Bell Anna Maria, Keltsch Nils, Schweyen Peter, Reifferscheid Georg, Ternes Thomas, Buchinger Sebastian
Federal Institute of Hydrology, Am Mainzer Tor 1, 56068 Koblenz, Germany.
Water Res X. 2021 Jun 2;12:100105. doi: 10.1016/j.wroa.2021.100105. eCollection 2021 Aug 1.
Organic coatings can guarantee long-term protection of steel structures due to causing a physical barrier against water and oxygen. Because of their mechanical properties and resistances to heat and chemicals, epoxy resin-based coatings are widely used for corrosion protection. Despite of the aromatic backbone and the resulting susceptibility to UV degradation, epoxy resins are frequently used as binding agent in top layers of anti-corrosion coating systems. Consequently, these organic polymers are directly exposed to sunlight and thus UV radiation. The present study was designed to investigate if toxic effects of epoxy resin-based-coatings are changed by UV-A irradiation. For this purpose, two epoxide-based top coatings were examined with and without UV aging for their bacterial toxicity and estrogenicity. In addition, chemical analyses were performed to identify released compounds as well as photolytic degradation products and to assign toxic effects to individual substances. UV-A irradiation of epoxy resin based top coatings resulted in an overall decrease of acute and specific ecotoxicological effects but as well to the formation of toxic transformation products. Both, in leachates of untreated and UV-A irradiated coatings, 4BP was identified as the main driver of estrogenicity and toxicity to luminescent bacteria. BPA and structural analogs contributing to estrogenic effects in leachates were formed by UV-A irradiation. The combination of HPTLC coupled bioassays and LC-MS analyses supported the identification of bioactive compounds in terms of an effect-directed analysis. The present findings indicate that epoxide-based coatings are less suitable for the application as top coatings and more UV stable coatings like aliphatic polyurethanes should be preferred.
有机涂层可以通过形成一道阻挡水和氧气的物理屏障来保证对钢结构的长期保护。由于其机械性能以及对热和化学品的耐受性，环氧树脂基涂层被广泛用于防腐。尽管环氧树脂具有芳香族主链且易受紫外线降解影响，但它仍经常被用作防腐涂层系统顶层的粘合剂。因此，这些有机聚合物直接暴露在阳光下，从而受到紫外线辐射。本研究旨在调查基于环氧树脂的涂层的毒性效应是否会因紫外线A照射而发生变化。为此，对两种基于环氧化合物的面漆进行了研究，检测了它们在有和没有紫外线老化情况下的细菌毒性和雌激素活性。此外，还进行了化学分析，以确定释放的化合物以及光解降解产物，并将毒性效应归因于个别物质。对基于环氧树脂的面漆进行紫外线A照射导致急性和特定生态毒理学效应总体下降，但也导致了有毒转化产物的形成。在未处理和经紫外线A照射的涂层的渗滤液中，4BP均被确定为雌激素活性和对发光细菌毒性的主要驱动因素。双酚A（BPA）及其结构类似物在渗滤液中对雌激素效应有贡献，它们是由紫外线A照射形成的。高效薄层层析（HPTLC）结合生物测定法与液相色谱-质谱联用（LC-MS）分析相结合，在效应导向分析方面支持了生物活性化合物的鉴定。本研究结果表明，基于环氧化合物的涂层不太适合用作面漆，应优先选择更耐紫外线的涂层，如脂肪族聚氨酯。
