Department of Biological Sciences, California State University, Long Beach, 90840, USA.
Aquat Toxicol. 2010 Feb 18;96(3):203-15. doi: 10.1016/j.aquatox.2009.10.023. Epub 2009 Oct 30.
It is well documented that many coastal and estuarine environments adjacent to developed and industrialized urban centers, such as the San Francisco Bay Area, are significantly contaminated by anthropogenic chemicals. However, it is not well understood to what extent existing contaminants, many with continuing inflows into the environment, may impact exposed wildlife. This study provided an initial characterization of thyroid endocrine-related effects and their relationship to accumulated contaminants in two indigenous fish species sampled from different San Franicsco Bay Area study sites. Plasma concentrations of thyroxine (T4) were significantly reduced in fish sampled from highly impacted locations such as Oakland Inner Harbor and San Leandro Bay as compared with fish from other locations representing relatively lower human impact, including Bodega Bay, Redwood City and a remote site on Santa Catalina Island. Triiodothyronine (T3) levels also varied significantly by location, with differing T3/T4 ratios in fish from some locations suggestive of altered peripheral deiodinase activity. The changes in thyroid endocrine parameters were significantly correlated with hepatic concentrations of certain environmental contaminants. A large number of polychlorinated biphenyl (PCB) congeners, both co-planar (dioxin-like) and non-co-planar, exhibited significant inverse correlations with T4 levels in the fish, while in contrast, T3 and T3/T4 ratio were positively correlated with PCB exposures. The positive correlation between T3/T4 ratio and PCBs supports the hypothesis that environmental PCBs may alter T4 deiodination or turnover, actions of PCBs reported in laboratory experiments. Some relationships between chlorinated pesticides including DDT and chlordanes, but fewer relationships with PAHs, were also observed. Together, these findings indicate that the thyroid endocrine system is exhibiting alterations associated with different aquatic environments in the San Francisco Bay Area, which are significantly related to current-day exposures of the fish to contaminant chemicals such as PCBs.
有大量文献记录表明，在毗邻发达工业化城市中心的许多沿海和河口环境中，人为化学物质的污染程度非常严重，比如旧金山湾区。然而，人们并不清楚现有的污染物（其中许多仍在不断流入环境中）在何种程度上会影响暴露于其中的野生动物。本研究初步分析了两种旧金山湾区不同采样点的本地鱼类的甲状腺内分泌相关效应及其与累积污染物的关系。与来自其他人类活动影响相对较低的地点（如博德加湾、雷德伍德城和圣卡塔利娜岛偏远地点）的鱼类相比，来自奥克兰内港和圣莱安德罗湾等受影响严重地点的鱼类，其甲状腺素（T4）的血浆浓度显著降低。T3 水平也因地点而异，一些地点的 T3/T4 比值不同，表明外周脱碘酶活性发生改变。甲状腺内分泌参数的变化与肝脏中某些环境污染物的浓度显著相关。大量多氯联苯（PCB）同系物，包括平面（类二噁英）和非平面同系物，与鱼类中的 T4 水平呈显著负相关，而 T3 和 T3/T4 比值则与 PCB 暴露呈正相关。T3/T4 比值与 PCBs 的正相关支持了这样一种假设，即环境 PCB 可能会改变 T4 的脱碘或转化，这是实验室实验中报道的 PCB 的作用。还观察到一些氯化农药（包括 DDT 和氯丹）与 PCBs 之间存在关系，而与多环芳烃（PAHs）之间的关系较少。这些发现表明，甲状腺内分泌系统在旧金山湾区的不同水生环境中表现出与污染物化学物质（如 PCB）暴露相关的改变。
