Abstract

A one health (one environmental health for toxicology studies) approach utilizes data from humans, animals and the ecosystem in an interconnected manner to gain a more comprehensive insight into the health of each. We used a one environmental health approach to study chromium, a toxic metal of environmental concern. Recent data from skin biopsies of free ranging sperm whales (Physeter macrocephalus) have identified chromium as a global marine pollutant with a global mean of 9.7 μg/g and with hotspots in various locations. One such hot spot is the North Atlantic. In this location, skin chromium levels were found to be high in right whales (Eubalaena glacialis), sperm whales (Physeter macrocephalus), humpback whales (Megaptera novaeangliae) and fin whales (Balaenoptera physalus) (7.1, 12.8, 18.25 and 10.07 μg/g, respectively) and in most cases exceeded the global mean chromium levels established in sperm whales (Physter macrocephalus). Chromium levels in other large whales (e.g., bowhead whales [Balaena mysticetus] from the Bering Sea and southern right whales [Eubalaena australis] from the South Atlantic), are quite low (0.54 and 0.64 μg/g, respectively) indicating the North Atlantic levels are remarkably high. The mean level of chromium in the skin of people with no known chromium exposure was reported to be 0.31 μg/g. Notably, North Atlantic whale skin chromium levels were similar to chromium levels in lung tissue from workers who died of chromium-induced lung cancer. Thus, human comparisons support the conclusion that North Atlantic whale chromium levels are high. Chromium is genotoxic and carcinogenic in many species; we evaluated the ability of chromium to induce damage in skin cells from these species and found concentration-dependent increases in chromosomal aberrations. For example 1, 2.5 and 5 μM sodium chromate induced 7, 11, and 20 aberrations, 4, 13 and 25 aberrations and 3, 13 and 26 aberrations in fin whale, northern right whale and sperm whale cells, respectively. Altogether, these data indicate chromium is a health concern for whales. However, comparisons with human cells indicate whales may have evolved protective mechanisms against metal-induced DNA damage. For example, chromium induces strand breaks and inhibits their repair in human cells, but did not inhibit this repair in whale cells. Specifically, prolonged exposure to 0.2 μg/cm² zinc chromate did not impact homologous recombination in whale cells, as measured by sister chromatid exchange (SCEs), but significantly reduced it by 315% in human cells. Thus, using a one environmental health approach we have been able to ascertain that whales are exposed to chromium levels of concern and may have evolved protective mechanisms that can provide insight into preventing metal-induced human cancer.

Acknowledgements

This work was supported by the National Institute of Environmental Health Sciences (ES016893 to J.P.W. Sr.).

* Presenting author