Do cats mirror their owner? Paired exposure assessment using silicone bands to measure residential PAH exposure.

It has been suggested that domestic animals can serve as sentinels for human exposures. In this study our objectives were to demonstrate that i) silicone collars can be used to measure environmental exposures of (domestic) animals, and that ii) domestic animals can be used as sentinels for human residential exposure. For this, we simultaneously measured polycyclic aromatic hydrocarbons (PAHs) using silicone bands worn by 30 pet cats (collar) and their owner (wristband). Collars and wristbands were worn for 7 days and analyzed via targeted Gas Chromatography-Mass Spectrometry (GC-MS). Demographics and daily routines were collected for humans and cats. Out of 16 PAHs, 9 were frequently detected (>50% of samples) in both wristbands and collars, of which Phenanthrene and Fluorene were detected in all samples. Concentrations of wristbands and collars were moderately correlated for these 9 PAHs (Median Spearman's r = 0.51 (range 0.16-0.68)). Determinants of PAH concentrations of cats and humans showed considerable overlap, with vacuum cleaning resulting in higher exposures and frequent changing of bed sheets in lower exposures. This study adds proof-of-principle data for the use of silicone collars to measure (domestic) animal exposure and shows that cats can be used as sentinels for human residential exposure.

Microbial exposures in moisture-damaged schools and associations with respiratory symptoms in students: A multi-country environmental exposure study.

Moisture-damaged buildings are associated with respiratory symptoms and underlying diseases among building occupants, but the causative agent(s) remain a mystery. We first identified specific fungal and bacterial taxa in classrooms with moisture damage in Finnish and Dutch primary schools. We then investigated associations of the identified moisture damage indicators with respiratory symptoms in more than 2700 students. Finally, we explored whether exposure to specific taxa within the indoor microbiota may explain the association between moisture damage and respiratory health. Schools were assessed for moisture damage through detailed inspections, and the microbial composition of settled dust in electrostatic dustfall collectors was determined using marker-gene analysis. In Finland, there were several positive associations between particular microbial indicators (diversity, richness, individual taxa) and a respiratory symptom score, while in the Netherlands, the associations tended to be mostly inverse and statistically non-significant. In Finland, abundance of the Sphingomonas bacterial genus and endotoxin levels partially explained the associations between moisture damage and symptom score. A few microbial taxa explained part of the associations with health, but overall, the observed associations between damage-associated individual taxa and respiratory health were limited.

Immune marker changes and risk of multiple myeloma: a nested case-control study using repeated pre-diagnostic blood samples.

Biomarkers reliably predicting progression to multiple myeloma (MM) are lacking. Myeloma risk has been associated with low blood levels of monocyte chemotactic protein-3 (MCP-3), macrophage inflammatory protein-1 alpha (MIP-1α), vascular endothelial growth factor (VEGF), fibroblast growth factor-2 (FGF-2), fractalkine, and transforming growth factor-alpha (TGF-α). In this study, we aimed to replicate these findings and study the individual dynamics of each marker in a prospective longitudinal cohort, thereby examining their potential as markers of myeloma progression. For this purpose, we identified 65 myeloma cases and 65 matched cancer-free controls each with two donated blood samples within the Northern Sweden Health and Disease Study. The first and repeated samples from myeloma cases were donated at a median 13 and 4 years, respectively, before the myeloma was diagnosed. Known risk factors for progression were determined by protein-, and immunofixation electrophoresis, and free light chain assays. We observed lower levels of MCP-3, VEGF, FGF-2, and TGF-α in myeloma patients than in controls, consistent with previous data. We also observed that these markers decreased among future myeloma patients while remaining stable in controls. Decreasing trajectories were noted for TGF-α (P=2.5 × 10-4) indicating progression to MM. Investigating this, we found that low levels of TGF-α assessed at the time of the repeated sample were independently associated with risk of progression in a multivariable model (hazard ratio = 3.5; P=0.003). TGF-α can potentially improve early detection of MM.

Oxidative capacity and hemolytic activity of settled dust from moisture-damaged schools.

