Rheological Properties of Industrial Hot Trub.

The boiling of beer wort with hops results in the formation of a hot trub, a sediment consisting mainly of water-insoluble tannin and protein conglomerates and hop residue. Hot trub is a waste product, removed in a clarifying tank and discarded. The use of barley malt substitutes in recipes for beer is associated with an increase in the amount of generated hot trub. In presented study, an analysis of the rheological properties of industrial hot trub was carried out. Samples varied with regard to the quantities of unmalted barley (0%, 35%, and 45%) and worts' extract (12.5, 14.1, 16.1, and 18.2 °Plato) in the recipe. The rheology of each type of sludge was determined using a hysteresis loop at four different temperatures. The results showed the shear-thinning and thixotropic properties of the hot trub. It was found that, regardless of the raw material and extract used, all samples exhibited the same rheological properties, but with different values. It was also proved that both raw material composition and temperature affected the hot trub's rheology. The highest values of viscosity were identified for malted barley, whereas the lowest apparent viscosity values were recorded for the hot trub with a 30% addition of unmalted barley. The Herschel-Bulkley model had the best fit to the experimental data.

Predictive Model for the Surface Tension Changes of Chemical Solutions Used in a Clean-in-Place System.

The paper presents the results concerning the influence of concentration and storage time on the equilibrium surface tension of chemical solutions used in a clean-in place (CIP) system. Standard cleaning solutions (prepared under laboratory conditions) and industrial solutions (used in a CIP system in a brewery) were subjected to tests. Solutions from the brewery were collected after being regenerated and changes in equilibrium surface tension were studied during a three-month storage. In the statistical analysis of the solutions, standard deviations were determined in relation to the averages, and a Tukey's multiple comparison test was performed to determine the effect of dependent variables on the surface tension of solutions. From the results, a nonlinear regression model was developed that provided a mathematical description of the kinetics of changes in the wetting properties of the solutions during their storage. A linear-logarithmic function was adopted to describe the regeneration. Numerical calculations were performed based on the nonlinear least squares method using the Gauss-Newton algorithm. The adequacy of the regression models with respect to the empirical data was verified by the coefficient of determination R and the standard error of estimation Se. The results showed that as the concentration of the substance in the cleaning solution increased, its wetting properties decreased. The same effect was observed with increased storage time as the greatest changes occurred during the first eight weeks. The study also showed that the use of substances to stabilize the cleaning solutions prevented deterioration of their wetting properties, regardless of the concentration of the active substance or storage time.

Increasing the Efficiency of Food Material Cutting during Inclined and Shear Movements of Knife.

Mathematical models for predicting the resistance forces that are developed during the inclined and sliding cutting of food materials have been developed. The dependence of the actual cutting angle on the angle of inclination and sliding speed of the cutting edge at various sharpening angles have been investigated. For the inclined cutting mode, the dependence of the useful resistance force on the cutting speed has been determined at various angles of inclination of the cutting edge and designed sharpening angles. For the sliding cutting mode, the dependence of the useful resistance force on the feeding speed has been demonstrated at various sliding speed values and designed knife sharpening angles. The dependence of the transformed dimensionless sharpness of the knife on the angle of inclination of the cutting edge and the sliding speed has been established for different constructional sharpness values of the knife. The results of the study indicate that the useful resistance force is significantly reduced during the inclined and sliding cutting processes when compared with the normal cutting process, and a change in the pattern of fiber destruction, which significantly increases the cutting efficiency of cutting tools, is obtained.

Simulation Studies on Centrifugal MQL-CCA Method of Applying Coolant during Internal Cylindrical Grinding Process.

This paper describes simulation studies regarding the application of the centrifugal minimum quantity lubrication (MQL) method simultaneously with the delivery of a compressed cooled air (CCA) stream in the internal cylindrical grinding process. The idea of a new hybrid cooling and lubrication method connecting centrifugal (through a grinding wheel) lubrication by MQL with a CCA stream is described. The methodology of computational fluid dynamics (CFD) simulation studies, as well as the results of numerical simulations, are presented in detail. The aim of the simulations was to determine the most favourable geometrical and kinematic parameters of the system in the context of air-oil aerosol and CCA flow, as well as heat exchange. In the simulation, the variables were the grinding arbor geometrical parameters, the angle of CCA supply line outlets, and the grinding wheel and workpiece peripheral speed. As a result of the simulation studies, the most favourable geometrical parameters were designated, determining the orientation of the ends of the two CCA supply line outlets before and after the grinding zone, the number of openings in the drilled-out grinding arbor, and the influence of the grinding speed on the parameters of the coolant flow and temperature of objects in the grinding zone. In addition, the results of simulation tests made it possible to visualise the velocity vectors of the two-phase coolant flow in a complex system of air-oil aerosol delivery centrifugally through an open structure of a very fast rotating porous layer (grinding wheel), with an additional supply of CCA using an external cold air gun (CAG).

