Abstract

Ocean pollution is emerging as a global concern. Between 2000 and 2005, the research vessel Odyssey collected biopsies from Mediterranean, Pacific, Indian, and Atlantic Ocean sperm whales (Physeter macrocephalus), a species with a global distribution feeding high on oceanic food chains. Here we present the first toxicological dataset from that global voyage, focusing on chromium levels in these whales. Chromium is a common marine and atmospheric pollutant, but few studies have assessed chromium in marine mammals and none have considered a global perspective. In this study, we measured chromium levels in 340 whales from each of the locations where the Odyssey worked. Chromium was found in all but two whales. Detectable levels ranged from 0.9 to 123 ug Cr/g tissue with a mean level of 10.2. Some regions were higher than others. Sperm whales sampled in the waters near the Islands of Kiribati in the Pacific and near the Seychelles in the Indian Ocean reached the highest mean levels (22.96 and 7.82 ug/g respectively. We also considered results by gender. The mean level for females (10.4 ± 3.2) was slightly higher than males (8.3 ± 3.2). Interestingly, this difference was not due to size or age as the lowest mean levels occurred in the much larger and older adult males (7.8 ± 2.4) compared to subadult males (12.2 ± 4.6). This observation is interesting because adult males spend significant time in polar regions suggesting a different exposure pattern. Remarkably, the whale Cr levels reached quite high levels (132 ug/g) and best resemble levels found in lung tissue from workers with Cr(VI)-induced lung cancer. Considering all of the whales, almost 8% of them have levels above the median level of these exposed workers. It is uncertain how the whales were exposed to Cr(VI), particularly given their location is such remote locations, but may reflect Cr being carried great distances through atmospheric mechanisms. More work is needed to determine the exposure route and the potential health effects, but these data suggest that chromium exposure may be a significant concern for the health of marine organisms.