Jessup William H, Wiegand Jenna, Delbridge-Perry Mikayla, MacAvoy Stephen E, Connaughton Victoria P
Department of Biology, American University, Washington, District of Columbia, USA.
Department of Environmental Science, American University, Washington, District of Columbia, USA.
J Appl Toxicol. 2022 Dec;42(12):1986-2004. doi: 10.1002/jat.4369. Epub 2022 Jul 29.
Siloxanes are used in personal care, biomedical, and industrial products. Their worldwide use and persistence in the environment cause consistent exposure for both humans and aquatic animals. Two siloxane congeners, decamethylcyclopentasiloxane (D5; CAS 541-02-6) and octamethylcyclotetrasiloxane (D4; CAS 556-67-2), are among the most prevalent, with measurable levels in air, sediment, water, and biological samples. However, few studies have examined the impact of developmental (embryo/larva) exposure. To address this gap, we performed parallel experiments using wildtype zebrafish (Danio rerio). One set of experiments used laboratory-mixed individual solutions containing either D4, D5, or 2,4,6,8-tetramethylcyclotetrasiloxane (D ; CAS 2370-88-9); the other used environmental water samples containing a mixture of siloxanes, including D4 and D5. These samples were collected from Bladensburg Waterfront Park (BWP) a site along the Anacostia River, Washington, DC. In both experiments, zebrafish (24-48 h postfertilization, hpf) were exposed until 7 or 14 days (d)pf. Chronic exposure to D4, D5, or BWP water until 7 dpf caused stress-like behaviors and reduced swim velocities; anatomical differences were noted only in BWP-exposed larvae. At 14 dpf, BWP-treated larvae still showed slower swimming velocities and increased immobility; anatomical differences were no longer evident and thigmotactic behavior was reduced. D4 and D5-exposed larvae did not survive after 10 dpf. Larvae exposed to D showed no decreases in behavior or growth at either age. These results suggest early developmental sensitivity to siloxane exposure and point to the need to consider embryonic/larval endpoints when assessing aquatic contaminants.
硅氧烷被用于个人护理产品、生物医学产品和工业产品中。它们在全球范围内的使用以及在环境中的持久性导致人类和水生动物持续接触到这些物质。两种硅氧烷同系物，十甲基环五硅氧烷（D5；化学物质登记号541 - 02 - 6）和八甲基环四硅氧烷（D4；化学物质登记号556 - 67 - 2），是最为普遍的，在空气、沉积物、水和生物样本中都有可测量的含量。然而，很少有研究考察发育阶段（胚胎/幼体）接触的影响。为了填补这一空白，我们使用野生型斑马鱼（Danio rerio）进行了平行实验。一组实验使用实验室混合的单独溶液，分别含有D4、D5或2,4,6,8 - 四甲基环四硅氧烷（D ；化学物质登记号2370 - 88 - 9）；另一组使用含有包括D4和D5在内的硅氧烷混合物的环境水样。这些样本采集自华盛顿特区阿纳科斯蒂亚河沿岸的布莱登斯堡滨水公园（BWP）。在这两个实验中，斑马鱼（受精后24 - 48小时，hpf）被暴露至7天或14天（d）pf。长期暴露于D4、D5或BWP水样直至7 dpf会导致类似应激的行为并降低游泳速度；仅在暴露于BWP的幼体中观察到解剖学差异。在14 dpf时，经BWP处理的幼体仍然表现出较慢的游泳速度和增加的静止不动；解剖学差异不再明显，趋触行为减少。暴露于D4和D5的幼体在10 dpf后未能存活。暴露于D 的幼体在两个年龄段的行为或生长均未出现下降。这些结果表明发育早期对硅氧烷暴露敏感，并指出在评估水生污染物时需要考虑胚胎/幼体终点。
