SARS-CoV-2 incidence in secondary schools; the role of national and school-initiated COVID-19 measures.

INTRODUCTION: Our aim was to gain insight into the effect of COVID-19 measures on SARS-CoV-2 incidence in secondary schools and the association with classroom CO2 concentration and airborne contamination. METHODS: Between October 2020-June 2021, 18 schools weekly reported SARS-CoV-2 incidence and completed surveys on school-initiated COVID-19 measures (e.g. improving hygiene or minimizing contacts). CO2 was measured in occupied classrooms twice, and SARS-CoV-2 air contamination longitudinally using electrostatic dust collectors (EDC) and analyzed using RT-qPCR. National COVID-19 policy measures varied during pre-lockdown, lockdown and post-lockdown periods. During the entire study, schools were recommended to improve ventilation. SARS-CoV-2 incidence rate ratios (IRR) were estimated by Generalized Estimating Equation (GEE) models. RESULTS: During 18 weeks follow-up (range: 10-22) SARS-CoV-2 school-incidence decreased during national lockdown (adjusted IRR: 0.41, 95%CI: 0.21-0.80) and post-lockdown (IRR: 0.60, 0.39-0.93) compared to pre-lockdown. School-initiated COVID-19 measures had no additional effect. Pre-lockdown, IRRs per 10% increase in time CO2 exceeded 400, 550 and 800 ppm above outdoor level respectively, were 1.08 (1.00-1.16), 1.10 (1.02-1.19), and 1.08 (0.95-1.22). Post-lockdown, CO2-concentrations were considerably lower and not associated with SARS-CoV-2 incidence. No SARS-CoV-2 RNA was detected in any of the EDC samples. CONCLUSION: During a period with low SARS-CoV-2 population immunity and increased attention to ventilation, with CO2 levels most of the time below acceptable thresholds, only the national policy during and post-lockdown of reduced class-occupancy, stringent quarantine, and contact testing reduced SARS-CoV-2 incidence in Dutch secondary schools. Widespread SARS-CoV-2 air contamination could not be demonstrated in schools under the prevailing conditions during the study.

An approach to the asthma-protective farm effect by geocoding: Good farms and better farms.

BACKGROUND: The highly consistent association of growing up on a farm with a reduced asthma risk has so far been attributed to direct farm exposure. In contrast, geographic determinants of the larger environment have never been assessed. In this study, the effects of proximity to farms and environmental variables in relation to the residential address on asthma and atopy were assessed. METHODS: Addresses of 2265 children of the Bavarian arm of the GABRIELA study were converted into geocodes. Proximity to the nearest cow farm was calculated, and environmental characteristics were derived from satellite data or terrestrial monitoring. Bacterial diversity in mattress dust samples was assessed in 501 children by sequencing of the 16S rRNA amplicons. Logistic regression models were used to calculate associations between outcomes and exposure variables. RESULTS: Asthma and atopy were inversely associated with the presence of a farm within a radius of maximum 100 m. The environmental variables greenness, tree cover, soil sealing, altitude, air pollution differed not only between farm and non-farm children but also between farm children with and without another farm nearby. The latter distinction revealed strong associations with characteristics of traditional farms including a broader diversity of microbial exposure, which mainly contributed to the protective effect on asthma. In non-farm children, the protective effect of a farm nearby was completely explained by consumption of farm milk. CONCLUSIONS: Clustering of farms within a neighborhood of 100 m is strongly associated with the protective effect on asthma and may represent a more traditional style of farming with broader microbial exposure.

Environmental and mucosal microbiota and their role in childhood asthma.

