Comparative Cytotoxic Effects of Hexavalent and Trivalent Chromium Compounds on Cultured Cells

Abstract

Toxicological studies were carried out on lnexavaleutt and trivalent chrommiumcompounds with the monolayer cultures of IIeLa and rat embryonic cells. The cells werepreincubated in Eagles minimum essential medium at 37C for one day. Then thismedium was changed for a fresh one containing a given concentration of the chromiumcompound to be tested. The cells were incubated further at 37C for 3 days. After theywere exposed to the chromium, the fifty per cent inhibitory dose (10..) for cell growthwas determined. The values of 10, . (pg/ml of the medium) obtained with the hexavalcntform in the culture of HeLa cells were: Na, Cr0)-4H.0, 0.34; K.Cr.O.?2H.0, 0.58; Na.Cr.0., 0.64; K.Cr0., 0.70; and CaCr0.-2H.0, 0.78. Those with the trivalent form were; Cr(C.0.)., 4.0; Cr(CH.C00).-H.0, 52.0; Cr(NO.).-9H.0, 720; CrC1., 1030; and rBrC., 1500. Those inthe culture of rat embryonic cells were approximately the same as those in that of HeLacells. The results mentioned above suggested that hexavalent chromium compoundsmight be more toxic than trivalent ones. The range of 10, . obtained witln the formerwas narrow, but that obtained with the latter was considerably wide. Cytomorphologicalexamination revealed that all the hexavalent compounds and chromic oxalate of thetrivalent compounds had produced polynuclear cells and irregularity in the size of celland/or nucleus. Some other trivalent compounds, however, produced spindle-shapedcells, but none of the changes mentioned above.