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Toxicological information

Carcinogenicity

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Description of key information

No adequate experimental animal studies are available to evaluate the carcinogenicity of zinc compounds in humans.

Key value for chemical safety assessment

Additional information

There are a range of epidemiological studies that investigated the association between zinc exposure either through occupational activities or food supplementation and increased cancer risks. While no associations were found between occupational zinc exposure and excess cancer risk, the main association that has been made in this context is related to dietary/supplemental zinc and prostate cancer risk.

In contrast to established clinical and experimental evidence that prostate cancer is associated with a decrease in the zinc uptake, numerous epidemiology studies and reports of the effect of dietary and supplemental zinc on the incidence of prostate cancer have provided divergent, inconsistent and inconclusive results which range from adverse effects of zinc, protective effects of zinc and no effect of zinc on the risk of prostate cancer. Clinical and experimental studies have established that zinc levels are decreased in prostate cancer and support a role of zinc as a tumour suppressor agent. Malignant prostate cells in situ are incapable of accumulating high zinc levels from circulation (Franklin R.B.et al.,2005; Costello L.C, and Franklin R.B., 2006; Franklin R.B. and Costello L.C,, 2007).

In a recent critical assessment of epidemiology studies regarding dietary/supplemental zinc and prostate cancer risk, Costello et al.,concluded that epidemiological studies have not provided an established relationship for any effect or lack thereof of dietary/supplemental zinc on the risk of prostate cancer. Proclamations of an association of dietary/supplemental zinc and increased prostate cancer are based on inconclusive and uncorroborated reports (Costello L.C.et al.,2008).

Justification for classification or non-classification

On the basis of the existing information it can be concluded that there is no conclusive evidence for carcinogenic activity of any of the zinc compounds considered in this chemical safety report.