Immediate ecotoxicological effects of short-lived oil spills on marine biota.

Marine environments are frequently exposed to oil spills as a result of transportation, oil drilling or fuel usage. Whereas large oil spills and their effects have been widely documented, more common and recurrent small spills typically escape attention. To fill this important gap in the assessment of oil-spill effects, we performed two independent supervised full sea releases of 5 m(3) of crude oil, complemented by on-board mesocosm studies and sampling of accidentally encountered slicks. Using rapid on-board biological assays, we detect high bioavailability and toxicity of dissolved and dispersed oil within 24 h after the spills, occurring fairly deep (8 m) below the slicks. Selective decline of marine plankton is observed, equally relevant for early stages of larger spills. Our results demonstrate that, contrary to common thinking, even small spills have immediate adverse biological effects and their recurrent nature is likely to affect marine ecosystem functioning.

First day of an oil spill on the open sea: early mass transfers of hydrocarbons to air and water.

During the first hours after release of petroleum at sea, crude oil hydrocarbons partition rapidly into air and water. However, limited information is available about very early evaporation and dissolution processes. We report on the composition of the oil slick during the first day after a permitted, unrestrained 4.3 m(3) oil release conducted on the North Sea. Rapid mass transfers of volatile and soluble hydrocarbons were observed, with >50% of ≤C17 hydrocarbons disappearing within 25 h from this oil slick of <10 km(2) area and <10 µm thickness. For oil sheen, >50% losses of ≤C16 hydrocarbons were observed after 1 h. We developed a mass transfer model to describe the evolution of oil slick chemical composition and water column hydrocarbon concentrations. The model was parametrized based on environmental conditions and hydrocarbon partitioning properties estimated from comprehensive two-dimensional gas chromatography (GC×GC) retention data. The model correctly predicted the observed fractionation of petroleum hydrocarbons in the oil slick resulting from evaporation and dissolution. This is the first report on the broad-spectrum compositional changes in oil during the first day of a spill at the sea surface. Expected outcomes under other environmental conditions are discussed, as well as comparisons to other models.

Effect of a standardized meal on the bioavailability of a single oral dose of tibolone 2.5 mg in healthy postmenopausal women.

STUDY OBJECTIVE: To assess the effect of food on absorption and pharmacokinetic disposition of tibolone. DESIGN: Open-label, randomized, crossover study with a 1-week washout period. SETTING: Institut für Klinische Pharmakologie, Hohenkirchen-Siegertsbrunn, Germany SUBJECTS: Twenty-four healthy, early postmenopausal women. INTERVENTION: Single doses of tibolone 2.5 mg were administered after subjects consumed a high-fat meal or fasted. MEASUREMENTS AND MAIN RESULTS: Plasma concentrations of tibolone and its three primary metabolites, delta4-tibolone, 3alpha-hydroxytibolone, and 3beta-hydroxytibolone, were assayed by gas chromatography with mass spectrometry. Peak plasma concentration (Cmax), time to Cmax, area under the plasma concentration versus time curve from time zero to infinity (AUC(0-infinity)), and elimination half-life were calculated, and food effects were evaluated. Plasma concentrations of tibolone and delta4-tibolone were too low to estimate AUC(0-infinity) and half-life. Absorption or formation of 3alpha-hydroxytibolone and 3beta-hydroxytibolone was slower in fed participants than in fasting participants, but this was of no clinical relevance because of the long-term nature of tibolone treatment. Meal consumption did not affect AUC(0-infinity) or half-life for 3alpha-hydroxytibolone and 3beta-hydroxytibolone. CONCLUSION: Food consumption decreased and delayed Cmax but had no effect on the exposure of tibolone and its metabolites. Tibolone therefore can be administered irrespective of meal timing.