BACKGROUND: High microbial diversity in the environment has been associated with lower asthma risk, particularly in children exposed to farming. It remains unclear whether this effect operates through an altered microbiome of the mucosal surfaces of the airways. METHODS: DNA from mattress dust and nasal samples of 86 school age children was analyzed by 454 pyrosequencing of the 16S rRNA gene fragments. Based on operational taxonomic units (OTUs), bacterial diversity and composition were related to farm exposure and asthma status. RESULTS: Farm exposure was positively associated with bacterial diversity in mattress dust samples as determined by richness (P = 8.1 × 10-6 ) and Shannon index (P = 1.3 × 10-5 ). Despite considerable agreement of richness between mattress and nasal samples, the association of richness with farming in nasal samples was restricted to a high gradient of farm exposure, that is, exposure to cows and straw vs no exposure at all. In mattress dust, the genera Clostridium, Facklamia, an unclassified genus within the family of Ruminococcaceae, and six OTUs were positively associated with farming. Asthma was inversely associated with richness [aOR = 0.48 (0.22-1.02)] and Shannon index [aOR = 0.41 (0.21-0.83)] in mattress dust and to a lower extent in nasal samples [richness aOR 0.63 = (0.38-1.06), Shannon index aOR = 0.66 (0.39-1.12)]. CONCLUSION: The stronger inverse association of asthma with bacterial diversity in mattress dust as compared to nasal samples suggests microbial involvement beyond mere colonization of the upper airways. Whether inhalation of metabolites of environmental bacteria contributes to this phenomenon should be the focus of future research.

ESBL carriage in pig slaughterhouse workers is associated with occupational exposure.

We investigated the prevalence of extended-spectrum ß-lactamase (ESBL) carriage in slaughterhouse workers and the association with occupational exposure to slaughter animals and products. Stool samples from 334 employees in a Dutch pig slaughterhouse were obtained. Presence of ESBL was determined by selective plating, microarray analysis, and gene sequencing. Questionnaires were used to collect personal and occupational information. The overall prevalence of ESBL carriage was 4·8% (16/334). All ESBL-producing isolates were Escherichia coli. The ESBL genes detected were bla CTX-M-1 (n = 8), bla CTX-M-15 (n = 3), bla CTX-M-27 (n = 2), bla CTX-M-24 (n = 1), bla CTX-M-55 (n = 1), and bla SHV-12 (n = 1). A higher prevalence of ESBL was seen in workers in jobs with as tasks 'removal of lungs, heart, liver, tongue' (33%), and 'removal of head and spinal cord' (25%). For further analysis, participants were divided in two groups based on potential exposure to ESBL as related to their job title. One group with an assumed higher exposure to ESBL (e.g. stable work, stabbing, dehairing, removal of organs) and another group with an assumed lower exposure to ESBL (e.g. refrigeration, packaging and expedition). In the 'higher exposure' group, ten out of 95 (10·5%) were carrying ESBL vs. six out of 233 (2·6%) in the 'lower exposure' group. Human ESBL carriage was significantly associated with job exposure in the slaughterhouse (OR 4·5, CI 1·6-12·6). Results suggest that ESBL carriage in slaughterhouse workers overall is comparable with the Dutch population. Within the slaughterhouse population a difference in carriage exists depending on their position along the slaughter line and tasks involved.

Prevalence and risk factors for colonization of Clostridium difficile among adults living near livestock farms in the Netherlands.

A cross-sectional study was performed among 2494 adults not living or working on a farm to assess prevalence of Clostridium difficile (CD) colonization and risk factors in a livestock dense area. CD prevalence was 1·2%. Twenty-one persons were colonized with a toxigenic strain and nine with a non-toxigenic strain. CD-positive persons did not live closer to livestock farms than individuals negative for CD. Antibiotic exposure in the preceding 3 months was a risk factor for CD colonization (odds ratio 3·70; 95% confidence interval 1·25-10·95).

School attendance and daily respiratory symptoms in children: influence of moisture damage.

We investigated the effect of weekends and school holidays on the daily frequency and severity of respiratory and other symptoms among children attending schools with (index) or without (reference) moisture damage in Spain, the Netherlands, and Finland. Throughout 1 year, parents of 419 children with a respiratory condition attending index (n=15) or reference (n=10) primary schools completed three symptom diaries. We assessed associations between lower respiratory tract, upper respiratory tract or allergy, and other symptom scores and school day, weekend, or summer holiday using mixed regression models stratified by country and moisture damage. We evaluated interactions between moisture damage and type of day. We combined country-specific estimates (incidence rate ratios [IRRs] and 95% confidence interval [CI]) in meta-analyses. Symptom scores were lower during weekends and holiday. Lower respiratory tract symptoms were statistically significantly less common during holiday with strongest effect in index schools (IRR=0.7; CI=0.6-0.8). Reporting of other symptoms was more reduced during holiday in index (IRR=0.6; CI=0.4-0.9) than in reference (IRR=0.95; CI=0.8-1.2) schools (interaction P<.01). In conclusion, symptoms were less frequent and/or severe during summer holiday and weekends. This pattern was stronger among children attending moisture-damaged schools, suggesting potential improvement in moisture damage-related symptoms during school breaks.

