Size-exclusion chromatographic study of ECF and TCF softwood kraft pulp bleaching liquors.

Background, Aims, And Scope: Currently, elemental chlorine-free (ECF) and totally chlorine-free (TCF) bleaching systems are widely used for pulp production. Low and medium molecular weight lignin break-down products are known to have harmful effects on the environment. According to some recent results, also high molecular weight (HMW) material consisting mainly of lignin and carbohydrates may cause toxic effects to the environment.

Biological effects of high molecular weight lignin derivatives.

A number of high molecular weight (HMW) lignin derivatives possessing varied chemical properties were screened for their biological effects in order to obtain more information on the possible structural features of HMW lignin-related effects. The studied compounds were both commercial and in-house extracted lignin derivatives. Bioassays used include reverse electron transport (RET), Vibrio fischeri, Daphnia magna, and juvenile rainbow trout (Oncorhynchus mykiss) hepatocytes.

Detecting AhR ligands in sediments using bioluminescent reporter yeast.

Sediments polluted with high concentrations of persistent organic pollutants, many of which are ligands of the aryl hydrocarbon receptor (AhR), are currently of concern around the industrialized world. Bioassays that can detect the presence of AhR ligands in environmental samples offer a relatively rapid and cost-effective means of prioritizing samples before more elaborate, laborious, and costly chemical analyses are applied. This paper presents a new bioluminescent yeast assay based on transcriptional activation of AhR.

Multivariate statistics of the pyrolysis products of high molecular components in pulping wastewaters to explain their toxicity.

Background, Aim And Scope: At present, large-scale paper manufacture involves delignification and bleaching by elemental chlorine free (ECF), or totally chlorine free (TCF) processes. The wastewater is purified by secondary treatment (mechanical, chemical and biological) which removes most of the toxic substances from the discharge. However, we found residual toxicity in the high molecular (> 1000 D) matter (HMWM) of the discharge by test of the RET (reverse electronic transfer) inhibition.

In vitro estrogenicity of polybrominated flame retardants.

Estrogenicity of five brominated flame retardants (BFRs), namely BDE-47, BDE-99, BDE-205, PBB-153 and technical Firemaster BP-6, were assessed by in vitro assays developed to detect chemicals with estrogenic properties. Recombinant yeast cells containing a human estrogen receptor gene failed to give any response to the chemicals tested. However, the positive control compound, estradiol-17beta, showed that the yeast cell assays had worked properly.

Evaluation of wastewater effluents by small-scale biotests and a fractionation procedure.

Municipal and industrial effluents were screened with a battery of biotests and with a modified toxicity identification evaluation Phase I procedure. The acute toxicities of the effluent samples were low and the submitochondrial reverse electron-transport (RET) test was the most sensitive toxicity test. Estrogenic effects were found in almost all effluent samples, and genotoxicity was detected in one concentrated effluent sample.

Elemental sulfur: toxicity in vivo and in vitro to bacterial luciferase, in vitro yeast alcohol dehydrogenase, and bovine liver catalase.

The aim of this research was to analyze the effects and the modes of action of elemental sulfur (S(0)) in bioluminescence and respiration of Vibrio fischeri cells and the enzymes crude luciferase, pure catalase, and alcohol dehydrogenase (ADH). Metallic copper removed sulfur and reduced the toxicity of acetone extracts of sediment samples analyzed in the bioluminescence test. The sulfur inhibition of cell bioluminescence was noncompetitive with decanal, the luciferase substrate; reversible, with maximum toxicity after 15 min (EC(50) = 11.

Biodegradation of chemicals in a standardized test and in environmental conditions.

The estimation of biodegradation rates is an important source of uncertainty in chemical risk assessment. The existing OECD tests for ready biodegradability have been developed to devise screening methods to determine whether a chemical is potentially easily biodegradable, rather than to predict the actual rate, of biodegradation in the environment. However, risk assessment needs degradation rates.