'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.     

Reproducibility of indoor environment characteristics obtained in a walk through questionnaire. A pilot study

Walk through questionnaires may be feasible tools to obtain data on the indoor environment in community studies. However, limited information is available regarding the reproducibility of the data obtained through these questionnaires. In this pilot study, two construction engineering students inspected ten dwellings twice by means of a standardized walk through questionnaire. The two engineering students inspected the dwellings independent of each other within two months. Time between the two visits varied between 14 and 40 days. The variables presented were based on information from the residents and inspection. The continuous variables recorded included number of rooms in the dwellings, room volume, length of filled shelves and textile area. The inter- and intra-observed variabilities were poorer for number of rooms and shelf factor than for the other variables. For the 3 of the 9 categorical variables based on inspection, the inter-observer comparison showed complete agreement with a kappa statistics of 1.0, these variables being condition of the window frames and construction of outside walls and roof. One of the categorical variables showed a kappa statistics of < 0.5, these variables being presence of basement and presence of condensation at windows. This study indicates a wide variation in observer variability between various items of a walk through questionnaire. Clear definitions of all the parts of the questionnaire are needed, as well as thorough training of observers.     

Amphibians as a model to study endocrine disruptors: I. Environmental pollution and estrogen receptor binding

Many chemicals released into the environment without toxicological risks have the capacities to disrupt the function of endocrine systems. These endocrine disruptors disturb normal endocrine mechanisms and have been observed in nearly all classes of vertebrates. The aim of this research is to develop a comprehensive model to study endocrine disruption using the amphibian Xenopus laevis. The assessment of estrogenic potencies of endocrine disruptors includes several levels of investigation: (I) binding to liver estrogen receptor, (II) estrogenic activity in vitro by inducing vitellogenin synthesis in primary cultured hepatocytes, and (III) in vivo effects on sexual development caused by exposure of larvae. The present paper is focused on the first part by establishing a radioreceptorassay for [3H]17 beta-estradiol ([3H]E2) binding using liver cytosol fraction. In order to get optimum binding conditions we performed kinetic, saturation, and competitive displacement experiments. Association of [3H]E2 to estrogen receptor revealed that maximum specific binding is achieved between 18 and 48 h of incubation. Scatchard analyses of saturation experiments resulted in a homogenous saturable population of estrogen receptors having no significant differences of binding parameters between both sexes. The values of Kd (dissociation constant) in males and females were 22.4 +/- 6.0 and 15.0 +/- 2.8 nM (mean +/- S.E.M.; n = 5), respectively, while corresponding Bmax (maximum binding capacity) revealed 89 +/- 46 and 136 +/- 46 fmol [3H]E2/mg protein. The specificity of estrogen receptors as shown by competitive displacement experiments demonstrated receptors being highly specific just for estrogens, but not for other endogenous steroids having the following ranking of binding affinities: E2 > estrone > dehydroepiandrosterone > aldosterone > or = testosterone > or = corticosterone > or = progesterone. The affinity ranking of environmental chemicals compared to E2 was: E2 > tetrachlorbiphenyl > diethylphthalate > 2,2-bis-(4-hydroxyphenyl)-propan (bisphenol A) > or = 4-nonylphenol > or = 3-t-butyl-4-hydroxyanisole > or = 4-octylphenol > dichlor-diphenyl-trichlor-ethan (4,4'-DDT). Analyses of five sewage effluents for displacement of [3H]E2 binding resulted in three samples displacing more than 50% of specific binding at their original concentration. Taken together the established radioreceptorassay for [3H]E2 binding in Xenopus laevis liver cytosol is useful to screen estrogen receptor binding of pure compounds or complex mixtures of them, which is the prerequisite for causing either estrogenic or antiestrogenic effects.     

Selective removal of gallium (III) from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate

Gallium was removed selectively from aqueous solutions containing zinc or aluminum using sodium di-(n-octyl) phosphinate as a ligand (NaL). At low pH or low mole ratios, the gallium was removed by complexation with the ligand as GaL(3(S)), while the zinc or the aluminum remained in the solution. Nearly complete separation of gallium was obtained. By increasing the amount of ligand or by increasing the pH, the zinc or aluminum remaining in the solution was then removed as a solid complex: ZnL(2(S)) or AlL(3(S)), respectively. At a pH between 1.5 and 2 and a mole ratio ligand to total metals of 0.75 for zinc solutions and 1.0 for aluminum solutions, more than 98% of the gallium was selectively removed with a high molar selectivity, alpha(Ga/Zn) and alpha(Ga/Al), respectively. Over 95% of gallium was recovered from the solid GaL(3(S)) complex by treatment of the complex with a 3M NaOH solution and diethyl ether. The gallium was concentrated in the aqueous solution to 4 times its initial concentration and the ligand was extracted into the ether phase. After evaporation of the ether, 95% of the ligand was regenerated in its sodium form as a solid.     

Synthesis of ettringite: a way to deal with the acid wastewaters of aluminium anodising industry

Synthesis of ettringite from acid wastewaters of the aluminium anodising industry has been studied as a possible route of reducing the emissions to the environment, recovering at the same time resource materials as a useful marketable mineral. Wastewaters of different concentrations have been subjected to the process of synthesis suspending calcium oxide and calcium aluminate powders at different time and pH conditions. High caustic alkalinity (pH approximately 12) and low sulphate concentrations (<0.1 M) are the most suitable conditions to synthesise ettringite. The mineral characterisation has been performed using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and differential thermal analysis (DTA), proving the high purity of the pursued solid product when hydrated in the appropriate sodium hydroxide concentrations. In such conditions, around 90% of the aluminium initially present in the wastewater solutions is recovered in the form of ettringite.     

THE EFFECTS OF IMPROVING SEWAGE SLUDGE DIGESTION

A model was developed and tested to investigate the effects of various parameters on the processing costs of anaerobic digestion. The model was based on empirical data collected from full-scale plants which varied in size from 35,000 to 900,000 population equivalents. (Equivalent to loading rates of 0.5 to 2.7 kg VS/m³/d.) In spite of different operating regimes and conditions of the plants analysed, various relationships were discovered between: sludge quality and volatile solids destruction; sludge quality and biogas yield; and, effluent volatile solids and dewatering. Where correlations existed, these were used to make predictions on operating costs of the digestion and dewatering plant based on sensitivity analysis. The results of the model were used to make recommendations on how to optimise the operation of an anaerobic digestion plant.