Pooled analysis of genotoxicity markers in relation to exposure in the Flemish Environment and Health Studies (FLEHS) between 1999 and 2018.

BACKGROUND: The Flemish Environment and Health Studies (FLEHS) are human biomonitoring surveys running in Flanders since 1999. Additionally to biomarkers of exposure, markers of genotoxicity and oxidative stress have been measured, including the alkaline comet and micronucleus assay in peripheral whole blood cells, and urinary concentrations of 8-oxo-2'-deoxyguanosine (8-oxodG). AIM: Exposure-effect associations were explored in a pooled dataset of nine different cross-sectional FLEHS surveys. Data of adolescents collected in a time frame of about 20 years (1999-2018) were compiled. The aim of the study was to examine whether increased variation in exposure, lifestyle and environmental factors would lead to more powerful and robust exposure-effect associations. MATERIALS & METHODS: The biomarkers were measured in 2283 adolescents in the age range of 14-18 years. Exposure to polycyclic aromatic hydrocarbons [1-hydroxypyrene (1-OHP)], benzene (tt'-muconic acid), metals (arsenic, cadmium, copper, nickel, thallium, lead, chromium), persistent organochlorines and phthalates were assessed in blood or urine. Furthermore, outdoor air levels of particulate matter (PM10 and PM2.5) at the residences of the youngsters were calculated. Pooled statistical analysis was done using mixed models. Study-specific differences in the genotoxicity markers and in the strength/direction of the association were accounted for. This was done by incorporating the random factor 'study' and a random study slope (if possible). The exposure markers were centered around the study-specific mean in order to correct for protocol changes over time. RESULTS: A significant association was observed for the urinary oxidative stress marker 8-oxodG, which was positively associated with 1-OHP (5% increase for doubling of 1-OHP levels, p = 0.001), and with urinary copper (26% increase for doubling of copper levels, p = 0.001), a metal involved in the Fenton reaction in biological systems. 8-oxodG was also associated with the sum of the metabolites of the phthalate di(2-ethylhexyl) phthalate (DEHP) (3% increase for doubling of the DEHP levels, p = 0.02). For those associations, data pooling increased the statistical power. However, some of the associations in the individual surveys, were not confirmed in the pooled analysis (such as comet assay and 8-oxodG vs. atmospheric PM; and 8-oxodG vs. urinary nickel). This may be due to inconsistencies in exposure-effect relations and/or variations in the pollutant mix over time and regions. CONCLUSION: Pooled analysis including a large population of 2283 Flemish adolescents showed that 8-oxodG, a marker of oxidative DNA damage is a valuable marker to assess impact of daily life pollutants, such as PAHs, Cu and the phthalate DEHP.

Gender differences in cadmium and cotinine levels in prepubertal children.

Susceptibility to environmental stressors has been described for fetal and early childhood development. However, the possible susceptibility of the prepubertal period, characterized by the orchestration of the organism towards sexual maturation and adulthood has been poorly investigated and exposure data are scarce. In the current study levels of cadmium (Cd), cotinine and creatinine in urine were analyzed in a subsample 216 children from 12 European countries within the DEMOCOPHES project. The children were divided into six age-sex groups: boys (6-8 years, 9-10 years and 11 years old), and girls (6-7 years, 8-9 years, 10-11 years). The number of subjects per group was between 23 and 53. The cut off values were set at 0.1 µg/L for Cd, and 0.8 µg/L for cotinine defined according to the highest limit of quantification. The levels of Cd and cotinine were adjusted for creatinine level. In the total subsample group, the median level of Cd was 0.180 µg/L (range 0.10-0.69 µg/L), and for cotinine the median wet weight value was 1.50 µg/L (range 0.80-39.91 µg/L). There was no significant difference in creatinine and cotinine levels between genders and age groups. There was a significant correlation between levels of cadmium and creatinine in all children of both genders. This shows that even at such low levels the possible effect of cadmium on kidney function was present and measurable. An increase in Cd levels was evident with age. Cadmium levels were significantly different between 6-7 year old girls, 11 year old boys and 10-11 year old girls. As there was a balanced distribution in the number of subjects from countries included in the study, bias due to data clustering was not probable. The impact of low Cd levels on kidney function and gender differences in Cd levels needs further investigation.