Exposure to moisture-damaged indoor environments is associated with adverse respiratory health effects, but responsible factors remain unidentified. In order to explore possible mechanisms behind these effects, the oxidative capacity and hemolytic activity of settled dust samples (n = 25) collected from moisture-damaged and non-damaged schools in Spain, the Netherlands, and Finland were evaluated and matched against the microbial content of the sample. Oxidative capacity was determined with plasmid scission assay and hemolytic activity by assessing the damage to isolated human red blood cells. The microbial content of the samples was measured with quantitative PCR assays for selected microbial groups and by analyzing the cell wall markers ergosterol, muramic acid, endotoxins, and glucans. The moisture observations in the schools were associated with some of the microbial components in the dust, and microbial determinants grouped together increased the oxidative capacity. Oxidative capacity was also affected by particle concentration and country of origin. Two out of 14 studied dust samples from moisture-damaged schools demonstrated some hemolytic activity. The results indicate that the microbial component connected with moisture damage is associated with increased oxidative stress and that hemolysis should be studied further as one possible mechanism contributing to the adverse health effects of moisture-damaged buildings.

Residential proximity to livestock farms is associated with a lower prevalence of atopy.

OBJECTIVES: Exposure to farm environments during childhood and adult life seems to reduce the risk of atopic sensitisation. Most studies have been conducted among farmers, but people living in rural areas may have similar protective effects for atopy. This study aims to investigate the association between residential proximity to livestock farms and atopy among non-farming adults living in a rural area in the Netherlands. METHODS: We conducted a cross-sectional study among 2443 adults (20-72 years). Atopy was defined as specific IgE to common allergens and/or total IgE ≥100 IU/mL. Residential proximity to livestock farms was assessed as 1) distance to the nearest pig, poultry, cattle or any farm, 2) number of farms within 500 m and 1000 m, and 3) modelled annual average fine dust emissions from farms within 500 m and 1000 m. Data were analysed with multiple logistic regression and generalised additive models. RESULTS: The prevalence of atopy was 29.8%. Subjects living at short distances from farms (<327 m, first tertile) had a lower odds for atopy compared with subjects living further away (>527 m, third tertile) (OR 0.79, 95% CI 0.63 to 0.98). Significant associations in the same direction were found with distance to the nearest pig or cattle farm. The associations between atopy and livestock farm exposure were somewhat stronger in subjects who grew up on a farm. CONCLUSIONS: Living in close proximity to livestock farms seems to protect against atopy. This study provides evidence that protective effects of early-life and adult farm exposures may extend beyond farming populations.

Air Pollution from Livestock Farms Is Associated with Airway Obstruction in Neighboring Residents.

RATIONALE: Livestock farm emissions may not only affect respiratory health of farmers but also of neighboring residents. OBJECTIVES: To explore associations between spatial and temporal variation in pollutant emissions from livestock farms and lung function in a general, nonfarming, rural population in the Netherlands. METHODS: We conducted a cross-sectional study in 2,308 adults (age, 20-72 yr). A pulmonary function test was performed measuring prebronchodilator and post-bronchodilator FEV1, FVC, FEV1/FVC, and maximum mid-expiratory flow (MMEF). Spatial exposure was assessed as (1) number of farms within 500 m and 1,000 m of the home, (2) distance to the nearest farm, and (3) modeled annual average fine dust emissions from farms within 500 m and 1,000 m of the home address. Temporal exposure was assessed as week-average ambient particulate matter <10 µm in diameter and ammonia (NH3) concentrations before lung function measurements. Data were analyzed with generalized additive models (smoothing). MEASUREMENTS AND MAIN RESULTS: A negative association was found between the number of livestock farms within a 1,000-m buffer from the home address and MMEF, which was more pronounced in participants without atopy. No associations were found with other spatial exposure variables. Week-average particulate matter <10 µm in diameter and NH3 levels were negatively associated with FEV1, FEV1/FVC, and MMEF. In a two-pollutant model, only NH3 remained associated. A 25-µg/m3 increase in NH3 was associated with a 2.22% lower FEV1 (95% confidence interval, -3.69 to -0.74), FEV1/FVC of -1.12% (-1.96 to -0.28), and MMEF of -5.67% (-8.80 to -2.55). CONCLUSIONS: Spatial and temporal variation in livestock air pollution emissions are associated with lung function deficits in nonfarming residents.

Predicting occupational asthma and rhinitis in bakery workers referred for clinical evaluation.

