Fate of pharmaceuticals--photodegradation by simulated solar UV-light

The fate of pharmaceuticals in surface waters under solar irradiation was investigated. Photodegradation of pharmaceuticals caused by sun irradiation may be of major significance in the natural elimination process. Based on a data compilation from the literature, the lipid lowering agent metabolite clofibric acid, the iodinated X-ray contrast media iomeprol, which contribute to the adsorbable organic halogen compounds, and the antiepileptic drug carbamazepine were selected. The irradiation experiments were carried out in batch experiments with simulated UV–sunlight. The photodegradation of the pharmaceuticals showed a pseudo-first-order kinetics. The objective of this investigation was to demonstrate that the extent of photoinduced degradation of pharmaceuticals can vary significantly for the different pharmaceuticals and it strongly depends on the water constituents present in solution. The influences of different initial pharmaceutical concentrations, the presence of other pharmaceuticals like carbamazepine or clofibric acid and the presence of natural organic matter on the photochemical degradation rate of pharmaceuticals in aqueous solutions were investigated. Analyses of the pharmaceuticals and their photodegradation products were carried out by high performance liquid chromatography with diode-array and fluorescence detection.     

Analysis of health or systemic effects caused by two toxicants

A method is presented for the analysis of the risk to man or other systems by effects caused by a combination of two insults. The approach is purely phenomenological and has no built-in restrictions other than those required by logic and those imposed by the limited set of trial functions. The analysis attempts to isolate the dominant contributions to the risks from either agent alone and from both agents in combination. To demonstrate the viability of the method, it is applied to the analysis of human health data on oral and esophageal cancer correlated with alcohol and tobacco consumption. For both cancers, it is found that the most probable form of the relative risk is separable into a factor related to tobacco and one related to alcohol. Both have the same algebraic form and the values of the risk coefficients are practically equal. An analysis of analogous but limited data on laryngeal cancer cannot assign an algebraic form of the risk function but still yields comparable risk coefficients. Thus it is possible that all three cancers have the same risk function as a function of alcohol and tobacco consumption.     

Influence of CO<Subscript>2</Subscript> on the micro-structural properties of spider dragline silk: X-ray microdiffraction results

The mechanical properties of spider dragline fibres are altered by CO₂ exposure under anaesthetizing conditions during the spinning process. In order to relate these macroscopic changes to a microscopic model, the extrusion of dragline silk was studied by synchrotron radiation microdiffraction. A brief exposure of a female Nephila senigalensis spider to CO₂ results after an incubation time of less than 7 min in the extrusion of a thread (two fibres) swollen with water. The data are interpreted for a model of crystalline -sheet domains containing nanofibrils, which reinforce a network of protein chains. The protein network absorbs water, leaving the nanofibrils unaffected. A continuous flow of CO₂ results in a co-extrusion of a dragline thread and an isotropic silk fraction, which probably has a glycine-rich sequence. Long CO₂ exposure reduces the axial alignment of nanofibrils, presumably due to a partial destruction of the amorphous network.