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Minnows (Phoxinus phoxinus) were exposed in the laboratory to 3 nM Cd (Cd group), 2000 nM Zn (Zn group), or to both metals (CdZn group) in soft water for 142 d. A fourth group was kept with no metals added to the water (Low group). After 80 d, the Cd and Zn groups were statically exposed to 109Cd and 65Zn, respectively, for 24 h. The CdZn group was exposed to both tracers. Fish were sampled for 61 d after the tracer exposure. At the end of the experiment, an increased metallothionein level was detected in the kidney of fish exposed to the metal mixture (Low group: 0.14 nmol/g fish; CdZn group: 0.54 nmol/g fish). However, the fish did not acquire tolerance to the metals because mortality continued at a constant rate during the whole experiment. Metabolism of Cd and Zn was altered in fish exposed to the metal mixture compared with fish exposed to Cd or Zn alone. The main effect was a Zn-induced increase in Cd turnover rate in the fish. Nevertheless, the toxic action of metals was additive, since mortality at the end of the experiment was 24, 32, and 54% in the Zn, Cd, and CdZn groups, respectively.

Non-ortho (coplanar) PCBs 77, 126 and 169 were determined in a number of fish species from the Swedish coastal environment, using either supercritical fluid extraction (SFE) or the traditional liquid/liquid extraction followed by HPLC separation on porous graphitic carbon (PGC) column prior to GC/MS analysis. While PCB 77 showed the highest concentration level, the TEQ value for PCB 126 was dominant in virtually all the samples analysed. The toxic equivalents, however, indicated some differences in analytical data between 1990 and 1992/93 but these are not significant probably owing to the short period in between.