BACKGROUND: Occupational allergic diseases are a major problem in some workplaces like in the baking industry. Diagnostic rules have been used in surveillance but not yet in the occupational respiratory clinic. OBJECTIVE: To develop diagnostic models predicting baker's asthma and rhinitis among bakery workers at high risk of sensitisation to bakery allergens referred to a specialised clinic. METHODS: As part of a medical surveillance programme, clinical evaluation was performed on 436 referred Dutch bakery workers at high risk for sensitisation to bakery allergens. Multivariable logistic regression analyses were developed to identify the predictors of onset of baker's asthma and rhinitis using a self-administered questionnaire and compared using a structured medical history. Performance of models was assessed by discrimination (area under the receiver operating characteristics curve) and calibration (Hosmer-Lemeshow test). Internal validity of the models was assessed by a bootstrapping procedure. RESULTS: The prediction models included the predictors of work-related upper and lower respiratory symptoms, the presence of allergy and allergic symptoms, use of medication (last year), type of job, type of shift and working years with symptoms (≥10 years). The developed models derived from both self-administered questionnaire and the medical history showed a relatively good discrimination and calibration. The internal validity showed that the models developed had satisfactory discrimination. To improve calibrations of models, shrinkage factors were applied to model coefficients. CONCLUSION: The probability of allergic asthma and rhinitis in referred bakers could be estimated by diagnostic models based on both a self-administered questionnaire and by taking a structured medical history.

Contact dermatitis is an unrecognized problem in the construction industry: Comparison of four different assessment methods.

BACKGROUND: A high contact dermatitis symptoms prevalence has been observed in Dutch construction workers. METHODS: Contact dermatitis was diagnosed by an expert panel using questionnaire data and photographs of 751 subjects' hands. A subset was evaluated by two occupational physicians. Their diagnoses were compared to those of the expert panel. In addition, two self-reported questionnaire-based assessment methods were compared to the expert panel evaluation. Associations between contact dermatitis and determinants were assessed using log-binomial regression analysis. RESULTS: Contact dermatitis prevalence was high: 61.4% (expert panel's diagnosis) and 32.9% (self-reported). Agreement between occupational physicians and the expert panel was low but increased after training. Washing hands with solvents and performing job-related tasks at home were related to contact dermatitis. CONCLUSIONS: Contact dermatitis prevalence among construction workers is high. Recognition of contact dermatitis by occupational physicians is poor but can be improved by training. Awareness of skin disorders should be raised.

Component-resolved diagnosis of baker's allergy based on specific IgE to recombinant wheat flour proteins.

BACKGROUND: Sensitization to wheat flour plays an important role in the development and diagnosis of baker's asthma. OBJECTIVES: We evaluated wheat allergen components as sensitizers for bakers with work-related complaints, with consideration of cross-reactivity to grass pollen. METHODS: Nineteen recombinant wheat flour proteins and 2 cross-reactive carbohydrate determinants were tested by using CAP-FEIA in sera of 101 bakers with wheat flour allergy (40 German, 37 Dutch, and 24 Spanish) and 29 pollen-sensitized control subjects with wheat-specific IgE but without occupational exposure. IgE binding to the single components was inhibited with wheat flour, rye flour, and grass pollen. The diagnostic efficiencies of IgE tests with single allergens and combinations were evaluated by assessing their ability to discriminate between patients with baker's allergy and control subjects based on receiver operating characteristic analyses. RESULTS: Eighty percent of bakers had specific IgE levels of 0.35 kUA/L or greater and 91% had specific IgE levels of 0.1 kUA/L or greater to at least one of the 21 allergens. The highest frequencies of IgE binding were found for thiol reductase (Tri a 27) and the wheat dimeric α-amylase inhibitor 0.19 (Tri a 28). Cross-reactivity to grass pollen was proved for 9 components, and cross-reactivity to rye flour was proved for 18 components. A combination of IgE tests to 5 components, Tri a 27, Tri a 28, tetrameric α-amylase inhibitor CM2 (Tri a 29.02), serine protease inhibitor-like allergen (Tri a 39), and 1-cys-peroxiredoxin (Tri a 32), produced the maximal area under the curve (AUC = 0.84) in receiver operating characteristic analyses, but this was still lower than the AUC for wheat- or rye flour-specific IgE (AUC = 0.89 or 0.88, respectively). CONCLUSIONS: Component-resolved diagnostics help to distinguish between sensitization caused by occupational flour exposure and wheat seropositivity based on cross-reactivity to grass pollen. For routine diagnosis of baker's allergy, however, allergen-specific IgE tests with whole wheat and rye flour extracts remain mandatory because of superior diagnostic sensitivity.

