Lucille A. Benedict

A global assessment of chromium pollution using sperm whales (Physeter macrocephalus) as an indicator species.

Chromium (Cr) is a well-known human carcinogen and a potential reproductive toxicant, but its contribution to ocean pollution is poorly understood. The aim of this study was to provide a global baseline for Cr as a marine pollutant using the sperm whale (Physeter macrocephalus) as an indicator species. Biopsies were collected from free-ranging whales around the globe during the voyage of the research vessel The Odyssey. Total Cr levels were measured in 361 sperm whales collected from 16 regions around the globe detectable levels ranged from 0.9 to 122.6 microg Cr g tissue(-1) with a global mean of 8.8+/-0.9 microg g(-1). Two whales had undetectable levels. The highest levels were found in sperm whales sampled in the waters near the Islands of Kiribati in the Pacific (mean=44.3+/-14.4) and the Seychelles in the Indian Ocean (mean=19.5+/-5.4 microg g(-1)). The lowest mean levels were found in whales near the Canary Islands (mean=3.7+/-0.8 microg g(-1)) and off of the coast of Sri Lanka (mean=3.3+/-0.4 microg g(-1)). The global mean Cr level in whale skin was 28-times higher than mean Cr skin levels in humans without occupational exposure. The whale levels were more similar to levels only observed previously in human lung tissue from workers who died of Cr-induced lung cancer. We conclude that Cr pollution in the marine environment is significant and that further study is urgently needed.

Global mercury and selenium concentrations in skin from free-ranging sperm whales (Physeter macrocephalus)

Pollution of the ocean by mercury (Hg) is a global concern. Hg persists, bioaccumulates and is toxic putting high trophic consumers at risk. The sperm whale (Physeter macrocephalus), is a sentinel of ocean health due to its wide distribution, longevity and high trophic level. Our aim was to survey Hg concentrations worldwide in the skin of free-ranging sperm whales considering region, gender and age. Samples were collected from 343 whales in 17 regions during the voyage of the research vessel, Odyssey, between 1999 and 2005. Skin was analyzed for total Hg and detected in all but three samples with a global mean of 2.5±0.1 μg g(-1) ranging from 0.1 to 16.0 μg g(-1). The Mediterranean Sea had the highest regional mean with 6.1 μg g(-1) followed by Australia with 3.5 μg g(-1). Considering gender, females and males did not have significantly different global Hg concentrations. The variation among regions for females was significantly different with highest levels in the Mediterranean and lowest in Sri Lanka; however, males were not significantly different among regions. Considering age in males, adults and subadults did not have significantly different Hg concentrations, and were not significantly different among regions. The toxic effects of these Hg concentrations are uncertain. Selenium (Se), an essential element, antagonizes Hg at equimolar amounts. We measured total Se concentrations and found detectable levels in all samples with a global mean of 33.1±1.1 μg g(-1) ranging from 2.5 to 179 μg g(-1). Se concentrations were found to be several fold higher than Hg concentrations with the average Se:Hg molar ratio being 59:1 and no correlation between the two elements. It is possible Hg is being detoxified in the skin by another mechanism. These data provide the first global analysis of Hg and Se concentrations in a free-ranging cetacean.

A Global Assessment of Gold, Titanium, Strontium and Barium Pollution Using Sperm Whales (Physeter Macrocephalus) As an Indicator Species

This study provides a global baseline for barium, gold, titanium and strontium as marine pollutants using the sperm whale (Physeter macrocephalus) as an indicator species. Barium, gold, titanium and strontium are metals that are little studied in marine environments. However, their recent emergence as nanomaterials will likely increase their presence in the marine environment. Moreover, nanosized particles are likely to exhibit toxic outcomes not seen in macrosized particles. Biopsies from free ranging sperm whales were collected from around the globe. Total barium levels were measured in 275 of 298 sperm whales tested for barium and collected from 16 regions around the globe. The global mean for barium was 0.93 +/- 0.2ug/g with a detectable range from 0.1 to 27.9ug. Total strontium levels were measurable in all 298 sperm whales producing a global mean level of 2.2 +/- 0.1ug/g and a range from 0.2 to 11.5ug/g. Total titanium levels were also measured in all 298 sperm whales producing a global mean level of 4.5 +/- 0.25ug/g with a range from 0.1 to 29.8ug/g. Total gold levels were detected in 50 of the 194 sperm whales collected from 16 regions around the globe. Detectable levels ranged from 0.1 to 2.3ug/g tissue with a global mean level equal to 0.2 +/- 0.02ug/g. Previous reports of these metals were much lower than the mean levels reported here. The likely explanation is location differences and consistent with this explanation, we found statistically significant variation among regions. These data provide an important global baseline for barium, gold, titanium and strontium pollution and will allow for important comparisons to be made over time to assess the impact of nanomaterials on whales and the marine environment.