A pilot study on the feasibility of European harmonized human biomonitoring: Strategies towards a common approach, challenges and opportunities.

In 2004 the European Commission and Member States initiated activities towards a harmonized approach for Human Biomonitoring surveys throughout Europe. The main objective was to sustain environmental health policy by building a coherent and sustainable framework and by increasing the comparability of data across countries. A pilot study to test common guidelines for setting up surveys was considered a key step in this process. Through a bottom-up approach that included all stakeholders, a joint study protocol was elaborated. From September 2011 till February 2012, 17 European countries collected data from 1844 mother-child pairs in the frame of DEMOnstration of a study to COordinate and Perform Human Biomonitoring on a European Scale (DEMOCOPHES).(1) Mercury in hair and urinary cadmium and cotinine were selected as biomarkers of exposure covered by sufficient analytical experience. Phthalate metabolites and Bisphenol A in urine were added to take into account increasing public and political awareness for emerging types of contaminants and to test less advanced markers/markers covered by less analytical experience. Extensive efforts towards chemo-analytical comparability were included. The pilot study showed that common approaches can be found in a context of considerable differences with respect to experience and expertize, socio-cultural background, economic situation and national priorities. It also evidenced that comparable Human Biomonitoring results can be obtained in such context. A European network was built, exchanging information, expertize and experiences, and providing training on all aspects of a survey. A key challenge was finding the right balance between a rigid structure allowing maximal comparability and a flexible approach increasing feasibility and capacity building. Next steps in European harmonization in Human Biomonitoring surveys include the establishment of a joint process for prioritization of substances to cover and biomarkers to develop, linking biomonitoring surveys with health examination surveys and with research, and coping with the diverse implementations of EU regulations and international guidelines with respect to ethics and privacy.

Human biomonitoring guidance values (HBM-GVs) for priority substances under the HBM4EU initiative - New values derivation for deltamethrin and cyfluthrin and overall results.

The European Initiative HBM4EU aimed to further establish human biomonitoring across Europe as an important tool for determining population exposure to chemicals and as part of health-related risk assessments, thus making it applicable for policy advice. Not only should analytical methods and survey design be harmonized and quality assured, but also the evaluation of human biomonitoring data. For the health-related interpretation of the data within HBM4EU, a strategy for deriving health-based human biomonitoring guidance values (HBM-GVs) for both the general population and workers was agreed on. On this basis, HBM-GVs for exposure biomarkers of 1,2-cyclohexane dicarboxylic acid diisononyl ester (DINCH), phthalates (diethyl hexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), butyl benzyl phthalate (BBzP), and bis-(2-propylheptyl) phthalate (DPHP)), bisphenols A and S, pyrethroids (deltamethrin and cyfluthrin), solvents (1-methyl-2-pyrrolidone (NMP), 1-ethylpyrrolidin-2-one (NEP), N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC)), the heavy metal cadmium and the mycotoxin deoxynivalenol (DON) were developed and assigned a level of confidence. The approach to HBM-GV derivations, results, and limitations in data interpretation with special focus on the pyrethroids are presented in this paper.

PFAS levels and exposure determinants in sensitive population groups.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants. The first exposure to PFAS occurs in utero, after birth it continues via breast milk, food intake, environment, and consumer products that contain these chemicals. Our aim was to identify determinants of PFAS concentrations in sensitive population subgroups- pregnant women and newborns. METHODS: Nine European birth cohorts provided exposure data on PFAS in pregnant women (INMA-Gipuzkoa, Sabadell, Valencia, ELFE and MoBa; total N = 5897) or newborns (3xG study, FLEHS 2, FLEHS 3 and PRENATAL; total N = 940). PFOS, PFOA, PFHxS and PFNA concentrations were measured in maternal or cord blood, depending on the cohort (FLEHS 2 measured only PFOS and PFOA). PFAS concentrations were analysed according to maternal characteristics (age, BMI, parity, previous breastfeeding, smoking, and food consumption during pregnancy) and parental educational level. The association between potential determinants and PFAS concentrations was evaluated using multiple linear regression models. RESULTS: We observed significant variations in PFAS concentrations among cohorts. Higher PFAS concentrations were associated with higher maternal age, primipara birth, and educational level, both for maternal blood and cord blood. Higher PFAS concentrations in maternal blood were associated with higher consumption of fish and seafood, meat, offal and eggs. In cord blood, higher PFHxS concentrations were associated with daily meat consumption and higher PFNA with offal consumption. Daily milk and dairy consumption were associated with lower concentrations of PFAS in both, pregnant women and newborns. CONCLUSION: High detection rates of the four most abundant PFAS demonstrate ubiquitous exposure of sensitive populations, which is of concern. This study identified several determinants of PFAS exposure in pregnant women and newborns, including dietary factors, and these findings can be used for proposing measures to reduce PFAS exposure, particularly from dietary sources.

