Jarvis Amanda, Prossner Kristen, Schnitker Brian, Gallagher Kathryn
Office of Water, Office of Science and Technology, Health and Ecological Criteria Division, Ecological Risk Assessment Branch, United States Environmental Protection Agency, Washington, DC.
Environ Toxicol Chem. 2025 Jul 24. doi: 10.1093/etojnl/vgaf189.
In June 2024, the United States Environmental Protection Agency (USEPA) Office of Water published aquatic life screening values for acute freshwater exposures to two widely distributed rubber-tire compounds, 6PPD (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene diamine) and 6PPD-quinone (N-(1,3-dimethylbutyl)-N'-phenyl-p-phenylene diamine quinone). The purpose of this critical review is to outline the derivation of these protective values and provide a thorough summary of the toxicity data available at the time of screening value development to help identify current data gaps to inform future research needs. The detection of these compounds in U.S. waterways and toxicity data indicate short-term exposure to these compounds may present a risk to aquatic organisms. 6PPD-quinone, a transformation product of 6PPD, has been found to be highly toxic to certain adult salmonid species. As emerging contaminants for which scientific understanding of toxicity is rapidly evolving, the current 6PPD and 6PPD-quinone data did not fulfill the USEPA's requirements for deriving national recommended 304(a)(1) aquatic life ambient water quality criteria. Therefore, the USEPA developed screening values in accordance with Section 304(a)(2) of the Clean Water Act (CWA) to provide states, authorized Tribes, and other stakeholders with the best available information on the toxicity of 6PPD and 6PPD-quinone to aquatic organisms. The 2024 USEPA screening values for acute exposures to 6PPD and 6PPD-quinone in freshwaters are 8.9 µg/L (8,900 ng/L) and 11 ng/L, respectively, and are intended to support protection of freshwater aquatic communities from acute effects including coho salmon (Oncorhynchus kisutch), listed as threatened or endangered in several states, based on the best available data. The USEPA will continue to monitor newly reported toxicity data to evaluate the protectiveness of these values.
2024年6月，美国环境保护局（USEPA）水办公室公布了两种广泛分布的橡胶轮胎化合物——6PPD（N-(1,3-二甲基丁基)-N'-苯基-对苯二胺）和6PPD-醌（N-(1,3-二甲基丁基)-N'-苯基-对苯二胺醌）在急性淡水暴露下的水生生物筛选值。本次关键综述的目的是概述这些保护值的推导过程，并全面总结在筛选值制定时可得的毒性数据，以帮助识别当前的数据空白，为未来的研究需求提供信息。在美国水道中检测到这些化合物以及毒性数据表明，短期接触这些化合物可能会对水生生物构成风险。6PPD-醌是6PPD的转化产物，已被发现对某些成年鲑科鱼类具有高毒性。作为毒性科学认识正在迅速发展的新兴污染物，当前的6PPD和6PPD-醌数据不符合美国环境保护局推导国家推荐的304(a)(1)水生生物环境水质标准的要求。因此，美国环境保护局根据《清洁水法》（CWA）第304(a)(2)条制定了筛选值，以便为各州、授权部落和其他利益相关者提供关于6PPD和6PPD-醌对水生生物毒性的最佳可用信息。2024年美国环境保护局针对淡水中6PPD和6PPD-醌急性暴露的筛选值分别为8.9微克/升（8900纳克/升）和11纳克/升，旨在根据最佳可用数据支持保护淡水水生群落免受急性影响，包括银大麻哈鱼（Oncorhynchus kisutch），该物种在几个州被列为受威胁或濒危物种。美国环境保护局将继续监测新报告的毒性数据，以评估这些值的保护作用。