Contact dermatitis in the construction industry: the role of filaggrin loss-of-function mutations.

BACKGROUND: A high prevalence of contact dermatitis (CD) and respiratory symptoms has been observed in the construction industry, probably due to widespread exposure to irritants and allergens. It is unknown whether carriers of loss-of-function mutations in the gene encoding filaggrin (FLG), a known risk gene for eczema and asthma, are at increased risk. OBJECTIVES: To investigate associations of FLG mutations with CD and respiratory symptoms in Dutch construction workers. METHODS: A questionnaire including items on dermal and respiratory symptoms such as wheeze, shortness of breath and asthma was administered to construction workers. Total and specific serum IgE was analysed by enzyme immunoassays. Four FLG loss-of-function mutations were genotyped. CD was diagnosed by a team of a dermatologist and a clinical occupational medicine specialist using photographs of the subjects' hands and self-reported questionnaire data. RESULTS: Of the 506 participating workers, 6·3% carried at least one FLG mutation. Mild CD was diagnosed by the specialists in 34·0%, and severe CD in an additional 24·3%. CD was considered work related in 282 of 295 subjects (95·6%). Carriers of FLG variants had an increased risk of CD compared with subjects carrying wild-type alleles [mild CD: odds ratio (OR) 5·71, 95% confidence interval (CI) 1·63-20·06; severe CD: OR 8·26, 95% CI 2·32-29·39]. FLG variants and the presence of CD were not associated with respiratory symptoms and atopy. CONCLUSIONS: Contact dermatitis prevalence in construction workers is high. FLG loss-of-function mutations increase the risk of CD even further. FLG mutations were not associated with respiratory symptoms or atopy.

Health and health-related quality of life in pig farmers carrying livestock-associated methicillin-resistant Staphylococcus aureus.

There is limited knowledge about the effect of livestock-associated methicillin-resistant Staphylococcus aureus (LA-MRSA) carriage on health-related quality of life (QoL). With this study, we explored whether LA-MRSA causes infections or affects health-related QoL in pig farmers. This prospective cohort study surveyed persons working on 49 farrowing pig farms in The Netherlands for 1 year (2010-2011). On six sampling moments, nasal swabs, environmental samples and questionnaires on activities and infections were collected. At the end of the study year, persons were asked about their QoL using the validated SF-36 and EQ-5D questionnaires. Of 120 persons, 44 (37%) were persistent MRSA carriers. MRSA carriage was not associated with infections, use of antimicrobials, healthcare contact and health-related QoL items in univariate or multivariate analysis, most likely due to the 'healthy worker effect'. Despite high carriage rates, the impact of LA-MRSA carriage in this population of relatively healthy pig farmers on health and health-related QoL appears limited; more research is needed for confirmation.

Inflammatory potential in relation to the microbial content of settled dust samples collected from moisture-damaged and reference schools: results of HITEA study.

Aiming to identify factors causing the adverse health effects associated with moisture-damaged indoor environments, we analyzed immunotoxicological potential of settled dust from moisture-damaged and reference schools in relation to their microbiological composition. Mouse RAW264.7 macrophages were exposed to settled dust samples (n = 25) collected from moisture-damaged and reference schools in Spain, the Netherlands, and Finland. After exposure, we analyzed production of inflammatory markers [nitric oxide (NO), tumor necrosis factor-α (TNF-)α, interleukin (IL)-6, and macrophage inflammatory protein (MIP)2] as well as mitochondrial activity, viability, apoptosis, and cell cycle arrest. Furthermore, particle counts, concentration of selected microbial groups as well as chemical markers such as ergosterol, 3-hydroxy fatty acids, muramic acid, endotoxins, and glucans were measured as markers of exposure. Dust from moisture-damaged schools in Spain and the Netherlands induced stronger immunotoxicological responses compared to samples from reference schools; the responses to Finnish samples were generally lower with no difference between the schools. In multivariate analysis, IL-6 and apoptosis responses were most strongly associated with moisture status of the school. The measured responses correlated with several microbial markers and numbers of particles, but the most important predictor of the immunotoxicological potential of settled dust was muramic acid concentration, a marker of Gram-positive bacteria.

