Evidence of exposure highest in whales sampled near Galapagos Islands

Newswise — Sperm whales throughout the Pacific carry evidence of exposure to polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants including the pesticide DDT, according to a study published online December 6 ahead of print in the peer-reviewed journal Environmental Health Perspectives (EHP). The broad study provides a baseline for future research on ocean pollution and health.

During 1999–2001, the study authors biopsied skin and blubber from 234 male and female sperm whales in five locations across the Pacific Ocean: the Gulf of California, Mexico; the Galapagos Islands, Ecuador; Pacific waters between the Galapagos Islands and Kiribati (Pacific Crossing); Kiribati; and Papua New Guinea.

Tissue samples from the whales were analyzed for expression of CYP1A1, an enzyme that metabolizes certain aromatic hydrocarbons—the more CYP1A1 is expressed, the more likely the animal has been exposed to compounds such as those examined in this study. Tissues from some of the whales from all five Pacific regions also were analyzed for DDT, hexachlorobenzene, PAHs, and 30 types of polychlorinated biphenyls (PCBs).

CYP1A1 expression was highest in whales from the Galapagos Islands, second highest in those from the Gulf of California, and lowest in those from waters farthest from the continents (Kiribati and Pacific Crossing). Pollutants were found in all the samples, but levels of the pollutants measured did not correlate directly with levels of CYP1A1 expression. However, the authors were unable to test for many types of pollutants because the small amounts of tissue allowed under standards for humane biopsying of marine mammals precluded extensive chemical analyses.

The authors speculate that sperm whales may be important sentinels of ocean health. These carnivores are likely to bioaccumulate and biomagnify lipophilic (fat-soluble) pollutants because they are massive (up to 50 tons) and long-lived (up to 70 years). Monitoring of sperm whales may also provide information on specific regions of the Pacific because females and juveniles tend to stay within a 1,000-km range.

“Our findings provide a unique baseline for global assessment of pollution exposures and sensitivity in the sperm whale, a globally distributed and threatened species,” says study co-author Céline A.J. Godard-Codding. She adds that additional study is needed to further characterize the relationship between CYP1A1 expression and pollutant burden in sperm whales and other cetaceans, as well as exposures to industrial and natural sources of PAHs.

Other authors of the “Pacific Ocean–wide Profile of CYP1A1 Expression, Stable Carbon and Nitrogen Isotope Ratios, and Organic Contaminant Burden in Sperm Whale Skin Biopsies” are Rebecca Clark, Maria Cristina Fossi, Letizia Marsili, Silvia Maltese, Adam G. West, Luciano Valenzuela, Victoria Rowntree, Ildiko Polyak, John C. Cannon, Kim Pinkerton, Nadia Rubio-Cisneros, Sarah L. Mesnick, Stephen B. Cox, Iain Kerr, Roger Payne, and John J. Stegeman.

The article will be available December 6, 2010, free of charge at http://ehponline.org/article/info:doi/10.1289/ehp.0901809.

EHP is published by the National Institute of Environmental Health Sciences, National Institutes of Health, U.S. Department of Health and Human Services. EHP is an open-access journal, and all EHP content is available free online at http://www.ehponline.org/. Brogan & Partners Convergence Marketing handles marketing and public relations for the publication and is responsible for creation and distribution of this press release.

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Environmental Health Perspectives (EHP)