Mixture toxicity assessment of a biocidal product based on reproduction and avoidance behaviour of the collembolan Folsomia candida.

Biocidal products represent mixtures that might be released into the environment at application and continuously during service life. Concentration addition (CA) has been proposed as default model to calculate theoretical mixture toxicity. However, the suitability of CA for chronic toxicity towards soil organisms has so far rarely been evaluated and therefore needs further experimental evidence. The present study investigated the toxicity of a wood preservative product and the individual active substances (tebuconazole and IPBC) therein with the aim to evaluate the compliance with the CA prediction for the product. Folsomia candida was selected as test organism for this purpose using the endpoints reproduction and avoidance behaviour. Both endpoints were increasingly impacted by increasing concentrations of the wood preservative product as well as its active substances tested individually. The chronic effects of the product could be predicted by CA with less than 4-fold deviation, while the assessment for avoidance behaviour indicated a strong underestimation. This underestimation could not be attributed to the one known formulation additive, an organic solvent. Overall, the present study provides some more evidence that CA could be applied as default model for standard endpoints of soil organisms, but warns against using CA for behavioural responses.

Quality assessment of digested sludges produced by advanced stabilization processes.

The European Union (EU) Project Routes aimed to discover new routes in sludge stabilization treatments leading to high-quality digested sludge, suitable for land application. In order to investigate the impact of different enhanced sludge stabilization processes such as (a) thermophilic digestion integrated with thermal hydrolysis pretreatment (TT), (b) sonication before mesophilic/thermophilic digestion (UMT), and (c) sequential anaerobic/aerobic digestion (AA) on digested sludge quality, a broad class of conventional and emerging organic micropollutants as well as ecotoxicity was analyzed, extending the assessment beyond the parameters typically considered (i.e., stability index and heavy metals). The stability index was improved by adding aerobic posttreatment or by operating dual-stage process but not by pretreatment integration. Filterability was worsened by thermophilic digestion, either alone (TT) or coupled with mesophilic digestion (UMT). The concentrations of heavy metals, present in ranking order Zn > Cu > Pb > Cr ~ Ni > Cd > Hg, were always below the current legal requirements for use on land and were not removed during the processes. Removals of conventional and emerging organic pollutants were greatly enhanced by performing double-stage digestion (UMT and AA treatment) compared to a single-stage process as TT; the same trend was found as regards toxicity reduction. Overall, all the digested sludges exhibited toxicity to the soil bacterium Arthrobacter globiformis at concentrations about factor 100 higher than the usual application rate of sludge to soil in Europe. For earthworms, a safety margin of factor 30 was generally achieved for all the digested samples.

Assessing the elimination of estrogenic activity in advanced wastewater treatment with a reporter gene-based bioassay.

Estrogen-like chemicals, so-called xenoestrogens, have become a topic of concern because they are potentially capable of disturbing the hormonal balance of wildlife and humans. Effluents of wastewater treatment plants (WWTPs) are presumably the major source of xenoestrogens in the aquatic environment. In this study, we investigated eight WWTPs with respect to their input, elimination efficiency, and output of estrogenic activity by means of a reporter gene-based bioassay. All WWTPs employed activated sludge treatment with nitrification/denitrification and tertiary treatment (second nitrification and/or filtration). Estradiol equivalents (EEQs) in the influents of the WWTPs were between 5.7 and 65.8 ng/L. The greatest inputs were found in plants treating pure domestic sewage and in samples collected in winter. Process waters either had no estrogenic activity or EEQs in the range of raw sewage, depending on the source of the process water. EEQs of effluents ranged from mostly below quantification limit (0.8 ng/L) to a maximum of 5.4 ng/L in secondary and 1.4 ng/L in tertiary effluents. These findings demonstrate the elimination efficiency of the activated sludge treatment and the further improvement by additional tertiary treatment. However, several concentrated effluents elicited little, but detectable estrogenic responses in the bioassay.

[Follow-up of tissue acidosis, lactic acid production and morphologic changes in testicular tissue in ischemia and the effect of cooling]. / Der Verlauf der Gewebeazidose, der Milchsäureproduktion und der morphologischen Veränderungen von Hodengewebe während der Ischämie und der Effekt von Kühlungsmassnahmen.

More than 90% of the patients with a testicular torsion are loosing their testis by orchiectomy or by following ischemic atrophy. The critical time of irreversible changes of the testis is according to literature 4-6 hours. The aim of our study was to measure the tissue acidification (pH) in the testis at different temperatures and to estimate the cooling effect on pH, lactate accumulation and morphological changes. We have measured in 36 human testis (orchiectomy in patients with metastatic prostate cancer) the tissue acidification (pH), the tissue lactate level and the morphology changes at a temperature of 35, 25, 15 and 5 C. In 12 testis of young dogs we have measured the same parameters. Starting with a normal testis temperature of 35 C the pH is falling to 6.0 within 1 hour of ischemia. By colling to 15 C this time can be prolonged to 6 hours. The tissue lactate level rises from 25 mumol/gdw to nearly 200 mumol/gdw at 35 C. The morphology of semi-thick slices of the testis shows a swelling of the intratubular tissue (spermatogenesis) by loss of the interstitial space. By reducing temperature also a slowdown of the changes can be observed. The critical pH value of the testis for irreversible changes is not known. A ph of less than 6.0 is probably a value, which may result in such changes.

[Course of tissue acidosis, lactic acid production and morphologic changes in testicular tissue during ischemia. Effect of hypothermic measures]. / Verlauf von Gewebeazidose, Milchsäureproduktion und morphologische Veränderungen von Hodengewebe während der Ischämie. Effekt von Kühlungsmassnahmen.

More than 90% of patients with testicular torsion lose their testis, either because orchiectomy is necessary or because ischaemic atrophy develops. The critical time before irreversible changes to the testis have taken place is, according to literature, 4-6 h. The aim of our study was to measure the tissue acidification (pH) in the testis at different temperatures and to estimate the effect of cooling on pH, lactate accumulation and morphological changes. In 36 human testes (obtained by orchiectomy in patients with metastatic prostate cancer) we measured the tissue acidification (pH), the tissue lactate level and the morphological changes at temperatures of 35, 25, 15 and 5 degrees C. We also measured the same parameters in 12 testes taken from young dogs. At the normal testicular temperature of about 35 degrees C the pH falls to 6.0 within 1 h of ischaemia. Cooling to 15 degrees C can extend this time to 6 h. The tissue lactate level rises from 25 mumol/gdw to nearly 200 mumol/gdw at 35 degrees C. The morphology of semithin sections of the testis shows swelling of the intratubular tissue (spermatogenesis) with loss of the interstitial space. Reducing temperature can also slow-down these changes. The critical pH value of the testis beyond which irreversible changes take place is not known; a pH of less than 6.0 is thought to be the probable threshold.