Urinary cotinine levels and environmental tobacco smoke in mothers and children of Romania, Portugal and Poland within the European human biomonitoring pilot study.

The aim of this study was to explore data from the DEMOCOPHES study population for Romania, Portugal and Poland, in order to assess smoking patterns and the extent of ETS exposure and compare the national study samples with reference to the respective anti-smoking laws. The subset of the DEMOCOPHES study sample consisted of 360 children and their mothers (120 in each of the three countries - Romania (RO), Portugal (PT) and Poland (PL). Smoking was assessed using a detailed questionnaire for the participants, which addresses both active and passive smoking. This assessment uses exposure-relevant questionnaire data, in particular on the home environment and residence, socio-demographic characteristics, lifestyle such as nutrition, smoking behavior, other exposure-relevant behavior and occupational history, as well as urinary cotinine and creatinine measurements. We performed general statistical analysis and innovative receiver operating characteristic (ROC) curve analyses. Smoking prevalence as evaluated by the questionnaire was generally high, and higher than official statistics, which suggests some under-reporting in the countries, particularly in Romania. Urinary cotinine levels provided biochemical confirmation of the high and similar smoking prevalence for the three countries. Concerning ETS exposure, Romania presented significantly higher levels, for children as well as for non-smoking mothers, with Portugal showing significantly lower levels. Compared to non-smoking mothers, the children showed relatively higher ETS exposure levels in all three countries. The established country-specific optimal cut-off values in urinary cotinine to distinguish smokers from non-smokers vary more than those to discriminate ETS exposure extent in non-smoking mothers and children. Although different between countries, these values are a valuable output to monitor effectiveness of both national antismoking laws and educational programs in the three countries. The findings of this study point to the urgent need for stronger, more effective and well enforced smoke-free legislation in the three countries.

First steps toward harmonized human biomonitoring in Europe: demonstration project to perform human biomonitoring on a European scale.

BACKGROUND: For Europe as a whole, data on internal exposure to environmental chemicals do not yet exist. Characterization of the internal individual chemical environment is expected to enhance understanding of the environmental threats to health. OBJECTIVES: We developed and applied a harmonized protocol to collect comparable human biomonitoring data all over Europe. METHODS: In 17 European countries, we measured mercury in hair and cotinine, phthalate metabolites, and cadmium in urine of 1,844 children (5-11 years of age) and their mothers. Specimens were collected over a 5-month period in 2011-2012. We obtained information on personal characteristics, environment, and lifestyle. We used the resulting database to compare concentrations of exposure biomarkers within Europe, to identify determinants of exposure, and to compare exposure biomarkers with health-based guidelines. RESULTS: Biomarker concentrations showed a wide variability in the European population. However, levels in children and mothers were highly correlated. Most biomarker concentrations were below the health-based guidance values. CONCLUSIONS: We have taken the first steps to assess personal chemical exposures in Europe as a whole. Key success factors were the harmonized protocol development, intensive training and capacity building for field work, chemical analysis and communication, as well as stringent quality control programs for chemical and data analysis. Our project demonstrates the feasibility of a Europe-wide human biomonitoring framework to support the decision-making process of environmental measures to protect public health.

Exposure determinants of cadmium in European mothers and their children.

