Search

Knowledge of the kinetics and pathways of hydrolytic degradation is crucial to the prediction of the fate and transport mechanism of chemicals. This work first describes the kinetics of the chemical hydrolysis of imazosulfuron, a new sulfonylurea herbicide, and evaluates the results to propose a degradation pathway. The hydrolysis of imazosulfuron has been studied in aqueous buffers both within the pH range 1.9-12.3 at ambient temperature (thermostated at 25 +/- 2 degrees C) and at pH 3.6 within the temperature range of 15-55 degrees C. The hydrolysis rate of imazosulfuron was characterized by a first-order kinetics, pH- and temperature-dependent, and accelerated by acidic conditions and higher temperatures. The calculated half-lives at pH 4.5 and 5.9 were 36.5 and 578 days, respectively. At pH 6.6, 7.4, 9.2, and 12.3 no significant change in imazosulfuron concentration was observed after 150 days. Half-lives were much lower at pH4 (= imazosulfuron pK(a)), at which they ranged from 3.3 to 6.3 days. Moreover, a change in temperature from 15 to 25 degrees C in acidic conditions (pH 3.6) decreased the half-life of imazosulfuron by a factor of approximately 4.0; in any case, a 3-5-fold increase in the rate of hydrolysis was found for each 10 degrees C increase in temperature. In acidic conditions the only hydrolysis products were the two molecules resulting from the cleavage of the sulfonylurea bridge.

In spite of their important impact on populations, a number of diseases--all types of cancer and coronary heart disease in women--are "rare" events for statistical analysis and often analyzed in designs affected by selection and information biases, such as case-control studies. Large cohort studies based on the storage of biological specimens appear to be the most suitable solution for identifying risks for those diseases. Progetto ATENA, a study on the etiology of major chronic diseases in women is based on this design. Ten thousand women, aged 30-69 years, living in the area of the city of Naples, free of cancer and cardiovascular disease, are being recruited over a four-year period. Ten per cent of the cohort is being randomly selected from the electoral roles, the rest will be volunteers. Information on dietary habits, reproductive history, familiarity for chronic disease, active smoking habits and passive smoking exposure, physical activity, and socio-demographic data are being collected. Clinical data such as blood pressure, anthropometry, and electrocardiogram are also taken. All the participants provide biological samples of blood (fasting drawing) and urine (timed morning spot). The biological samples are processed in order to explore the main areas under study (nutritional markers, metabolism, endocrinology, genetics, environmental exposure markers, thrombogenesis). The samples are stored in liquid nitrogen (-196 degrees C) as soon as the blood and urine processing have been finished. An appropriate follow-up information system on the health status of the participants is being set up to estimate incidence and mortality rates.