In-vivo passive sampling to measure elimination kinetics in bioaccumulation tests Margaretha Adolfsson-Erici ⇑ , Gun Åkerman, Michael S. McLachlan Department of Applied Environmental Science (ITM), Stockholm University, SE-106 91, Stockholm, Sweden article info Article history: Received 22 November 2011 Received in revised form 15 February 2012 Accepted 16 February 2012 Available online 17 March 2012 Keywords: Passive sampling Fish Bioconcentration test OECD 305 Bioaccumulation test abstract The application of in-tissue passive sampling to quantify chemical kinetics in ﬁsh bioconcentration exper- iments was investigated. A passive sampler consisting of an acupuncture needle covered with a PDMS tube was developed together with a method for its deployment in rainbow trout. The time to steady state for chemical uptake into the passive sampler was >1 d, so it was employed as a kinetically limited sampler with a deployment time of 2 h. The passive sampler was employed in parallel with the established whole tissue extraction method to study the elimination kinetics of 10 diverse chemicals in rainbow trout. 4-n- nonylphenol and 2,4,6-tri-tert-butylphenol were close to or below the limit of quantiﬁcation in the sam- pler. For chlorpyrifos, musk xylene, hexachlorobenzene, 2,5-dichlorobiphenyl and p,p 0 -DDT, the elimina- tion rate constants determined with the passive sampler method and the established method agreed within 18%. Poorer agreement (35%) was observed for 2,3,4-trichloroanisole and p-diisopropylbenzene because fewer data were obtained with the passive sampling method due to its lower sensitivity. The work shows that in-tissue passive sampling can be employed to measure contaminant elimination kinetics in ﬁsh. This opens up the possibility of studying contaminant kinetics in individual ﬁsh, thereby reducing the ﬁsh requirements and analytical costs for the determination of bioconcentration factors. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Fish bioconcentration experiments play an important role in the regulatory assessment of chemicals. In these experiments the up- take and elimination kinetics of a chemical is studied by exposing a group of ﬁsh to water containing the chemical, sacriﬁcing several ﬁsh at a number of intervals during the exposure, transferring the remaining ﬁsh to chemical free water, and again sacriﬁcing these ﬁsh at intervals during this depuration part of the experiment. The sacriﬁced ﬁsh are then homogenized, the chemical residue in each ﬁsh is determined, and the results are used to assemble a pic- ture of the chemical uptake and elimination during the experi- ment, which then serves to determine the bioconcentration factor (BCF). The OECD 305 guideline for bioconcentration in a ﬂow-through ﬁsh test, a recognized standard method for this kind of experiment, requires on the order of 100 ﬁsh to study one chem- ical (OECD, 1996). Given that regulations foresee the testing of large numbers of chemicals, many ﬁsh are required. For instance, of the 2.6 million test animals that were estimated to be needed for the implementation of the European chemicals management program REACH, 2.5% or 65 000 were ﬁsh for bioconcentration experiments (Van der Jagt et al., 2004). Finding alternative meth- ods that require fewer ﬁsh is desirable. In-tissue passive sampling may open possibilities to reduce the number of ﬁsh required, since it would then be possible to study kinetics in a single ﬁsh, rather than sacriﬁcing ﬁsh at 10 or more time points. Passive sampling, which has long been applied in air, water and biological ﬂuids (Huckins et al., 1990; Cao and He- witt, 1991; Krogh et al., 1995), was extended to biological tissue when Ossiander et al. (2008) reported that repeatable PCB signals were obtained when solid phase microextraction (SPME) ﬁbres were inserted into lipid-rich tissue and then thermally desorbed in a GC/MS injector. When applied to harbour porpoise blubber the PCB signal from the SPME ﬁbre correlated well with the PCB concentration in the blubber. This application of passive sampling to tissue was further explored by Jahnke and co-workers. Using polydimethylsiloxane (PDMS) sheets as their sampling material, they demonstrated the absence of fouling effects following inser- tion of PDMS into a wide range of lipid rich biological matrices (Jahnke and Mayer 2010); they showed that the PDMS quickly ap- proached a partitioning equilibrium when inserted into the muscle tissue in lipid-rich ﬁsh, but that the approach to equilibrium took longer than several days when inserted into lean ﬁsh (Jahnke et al., 2009); and they showed that the concentrations in PDMS in- serted into muscle tissue of fatty ﬁsh, when converted into lipid normalized concentrations using PDMS/lipid partition coefﬁcients, were very similar to the lipid normalized concentrations deter- mined by traditional tissue extraction (Jahnke et al., 2011). In-tissue passive sampling was extended from in vitro to in-vivo conditions by Zhou et al. (2008). They inserted PDMS coated SPME ﬁbres into the dorsal muscle of rainbow trout that had been ex- 0045-6535/$ - see front matter Ó 2012 Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2012.02.063 ⇑ Corresponding author. Tel.: +46 8 674 7171; fax: +46 8 674 7638. E-mail addresses: margaretha.adolfsson-erici@itm.su.se (M. Adolfsson-Erici), gun.akerman@itm.su.se (G. Åkerman), michael.mclachlan@itm.su.se (M.S. McLa- chlan). Chemosphere 88 (2012) 62–68 Contents lists available at SciVerse ScienceDirect Chemosphere journal homepage: www.elsevier.com/locate/chemosphere