The metal cadmium (Cd) is a widespread environmental pollutant with documented adverse effects on the kidneys and bones from long-term environmental exposure, but with insufficiently elucidated public health consequences such as risk of cardiovascular disease, hormone-related cancer in adults and developmental effects in children. This study is the first pan-European human biomonitoring project that succeeded in performing harmonized measurements of Cd in urine in a comparable way in mother-child couples from 16 European countries. The aim of the study was to evaluate the overall Cd exposure and significant determinants of Cd exposure. A study population of 1632 women (24-52 years of age), and 1689 children (5-12 years of age), from 32 rural and urban areas, was examined within a core period of 6 months in 2011-2012. Women were stratified as smokers and non-smokers. As expected, smoking mothers had higher geometric mean (gm) urinary cadmium (UCd; 0.24 µg/g crea; n=360) than non-smoking mothers (gm 0.18 µg/g crea; n=1272; p<0.0001), and children had lower UCd (gm 0.065 µg/g crea; n=1689) than their mothers at the country level. Non-smoking women exposed to environmental tobacco smoke (ETS) at home had 14% (95% CI 1-28%) higher UCd than those who were not exposed to ETS at home (p=0.04). No influence of ETS at home or other places on UCd levels was detected in children. Smoking women with primary education as the highest educational level of the household had 48% (95% CI 18-86%) higher UCd than those with tertiary education (p=0.0008). The same observation was seen in non-smoking women and in children; however they were not statistically significant. In children, living in a rural area was associated with 7% (95% CI 1-13%) higher UCd (p=0.03) compared to living in an urban area. Children, 9-12 years had 7% (95% CI 1-13%) higher UCd (p=0.04) than children 5-8 years. About 1% of the mothers, and 0.06% of the children, exceeded the tolerable weekly intake (TWI) appointed by EFSA, corresponding to 1.0 µg Cd/g crea in urine. Poland had the highest UCd in comparison between the 16 countries, while Denmark had the lowest. Whether the differences between countries are related to differences in the degree of environmental Cd contamination or to differences in lifestyle, socioeconomic status or dietary patterns is not clear.

A proposal for calculating the no-observed-adverse-effect level (NOAEL) for organic compounds responsible for liver toxicity based on their physicochemical properties.

OBJECTIVES: Both environmental and occupational exposure limits are based on the no-observed-adverse-effect level (NOAEL), lowest-observed-adverse-effect level (LOAEL) or benchmark dose (BMD) deriving from epidemiological and experimental studies. The aim of this study is to investigate to what extent the NOAEL values for organic compounds responsible for liver toxicity calculated based on their physicochemical properties could be used for calculating occupational exposure limits. MATERIAL AND METHODS: The distribution coefficients from air to the liver (log K(liver)) were calculated according to the Abraham solvation equation. NOAEL and LOAEL values for early effects in the liver were obtained from the literature data. The descriptors for Abraham's equation were found for 59 compounds, which were divided into 2 groups: "non-reactive" (alcohols, ketones, esters, ethers, aromatic and aliphatic hydrocarbons, amides) and "possibly reactive" (aldehydes, allyl compounds, amines, benzyl halides, halogenated hydrocarbons, acrylates). RESULTS: The correlation coefficients between log-log K and log NOAEL for non-reactive and reactive compounds amounted to r = -0.8123 and r = -0.8045, respectively, and were statistically significant. It appears that the Abraham equation could be used to predict the NOAEL values for compounds lacking information concerning their liver toxicity. CONCLUSIONS: In view of the tendency to limit animal testing procedures, the method proposed in this paper can improve the practice of setting exposure guidelines for the unstudied compounds.

The use of PowerPrep and HRGC/HRMS for biological monitoring of exposure to PCDD, PCDF and dl-PCB in Poland.

PURPOSE: The aim of this study was to design the optimized laboratory protocol as a tool for human biomonitoring of selected Persistent Organic Pollutants (POPs) in Poland. In this study, we present the method developed for the determination of 29 congeners of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs), as well as individual results of the measurements in 40 human breast milk samples collected in central Poland in 2008-2010. METHODS: The protocol of sample preparation and quantitative analysis of PCDD/Fs and dl-PCBs was optimized for the isotopic dilution method with high resolution gas chromatography/high resolution mass spectrometry HRGC/HRMS. Fat content in the extracts was determined gravimetrically. The results were corrected by fat content in the samples. RESULTS: The average sum of PCDD/F and dl-PCBs in the human milk samples from the urban area was 7.429 WHO-TEQpg/g fat (with the range 0.431-14.27), and in the rural area it was 6.448pg WHO-TEQ/g fat (0.539-12.61). CONCLUSIONS: The results obtained in this study indicate that the mothers were exposed uniformly to PCDD/Fs and PCBs regardless of location. The significant difference of p<0.1 between the milk samples from the urban and rural mothers in 2,3,7,8-TCDD; 1,2,37,8,9-HxCDD and 2,3,4,6,7-HxCDF were observed. For the other 14 PCDD/F and 12 dl-PCB congeners, the observed differences were not significant. The total WHO-TEQ values are lower in comparison with the average results in Europe from the fourth round of a WHO-coordinated study.

