Proactive limit values for responsible management of chemicals

Limit values (LVs) are legal concentration limits for constituents, residues and contaminants in consumer products or for emissions from production processes into environmental compartments. They are a traditional regulatory aid to manage chemicals in human environments. To make them proactive, LVs should become enforced by means of a transparent and informed decision process whose starting point is the Basic Rule of Environmental Hygiene, BREH:Avoid useless exposure as far as possible, minimize useful exposure in a reasonable manner, and prevent that exposure which is dangerous. The BREH calls upon minimizing exposure not only according toon site risk potentials and acceptance, but also tooff site avoidability and acceptability.     

Predictions for isomer distributions of toxic dioxins and furans in selected industrial combustion processes

Three thermodynamic databases of polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) have been used to simulate the PCDD/F isomer distribution in industrial combustion processes. The three databases had been derived using the Group Additivity approach and two computational molecular modelling methods, Modified Neglect of Diatomic Overlap (MNDO) and Parametrized Model 3 (PM3), respectively. The predictions of the toxic PCDD/F isomer distributions using the three different databases have been compared with measured values from industrial processes. An excellent agreement between the predictions using the MNDO method and the measured data has been obtained. It is concluded that the PCDD/F isomer distributions within each group observed in these combustion processes may be thermodynamically controlled.     

Treatment of spent wash in anaerobic mesophilic suspended growth reactor (AMSGR)

Approximately 400 KL of spent wash or vinasse per annum is generated at an average COD concentration of 100,000 mg/l, by over 250 distilleries in India. There is an urgent need to develop, assess and use ecofriendly methods for the disposal of this high strength wastewater. Therefore, an attempt was made to investigate a few aspects of anaerobic digestion of spent wash collected from a distillery. The study was carried out in a 4 L laboratory scale anaerobic mesophilic suspended growth reactor. After the successful startup, the organic loading was increased stepwise to assess the performance of the reactor. During the study period, biogas generated was recorded and the maximum gas generated was found to be 16.9 L at an Organic Loading Rate (OLR) of 38 g COD/L. A 500% increase in the Volatile Fatty Acid (VFA) concentration (2150 mg/L) was observed, when the OLR was increased from 38 to 39 g COD/L. During the souring phase the removal of COD, Total Solids (TS) and Volatile Solids (VS) were in the order of 52%, 40% and 46% respectively. The methane content in the biogas varied from 65% to 75%.     

Prenatal diagnosis of a de novo supernumerary marker derived from chromosome 16

Marker chromosomes are supernumerary chromosomes of unknown origin and are seldom found in prenatal diagnosis. Application of fluorescent in situ hybridization (FISH) allows the identification of the chromosomal origin of markers. Estimation of the risk of an abnormal phenotype outcome can be enabled by collecting data on phenotypes associated with markers of the same chromosomal origin. So far only very few cases of prenatal diagnosis of de novo supernumerary markers derived from chromosome 16 have been reported. Here the prenatal diagnosis of a de novo supernumerary marker chromosome 16 is described and the relevant literature discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

An experimental study on the causal relationships between (ecto-)parasites, testosterone and sexual signalling

Bird song is considered to have evolved via sexual selection and should as such honestly signal aspects of the quality of its bearer. To ensure honesty, the immunocompetence handicap hypothesis proposed a dual role of testosterone, having positive effects on sexual signalling but suppressive effects on immune function. However, recent studies showed that it is rather an immune activation that suppresses the androgen production. This reversed chain of causation may significantly alter the pathways, which translate the effects of parasites and pathogens into changes in the expression of male sexual traits. We infested male canaries with Ixodes ricinus tick nymphs to investigate the causal relationships between (ecto-)parasites, testosterone and sexual signalling, here singing behaviour. We focused on flexible song traits, which may quickly reflect changes in the infestation status, and tested whether these effects relate to changes in the plasma testosterone levels or health state. The experimental tick infestation altered the males’ song performance by reducing song consistency, a trait that had previously been identified to reflect male quality. The tick infestation lowered the plasma testosterone levels and had a negative effect on the health status in terms of a reduced hematocrit. Our pathway analysis then revealed that it is the parasite-induced reduction of the plasma testosterone levels but not of the health state that caused the changes in song consistency. Thus, our study supports the view that it is the effect of parasites and immune activation on plasma testosterone levels that generates the trade-off between immunocompetence and sexual signalling.