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Polycyclic aromatic hydrocarbons (PAHs), which contain many carcinogenic compounds, are a major ingredient of petroleum/oil. PAH pollution of the Caspian Sea, the world's largest lake, is rapidly occurring and may be affecting the endangered Caspian seal (Pusa caspica), the only marine mammal in this lake. To analyze the entrance of PAHs into the Caspian Sea food chain and the health status of Caspian seals, we measured 16 carcinogenic PAHs in the liver, kidney, and blubber tissues of ten Caspian seal carcasses from the coastal region of northeastern Iran using gas chromatography-mass spectrophotometry. Of the 16 PAHs investigated, only anthracene, phenanthrene, and naphthalene were identified in nine sampled Caspian seals. Concentrations of anthracene (=84.83 ± 79.86 ppb wet weight [w.w.]), phenanthrene (=31.75 ± 52.22 ppb w.w.), and naphthalene (=25.1 ± 31.57 ppb w.w.) in blubber tissues were higher than in liver and kidney tissues. The concentration of PAHs in tissues was significantly higher in male than in female seals, and we found an inverse relationship between seal age and PAH concentration in tissues. Although no data exist concerning toxic effect concentrations of PAHs in Caspian seals, PAH detection in seal carcasses highlights a potentially stressful condition that may impact the health of Caspian seals and other sea life in this lake. Appropriate strategies for the control of PAH entrance into the Caspian Sea should be sought, and studies for the determination of pathogenic and lethal doses of PAHs in Caspian seals should be pursued. [ABSTRACT FROM AUTHOR]

Thousands of Caspian seals (Phoca caspica) died in the Caspian Sea from April to August 2000. Lesions characteristic of morbillivirus infection were found in tissue specimens from dead seals. Canine distemper virus infection was identified by serologic examination, reverse transcriptase-polymerase chain reaction, and sequencing of selected P gene fragments. These results implicate canine distemper virus infection as the primary cause of death.