| Résumé : |
Chromium compounds exists in several different oxidation of valence states, the most important being trivalent [Cr(III)] and hexavalent [Cr(VI)]. These two valence states differ significantly in environmental compatibility, so it important to consider this difference in regulatory and remedial action determinations. Under normal environmental conditions, Cr (VI) compounds are more soluble, more mobile and more toxic, and are the basis for nearly all chromium regulatory standards.
Since chromium is the predominant leather tanning agent in use today, most tannery and other leather product wastes contain significant amounts of chromium, which is present exclusively as Cr(III). Federal rules under the Resource Conservation and Recovery Act (RCRA) and the Superfund Act (CERCLA) pertaining to these wastes are in direct conflict, since RCRA recognizes the chromium valence distinction but CERCLA does not. As a consequence, wastes which are classified non-hazardous under RCRA and legally disposed may become a Superfund concern and require costly remediation. Examination of available data indicate such concern is unfounded, as land disposal of Cr(III) waste presents little or no environmental risk. Data from existing land disposal sites show no evidence of Cr(III) migration, Cr(III) oxidation or contamination of groundwater in excess of the Drinking Water Standard. Based on these findings, remediation of Cr(III) wastes at land disposal sites appears entirely unwarranted.
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Environmental compatibility of chromium-containing tannery and other leather product wastes at land disposal sites in JOURNAL OF THE AMERICAN LEATHER CHEMISTS ASSOCIATION (JALCA), Vol. LXXXVI, N° 10 (10/1991)