Domestic use of bleach and infections in children: a multicentre cross-sectional study.

OBJECTIVE: To report the effects of bleach use at home on the frequency of infections in 9102 school-age children participating in the HITEA project. METHODS: Parents of pupils aged 6-12 years from schools in Barcelona province (Spain), Utrecht province (the Netherlands) and Eastern and Central Finland were administered a questionnaire including questions on the frequency of infections (influenza, tonsillitis, sinusitis, otitis, bronchitis and pneumonia) in the past 12 months and bleach use at home. We developed multivariable mixed-effects multilogistic regression models to obtain relative risk ratios (RRR) and their 95% CI per country, and combined the RRR using random-effects meta-analyses. RESULTS: Bleach use was common in Spain (72%, n=1945) and uncommon in Finland (7%, n=279). Overall, the prevalence of infections (recurrent or once) was higher among children of bleach users. Significant combined associations were shown for influenza only once (RRR=1.20, 95% CI 1.04 to 1.38), recurrent tonsillitis (RRR=1.35, 95% CI 1.07 to 1.71) and any infection (RRR=1.18, 95% CI 1.01 to 1.38). CONCLUSIONS: Passive exposure to cleaning bleach in the home may have adverse effects on school-age children's health by increasing the risk of respiratory and other infections. The high frequency of use of disinfecting irritant cleaning products may be of public health concern, also when exposure occurs during childhood.

Dampness, bacterial and fungal components in dust in primary schools and respiratory health in schoolchildren across Europe.

BACKGROUND: Respiratory health effects of damp housing are well recognised, but less is known about the effect of dampness and water damage in schools. The HITEA study previously reported a higher prevalence of respiratory symptoms in pupils from moisture damaged schools, but the role of specific microbial exposures remained unclear. OBJECTIVES: To study associations between school dampness, levels of fungal and bacterial markers, respiratory symptoms and lung function in children. METHODS: Primary schools in Spain, the Netherlands and Finland were selected on the basis of the observed presence (n=15) or absence (n=10) of moisture, dampness and/or mould. Settled dust was repeatedly sampled in 232 classrooms and levels of 14 different microbial markers and groups of microbes were determined. Parental reports of respiratory symptoms were available from 3843 children aged 6-12 years, of whom 2736 provided acceptable forced spirometry testing. Country-specific associations between exposure and respiratory health were evaluated by multilevel mixed-effects logistic and linear regression models and combined using random-effects meta-analysis. RESULTS: The prevalence of respiratory symptoms was higher in moisture damaged schools, being more pronounced in Finnish pupils. Effects on lung function were not apparent. Levels of microbial markers were generally higher in moisture damaged schools, varied by season and were lower in Finnish schools. Wheeze tended to be inversely associated with microbial levels. All other respiratory symptoms were not consistently associated with microbial marker levels. CONCLUSIONS: Health effects of moisture and microbial exposures may vary between countries, but this requires further study.

Endotoxin levels in homes and classrooms of Dutch school children and respiratory health.

Several studies describe indoor pollutant exposure in homes and to a lesser extent in schools. Population studies that include both environments are sparse. This study aims to assess endotoxin levels in primary schools and homes of children. Endotoxin was also studied in relation to asthma and sensitisation. 10 schools with (index) and without (reference) dampness were selected, based on reports and inspections. Cases and controls were selected from 169 homes based on the presence or absence of asthma-like symptoms of children. Classroom and bedroom airborne settled dust was sampled using electrostatic dust fall collectors. Average endotoxin levels in schools ranged from 2178 to 6914 endotoxin units (EU)·m(-2) per week compared with 462-1285 EU·m(-2) per week in homes. After mutual adjustment for home and school endotoxin, school endotoxin was positively associated with nonatopic asthma (OR 1.11, 95% CI 0.97-1.27), while no associations with endotoxin were found at home. The high endotoxin levels in schools compared with homes indicate that exposure at school can contribute considerably to environmental endotoxin exposure of children and teachers. Our results also suggest that endotoxin in schools may be associated with nonatopic asthmatic symptoms in pupils, although the results require reproduction because of the modest sample size.

