The decline of the populations of otters in Western Europe is assumed to be related to the accumulation of polychlorinated biphenyls (PCBs) in this species. A study was conducted to investigate the trophic transfer of non-ortho, mono-ortho-, and di-ortho-substituted PCBs in the food web of the otter (Lutra lutra) in the Oude Venen lake system in the Netherlands, with relatively low PCB contamination. This area was one of the last strongholds of otters In the Netherlands and the species is considered to be virtually extinct since 1988. A marked increase in concentration of chlorinated biphenyls (CBs) was observed with successive trophic levels of the aquatic food web. Mean concentrations of the sum of 28 CB congeners (Sigma CB) increased from 142 ng CB/g (organic carbon basis) in sediment and particulate matter to 588 ng CB/g (lipid weight basis) in invertebrates, to 2,450 ng CB/g (lipid weight) in fish, and 70,940 ng CB/g (lipid weight)in otter. A diet-specific biomagnification factor (BMF) of 14 was calculated from fish to otter based on Sigma CB; however, on the basis of toxic equivalent concentrations (Sigma TEQ), a BMF of 41 was found. This higher BMF on TEQ basis was mainly due to the enrichment of non-ortho-substituted CB 126 in otter, compared to fish. In fish CB 126 contributed 30 to 50% to Sigma TEQ, while this congener contributed 60 to 80% in otters. A shift in the CB patterns was Found from relatively high concentrations of lowly chlorinated CBs in the abiotic compartments to the higher chlorinated CBs (five to seven chlorine atoms) at the highest trophic level. The relatively low concentrations of CB 77 and CBs with vicinal H-atoms at the meta-para position in otter compared to fish indicates that otters can metabolize these CBs and have P4501A-like and P4502B-like enzyme systems. It appears that even in an ecosystem with relatively low CB contamination, concentrations of CBs can be relatively high in aquatic top predators. The non-ortho-substituted CBs seem to be the most important toxic threat for otters, firstly because of the relatively high BMFs of CB 126 and CB 169 and secondly because of the formation of metabolites of CB 77.

This paper describes an attempt to derive a median effect level (EC50) of PCBs for reproduction of mink based on experimental literature data. Unfortunately, the conditions of the mink studies carried out during the last two decades vary widely, which makes it difficult to establish unequivocal dose-effect relationships. This study describes an attempt to correct for the differences in exposure time using a one-compartment bioaccumulation model. This model estimates the whole-body concentration of PCBs in mink, Two approaches are tested. First, the whole-body concentration of 10 isomer groups of PCBs in mink were estimated and compared with reproduction data to calculate an EC50 value. Alternatively, estimates for the whole-body concentration in mink of 11 individual biologically active PCB congeners were made. With these, the toxic equivalent concentration (TEC) in mink was estimated using the 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalent factor (TEF) approach. Whole-body dose-effect relationships were estimated and EC50 values for litter size and kit survival were calculated. The application of the one-compartment bioaccumulation model of the first approach resulted in a significant improvement in the dose-effect relationship in comparison to the raw data set. A further improvement in this relationship was achieved using the congener-specific bioaccumulation model in combination with the TEF approach. This study proposes a critical body residue (EC50) for mink litter size of 1.2 mu g/g (total PCBs/wet weight). From the second approach a critical body residue (EC50) expressed in TCDD equivalency for litter size of 160 pg/g (TCDD equivalence/wet weight) and 200 ng/g (TCDD equivalence/wet weight) for kit survival is proposed.

The presence and concentrations of non-ortho-, mono-ortho-, and di-ortho-substituted PCB congeners in the polecat (n = 7), a member of the mustelid family, were investigated. PCBs were extracted with a Soxhlet apparatus. After cleanup the non-ortho-substituted PCB congeners were separated from the other PCBs by HPLC. Determinations were accomplished with GC-ECD or GC-MSD. Patterns of PCBs were examined in different organs and tissues: liver, kidney, muscle, anal gland secretion, mesenteric fat, and subcutaneous fat. Using a multivariate statistical method for data analysis (SIMCA), a significant difference of PCB patterns between anal gland secretion and the other organs and tissues was revealed. Lesser concentrations of congeners with seven and eight chlorine atoms in anal gland secretion were mainly responsible for this phenomenon. A more or less organ- and tissue-specific PCB pattern was observed in all animals. PCB patterns were not dependent on prey choice, which ranged from terrestrial (small rodents) to aquatic (amphibians). This finding implies that PCB patterns in the polecat seem to be controlled by metabolic processes rather than diet factors. The total concentration of PCBs (sum of 29 congeners) in polecats varies widely, two orders of magnitude, from 1 to 370 mug/g lipid. In some animals, PCBs exceeded the experimentally determined reproduction effect concentrations of mink and ferrets. Using the toxic equivalent approach, it was observed that planar PCB 126 accounts for 63 to 98% of the toxic equivalents. The results showed that juvenile animals contain greater PCB levels than adult males and females, which might be related to an increased elimination of PCBs in adult animals due to anal gland secretion. High concentrations of PCBs were observed in such secretion. A preliminary model for concentrations of PCBs in polecats including this effect is proposed.