The relation between modeled odor exposure from livestock farming and odor annoyance among neighboring residents.

PURPOSE: Odor annoyance is an important environmental stressor for neighboring residents of livestock farms and may affect their quality of life and health. However, little is known about the relation between odor exposure due to livestock farming and odor annoyance. Even more, the relation between odor exposure and odor annoyance is rather complicated due to variable responses among individuals to comparable exposure levels and a large number of factors (such as age, gender, education) that may affect the relation. In this study, we (1) investigated the relation between modeled odor exposure and odor annoyance; (2) investigated whether other factors can affect this relation; and (3) compared our dose-response relation to a dose-response relation established in a previous study carried out in the Netherlands, more than 10 years ago, in order to investigate changes in odor perception and appreciation over time. METHODS: We used data from 582 respondents who participated in a questionnaire survey among neighboring residents of livestock farms in the south of the Netherlands. Odor annoyance was established by two close-ended questions in a questionnaire; odor exposure was estimated using the Stacks dispersion model. RESULTS: The results of our study indicate a statistically significant and positive relation between modeled odor exposure and reported odor annoyance from livestock farming (OR 1.92; 95 % CI 1.53-2.41). Furthermore, age, asthma, education and perceived air pollution in the environment are all related to odor annoyance, although they hardly affect the relation between estimated livestock odor exposure and reported odor annoyance. We also found relatively more odor annoyance reported among neighboring residents than in a previous study conducted in the Netherlands. CONCLUSIONS: We found a strong relation between modeled odor exposure and odor annoyance. However, due to some uncertainties and small number of studies on this topic, further research and replication of results is recommended.

Climate change effects on airborne pathogenic bioaerosol concentrations: a scenario analysis.

The most recent IPCC report presented further scientific evidence for global climate change in the twenty-first century. Important secondary effects of climate change include those on water resource availability, agricultural yields, urban healthy living, biodiversity, ecosystems, food security, and public health. The aim of this explorative study was to determine the range of expected airborne pathogen concentrations during a single outbreak or release in a future climate compared to a historical climatic period (1981-2010). We used five climate scenarios for the periods 2016-2045 and 2036-2065 defined by the Royal Netherlands Meteorological Institute and two conversion tools to create hourly future meteorological data sets. We modelled season-averaged airborne pathogen concentrations by means of an atmospheric dispersion model and compared these data to historical (1981-2010) modelled concentrations. Our results showed that modelled concentrations were modified several percentage points on average as a result of climate change. On average, concentrations were reduced in four out of five scenarios. Wind speed and global radiation were of critical importance, which determine horizontal and vertical dilution. Modelled concentrations decreased on average, but large positive and negative hourly averaged effects were calculated (from -67 to +639 %). This explorative study shows that further research should include pathogen inactivation and more detailed probability functions on precipitation, snow, and large-scale circulation.

Prenatal exposure to environmental chemical contaminants and asthma and eczema in school-age children.

BACKGROUND: Emerging evidence suggests that prenatal or early-life exposures to environmental contaminants may contribute to an increased risk of asthma and allergies in children. We aimed to the explore associations of prenatal exposures to a large set of environmental chemical contaminants with asthma and eczema in school-age children. METHODS: We studied 1024 mother-child pairs from Greenland and Ukraine from the INUENDO birth cohort. Data were collected by means of an interview-based questionnaire when the children were 5-9 years of age. Questions from the ISAAC study were used to define asthma, eczema, and wheeze. We applied principal components analysis (PCA) to sixteen contaminants in maternal serum sampled during pregnancy, including perfluoroalkyl substances (PFASs), metabolites of diethylhexyl (DEHP) and diisononyl (DiNP) phthalates, PCB-153, and p,p'-DDE. Scores of five principal components (PCs) explaining 70% of the variance were included in multiple logistic regression models. RESULTS: In a meta-analysis that included both populations, the PC2 score, reflecting exposure to DiNP, was negatively associated with current eczema (OR 0.71, 95% CI 0.52-0.96). Other associations were not consistent between the two populations. In Ukrainian children, the PC3 score (DEHP) was positively associated with current wheeze (adjusted OR 1.56, 95% CI 1.03-2.37), whereas the PC5 score, dominated by perfluorooctanoic acid (PFOA), was inversely associated with current wheeze (OR 0.64, 0.41-0.99). In Greenlandic children, a negative association of PC4 (organochlorines) with ever eczema (OR 0.78, 0.61-0.99) was found. CONCLUSIONS: We found limited evidence to support a link between prenatal exposure to environmental chemical contaminants and childhood asthma and eczema.