Dampness and mould in schools and respiratory symptoms in children: the HITEA study.

BACKGROUND: The adverse respiratory health effects of dampness and mould in the home have been extensively reported, but few studies have evaluated the health effects of such exposures in schools. OBJECTIVES: To assess the associations between dampness and mould in school buildings and respiratory symptoms among 6-12-year-old pupils in three European countries with different climates. METHODS: Based on information from self-reports and observations, we selected 29 primary schools with and 27 without moisture damage in Spain, the Netherlands and Finland. Information on respiratory symptoms and potential determinants was obtained using a parent-administered questionnaire among 6-12-year-old pupils. Country-specific associations between moisture damage and respiratory symptoms were evaluated using multivariable multilevel mixed effects logistic regression analysis. RESULTS: Data from 9271 children were obtained. Nocturnal dry cough was consistently associated with moisture damage at school in each of the three countries: OR 1.15; 95% CI 1.00 to 1.30 with p for heterogeneity 0.54. Finnish children attending a moisture damaged school more often had wheeze (OR 1.36; CI 1.04 to 1.78), nasal symptoms (OR 1.34; CI 1.05 to 1.71) and respiratory-related school absence (OR 1.50; CI 1.10 to 2.03). No associations with these symptoms were found in the Netherlands or Spain (p for heterogeneity <0.05). CONCLUSIONS: Moisture damage in schools may have adverse respiratory health effects in pupils. Finnish school children seem to be at higher risk, possibly due to quantitative and/or qualitative differences in exposure.

Can f 1 levels in hair and homes of different dog breeds: lack of evidence to describe any dog breed as hypoallergenic.

BACKGROUND: Certain dog breeds are described and marketed as being "hypoallergenic" on the basis of anecdotal reports that these dogs are better tolerated by patients allergic to dogs. OBJECTIVE: These observations were investigated by comparing Can f 1 (major dog [Canis familiaris] allergen) levels in hair and coat samples and in the home environment of various hypoallergenic (Labradoodle, Poodle, Spanish Waterdog, and Airedale terrier) and non-hypoallergenic dogs (Labrador retriever and a control group). METHODS: Hair and coat samples were obtained from dogs, and settled floor and airborne dust samples were taken from the dogs' homes. Can f 1 concentrations were measured by using ELISA, and results were analyzed by using multiple linear regression analyses. RESULTS: Significantly higher Can f 1 concentrations were found in hair and coat samples of hypoallergenic dogs (n = 196, geometric mean [GM], 2.26 µg/g, geometric standard deviation [GSD], 0.73, and GM, 27.04 µg/g, GSD, 0.57, respectively) than of non-hypoallergenic dogs (n = 160, GM, 0.77 µg/g, GSD, 0.71, and GM, 12.98 µg/g, GSD, 0.76, respectively). Differences between breeds were small, relative to the variability within a breed. Can f 1 levels in settled floor dust samples were lower for Labradoodles, but no differences were found between the other groups. No differences in airborne levels were found between breeds. CONCLUSION: So-called hypoallergenic dogs had higher Can f 1 levels in hair and coat samples than did control breeds. These differences did not lead to higher levels of environmental exposure to dog allergens. There is no evidence for the classification of certain dog breeds as being "hypoallergenic."

Swimming pool attendance and respiratory symptoms and allergies among Dutch children.