Organotin compounds (OTs) were analyzed after derivatization using a methyl Grignard reagent with gas chromatography with ion trap detection (GC-ITD) for detection. GC-ITD allows full scan mass spectrometry at trace levels and thus allows good verification of the presence of the OTs. With the described methods all currently used OT biocides can be determined in water, sediment and suspended matter: tributyltin (TBT), triphenyltin (TPT), tricyclohexyltin (TCT) and fenbutatin oxide (hexakis-(2-methyl-2-phenylpropyl)-distannoxane, FBTO). Additionally in water also some degradation products of the above mentioned biocides can be determined: dibutyltin (DBT), monobutyltin (MBT), diphenyltin (DPT), monophenyltin (MPT) and dicyclohexyltin (DCT). Detection limits are 1–40 ng/l (as tin) for water samples and 2–10 ng/g (as tin) for suspended matter and sediment samples. Transport routes of triphenyltin acetate (TPT) used in potato culture in the Flevoland polder in the Netherlands were studied. TPT levels were detected in freshwater and suspended matter and the sorption coefficient (Kd) was calculated. On the basis of concentrations in water and suspended matter it was calculated that only a negligible portion of TPT used is pumped out of the polder by the pumping-engines. Evaporation of TPT is probably a much more important transport route. Therefore a first attempt was made to investigate concentration of OTs in rainwater. The results show that at distances of over 20 km from potato fields, TPT in rainwater is around the proposed general quality objective for freshwater of 10 ng/l (as tin). These observations support the modelling study by Baart and Diederen, indicating that evaporation of TPT is one of the transport routes of TPT.

Asellus aquaticus (L.) was exposed in microcosms to littoral sediments from Lake Ketelmeer (River Rhine estuary) and from a control site in order to study effects of substrate characteristics, temperature and pH on the kinetics of trace metal accumulation. Elimination patterns were studied in parallel experiments with preloaded animals kept on control sediment or in test water. In a 50 day semistatic bioassay at three different temperatures (5, 10 and 20°C) and two pH levels (7.3 vs 8.1) a highly significant accumulation of Cd, Pb, Cu and Zn by the isopods was observed. No net uptake was recorded in animals kept on control substrates. The most marked accumulation by Asellus was noted for the non-essential trace metals Cd and Pb. Element-specific effects of sediment characteristics and temperature were encountered on sediment-water partitioning (Cd, Cu and Zn) and on accumulation and elimination kinetics (Cd, Cu and Pb). No significant effects were observed for the different pH levels. Accumulation of Cd and Cu increased significantly with temperature. Pb concentrations in animals exposed at 20°C were found to be significantly lower compared to other temperatures. The accumulation of Zn appeared to be unaffected by temperature. Two distinct elimination patterns were observed. Elimination of Cd and Cu was absent at the higher temperatures. A slight elimination of these metals was recorded only in some of the treatment groups at 5°C. Both elements seemed to be stored in stable body compartments. A relatively rapid elimination, not affected by temperature, was observed for Pb (biological) half-life: 8–15 days) and Zn (half-life: 21–44 days); above the control sediments Asellus maintained a Zn concentration of c. 100–150 μgg−1 (dry wt). Several explanations for the observed accumulation patterns and temperature effects are presented. The results indicated that freshwater isopods could be suitable organisms for bioassays and biological monitoring studies on the bioavailability of sediment-bound trace metals.

A method has been developed for the determination of the organotin pesticides fentin, cyhexatin and fenbutatin oxide by high-performance liquid chromatography combined with UV photoconversion and post-column morin complexation followed by fluorescence detecton. After optimization of the relevant parameters the feasibility of the method for analysing environmental samples was investigated. Detection limits are 1–2 ng in standard solutions, 0.02–0.03 μg/1 in surface water and 0.2–0.3 μg/g in soil and sediment. The higher detection limits for soil and sediment samples are due to interfering compounds present in the matrix. The method allows trace level determinations in water samples. As an example, in a ditch adjacent to a potato field 16 days after a routine spraying with triphenyltin acetate, water concentrations of 0.03 μg/1 could still be detected.

