The Use of Mussels in Estimating Benzo(a)Pyrene Contamination of the Marine Environment

Abstract

In assessing the potential health hazards of a contaminated marine environment, particular attention should be directed to chemical carcinogens and mutagens. Such compounds may exert only a delayed effect, and remain undetected for a prolonged period, thus possibly accumulating to dangerous levels.

The presence of carcinogenic polycyclic aromatic hydrocarbons (PAH) in plankton, seaweeds, filter feeding organisms, and bottom samples has been reported (reviews, 1-4). Unsolved remains the question of their geographical distribution and source, and the problem of a simple yet reliable detection method that would be applicable in a large-scale monitoring system. In this paper we explore the possible use of mussels (Mytilus edulis and Mytilus californianus) in estimating the distribution of benzo(a)pyrene (B(a)P) in coastal waters, and attempt to assess their suitability in an economic, simple, and relevant monitoring system. Mussels were chosen because of their widespread distribution, their sedentary habits, and their capacity to accumulate foreign compounds, including PAH (5). Benzo(a)-pyrene was selected because of its potency as a carcinogen, and its presence in a great variety of contaminating discharges that may enter shallow coastal waters (1, 3).

Methods. The levels of benzo(a)pyrene in mussels and other samples were measured using a modification of a previously described procedure (6); 20-40 g (wet drained weight) of mussel tissue (generally 10-15 mussels) or 5-10 mg of creosoted wood were refluxed with ethanol and KOH, then water added and the PAH extracted into isooctane. Interfering materials were removed by chromatography on a column of Florisil, followed by dimethylsulfoxide extraction. Benzo(a)pyrene was separated from other PAH by thin-layer chromatography on cellulose-acetate. The B(a)P was quantitated fluorimetrically in hexadecane, using a baseline technique (7) to estimate the height of one of the peaks in the B(a)P emission spectrum.