Fujian Key Laboratory of Functional Marine Sensing Materials, Institute of Oceanography, Minjiang University, Fuzhou 350108, China.
Laboratory of Marine Biology and Ecology, Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China.
Sci Total Environ. 2021 Apr 1;763:143040. doi: 10.1016/j.scitotenv.2020.143040. Epub 2020 Oct 16.
Plastics have been recognized as a serious threat to the environment. Besides their own toxicity, microplastics can interact with other environmental pollutants, acting as carriers and potentially modulating their toxicity. In this study, the toxicity of polystyrene (PS) microplastic fragments (plain PS; carboxylated PS, PS-COOH and aminated PS, PS-NH) and triphenyl phosphate (TPhP) (an emerging organophosphate flame retardant) at the environmentally relevant concentrations to the marine medaka (Oryzias melastigma) larvae was investigated. Larvae were exposed to 20 μg/L of microplastic fragments or 20 and 100 μg/L of TPhP or a combination of both for 7 days. The results showed that the three microplastics did not affect the larval locomotor activity. For TPhP, the larval moving duration and distance moved were significantly decreased by the TPhP exposure, with a maximum decrease of 43.5% and 59.4% respectively. Exposure to 100 μg/L TPhP respectively down-regulated the expression levels of sine oculis homeobox homologue 3 (six3) and short wavelength-sensitive type 2 (sws2) by 19.1% and 41.7%, suggesting that TPhP might disturb eye development and photoreception and consequently the low locomotor activity in the larvae. Interestingly, during the binary mixture exposure, the presence of PS, PS-COOH or PS-NH reversed the low locomotor activity induced by 100 μg/L TPhP to the normal level. Relative to the larvae from the 100 μg/L TPhP group, the movement duration and distance moved were increased by approximately 60% and 100%, respectively, in the larvae from the TPhP + PS, TPhP + PS-COOH and TPhP + PS-NH groups. However, the gene expression profiles were distinct among the fish from the TPhP + PS, TPhP + PS-COOH and TPhP + PS-NH groups, implying different mechanisms underlying the reversal of the locomotor activity. The findings in this study challenge the general view that microplastics aggravate the toxicity of the adsorbed pollutants, and help better understand the environmental risk of microplastic pollution.
塑料已被公认为对环境的严重威胁。除了自身的毒性外，微塑料还可以与其他环境污染物相互作用，充当载体，并可能调节其毒性。在这项研究中，研究人员研究了聚苯乙烯（PS）微塑料碎片（普通 PS；羧基化 PS，PS-COOH 和氨基化 PS，PS-NH）和磷酸三苯酯（TPhP）（一种新兴的有机磷阻燃剂）在环境相关浓度下对海洋泥鳅（Oryzias melastigma）幼虫的毒性。幼虫暴露于 20μg/L 的微塑料碎片或 20 和 100μg/L 的 TPhP 或两者的组合中 7 天。结果表明，这三种微塑料均未影响幼虫的游动活性。对于 TPhP，暴露于 TPhP 后，幼虫的游动持续时间和移动距离明显减少，最大减少分别为 43.5%和 59.4%。暴露于 100μg/L TPhP 分别使 sine oculis homeobox homologue 3（six3）和短波长敏感型 2（sws2）的表达水平下调了 19.1%和 41.7%，表明 TPhP 可能干扰眼睛发育和光感，从而导致幼虫的低游动活性。有趣的是，在二元混合物暴露期间，PS、PS-COOH 或 PS-NH 的存在逆转了 100μg/L TPhP 引起的低游动活性，使其恢复正常水平。与来自 100μg/L TPhP 组的幼虫相比，来自 TPhP+PS、TPhP+PS-COOH 和 TPhP+PS-NH 组的幼虫的游动持续时间和移动距离分别增加了约 60%和 100%。然而，来自 TPhP+PS、TPhP+PS-COOH 和 TPhP+PS-NH 组的鱼的基因表达谱不同，这表明运动活性逆转的机制不同。本研究的结果挑战了微塑料加剧吸附污染物毒性的普遍观点，并有助于更好地理解微塑料污染的环境风险。