Bioconcentration factors (BCFs) of 19 parent and hetero polycyclic aromatic hydrocarbons (PAH) were obtained from static bioconcentration experiments with Poecilia reticulata by monitoring the decrease in the initial aqueous concentration. The BCFs were obtained by fitting the observed concentrations to a one-compartment first-order kinetic model. The BCFs thus obtained showed a satisfactory linear relationship with the experimental n-octanol/water partition coefficient, log K(ow) (r = 0.91, s = 0.30). By comparison with a limited number of semi-static tests, it was concluded that the static bioconcentration experiment is a satisfactory alternative for more laborious bioconcentration tests to obtain BCFs of (hetero) PAH. However, the static tests are less valuable for the acquisition of kinetic bioconcentration parameters such as, e.g., uptake or elimination rate constants. For several of the compounds in this study, the estimates resulting from the static tests did not match with those from a limited number of depuration experiments carried out in this study or with values expected from the relationship between the depuration rate constant and the log K(ow) reported in the literature. The distribution of three parent PAH within the fish after a 7-day semi-static exposure was also investigated. Relatively high concentrations were found in liver and kidneys. The major part of the body burden was found in muscle and the gastro-intestinal tract.

We examined the potential of a multiple regression model, including both biotic and abiotic variables, to predict trace metal levels (Cd, Pb, Cu and Zn) in benthic invertebrate communities from various aquatic habitats in The Netherlands. Variables included in the regression model and their relative contribution to the predictive power appeared to be highly element-specific. Sediment- and water-related abiotic variables were especially important for the prediction of Cd, Pb and, to a lesser extent, Zn. For the essential trace metals, the biotic variables such as the presence of hemocyanin (in the case of Cu) and trophic level (Zn) appeared to have a dominant influence. Species-body weight showed a negative log-linear relationship with trace metal levels of Pb and, to a lesser extent, Cu and Cd. For all metals, significant coefficients of multiple correlation were observed. The variance in invertebrate trace metal levels explained by the model ranged from 25% for Zn to 37% for Cd and Cu. For all trace metals, the introduction of biotic variables resulted in a significant increase in predictive power (p < 0.02), compared to the use of only abiotic predictors. Marked differences in predictive power of the model were observed among various species or taxonomic categories. For several species remarkably significant relationships were revealed, indicating the potential usefulness of the organisms for biological monitoring and further modeling studies.

Cadmium, lead, zinc and copper concentrations were determined in 15 species of freshwater macro-invertebrates collected from a littoral foodweb. Indications of a biomagnification process, in which predators had a higher concentration than their prey, were only found in the case of zinc. Organisms with copper as an essential component of their haemolymph, such as Crustacaea, Gastropoda and Bivalvia, contained higher concentrations of that metal than other species. Another important factor in the determination of trace metal concentrations, apart from physiological equipment, was body weight, resulting in higher concentrations in smaller, and lower concentrations in larger, organisms. This seemed to be the case within populations of single species, as well as in different species of deposit feeders. Furthermore, feeding habit, proximity to the sediment and physico-chemical factors appeared to be determining factors for trace metal concentrations in macro-invertebrates. The results of this study are related to ecotoxicological theories which explain the causes of pollutant residues in organisms. It is concluded that various explanations for the differences in pollutant residues, e.g. trophic level, feeding habit, body weight, association with the substrate, physiological equipment and abiotic factors, are valid.

Experiments were conducted to determine the kinetics and relative importance of aqueous and dietary uptake of cadmium by the freshwater isopod Asellus aquaticus (L.). Test animals were exposed during 30 days to aqueous Cd in a continuous flow system (exposure levels: 0.2 - 10 microg litre(-1)) and kept on a diet of previously contaminated Elodea sp. (range of Cd concentrations: 2-350 microg g(-1), dry weight). Preceding semi-static experiments on dosage-control of the dietary factor revealed a rapid uptake of Cd by Elodea, with relatively high concentration factors (CF), which ranged from 4.8 to 5.5 (dry weight log (CF) after 16 days). For Asellus uptake from water appeared to be the predominant route. Highly significant bioconcentration of cadmium from water was observed in the animals, even at exposure levels below 1.0 microg litre(-1). In the various treatments, direct uptake from water accounted for 50-98% of the body burdens after 30 days exposure. The experimental results were described with a first order one-compartment bioaccumulation model. Model parameter estimates (mean +/- standard error) were obtained for rate constant of uptake (560 +/- 110 day(-1)), rate constant of elimination (0.032 +/- 0.017 day(-1)) and assimilation efficiency of Cd uptake from food (1.1 +/- 0.7%). The (dry weight) bioconcentration factor (BCF) and bioaccumulation factor (BAF) for extrapolated steady state conditions were estimated at 18 000 (BCF) and 0.08 (BAF). Experiments conducted at two different pH levels (5.9 versus 7.6) revealed no significant effects of pH on the uptake of aqueous Cd by the isopods. The results are discussed in relation to their potential significance to the field situation.