Approaches to mixture risk assessment of PFASs in the European population based on human hazard and biomonitoring data.

Per- and polyfluoroalkyl substances (PFASs) are a highly persistent, mobile, and bioaccumulative class of chemicals, of which emissions into the environment result in long-lasting contamination with high probability for causing adverse effects to human health and the environment. Within the European Biomonitoring Initiative HBM4EU, samples and data were collected in a harmonized way from human biomonitoring (HBM) studies in Europe to derive current exposure data across a geographic spread. We performed mixture risk assessments based on recent internal exposure data of PFASs in European teenagers generated in the HBM4EU Aligned Studies (dataset with N = 1957, sampling years 2014-2021). Mixture risk assessments were performed based on three hazard-based approaches: the Hazard Index (HI) approach, the sum value approach as used by the European Food Safety Authority (EFSA) and the Relative Potency Factor (RPF) approach. The HI approach resulted in the highest risk estimates, followed by the RPF approach and the sum value approach. The assessments indicate that PFAS exposure may result in a health risk in a considerable fraction of individuals in the HBM4EU teenager study sample, thereby confirming the conclusion drawn in the recent EFSA scientific opinion. This study underlines that HBM data are of added value in assessing the health risks of aggregate and cumulative exposure to PFASs, as such data are able to reflect exposure from different sources and via different routes.

PFAS levels and determinants of variability in exposure in European teenagers - Results from the HBM4EU aligned studies (2014-2021).

BACKGROUND: Perfluoroalkyl substances (PFAS) are man-made fluorinated chemicals, widely used in various types of consumer products, resulting in their omnipresence in human populations. The aim of this study was to describe current PFAS levels in European teenagers and to investigate the determinants of serum/plasma concentrations in this specific age group. METHODS: PFAS concentrations were determined in serum or plasma samples from 1957 teenagers (12-18 years) from 9 European countries as part of the HBM4EU aligned studies (2014-2021). Questionnaire data were post-harmonized by each study and quality checked centrally. Only PFAS with an overall quantification frequency of at least 60% (PFOS, PFOA, PFHxS and PFNA) were included in the analyses. Sociodemographic and lifestyle factors were analysed together with food consumption frequencies to identify determinants of PFAS exposure. The variables study, sex and the highest educational level of household were included as fixed factors in the multivariable linear regression models for all PFAS and each dietary variable was added to the fixed model one by one and for each PFAS separately. RESULTS: The European exposure values for PFAS were reported as geometric means with 95% confidence intervals (CI): PFOS [2.13 µg/L (1.63-2.78)], PFOA ([0.97 µg/L (0.75-1.26)]), PFNA [0.30 µg/L (0.19-0.45)] and PFHxS [0.41 µg/L (0.33-0.52)]. The estimated geometric mean exposure levels were significantly higher in the North and West versus the South and East of Europe. Boys had significantly higher concentrations of the four PFAS compared to girls and significantly higher PFASs concentrations were found in teenagers from households with a higher education level. Consumption of seafood and fish at least 2 times per week was significantly associated with 21% (95% CI: 12-31%) increase in PFOS concentrations and 20% (95% CI: 10-31%) increase in PFNA concentrations as compared to less frequent consumption of seafood and fish. The same trend was observed for PFOA and PFHxS but not statistically significant. Consumption of eggs at least 2 times per week was associated with 11% (95% CI: 2-22%) and 14% (95% CI: 2-27%) increase in PFOS and PFNA concentrations, respectively, as compared to less frequent consumption of eggs. Significantly higher PFOS concentrations were observed for participants consuming offal (14% (95% CI: 3-26%)), the same trend was observed for the other PFAS but not statistically significant. Local food consumption at least 2 times per week was associated with 40% (95% CI: 19-64%) increase in PFOS levels as compared to those consuming local food less frequently. CONCLUSION: This work provides information about current levels of PFAS in European teenagers and potential dietary sources of exposure to PFAS in European teenagers. These results can be of use for targeted monitoring of PFAS in food.