Biological monitoring versus air monitoring strategies in assessing environmental-occupational exposure.

Assessment of environmental and occupational exposure to chemicals can be performed with environmental monitoring (EM) and biological monitoring (BM). Biological monitoring was for a long time considered as a method complementary to environmental monitoring. At present this attitude is changing and in certain areas biological monitoring is applied as the method of choice for exposure and health-risk assessment. This paper examines advantages and disadvantages of those two approaches. In occupational settings environmental monitoring of exposure to VOCs seems to be superior to biological monitoring (possibility of simultaneous determination of components of mixtures, simple interpretation, possibility of evaluation of short-term exposure to local irritants). In the case of this group of compounds BM can be useful in selected cases such as evaluation of dermal absorption or efficiency of protective measures. In the case of metals both forms of monitoring can be used depending on the available methods for interpretation of results. BM of exposure may be considered as superior for evaluating the effects of exposure to lead, cadmium and mercury. However, quantitative evaluation of cancer risk after exposure to arsenic or chromium is possible only on the basis of determination in the air and the use of unit risk values. Both environmental and biological monitoring are useful for evaluation of occupational and environmental exposure to polycyclic aromatic hydrocarbons (PAHs). In certain areas such as evaluation of exposure to external tobacco smoking, cytostatic drugs, and pesticides, biological monitoring is the method of choice used for individual exposure assessment or tracing the trends of environmental exposure.

Evaluation of the TRA ECETOC model for inhalation workplace exposure to different organic solvents for selected process categories.

OBJECTIVE: The aim of this work is to describe the operation principle of the TRA ECETOC model developed using the descriptor system, and the utilization of that model for assessment of inhalation exposures to different organic solvents for selected process categories identifying a given application. METHOD: Measurement results were available for toluene, ethyl acetate and acetone in workplace atmosphere in Poland. The following process categories have been postulated: (1) Paints and lacquers factory: use in closed, continuous process with occasional controlled exposure; (2) Shoe factory: roller or brush application of glues; (3) Refinery: use in closed process, no likelihood of exposure. The next step was to calculate the workplace concentration at chosen process categories by applying the TRA ECETOC model. RESULTS: The selected categories do not precisely describe the studied applications. Very high concentration values of acetone were measured in the shoe factory, mean 443 ppm. The concentration obtained with the aid of the model is underestimated, ranging from 25.47 to 254.7 ppm, for the case with and without activation of the local exhaust ventilation (LEV), respectively. Estimated concentration at a level corresponding to that of the measured concentration would be possible if the process category involving spraying, e.g., PROC 7 was considered. For toluene and ethyl acetate, the measured concentrations are within the predicted ranges determined with the use of the model when we assume the concentration predicted with active ventilation for the beginning, and the concentration predicted with inactive ventilation for the end of the range. CONCLUSIONS: Model TRA ECETOC can be easily used to assess inhalation exposure at workplace. It has numerous advantages, its structure is clear, requires few data, is available free of charge. Selection of appropriate process categories related to the uses identified is guarantee of successful exposure assessment.

Low-level environmental lead exposure and intellectual impairment in children--the current concepts of risk assessment.

Lead is an environmental contaminant. The majority of epidemiological research on the health effects of lead has been focused on children, because they are more vulnerable to lead than adults. In children, an elevated blood lead (B-Pb) is associated with reduced Intelligence Quotient (IQ) score. This paper summarizes the current opinions on the assessment of the health risk connected with the children's environmental exposure to lead. The B-Pb level of concern of 100 µg/l proposed by the US Centers of Disease Control in 1991 was for a long time accepted as the guideline value. In the meantime there has been a significant worldwide decrease of B-Pb levels in children and present geometric mean values in the European countries range from 20 to 30 µg/l. The recent analyses of the association of intelligence test scores and B-Pb levels have revealed that the steepest declines in IQ occur at blood levels < 100 µg/l and that no threshold below which lead does not cause neurodevelopmental toxicity can be defended. European Food Safety Authority (EFSA) concluded in 2010, on the basis of results of Benchmark Dose (BMD) analysis, that an increase in B-Pb of 12 µg/l (BMDL01) could decrease the IQ score by one point. It seems that this value can be used as a "unit risk" to calculate the possible decrease of IQ and, consequently, influence of the low-level exposure to lead (< 100 µg/l) on the health and socioeconomic status of the exposed population.

