Global assessment of arsenic pollution using sperm whales (Physeter macrocephalus) as an emerging aquatic model organism

Arsenic is an oceanic pollutant of global concern due to its toxicity, ability to bioaccumulate and continued input into the environment by anthropogenic activities. The sperm whale (Physeter macrocephalus) is an emerging aquatic model for both human disease and ocean health having global distribution and high trophic level. The aim of this study was to establish global and regional baselines of total arsenic concentrations using free-ranging sperm whales. Skin biopsies (n = 342) were collected during the voyage of the Odyssey (2000–2005) from 17 regions considering gender and age in males. Arsenic was detectable in 99% of samples with a global mean of 1.9 μg/g ww ranging from 0.1 to 15.6 μg/g ww. Previous work in toothed whale skin found mean concentrations 3 fold lower with 0.6 μg/g ww. A significant gender-related effect was found with males having higher mean arsenic concentrations than females. There was no significant age-related effect between adult and subadult males. Arsenic concentrations in sloughed skin samples were similar to levels in skin biopsies indicating that arsenic excretion can occur by skin sloughing. Regional mean concentrations were highest in the Maldives, Seychelles and Sri Lanka with 3.5, 2.5, and 2.4 μg/g ww, respectively, raising concern for arsenic pollution in the Indian Ocean. Literature suggests that arsenic exposure is emitted from natural sources and the heavy use of arsenic-containing pesticides and herbicides in this region. These data suggest that research is needed in determining the extent and source of arsenic pollution in the Indian Ocean.