Internal exposure of Flemish teenagers to environmental pollutants: Results of the Flemish Environment and Health Study 2016-2020 (FLEHS IV).

The Flemish Environment and Health Study (FLEHS) collects information on internal exposure to a broad range of environmental chemicals in the general population in Flanders, the Northern region of Belgium. The aim is to establish biomonitoring exposure distributions for the general population in support of public health and environmental policy, environmental risk assessment and risk management decisions. In 2017-2018, urine and blood samples were collected from 428 teenagers by a stratified clustered two stage randomized design. Samples were analyzed for a broad range of biomarkers related to exposure to chlorinated and newer pesticides, brominated and organophosphate flame retardants (BFR/OPFR), polychlorinated biphenyls (PCBs), bisphenols, phthalates and alternative plasticizers, per-and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbons (PAHs), benzene, metals and trace elements. The geometric mean levels and percentiles of the distribution were estimated for each biomarker, for the whole study population and following stratification for sex, the household educational attainment and the residence area's urbanicity. Geometric means of biomarkers of lead, dichlorodiphenyltrichloroethane (DDT), PCBs, PAHs, regulated phthalates and bisphenol A (BPA) were lower than in the previous FLEHS cycles. Most biomarker levels were below health-based guidance values (HB-GVs). However, HB-GVs of urinary arsenic, blood lead, blood cadmium, sum of serum perfluorooctane sulfonate (PFOS) and perfluoro-1-hexanesulfonate (PFHxS) and the urinary pyrethroid metabolite (3-PBA) were exceeded in respectively 25%, 12%, 39.5%, 10% and 22% of the teenagers. These results suggest that the levels of exposure in the Flemish population to some environmental chemicals might be of concern. At the same time, we noticed that biomarkers for BPA substitutes, metabolites of OPFRs, an expanded list of PFAS, glyphosate and its metabolite could be measured in substantial proportions of participants. Interpretation of these levels in a health-risk context remains uncertain as HB-GVs are lacking. Household educational attainment and residential urbanicity were significant exposure determinants for many biomarkers and could influence specific biomarker levels up to 70% as shown by multiple regression analysis. The research consortium also took care of the broader external communication of results with participants, policy makers, professional groups and civil society organizations. Our study demonstrated that teenagers are exposed to a wide range of chemicals, it demonstrates the success of public policies to reduce exposure but also points to concern and further priorities and needs for follow up.

A new approach to study exhaled proteins as potential biomarkers for asthma.

BACKGROUND: Asthma is a complex clinical disease characterized by airway inflammation. Recently, various studies reported on the analysis of exhaled breath condensate (EBC) in the search for potential biomarkers for asthma. However, in a complex disease such as asthma, one biomarker might not be enough for early diagnosis or follow-up. OBJECTIVE: The use of proteome analysis may reveal disease-specific proteolytic peptide or protein patterns, and may lead to the identification of novel proteins for the detection of asthma. METHODS: Liquid chromatography and mass spectrometry were used to separate and detect proteins (proteolytic peptides) present in EBC samples from 30 healthy children and 40 children with asthma in the age group of 6-12 years. RESULTS: Support vector machine analysis resulted in differentiating profiles based on asthma status. These proteolytic peptide patterns were not correlated to some well known (spirometry, exhaled nitric oxide) and more recently described exhaled markers (EBC pH, LTB4). The more abundant proteins in EBC were identified as cytokeratins, albumin, actin, haemoglobin, lysozyme, dermcidin, and calgranulin B. CONCLUSION: Although the exact role in the disease development or physiological state of the airways of the proteins described in the presented pattern is not clear at this moment, this is an important step in the search for exhaled biomarkers for asthma. This study shows that EBC contains proteins that are of interest for future non-invasive asthma diagnosis or follow-up.