Exposure-response relationships for inhalant wheat allergen exposure and asthma.

BACKGROUND: A few studies have investigated exposure-response relationships for sensitisation to wheat, work-related symptoms and wheat allergen exposure. IgG4 is suggested to protect against the development of allergic sensitisation. The main aim of this current study was to explore the nature of exposure-response relationships for a range of clinically relevant endpoints among bakery workers, and to investigate the role of IgG4 in these relationships. METHODS: A cross-sectional study of 517 supermarket bakery workers in 31 bakeries used a questionnaire, serum-specific IgE and IgG4 to wheat, and methacholine challenge testing. Exposure models were developed previously using job, bakery size, tasks and specific ingredients used. These models were used to predict average personal exposure to wheat allergens. RESULTS: The exposure-response relationships for average exposure followed a linear relationship for sensitisation, but a bell-shaped curve for allergic symptoms and probable occupational asthma, increasing up to 10-15 µg/m(3) wheat allergen concentration after which they plateau off and decrease at higher exposure concentrations. This relationship was modified by atopic status. IgG4 levels were strongly exposure related: a clear increase in prevalence of higher IgG4 with increase in wheat allergen exposure was observed among those sensitised and non-sensitised to wheat, with IgG4 even more strongly associated with exposure than IgE to wheat. CONCLUSIONS: The bell-shaped exposure-response relationship in the current study is consistent with the findings of previous studies. IgG4 showed no protective effect for sensitisation, confirming the findings of previous studies, suggesting that the pattern is probably related to a healthy worker effect.

Healthy worker survivor analysis in an occupational cohort study of Dutch agricultural workers.

OBJECTIVES: High microbial exposures in farmers and agricultural workers are associated with less atopy. Although it has been speculated that healthy worker survival could be an explanation, this has not been studied so far. Therefore, we investigated the presence of healthy worker survival in a five-year follow-up study of an occupational cohort of Dutch farmers and agricultural industry (company) workers. METHODS: We compared baseline demographic characteristics, respiratory health, atopy and endotoxin exposure of 259 workers followed up with 124 workers lost to follow-up. Additionally, baseline health status of 31 participants who had changed to lower exposure jobs at follow-up was compared to those with similar or higher exposure jobs at follow-up. RESULTS: In general, no major healthy worker survival effect was found. Nonetheless, small differences were observed between subjects included in follow-up and those lost to follow-up. Those lost to follow-up were older, had a lower peak expiratory flow, and were less often raised on a farm. Company workers lost to follow-up with a farm childhood had more often self-reported allergy, but this was not observed for subjects with atopic sensitization or other respiratory symptoms. No differences were found for any of the studied characteristics in participants with lower exposure at follow-up compared to participants with similar or higher exposure at follow-up. CONCLUSIONS: No major healthy worker survival is present in this organic dust exposed cohort. Differences between participants lost to follow-up and participants included in follow-up with regard to health characteristics are small and unlikely to explain the previously reported inverse associations between endotoxin exposure and atopy.

Shifted T-cell polarisation after agricultural dust exposure in mice and men.

