Uptake, distribution and retention of zineb and ziram in rainbow trout (Salmo gairdneri).

In short-term static bioaccumulation experiments with 14C-labelled zinc ethylenebisdithiocarbamate (zineb) and zinc dimethyldithiocarbamate (ziram) both compounds were rapidly disseminated through the tissues. Whole-body accumulation was low, with bioconcentration factors less than 100. Whole-body elimination was rapid with 45% and 25% of the initial radioactivity from ziram and zineb, respectively, being retained by the end of the 16-day depuration period. Pigmented tissues appeared to be major distribution sites as well. This may be related to the affinity of the compounds and/or their degradation products to melanin or to complexation with phenoloxidase, a copper-containing enzyme involved in melanin synthesis. Autoradiography also revealed a high labelling of thyroid follicles. The results show that dithiocarbamates are selectively localized in various tissues, reported to be the target organs for their toxic action. The observed differences in toxicokinetics between zineb and ziram may, in part, explain the differences in toxicity to fish between ethylenebisdithiocarbamates and dialkyldithiocarbamates.