OBJECTIVES: To describe associations among swimming, respiratory health, allergen sensitisation and Clara cell protein 16 (CC16) levels in Dutch schoolchildren. Trichloramine levels in swimming pool air were determined to assess potential exposure levels. METHODS: Respiratory health and pool attendance information was collected from 2359 children, aged 6-13 years. Serum from 419 children was tested for allergen sensitisation and CC16 levels. Trichloramine levels were assessed in nine swimming facilities. RESULTS: Trichloramine levels ranged from 0.03 to 0.78 mg/m3 (average 0.21 mg/m3). Reported swimming pool attendance and trichloramine exposure were both not associated with asthma, wheezing, rhinitis or CC16 levels. Birch and house dust mite sensitisation were associated with recent indoor swimming (OR>1.86), but not after considering recent swimming frequency multiplied by trichloramine levels. Sensitisation to house dust mites was associated with frequent baby swimming (ORs=1.75; 95% CI 1.09 to 2.79). Furthermore, sensitisation was associated with lower serum CC16 levels. CC16 levels were associated with average trichloramine concentrations in pools; however, not after considering swimming frequency multiplied by trichloramine levels. CONCLUSIONS: Measured trichloramine levels were comparable with other studies but lower than in an earlier Dutch study. Swimming pool attendance was not associated with respiratory symptoms. The association between sensitisation and swimming during the first 2 years of life suggests that early-life exposures might be important, although this needs further study. The interpretation of transient and chronic changes of CC16 and other inflammatory markers in relation to the pool environment and health impacts warrants further investigation. Detailed comparisons with other studies are limited as few studies have measured trichloramine levels.

Acute respiratory effects in firefighters.

BACKGROUND: Associations between acute respiratory inflammatory responses, changes in bronchial hyperresponsiveness, serum pneumoprotein levels, and exposure to fire smoke were studied. METHODS: The study comprised 51 firefighters. Blood samples were taken within 24 hr following exposure to fire smoke, and after a week and 3 months. Sputum was induced within 5 days post-exposure and subjects underwent spirometry and methacholine provocation one week post-exposure. Exposure was registered by a questionnaire. RESULTS: No changes were observed following smoke exposure in bronchial hyperresponsiveness and serum pneumoprotein levels. Nevertheless, in a sizable proportion of the firefighters (44%) elevated sputum neutrophil levels (≥60%) were found. Serum IL-8 concentrations were higher 24 hr post-exposure compared to pre-exposure. Elevated neutrophil levels in sputum were associated with elevated serum IL-8 (ß = 0.010, P = 0.004) and TNFα (ß = 0.005, P = 0.034) levels within 24 hr post-exposure and IL-8 elevation lasted up to 3 months. CONCLUSIONS: Acute exposure to fire smoke induces acute neutrophilic airway and long-lasting systemic inflammation in healthy firefighters in the absence of bronchial hyperresponsiveness.

Microbial secondary metabolites in school buildings inspected for moisture damage in Finland, The Netherlands and Spain.

Secondary metabolites produced by fungi and bacteria are among the potential agents that contribute to adverse health effects observed in occupants of buildings affected by moisture damage, dampness and associated microbial growth. However, few attempts have been made to assess the occurrence of these compounds in relation to moisture damage and dampness in buildings. This study conducted in the context of the HITEA project (Health Effects of Indoor Pollutants: Integrating microbial, toxicological and epidemiological approaches) aimed at providing systematic information on the prevalence of microbial secondary metabolites in a large number of school buildings in three European countries, considering both buildings with and without moisture damage and/or dampness observations. In order to address the multitude and diversity of secondary metabolites a large number of more than 180 analytes was targeted in settled dust and surface swab samples using liquid chromatography/mass spectrometry (LC/MS) based methodology. While 42%, 58% and 44% of all samples collected in Spanish, Dutch and Finnish schools, respectively, were positive for at least one of the metabolites analyzed, frequency of detection for the individual microbial secondary metabolites - with the exceptions of emodin, certain enniatins and physcion - was low, typically in the range of and below 10% of positive samples. In total, 30 different fungal and bacterial secondary metabolites were found in the samples. Some differences in the metabolite profiles were observed between countries and between index and reference school buildings. A major finding in this study was that settled dust derived from moisture damaged, damp schools contained larger numbers of microbial secondary metabolites at higher levels compared to respective dust samples from schools not affected by moisture damage and dampness. This observation was true for schools in each of the three countries, but became statistically significant only when combining schools from all countries and thus increasing the sample number in the statistical analyses.

Residential proximity to crops and agricultural pesticide use and cause-specific mortality: A prospective census-based cohort study in the Netherlands.

