Comparison of toxicological effects of environmental accumulating material, perfluorooctanesulfonate (PFOS) on isolated rat arteries

Y Kobayashi, M. S. Islam. Shimane University, Faculty of Medicine, Fundamental Nursing 693-8501, Japan

Perfluorooctanesulfonate (PFOS) and its perfluoro-analogues (PFAs) have been widely used in industrial application and civilian production because of their high stability and strong lipophobic and hydrophobic properties as a surfactant for fire foam extinguishers since the 1950s. The widespread applications, environmental persistence of PFAs have resulted in global occurrence of these substances in air, water, sediments and sludge. Bioaccumulation of them in various wildlife species was reported. The highest PFOS concentration reported in a fish blood from Tokyo bay was 1 μM. Poor information on the bioactivities of PFOS-like compounds was available. Still it is not clear whether the pollution with PFAs in the environment is really potential hazards to human health as well as wild animals. In the present study, toxicological effects of PFOS on isolated Wistar strain rats arterial rings were compared. Cumulative concentration response curves for PFOS (1-100 μM) were obtained in thoracic aorta (TA), common carotid artery (CA), femoral artery (FA), pulmonary artery (PA), renal artery (RA) and supramesenteric artery (SMA) ring preparations. The contraction was compared with that of noradrenaline (NA). For structure-activity relationship study, PFOS was compared with perfluorooctanoic acid (PFOA), octanesulfonate (OS) or octanoic acid (OA). The most sensitive region was CA and 10 μM of PFOS showed significant contraction. This concentration is almost 10 fold less compared with so-called non-toxic concentration described previously. The contraction for PFOS was developed slowly and the tension kept stably. After washing, the tension returned to basic level. The maximum contraction for PFOS on CA was larger than that of NA. Small contraction was also observed in RA, TA and SMA preparations, but not in FA and PA preparations at 100 μM of PFOS. PFOS may affect on brain circulation. Concerning structure-activity relationship, PFOS was the most potent compared with PFOA, OS or OA in CA preparation, suggesting the importance of carbon-fluoride structure as well as sulfonate. Present results indicated the possible toxicity of PFOS as an environmental contaminant and further studies on pollution of PFAs in the environment and biological effects of them are necessary.