A kinetic model for predicting biodegradation.

Biodegradation plays a key role in the environmental risk assessment of organic chemicals. The need to assess biodegradability of a chemical for regulatory purposes supports the development of a model for predicting the extent of biodegradation at different time frames, in particular the extent of ultimate biodegradation within a '10 day window' criterion as well as estimating biodegradation half-lives. Conceptually this implies expressing the rate of catabolic transformations as a function of time. An attempt to correlate the kinetics of biodegradation with molecular structure of chemicals is presented. A simplified biodegradation kinetic model was formulated by combining the probabilistic approach of the original formulation of the CATABOL model with the assumption of first order kinetics of catabolic transformations. Nonlinear regression analysis was used to fit the model parameters to OECD 301F biodegradation kinetic data for a set of 208 chemicals. The new model allows the prediction of biodegradation multi-pathways, primary and ultimate half-lives and simulation of related kinetic biodegradation parameters such as biological oxygen demand (BOD), carbon dioxide production, and the nature and amount of metabolites as a function of time. The model may also be used for evaluating the OECD ready biodegradability potential of a chemical within the '10-day window' criterion.

[Effectiveness of an anti-snoring prosthesis in obstructive sleep apnea syndrome]. / Wirksamkeit einer Antischnarchprothese beim obstruktiven Schlafapnoesyndrom.

Nasal CPAP is a well documented successful therapy for obstructive sleep apnoea syndrome (OSAS), but adverse effects are common and the compliance is 80 percent or less. We investigated the value of an oral device called "Snor Ex"). Eleven obese patients with severe OSAS were examined. Complete polysomnographic studies were performed while sleeping one night without therapy, with nCPAP and after an adaptation period with Snor Ex, respectively. The apopnoeahypopnoea index and the minimal SaO2 could be normalised for all patients using CPAP but only for three patients with Snor Ex. Nine patients tolerated nCPAP and Snor-Ex, respectively. We conclude that this oral device is a successful therapy for only few patients with OSAS.

Assessment of structurally related chemicals: toxicity and ecotoxicity of acrylic acid and acrylic acid alkyl esters (acrylates), methacrylic acid and methacrylic acid alkyl esters (methacrylates).

BUA compiled the available data on toxicity and ecotoxicity for several acrylic and methacrylic acid esters and their corresponding acids. A comparison of these data revealed a qualitative similarity in the toxicological and ecotoxicological properties of the compounds considered. The data indicate that methacrylates are less reactive than the corresponding acrylates.