of FLC needs further consideration. This study investigated the potential effects of FLC on fertility and early embryonic development in rats. METHODS One hundred rats of each sex were divided into four groups including three FLC-treated groups at doses of 2 mg/kg, 5 mg/kg and 15 mg/kg, and a vehicle control group (0.5% (w/v) sodium carboxymethyl cellulose). Male and female rats were dosed for 9 and 2 consecutive weeks, intragastrically, prior to cohabitation and lasted throughout the mating period for males and continued until Gestation Day 7 (GD7) for females. Parameters such as weights and coefficients of reproductive organs, epididymal sperm number and motility, indexes of copulation, fecundity and fertility indexes, mating period, estrous cycle, corporalutea number, implantations, live, dead and resorbed fetuses, preimplantation loss rate, and postimplantation loss rate were observed in this study. RESULTS Obvious toxicity of male reproductive system was found at the dose of 15 mg/kg including decreases in testicular and epididymal weight, also in sperm motility rate. Whereas the increase in sperm abnormality rate was observed. However, no significant effects of FLC were found on lutea count, implantations count, fetuses count and weight, live fetuses count (rate), dead fetuses count (rate), resorbed fetuses count (rate), placentas weight, fetuses gender, preimplantation loss (rate) and postimplantation loss (rate). Furthermore, FLC had no adverse effects on fertility and early embryonic development in rats. CONCLUSION The no-observable-adverse-effect level (NOAEL) of FLC on fertility and early embryonic development in rats was considered to be 5 mg/kg/day.

中文翻译：

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低剂量氟氯酮影响雄性大鼠的生殖系统，但不影响生育力和早期胚胎发育。

背景技术氟氯酮(FLC)是一种广泛使用的除草剂，其靶器官是睾丸和附睾。全球化学品统一分类和标签制度将 FLC 归类为 2 级——可能导致生育或胎儿损伤（无相关数据支持）。欧洲食品安全局（EFSA）2018年最新报告中对加工作物中FLC的最大残留水平进行了审查。但FLC对生育力和早期胚胎发育的毒性作用有限，需要对FLC进行健康风险评估进一步考虑。本研究调查了 FLC 对大鼠生育力和早期胚胎发育的潜在影响。方法 将 100 只大鼠，每种性别分为 4 组，包括 3 个 FLC 治疗组，剂量分别为 2 mg/kg、5 mg/kg 和 15 mg/kg，以及载体对照组（0.5%（w/v）钠）羧甲基纤维素）。雄性和雌性大鼠在同居前连续9周和2周胃内给药，雄性大鼠持续整个交配期，雌性大鼠持续到妊娠第7天（GD7）。生殖器官重量和系数、附睾精子数量和活力、交配指数、受精率和受精指数、交配期、动情周期、黄体数、植入、活胎、死胎和吸收胎儿、植入前丢失率、植入后丢失等参数本研究中观察到的比率。结果 15mg/kg剂量时发现男性生殖系统有明显毒性，包括睾丸和附睾重量下降，精子活力下降。而观察到精子异常率增加。然而，FLC 对黄体计数、着床计数、胎儿计数和体重、活胎计数（率）、死胎计数（率）、吸收胎儿计数（率）、胎盘重量、胎儿性别、植入前丢失没有显着影响（率）和植入后损失（率）。此外，FLC 对大鼠的生育力和早期胚胎发育没有不利影响。结论 FLC对大鼠生育力和早期胚胎发育的无观察不良反应水平（NOAEL）被认为是5 mg/kg/天。