A COMPARATIVE-STUDY OF THE TOXICITY AND INHIBITORY EFFECTS OF INORGANIC TIN-COMPOUNDS ON VARIOUS BIOLOGICAL SUBJECTS

The toxic and inhibitory effects of Sn2+ (SnCl2.2H2O) and Sn4+ (Na2SnO 3) compounds were determined under standardized conditions on four bio logical subjects: Tubifex tubifex, Chironomus plumosus, Sinapis alba s eeds and the alga Scenedesmus quadricauda. Observed were the mortality rates of Tubifex tubifex and Chironomus plumosus, the root growth inh ibition of Sinapis alba seeds, and the inhibition of growth rates of S cenedesmus quadricauda. Of the bentic organisms, Chironomus plumosus w as more sensitive (LC50/96 h for Sn2+ was 3.6 mg.l-1 and for Sn4+ 3.0 mg.l-1) to both tested compounds than Tubifex tubifex (LC50/96 h for S n2+ was 30.0 mg.l-1 and for Sn4+ 27.5 mg.l-1). For both of these subje cts, no differences between the toxic effects of Sn2+ and Sn4+ ions we re observed. Sinapis alba seeds exhibited low sensitivity to Sn ions ( EC50/72 h for Sn2+ was 281.2 mg.l-1 and for Sn4+ 416.9 mg.l-1). Estima ted EC50 values were high, especially for the Sn4+ ion. Root growth wa s more inhibited when Sn2+ ion was applied. For Scenedesmus quadricaud a, Sn4+ ion also had lower inhibitory effects on growth rates than the Sn2+ ion.