[Application of predictive model to estimate concentrations of chemical substances in the work environment]. / Zastosowanie modelu predykcyjnego do szacowania wielkosci stezen wybranych substancji chemicznych w powietrzu srodowiska pracy.

BACKGROUND: Based on the Estimation and Assessment of Substance Exposure (EASE) predictive model implemented into the European Union System for the Evaluation of Substances (EUSES 2.1.), the exposure to three chosen organic solvents: toluene, ethyl acetate and acetone was estimated and compared with the results of measurements in workplaces. MATERIAL AND METHODS: Prior to validation, the EASE model was pretested using three exposure scenarios. The scenarios differed in the decision tree of pattern of use. Five substances were chosen for the test: 1,4-dioxane tert-methyl-butyl ether, diethylamine, 1,1,1-trichloroethane and bisphenol A. After testing the EASE model, the next step was the validation by estimating the exposure level and comparing it with the results of measurements in the workplace. We used the results of measurements of toluene, ethyl acetate and acetone concentrations in the work environment of a paint and lacquer factory, a shoe factory and a refinery. Three types of exposure scenarios, adaptable to the description of working conditions were chosen to estimate inhalation exposure. RESULTS: Comparison of calculated exposure to toluene, ethyl acetate and acetone with measurements in workplaces showed that model predictions are comparable with the measurement results. Only for low concentration ranges, the measured concentrations were higher than those predicted. CONCLUSIONS: EASE is a clear, consistent system, which can be successfully used as an additional component of inhalation exposure estimation. If the measurement data are available, they should be preferred to values estimated from models. In addition to inhalation exposure estimation, the EASE model makes it possible not only to assess exposure-related risk but also to predict workers' dermal exposure.

Unmetabolized VOCs in urine as biomarkers of low level occupational exposure.

OBJECTIVES: To compare the usefulness of determining unchanged forms of volatile organic compounds (VOCs), namely toluene (TOL), ethylbenzene (EB) and xylene (XYL), in urine with the effectiveness of the already used biomarkers of occupational exposure. MATERIALS AND METHODS: Surveys were conducted in two workplaces (paint factory and footwear factory). In total, 65 subjects participated in the study. Air samples were collected using individual samplers during work shift. Urine and blood samples were collected at the end of work shift. Urine samples were analyzed for unchanged compounds and selected metabolites, while blood samples were tested for unchanged compounds. VOCs in blood and urine were determined by solid phase microextraction gas chromatography (SPME-GC-MS). RESULTS: In the paint factory, the geometric mean (GM) concentrations of VOCs in the air ranged as follows: 0.2-4.7 mg/m(3) for TOL, 0.4-40.9 mg/m(3) for EB and 0.1-122.6 mg/m(3) for XYL. In the footwear factory, the GM concentration of TOL in the air amounted to 105.4 mg/m(3). A significant correlation (p < 0.05) was observed between VOCs in blood, urine and air. The regression analyses performed for paint factory workers showed that TOL-U and TOL-B were better biomarkers of exposure (r = 0.72 and r = 0.81) than benzoic acid (r = 0.12) or o-cresol (r = 0.55). CONCLUSION: The findings of the study point out that the concentration of unchanged VOCs in urine can be a reliable biological indicator of low level occupational exposure to these compounds.

A proposal for calculating occupational exposure limits for volatile organic compounds acting as sensory irritants on the basis of their physicochemical properties.

A common biological effect of exposure to workplace chemicals is sensory irritation. The ACGIH(R) threshold limit values (TLVs(R)) are developed based on data derived from industrial settings as well as experimental human and animal studies. Considering the limited amount of human data and the tendency to reduce the volume of animal testing, there is a need for an alternative method to assess sensory irritation. Nasal pungency involves transfer of a compound through the mucosa into the receptor area. This environment is inhomogeneous, being partly a hydrophobic lipid-like and hydrophilic aqueous-like area. A general equation has been developed that seems satisfactory for explaining the transfer of volatile organic compounds (VOCs) from the gaseous phase to biophases, making it possible to calculate the nasal pungency threshold (NPT). The obtained correlation between log 1/NPT and log TLV for 71 VOCs, which is based exclusively on their irritant properties, indicates that for the compounds that act through a nonreactive mechanism (alcohols, ketones, esters, ethers, aromatic and aliphatic hydrocarbons, amides) the relationship between these values differs from that calculated for compounds that act through a reactive mechanism (aldehydes, allyl compounds, aliphatic amines, benzyl halides, carboxylic acids, acrylates, and mercaptans). The correlation coefficient for nonreactive VOCs is very high (n = 46, r = 0.89), and it appears that the regression equation (log TLV = -0.422 log 1/NPT + 0.309) could be used to predict occupational exposure limits (OELs) for this group of compounds. Regarding reactive VOCs, the correlation coefficient is considerably lower (n = 25, r = 0.32), which implies that some kind of correction for their reactivity would have to be applied to calculate the OEL values.

