Ecotoxicology & Wildlife Health Division, Science & Technology Branch, Environment Canada, Burlington, Ontario, Canada.
Environ Sci Technol. 2012 Aug 7;46(15):8440-7. doi: 10.1021/es301032a. Epub 2012 Jul 20.
Captive American kestrels (Falco sparverius) were exposed via diet during reproduction to an environmentally relevant concentration of β-1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (β-TBECH). The β-TBECH isomer was injected into the food source at a daily dosing concentration of 0.239 ng/g kestrel/day (22 pairs); control birds were exposed via diet to the safflower oil vehicle only (24 pairs). Eight pairs in each group were exposed for four weeks and sacrificed for tissue analysis; the remaining pairs completed their breeding cycle, with exposure ceasing at the end of incubation (82 days). α- and β-TBECH appeared to be rapidly metabolized and/or eliminated from fat, liver, and plasma; both isomers and potential hydroxylated metabolites of β-TBECH (plasma) were undetected. Notwithstanding, compared to controls, pairs exposed to β-TBECH laid fewer eggs (p = 0.019) and laid lighter eggs (successful eggs: p = 0.009). Exposed pairs also demonstrated poorer egg fertility (p = 0.035) although testis mass and histology were similar among males. Reductions in egg production and fertility resulted in decreased hatchling success (p = 0.023). The β-TBECH-exposed pairs also produced fewer males overall (p = 0.009), which occurred concurrently with increased estradiols maternally deposited in eggs (p = 0.039). These findings demonstrate that β-TBECH may be detrimental for breeding in wild birds receiving similar exposure levels.
被圈养的美洲红隼（Falco sparverius）在繁殖期间通过饮食暴露于环境相关浓度的β-1,2-二溴-4-(1,2-二溴乙基)环己烷（β-TBECH）中。β-TBECH 异构体以每天 0.239ng/g 红隼的剂量浓度（22 对）注入食物源中；对照组的鸟类仅通过饮食暴露于红花油载体（24 对）。每组有 8 对暴露于 4 周并进行组织分析；其余的对完成了它们的繁殖周期，在孵化结束时停止暴露（82 天）。α-TBECH 和 β-TBECH 似乎迅速代谢和/或从脂肪、肝脏和血浆中消除；两种异构体和 β-TBECH 的潜在羟基化代谢物（血浆）均未检测到。尽管如此，与对照组相比，暴露于 β-TBECH 的对产卵较少（p = 0.019），且产下的卵较轻（成功的卵：p = 0.009）。暴露对的卵也表现出较差的受精能力（p = 0.035），尽管雄性的睾丸质量和组织学相似。产卵量和受精能力的降低导致幼鸟孵化成功率降低（p = 0.023）。β-TBECH 暴露对总体上也产生了较少的雄性（p = 0.009），这与母体内沉积的雌二醇增加同时发生（p = 0.039）。这些发现表明，β-TBECH 可能对接受类似暴露水平的野生鸟类的繁殖有害。
