Division of Environmental Science and Ecological Engineering, Korea University , 145 Anam-ro, Seongbuk-gu, Seoul 02841, Republic of Korea.
Department of Environmental Engineering, Technical University of Denmark , Bygningstorvet B115, DK-2800 Kongens Lyngby, Denmark.
Environ Sci Technol. 2016 Nov 1;50(21):12004-12011. doi: 10.1021/acs.est.6b03942. Epub 2016 Oct 19.
Worldwide, regulations of chemicals require short-term toxicity data for evaluating hazards and risks of the chemicals. Current data requirements on the registration of chemicals are primarily based on tonnage and do not yet consider properties of chemicals. For example, short-term ecotoxicity data are required for chemicals with production volume greater than 1 or 10 ton/y according to REACH, without considering chemical properties. Highly hydrophobic chemicals are characterized by low water solubility and slow bioconcentration kinetics, which may hamper the interpretation of short-term toxicity experiments. In this work, internal concentrations of highly hydrophobic chemicals were predicted for standard acute ecotoxicity tests at three trophic levels, algae, invertebrate, and fish. As demonstrated by comparison with maximum aqueous concentrations at water solubility, chemicals with an octanol-water partition coefficient (K) greater than 10 are not expected to reach sufficiently high internal concentrations for exerting effects within the test duration of acute tests with fish and invertebrates, even though they might be intrinsically toxic. This toxicity cutoff was explained by the slow uptake, i.e., by kinetics, not by thermodynamic limitations. Predictions were confirmed by data entries of the OECD's screening information data set (SIDS) (n = 746), apart from a few exceptions concerning mainly organometallic substances and those with inconsistency between water solubility and K. Taking error propagation and model assumptions into account, we thus propose a revision of data requirements for highly hydrophobic chemicals with log K > 7.4: Short-term toxicity tests can be limited to algae that generally have the highest uptake rate constants, whereas the primary focus of the assessment should be on persistence, bioaccumulation, and long-term effects.
全球范围内，化学品法规要求提供短期毒性数据，以评估化学品的危害和风险。目前化学品注册的现有数据要求主要基于吨位，尚未考虑化学品的性质。例如，根据 REACH 法规，对于生产量大于 1 或 10 吨/年的化学品，需要提供短期生态毒性数据，而不考虑化学品的性质。高疏水性化学品的特点是水溶性低，生物浓缩动力学缓慢，这可能会影响短期毒性实验的解释。在这项工作中，针对三种营养级（藻类、无脊椎动物和鱼类）的标准急性生态毒性试验，预测了高疏水性化学品的内部浓度。通过与水溶性的最大水相浓度进行比较，结果表明，辛醇-水分配系数（K）大于 10 的化学品预计不会在鱼类和无脊椎动物急性试验的试验持续时间内达到足够高的内部浓度，以发挥作用，即使它们可能具有内在毒性。这种毒性截止值可以通过动力学来解释，而不是通过热力学限制来解释，即吸收缓慢。预测结果通过 OECD 筛选信息数据集（SIDS）的数据条目（n = 746）得到了证实，除了少数例外，主要涉及有机金属物质和那些在水溶性和 K 之间不一致的物质。考虑到误差传播和模型假设，我们因此提出了对疏水性大于 log K > 7.4 的化学品的数据要求的修订：短期毒性试验可以仅限于藻类，因为藻类通常具有最高的吸收速率常数，而评估的主要重点应该放在持久性、生物累积性和长期效应上。
