Primary Aromatic Amines: the Contribution of Sedi- Ment Organisms to Human Exposure

3,4-Dichloroaniline (DCA) showed an unusually high bioconcentration factor (BCF) up to 800 in the sediment dweller Lumbriculus variegatus, exceeding BCFs found in fish and other aquatic organisms by a factor of 8–40. In the scope of the European Risk Assessment process for different aromatic amines, concern was expressed with regards to biomagnification and secondary poisoning of man. Although measured BCF data in fish may be not critical, biomagnification in food chain of sediment, sediment dwelling organisms, fish eating birds or mammal (including man) can not be excluded. To address this issue, the concentration of DCA in fish due to dietary uptake via L. variegatus (i. e., the biomagnifications factor, BMF) was calculated, based on two different assumptions: 1) Either DCA is accumulated in L. variegatus in the form of a metabolite, but instantaneously released as DCA in fish, or 2) a DCA metabolite is accumulated in L. variegatus and further accumulated in fish. In the first case, application of an existing experimental kinetic model showed that the experimental BCF is likely to increase from 22 to approx. 25 if uptake via food has to be taken into account. In the second case, use of a physiology-based toxicokinetic model (PBTK) resulted in a BCF of 1.7 to 46 for the DCA metabolite. The daily uptake for a consumer, given in the European Union Risk Assessment Report for DCA, would rise by 0.6 to 1.3 %. These analyses demonstrate that biomagnifications via sediment organisms is an exposure route that deserves attention in environmental risk assessments. However, the bioconcentration factor established in sediment organisms may overestimate the threat for human beings. The use of PBTK modeling is proposed as a means of estimating the increased daily uptake for a consumer.