Translating biomonitoring data into risk management and policy implementation options for a European Network on Human Biomonitoring.

BACKGROUND: The "European Environment & Health Action Plan 2004-2010" originates from the concern of the European Commission on the well-being of individuals and the general population. Through this plan, the Commission has set the objectives to improve the information chain for a better understanding of the link between sources of pollution and health effects, to better identify existing knowledge gaps, and improve policy making and communication strategies. Human biomonitoring (HBM) has been included as one of the tools to achieve these objectives. As HBM directly measures the amount of a chemical substance in a person's body, taking into account often poorly understood processes such as bioaccumulation, excretion, metabolism and the integrative uptake variability through different exposure pathways, HBM data are much more relevant for risk assessment than extrapolations from chemical concentrations in soil, air, and water alone. However, HBM primarily is a stepping stone between environmental and health data, and the final aim should be an integrated and holistic systematic risk assessment paradigm where HBM serves as a pivotal point between environment and health, on the one hand leaning on environmental data to provide detailed information on the sources and pathways of pollutants that enter the human body, and on the other hand clarifying new and existing hypotheses on the relationship between environmental pollutants and the prevalence of diseases. With the large amount of data that is being gathered in the different national survey projects, and which is expected to become available in Europe in the near future through the expected European Pilot Project on HBM, a framework to optimize data interpretation from such survey projects may greatly enhance the usefulness of HBM data for risk managers and policy makers. RESULTS: This paper outlines an hierarchic approach, based on the stepwise formulation of 4 subsequent steps, that will eventually lead to the formulation of a variety of policy relevant risk reduction options. CONCLUSION: Although the usefulness of this approach still needs to be tested, and potential fine-tuning of the procedure may be necessary, approaching the policy implications of HBM in an objective framework will prove to be essential.

Gene expression profiling of in vitro cultured macrophages after exposure to the respiratory sensitizer hexamethylene diisocyanate.

Occupational exposure to chemicals is one of the main causes of respiratory allergy and asthma. Identification of chemicals that trigger allergic asthma is difficult as underlying processes and specific markers have not yet been clearly defined. Moreover, adequate classification of the respiratory toxicity of chemicals is hampered due to the lack of validated in vivo and in vitro test methods. The study of differential gene expression profiles in appropriate human in vitro cell systems is a promising approach to identify selective markers for respiratory allergy. As alveolar macrophages display important immunological and inflammatory properties in response to foreign substances in the lung, we aimed at gaining more insight in changes of human macrophages transcriptome and to identify selective genetic markers for respiratory sensitization in response to hexamethylene diisocyanate (HDI). In vitro cultures of human THP-1 cells were differentiated into macrophages and exposed to 55 microg/ml HDI for 6 and 10h. Using human oligonucleotide microarrays, changes were observed in the expression of genes that are involved in diverse biological and molecular processes, including detoxification, oxidative stress, cytokine signaling, and apoptosis, which can lead to the development of asthma. These genes are possible markers for respiratory sensitization caused by isocyanates.

Cell types involved in allergic asthma and their use in in vitro models to assess respiratory sensitization.

This review first describes the mechanism and cell types involved in allergic asthma, which is a complex clinical disease characterized by airway obstruction, airway inflammation and airway hyperresponsiveness to a variety of stimuli. The development of allergic asthma exists of three phases, namely the induction phase, the early-phase asthmatic reaction (EAR) and the late-phase asthmatic reaction (LAR). In the induction phase, antigen-presenting cells play a major role. Most important cells in the EAR are mast cells, and during the LAR, various cell types, such as eosinophils, neutrophils, T cells, macrophages, dendritic cells (DCs), and cells that endow structure are involved. In occupational asthma, this immunological mechanism is involved in 90% of the cases. The second part of this review gives an overview of in vitro models to assess the hazardous potential of high- and low-molecular weight chemicals on the respiratory system. In order to develop a good in vitro model for respiratory allergy, the choice of appropriate cell types is important. Epithelial cells, macrophages and DCs are currently the most used models in this field of research.

