Chromium trichloride

Endpoint summary

Description of key information

Only very limited information is available on sole chromium(III) exposure. Much literature is available to chromium(VI) exposure but there are only very view reports on chromium exposure that can reasonably be considered being primarily or exclusively chromium(III) exposure. One of them performed in ferro-alloy industry showed that no renal impairment was seen amongst all workers exposed.
Two studies investigating skin sensitisation behaviour in human patch tests showed, that chromium(III) did cause only low skin effects in chromium(VI) sensitised humans which is explained by the very poor skin penetration ability of chromium(III) compounds.

Additional information

Workers in a ferro-chromium metallurgy plant with 236 workers have been observed for chromium(III) absorption. The levels of absorption were very low, especially if compared with those observed in chromium electro-plating, special steel welding and chromate production (T. Norseth, The carcinogeniticy of chromium, Environ. Health Persp., 40 (1981) p. 121) where exposure is to hexavalent chromium. The values found in this study even appear not to be very different from those observed by other authors in non-occupationally exposed subjects.

Nevertheless, the absorption levels varied according to the job, thus agreeing with the environmental pollution data. If a measurable exposure to hexavalent chromium can be excluded on the basis of these environmental data (further checks are under way), it must be assumed that total urinary chromium is derived exclusively from absorption of chromium originally in the trivalent state.

It would, therefore, appear that this form of chromium, too, can be absorbed, as reported by other authors. The low levels of urinary chromium observed at the end of the shift indicate a low renal clearance of chromium and, therefore, little or practically no accumulation, in spite of long-term exposure. The observations are confirmed by the fact that no early functional renal damage was found, in spite of the reliability and sensitivity of the indicators used.

In the working conditions under this study, not even initial renal impairment could be observed. The study of other possible health effects (skin effects or effects of respiratory and digestive systems) and of a possible excess of cancer would furnish further data which may help to throw light on these points.

Samitz et al. have investigated in human patch tests, whether subjects sensitized to hexavalent chromium would also react to trivalent chromium, when exposed via skin. Four out of five subjects showed no reaction whereas one subject showed mild reactions at 5% CrCl3 solution exposure and equivocal reactions at 0.5% CrCl3 solution. In contrast, exposure to potassium dichromate showed strong reactions in the subjects. In investigating stripped skin (removal of skin barrier) 2 subjects showed strong reactions to 5% CrCl3 solution. Thus, it was concluded that the relative inefficacy of trivalent chromium compounds as elicitors may be due to their poor skin penetrating capacities.

Similar observations were made by Hansen et al. reporting that chromate sensitised persons may have allergic reactions not only to chromium(VI) upon exposure to skin but also to chromium(III) compounds, although to a lesser degree (i.e. higher chromium concentrations required for chromium(III)).