Calculating the dermal flux of chemicals with OELs based on their molecular structure: An attempt to assign the skin notation.

Our objectives included calculating the permeability coefficient and dermal penetration rates (flux value) for 112 chemicals with occupational exposure limits (OELs) according to the LFER (linear free-energy relationship) model developed using published methods. We also attempted to assign skin notations based on each chemical's molecular structure. There are many studies available where formulae for coefficients of permeability from saturated aqueous solutions (K(p)) have been related to physicochemical characteristics of chemicals. The LFER model is based on the solvation equation, which contains five main descriptors predicted from chemical structure: solute excess molar refractivity, dipolarity/polarisability, summation hydrogen bond acidity and basicity, and the McGowan characteristic volume. Descriptor values, available for about 5000 compounds in the Pharma Algorithms Database were used to calculate permeability coefficients. Dermal penetration rate was estimated as a ratio of permeability coefficient and concentration of chemical in saturated aqueous solution. Finally, estimated dermal penetration rates were used to assign the skin notation to chemicals. Defined critical fluxes defined from the literature were recommended as reference values for skin notation. The application of Abraham descriptors predicted from chemical structure and LFER analysis in calculation of permeability coefficients and flux values for chemicals with OELs was successful. Comparison of calculated K(p) values with data obtained earlier from other models showed that LFER predictions were comparable to those obtained by some previously published models, but the differences were much more significant for others. It seems reasonable to conclude that skin should not be characterised as a simple lipophilic barrier alone. Both lipophilic and polar pathways of permeation exist across the stratum corneum. It is feasible to predict skin notation on the basis of the LFER and other published models; from among 112 chemicals 94 (84%) should have the skin notation in the OEL list based on the LFER calculations. The skin notation had been estimated by other published models for almost 94% of the chemicals. Twenty-nine (25.8%) chemicals were identified to have significant absorption and 65 (58%) the potential for dermal toxicity. We found major differences between alternative published analytical models and their ability to determine whether particular chemicals were potentially dermotoxic.

Calculating the retention of volatile organic compounds in the lung on the basis of their physicochemical properties.

In the workplace, deliberate or accidental exposure to volatile organic compounds (VOCs) may occur by ingestion, but more usually through inhalation or dermal contact. The basic model of occupational exposure assumes repeated inhalation exposure during long periods of time, such as 8-h daily, 40-h per working week. Evaluation of the systemic health effects of industrial chemicals can be based on biological levels or internal doses absorbed in dermal or inhalation exposures. The lungs are the primary route of absorption in exposure to gases, vapors, and aerosols. In inhalation exposure, the dose absorbed can be calculated using the following equation: [formula in text] where C, concentration in the air; T, duration of exposure; V, lung ventilation; R, lung retention expressed as % of intake. As lung retention of VOCs has been studied on human volunteers in costly and time-consuming chamber-type experiments, available data are limited. To calculate dosage for the purpose of risk assessment, the default value of 100% is used. As the lung retention of VOCs in lungs can vary from less than 20 to more than 90%, a possibility of predicting the retention values on the basis of blood/air partition coefficients (K(B)) has been investigated. Lung retention data for 36 compounds were obtained from the existing scientific literature. These values derive from human volunteer studies lasting at least 2h. The K(B) values were either the already published experimental data or were calculated based on their physicochemical properties using a published solvation equation. The compounds under study were divided arbitrarily into two groups: water soluble (>10 g/l) and slightly soluble in water (<10 g/l) compounds. For water soluble compounds, the correlation between K(B) and lung retention was high (r=0.75 and 0.73 respectively); this referred both to K(B) values obtained experimentally or calculated in this report. For the compounds slightly soluble in water, the respective values amounted to 0.79 and 0.82. The obtained results indicate that VOC retention in the lung can be calculated solely on the basis of the partition coefficient K(B). As the descriptors used in the solvation equation can be predicted from chemical structure, this finding indicates that it is possible to assess lung retention for any chemical structure of VOC. The model described in the present report can be a practical alternative to the necessity costly and long-lasting chamber-type experiments which are also questionable on ethical grounds.