Successful prevalidation of the slug mucosal irritation test to assess the eye irritation potency of chemicals.

A previous 'in house' validation study showed that the SMI assay can be used as an alternative to the in vivo Draize eye irritation test. The aim of this multi-centre study with four participating laboratories was to assess the transferability and inter-laboratory variability of the assay using 20 reference chemicals covering the whole irritancy range. The eye irritation potency of the chemicals was assessed by measuring the amount of mucus produced during a 60-min contact period with a 1% dilution, and a second 60-min treatment with a 3.5% dilution. After each contact period the protein release from the mucosal surface was measured. Linear discriminant equations were used to convert the results into the corresponding EU eye irritation categories (NI, R36 and R41). All the non-irritants were predicted correctly by the four laboratories resulting in a 100% specificity. For the R36 compounds a correct classification rate of 89% (VITO) and 100% (SPL, JNJ and UGent) was obtained. The R41 compounds were classified correctly in 78% of the cases for VITO, 89% for SPL and JNJ and 100% for UGent. We can conclude that the SMI assay is a relevant, easily transferable and reproducible alternative to predict the eye irritation potency of chemicals.

Internal exposure to pollutants measured in blood and urine of Flemish adolescents in function of area of residence.

The Centre for Environment and Health in Flanders, the Northern part of Belgium, started a biomonitoring program on adolescents in 2003. 1679 adolescents residing in nine areas with different patterns of pollution participated in the study. Possible confounding effects of lifestyle and personal characteristics were taken into account. The geometric mean levels of cadmium and lead in whole blood amounted to 0.36 and 21.7 microg l(-1), those of PCBs, DDE and HCB in serum to 68, 94 and 20.9 ng g(-1) fat, and those of 1-hydroxypyrene and t,t'-muconic acid in urine to 88 ng g(-1) creatinine and 72 microg g(-1) creatinine. Significant regional differences in internal lead, cadmium, PCBs, DDE and HCB exposure were observed in function of area of residence, even after adjustment for age, sex, smoking (and body mass index for the chlorinated compounds). Compared to a reference mean, internal exposure was significantly higher in one or more of the areas: Cd and Pb in the Antwerp agglomeration, Cd in the Antwerp harbour, PCBs in the Ghent agglomeration, PCBs, DDE and HCB in the Ghent harbour, Cd, PCBs, DDE and HCB in the rural area, DDE in Olen and in the Albert canal areas. Adolescents living in an area with intensive fruit cultivation (showing overall the lowest values) and, surprisingly, in areas around household waste incinerators (average of six areas), had no significantly increased internal exposures. Subjects from separate areas around waste incinerators showed significant differences in body load of various environmental contaminants.

Determinants of variability of protein content, volume and pH of exhaled breath condensate.

Collection of exhaled breath condensate (EBC) is a simple and noninvasive method to obtain information on the respiratory system. Different mediators can be determined in EBC. However, determinants of variability are not well described. The aim of this study was to evaluate variability of pH, volume and protein concentration of EBC between individuals and between sampling times. Therefore, EBC was collected from 20 healthy volunteers on two different days. Median pH for all samples, measured 5 min after collection without deaeration, was 6.17. Median volume was 1.70 ml and median total protein concentration was 1.02 microg/ml. Coefficients of variation were 5.17%, 21.84% and 37.93%, respectively. No intra- or interday variability could be found, except for the first collection time. Between individuals, significant differences were observed for all three mediators. Age, height and gender can explain part of this variation. In conclusion, no significant difference between sampling times on the same day or on different days was obtained for pH, volume and total protein concentration, provided that subjects are experienced in collecting EBC.

Identifying opportunities and gaps for establishing an integrated EDR-triad at a European level.