RATIONALE: A low prevalence of asthma and atopy has been shown in farmers and agricultural workers. However, in these workers, a higher prevalence of respiratory symptoms has been reported, in which T helper 1 (Th1) and/or Th17 responses may play a role. AIM: We investigated the effect of exposure to dust extracts (DEs) from different farms on airway inflammation and T-cell polarisation in a mouse model and assessed T-cell polarisation in agricultural workers from the same farms. METHODS: DEs were prepared from settled dust collected at cattle and pig farms and bulb and onion industries. Mice were exposed to phosphate-buffered saline (PBS), DEs, house dust mite (HDM) or HDM+DE via nasal instillation, four times per week during 5 weeks. Hyperresponsiveness, airway inflammation, IgE levels and T-cell polarisation were assessed. Th-cell and T cytotoxic (Tc)-cell subsets were investigated in peripheral blood samples from 33 agricultural workers and 9 non-exposed controls. RESULTS: DEs induced interleukin(IL)-17, IL-1ß and IL-6 in mouse lung homogenates. DE-exposed mice had more mixed inflammatory infiltrates in the lungs, and more neutrophils compared with PBS-exposed mice. DEs protected against the HDM-induced Th2 response and methacholine hyperresponsiveness. Interestingly, occupationally exposed humans had higher frequencies of Th cells spontaneously expressing IL-17 and interferon γ compared with controls. CONCLUSION: Chronic exposure to different types of farm dust induces a Th/Tc-17 inflammatory response in mice and agricultural workers. This may contribute to the low prevalence of Th2-related diseases but may constitute a risk for other chronic respiratory diseases.

Body mass index in young school-age children in relation to organochlorine compounds in early life: a prospective study.

OBJECTIVE: To investigate the association between maternal pregnancy and estimated postnatal serum concentrations of the organochlorines 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene (p,p'-DDE) and body mass index (BMI) z-scores in 5- to 9-year-old children. METHODS: Maternal sera from the INUENDO birth cohort (2002-2004) comprising mother-child pairs (N=1109) from Greenland, Warsaw (Poland), and Kharkiv (Ukraine) were analysed for CB-153 and p,p'-DDE, using gas chromatography-mass-spectrometry, and were grouped into tertiles for statistical analyses. A toxicokinetic model was used to estimate the first 12 months cumulative exposure to the compounds. Associations between these compounds and child age- and sex-specific BMI z-scores were calculated at follow-up (2010-2012), using multiple linear regression analysis. RESULTS: No clear associations between pregnancy CB-153 and p,p'-DDE and child BMI were observed (the pooled differences in BMI z-score (95% confidence interval) comparing 3rd tertile to 1st tertile were -0.07 (-0.32 to 0.18) and -0.10 (-0.30 to 0.10) kg m(-2), respectively). For postnatal CB-153 and p,p'-DDE and BMI, the overall differences in BMI z-score comparing 3rd tertile to 1st tertile were 0.12 (-0.15 to 0.39) and -0.03 (-0.20 to 0.27) kg m(-2), respectively. CONCLUSIONS: This follow-up study of Greenlandic, Polish and Ukrainian populations showed no clear association between pregnancy and postnatal exposure to p,p'-DDE and CB-153 and BMI at the age of 5-9 years.

Indices of methylation in sperm DNA from fertile men differ between distinct geographical regions.

STUDY QUESTION: Which are the main determinants, if any, of sperm DNA methylation levels? SUMMARY ANSWER: Geographical region resulted associated with the sperm methylation status assessed on genome-wide repetitive sequences. WHAT IS KNOWN ALREADY: DNA methylation level, assessed on repetitive sequences from peripheral blood lymphocyte, can vary with age, gender, alcohol consumption and white blood cell counts. STUDY DESIGN, SIZE, DURATION: A cross-sectional study. Individual data were collected from 269 young healthy men of proven fertility living in three geographical regions: Inuits from Greenland, Caucasians from Warsaw (Poland) and Kharkiv (Ukraine). Semen samples were collected between May 2002 and February 2004 and aliquots were immediately frozen. PARTICIPANTS/MATERIALS, SETTING, METHODS: We estimated sperm DNA global methylation level (DGML) in two ways. First DNA methylation in repetitive DNA sequences (LINE-1, Satα and Alu) was quantified by PCR pyrosequencing after bisulfite conversion and second by flow cytometry (FCM) using fluorescently labeled monoclonal antibodies anti-5-methylcytosine. We analyzed whether personal characteristics and habits, body mass index, semen quality parameters, sperm chromatin integrity, biomarkers of accessory gland function and the plasma concentration of reproductive hormones were associated with sperm DNA methylation levels in men. Associations were evaluated by analysis of variance and linear regression analyses. MAIN RESULTS AND THE ROLE OF CHANCE: The geographical location emerged as the main determinant when using the methylation level in repetitive sequences. FCM DGML results were not associated with those from repetitive sequence analysis. No other consistent associations between methylation markers and the assessed variables were identified across countries. LIMITATIONS, REASONS FOR CAUTION: The methods used are only surrogates of the actual sperm methylome and the methylation levels at individual specific loci were not explored. WIDER IMPLICATIONS OF THE FINDINGS: Sperm DGML is relatively independent from semen quality parameters and is a new candidate biomarker for epidemiological studies of the impact of environmental contaminants on male fertility. STUDY FUNDING/COMPETING INTERESTS: The study is part of the project CLEAR (Climate change, Environmental contaminants and Reproductive health) supported by the European Commission 7th framework program, contract no: FP7-ENV-2008-1-226217. No competing interest is declared.