Excretion of unchanged volatile organic compounds (toluene, ethylbenzene, xylene and mesitylene) in urine as result of experimental human volunteer exposure.

OBJECTIVES: To investigate elimination of unchanged volatile organic compounds (VOC's) through urine and the use of respective data for occupational exposure assessment, six volunteers were exposed under controlled conditions to toluene (TOL), ethylbenzene (EB), xylene (XYL) and mesitylene (MES) at concentrations ranging from 20 to 200 mg/m(3). The study was to elicit the toxicokinetic data and compare the precision of VOC's exposure assessment based on determining unchanged compounds in blood, urine and their metabolites in urine. METHODS: During and after exposure blood and urine samples were analysed by gas chromatography using the headspace and SPME headspace technique RESULTS: The kinetics of VOC's elimination in urine complied with an open two-compartment model. The (half-time) T (1/2 )values varied from 0.45 to 0.88 h for phase I and from 6.7 to 19.2 h for phase II. The precision of the method for unchanged VOC's was similar to that based on unchanged compounds in blood and better than their main metabolites in urine. CONCLUSION: The obtained result indicate that determining unchanged VOC's in urine can be used as an exposure test even in the ranges of VOC's in the air that are much lower than the current TWA for occupational exposure.

Renal and neurologic effects of cadmium, lead, mercury, and arsenic in children: evidence of early effects and multiple interactions at environmental exposure levels.

Lead, cadmium, mercury, and arsenic are common environmental pollutants in industrialized countries, but their combined impact on children's health is little known. We studied their effects on two main targets, the renal and dopaminergic systems, in > 800 children during a cross-sectional European survey. Control and exposed children were recruited from those living around historical nonferrous smelters in France, the Czech Republic, and Poland. Children provided blood and urine samples for the determination of the metals and sensitive renal or neurologic biomarkers. Serum concentrations of creatinine, cystatin C, and beta2-microglobulin were negatively correlated with blood lead levels (PbB), suggesting an early renal hyperfiltration that averaged 7% in the upper quartile of PbB levels (> 55 microg/L; mean, 78.4 microg/L). The urinary excretion of retinol-binding protein, Clara cell protein, and N-acetyl-beta-d-glucosaminidase was associated mainly with cadmium levels in blood or urine and with urinary mercury. All four metals influenced the dopaminergic markers serum prolactin and urinary homovanillic acid, with complex interactions brought to light. Heavy metals polluting the environment can cause subtle effects on children's renal and dopaminergic systems without clear evidence of a threshold, which reinforces the need to control and regulate potential sources of contamination by heavy metals. Key words: arsenic, biomarkers, cadmium, dopaminergic, heavy metals, interactions, lead, mercury, renal.

[Effectiveness of preventive actions for lead exposed workers: an assessment based on biological monitoring]. / Ocena skutecznosci dzialan profilaktycznych u pracowników narazonych na olów na podstawie badan monitoringu biologicznego.

Biological monitoring plays a significant part in the assessment of occupational exposure to lead. The method basically comprises determinations of blood lead concentration and of one of early toxic-effect biomarkers: the level of either zincprotoporphyrin (ZnPP) in blood or deltaaminolevulinic acid (ALA) in urine. However, biological monitoring is conducted only in 25% of all industrial plants, where the employed technological processes are the source of occupational lead exposure. The project that has been implemented by the Nofer Institute of Occupational Medicine, Lódz, Poland and Outpatient Clinic for Occupational Health, Poznan, Poland, since 1997 made it possible to assess the dynamics of lead exposure in one of the largest battery plants in Western Poland. Based on the analysis of blood lead determinations in lead-exposed workers, the authors could trace the effectiveness of the project aimed at reducing lead exposure in the plant. The findings revealed that the preventive measures applied over the years 1997-2005 resulted in a considerably decreased percentage of blood lead concentrations exceeding the relevant BEI (biological exposure index) value of 500 microg/l: from 19% in 1997 to 1% in 2005. Such a high effectiveness of the project can be mostly attributed to a successful cooperation between the occupational physician, in-plant occupational health services, and the employer. They were all actively involved in a wide-range of activities for workers' health protection and workplace health promotion.