It is the explicit objective of the ESBIO project (Expert team to Support BIOmonitoring in Europe) to develop a harmonized and integrated human biomonitoring (HBM) framework within the EU, and to elaborate how HBM can be integrated most efficiently with environmental monitoring and registered health data. Work package 3 of the ESBIO projects aims at developing scenarios for linking biomonitoring data to available data on environmental exposure and population health. Although it is recognized that there is a wide variety of data available, it is often difficult to integrate these different data layers because of differences in database structures, geographical detail and spatial distribution, or most importantly because the data simply were not meant to be interpreted in the context of integrated human risk assessment. This paper briefly explores the available information on Europe-wide environmental quality and health data that could be used in cooperation with HBM. Because ESBIO focuses on the whole of Europe, but also needs opportunities for further refinement on a more detailed local scale, the applicability of geographical information systems (GIS) in environmental health, HBM and human health assessments were highlighted. It was concluded that there is an abundance of information on the presence and behavior of pollutants in the environment for some compartments (e.g., ambient air), while for other compartments, measurements are more difficult to gather, and/or no clearly defined geographically explicit networks appear to be in place.

Flow cytometric characterisation of antigen presenting dendritic cells after in vitro exposure to diesel exhaust particles.

The aim of this study was to obtain more insight into the effect of diesel exhaust particles (DEP) on the maturation of primary human dendritic cells. Monocyte-derived dendritic cells (Mo-DC) derived from seven different donors were exposed to different DEP concentrations (0.2,2,20,200 and 2,000 ng/ml) in the presence or absence of lipopolysaccharide (LPS), and changes in the surface expression of HLA-DR, CD86 and CD83 were examined. Exposure of Mo-DC to DEP alone did not alter expression levels of any of the markers. Treatment with LPS alone increased the expression levels of all three surface markers, although the levels were not significantly different compared to untreated DCs. The LPS-induced marker expression could be further enhanced by co-stimulation of the cells with DEP. Statistical significantly increased levels of CD83 expression were observed after exposure to 0.2 (p=0.018), 20 (p=0.010) and 200 ng/ml (p=0.047) DEP combined with LPS in the group of responders. We conclude that DEP has an adjuvant effect on LPS-induced maturation of Mo-DC.

Expression analysis of immune-related genes in CD34(+) progenitor-derived dendritic cells after exposure to the chemical contact allergen DNCB.

We studied the changes in gene expression after exposure of human dendritic cells (DCs) to the model allergen dinitrochlorobenzene (DNCB). DCs were derived from CD34(+) progenitor cells of three different donors and exposed to 10 microM DNCB or solvent for several time intervals (3, 6 and 12h). cDNA microarrays were used to assess the transcriptional activity of 11,000 human genes. Compared to control gene expression, changes larger than +/-two-fold were observed for 241 genes after exposure to DNCB. Of these genes, 137 were up-regulated and 104 down-regulated. Twenty of these genes encode proteins that are related to the immune response (cytokines, chemokines, their receptors, cytokine/chemokines-related genes, transcription and signal transduction genes) and are discussed in more detail. Our data indicate that exposure to DNCB does not induce a typical maturation pattern in DCs.

Stromal cells in long-term cultures of liver, spleen, and bone marrow at different developmental ages have different capacities to maintain GM-CFC proliferation.

Measurements were made of the granulocyte-macrophage colony-forming cell (GM-CFC) yield in long-term cultures established from different combinations of stroma and hemopoietic recharge inocula derived from hemopoietic organs at different stages of their embryological development. Results indicated differences in the supporting capacity of the stroma, related to the hemopoietic activity of the organ of origin. Stroma derived from hemopoietically active organs (adult bone marrow, neonatal spleen, fetal liver) supported the proliferation of GM-CFC to a larger extent than stroma derived from organs with a low hemopoietic activity (neonatal bone marrow liver at 2 days; spleen at 3 weeks). Regardless of the origin of the hemopoietic cells, stroma from adult bone marrow displayed the highest ability to support GM-CFC proliferation. The capacity of GM-CFC from hemopoietic recharge cell populations to proliferate on stroma was not related to the hemopoietic activity of their organ of origin. Regardless of their organ of origin the GM-CFC present in each of the different hemopoietic recharge populations were able to proliferate provided that they were seeded on an appropriate stroma. These experiments showed that stromal cells cultured from hemopoietic organs at different developmental ages determine the hemopoietic activity of long-term cultures as measured via GM-CFC recovery.