Monitoring of occupational and environmental aeroallergens-- EAACI Position Paper. Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution.

Exposure to high molecular weight sensitizers of biological origin is an important risk factor for the development of asthma and rhinitis. Most of the causal allergens have been defined based on their reactivity with IgE antibodies, and in many cases, the molecular structure and function of the allergens have been established. Significant information on allergen levels that cause sensitization and allergic symptoms for several major environmental and occupational allergens has been reported. Monitoring of high molecular weight allergens and allergen carrier particles is an important part of the management of allergic respiratory diseases and requires standardized allergen assessment methods for occupational and environmental (indoor and outdoor) allergen exposure. The aim of this EAACI task force was to review the essential points for monitoring environmental and occupational allergen exposure including sampling strategies and methods, processing of dust samples, allergen analysis, and quantification. The paper includes a summary of different methods for sampling and allergen quantification, as well as their pros and cons for various exposure settings. Recommendations are being made for different exposure scenarios.

Endotoxin levels in settled airborne dust in European schools: the HITEA school study.

Indoor exposure to microbial agents is known to influence respiratory health. Besides home exposure, exposure in schools can affect respiratory health. In this study, we measured endotoxin in settled dust in primary schools in three European countries from three different geographical regions with different climates. Our aim was to characterize endotoxin levels in primary schools and evaluate associations with potential determinants. Endotoxin levels were repeatedly assessed in 23 schools in Spain (n = 7), the Netherlands (n = 10), and Finland (n = 6) using electrostatic dustfall collectors. In total, 645 measurements were taken in 237 classrooms. Endotoxin levels differed significantly between countries; Dutch schools had the highest levels, while Finnish schools showed the lowest levels. In each country, differences in endotoxin levels were observed between schools and over the sampling periods. Estimates improved after adjustment for sampling period. Factors affecting endotoxin levels in a school differed per country. In general, endotoxin levels were higher in lower grades and in classrooms with higher occupancy. School endotoxin levels may contribute significantly to total endotoxin exposure in children and teachers. As the correlation between the repeated measurements is reasonable, single endotoxin measurements form a reasonable basis for estimating annual endotoxin levels in schools.

Asthma and allergies: is the farming environment (still) protective in Poland? The GABRIEL Advanced Studies.

BACKGROUND: Evidence exists that a farming environment in childhood may provide protection against atopic respiratory disease. In the GABRIEL project based in Poland and Alpine regions of Germany, Austria and Switzerland, we aimed to assess whether a farming environment in childhood is protective against allergic diseases in Poland and whether specific exposures explain any protective effect. METHODS: In rural Poland, 23 331 families of schoolchildren completed a questionnaire enquiring into farming practices and allergic diseases (Phase I). A subsample (n = 2586) participated in Phase II involving a more detailed questionnaire on specific farm exposures with objective measures of atopy. RESULTS: Farming differed between Poland and the Alpine centres; in the latter, cattle farming was prevalent, whereas in Poland 18% of village farms kept ≥1 cow and 34% kept ≥1 pig. Polish children in villages had lower prevalences of asthma and hay fever than children from towns, and in the Phase II population, farm children had a reduced risk of atopy measured by IgE (aOR = 0.72, 95% CI 0.57, 0.91) and skin prick test (aOR = 0.65, 95% CI 0.50, 0.86). Early-life contact with grain was inversely related to the risk of atopy measured by IgE (aOR = 0.66, 95% CI 0.47, 0.92) and appeared to explain part of the farming effect. CONCLUSION: While farming in Poland differed from that in the Alpine areas as did the exposure-response associations, we found in communities engaged in small-scale, mixed farming, there was a protective farming effect against objective measures of atopy potentially related to contact with grain or associated farm activities.