BACKGROUND: There is continued concern about residential proximity to agricultural pesticide use and possible adverse health effects. Studies on this subject have been scarce with inconsistent results. We explored associations between residential proximity to specific crops, pesticide use and cause-specific mortality in a prospective census-based cohort study in The Netherlands. METHODS: Selecting inhabitants aged >30 living in less urbanized areas, at the same address for nine years up to baseline (2004) from a national register-based cohort, we followed ~3.1 million individuals for cause-specific mortality until 2012. We estimated the area of specific crop groups cultivated within buffers of 50 m, 100 m and 250 m around each individual's residence and the amount of fungicides, herbicides and insecticides used within the same buffers for the period 1995-2003. The association between these exposure proxies and 25 primary causes of death was investigated using Cox proportional hazards regression, adjusting for individual and area-level confounders. RESULTS: Residential proximity to crops was associated with decreased mortality risks overall. In contrast to the overall trend an increased risk was observed for chronic lower respiratory diseases and proximity to maize cultivation. We found no evidence of an association between the amount of pesticides used and cause-specific mortality. CONCLUSIONS: In a large prospective census-based cohort study in The Netherlands we found evidence of an increased risk of chronic lower respiratory diseases in relation to maize cultivation which was not reflected in general pesticide use, hinting to specific pesticides or practices in maize cultivation that may lead to the observed increased risk.

Pesticides in doormat and floor dust from homes close to treated fields: Spatio-temporal variance and determinants of occurrence and concentrations.

Indoor dust has been postulated as an important matrix for residential pesticide exposure. However, there is a lack of information on presence, concentrations and determinants of multiple pesticides in dust in residential homes close to treated fields. Our objective was to characterize the spatial and temporal variance of pesticides in house dust, study the use of doormats and floors as proxies for pesticides in indoor dust and identify determinants of occurrence and concentrations. Homes within 250 m from selected bulb fields were invited to participate. Homes within 20 km from these fields but not having agricultural fields within 500 m were selected as controls. House dust was vacuumed in all homes from floors (VFD) and from newly placed clean doormats (DDM). Sampling was done during two periods, when pesticides are used and not-used. For determination of 46 prioritized pesticides, a multi-residue extraction method was used. Most statistical analyses are focused on the 12 and 14 pesticides that were detected in >40% of DDM and VFD samples, respectively. Mixed models were used to evaluate relationships between possible determinants and pesticides occurrence and concentrations in DDM and VFD. 17 pesticides were detected in more than 50% of the homes in both matrixes. Concentrations differed by about a factor five between use and non-use periods among homes within 250 m of fields and between these homes and controls. For 7 pesticides there was a moderate to strong correlation (Spearman rho 0.30-0.75) between concentrations in DDM and VFD. Distance to agricultural fields and air concentrations were among the most relevant predictors for occurrence and levels of a given pesticide in DDM. Concentrations in dust are overall higher during application periods and closer to fields (<250 m) than further away. The omnipresence of pesticides in dust lead to residents being exposed all year round.

OBOMod - Integrated modelling framework for residents' exposure to pesticides.

BACKGROUND: Pesticides can be transported from the site of application to homes via different routes and lead to exposure of residents, raising concerns regarding health effects. We built a deterministic model framework (OBOmod) to assess exposure of residents living near fields where pesticides are applied. METHODS: OBOmod connects five independent models operating on an hourly timescale and high spatial resolution (meters). Models include descriptions of spray drift, volatilization, atmospheric transport and dispersion, exchange between outdoor and indoor air and exchange between indoor air and dust. Fourteen bulb field applications under different weather conditions and comprising 12 pesticides were simulated. Each simulation included the first seven days after the application. The concentrations computed with OBOmod were compared with those measured in outdoor and indoor air and the amounts measured in indoor dust samples. RESULTS: Model evaluation indicated suitability of the developed framework to estimate outdoor and indoor air concentrations. For most pesticides, model accuracy was good. The framework explained about 30% to 95% of the temporal and spatial variability of air concentrations. For 20% of the simulations, the framework explained more than 35% of spatial variability of concentrations in dust. In general, OBOmod estimates remained within one order of magnitude from measured levels. Calculations showed that in addition to spray drift during application, volatilization from the field after spraying and pesticides in house dust are important routes for residents' exposure to pesticides. CONCLUSIONS: Our framework covers many processes needed to calculate exposure of residents to pesticides. The evaluation phase shows that, with the exception of the dust model, the framework can be used in support of health and epidemiological studies, and can serve as a tool to support development of regulations and policy making regarding pesticide use.