Thomas Paul C, Velthoven Kirsten, Geurts Marc, van Wijk Dolf
CEHTRA S.A.R.L., Corvette, ZAC du Parc Technologique-Lieu-dit La Verne, Avenue Antoine de Condorcet, 38090 VAULX MILIEU, France.
Chemosphere. 2009 Apr;75(3):310-8. doi: 10.1016/j.chemosphere.2009.02.003. Epub 2009 Mar 14.
The toxicity of the dialkyl quat, didecyldimethylammonium bromide (DDAB), was used as a typical quaternary ammonium compound in studies investigating the role of sorption in reducing DDAB bioavailability in sediment and soil for natural and artificial substrates. Fatty acid derivatives are known to interact ionically with negative charged particles such as clays, humic and fulvic acids, dramatically reducing their bioavailability. Sorption potential was measured using cationic exchange capacities (CEC). The CEC of the substrates was correlated with toxicity of DDAB to the nematode Caenorhabditis elegans considered to be representative of soil and sediment dwelling, free-living nematodes in terms of its sensitivity, size and feeding strategy. Decreased toxicity was found with increasing CEC for both laboratory and field substrates when tested under both soil and sediment conditions and QSARs developed. Testing under soil or sediment conditions had less impact on the toxicity than the CEC of the soil/sediment or whether the substrate was artificial or natural. Habitat preferences were observed during a test in which nematodes were placed into substrates with different CECs. The worms favoured mid-range CECs. Similar preference behaviour may be expected in the environment and a threshold CEC for likely presence of nematodes in a substrate is proposed. Coupled with the substrate toxicity QSAR, threshold CEC preference can be used to provide a no observed effect concentration for DDAB. Expressed as a molar fraction of the CEC, the QSAR obtained for DDAB may be extrapolable to other fatty amine derivatives. If supported by further experimentation and complemented with data from other sediment and soil dwellers the QSAR and threshold CEC value can be validated for use in future regulatory risk assessments of fatty amine derivatives.
在研究吸附作用对降低二癸基二甲基溴化铵（DDAB）在沉积物和土壤中对天然及人工基质的生物有效性的作用时，将二烷基季铵盐DDAB的毒性用作典型的季铵化合物。已知脂肪酸衍生物会与带负电荷的颗粒（如粘土、腐殖酸和富里酸）发生离子相互作用，从而显著降低其生物有效性。使用阳离子交换容量（CEC）来测量吸附潜力。底物的CEC与DDAB对线虫秀丽隐杆线虫的毒性相关，秀丽隐杆线虫在敏感性、大小和摄食策略方面被认为是土壤和沉积物中自由生活线虫的代表。在土壤和沉积物条件下进行测试并建立定量构效关系（QSAR）时，发现无论是实验室底物还是现场底物，随着CEC的增加，毒性都会降低。在土壤或沉积物条件下进行测试对毒性的影响小于土壤/沉积物的CEC，也小于底物是人工的还是天然的。在一项将线虫放入具有不同CEC的底物中的测试中观察到了栖息地偏好。线虫喜欢中等范围的CEC。在环境中可能会预期到类似的偏好行为，并提出了底物中线虫可能存在的CEC阈值。结合底物毒性QSAR，CEC阈值偏好可用于提供DDAB的未观察到效应浓度。以CEC的摩尔分数表示，为DDAB获得的QSAR可能可外推至其他脂肪胺衍生物。如果得到进一步实验的支持，并辅以来自其他沉积物和土壤栖息生物的数据，则QSAR和CEC阈值可用于未来脂肪胺衍生物的监管风险评估的验证。
