Laserfiche WebLink
r • <br /> A Chromium-6 Convergence Chromium-6's Carcinogenicity <br /> (Summer 2000) When Ingested <br /> • The movie • PHG's basis for cancer: <br /> • The press —Cr-6 known human carcinogen when inhaled in <br /> • The politics certain occupational situations. <br /> —General assumption that a substance that causes <br /> cancer by one route causes cancer by other <br /> routes,unless evidence suggests otherwise. <br /> —One mouse study of limited evidence <br /> The PHG's Mouse Study Issues with the Mouse Study <br /> (Bomeff, et al., 1968) <br /> • Mice given 500,000 pg/L per day • Used for a quantitative risk assessment, <br /> • Tumors of the forestomach,with authors despite: <br /> finding no significant difference between —half the study animals died from viral infection <br /> exposed and control mice —water consumption was reduced by 20% <br /> —OEHHA analyzed females alone,and when • Assumed linear dose-response <br /> benign nodules and malignancies were <br /> combined,there was a significant increase <br /> Other Issues That Suggest Non- Things to Ponder <br /> Linear (Threshhold Model) <br /> • Applicability of mouse forestomach tumors • The MCL for total chromium is essentially <br /> to people a Cr-6 MCL,since Cr-3 is relatively <br /> • Reduction of Cr-6 to Cr-3 in human innocuous,toxicologically speaking <br /> stomach by gastric juices • Given the nature of the human GI tract, <br /> • Very high doses might have irritated mouse does Cr-6 pose a risk at levels in drinking <br /> GI tract,setting it up for ttanors water,particularly since they are limited to <br /> 50 pg/L? <br /> 2 <br />