Relative Exposure Levels Research Articles

Cattle aggregations at shared resources create potential parasite exposure hotspots for wildlife.

Globally rising livestock populations and declining wildlife numbers are likely to dramatically change disease risk for wildlife and livestock, especially at resources where they congregate. However, limited understanding of interspecific transmission dynamics at these hotspots hinders disease prediction or mitigation. In this study, we combined gastrointestinal nematode density and host foraging activity measurements from our prior work in an East African tropical savannah system with three estimates of parasite sharing capacity to investigate how interspecific exposures alter the relative riskiness of an important resource - water - among cattle and five dominant herbivore species. We found that due to their high parasite output, water dependence and parasite sharing capacity, cattle greatly increased potential parasite exposures at water sources for wild ruminants. When untreated for parasites, cattle accounted for over two-thirds of total potential exposures around water for wild ruminants, driving 2-23-fold increases in relative exposure levels at water sources. Simulated changes in wildlife and cattle ratios showed that water sources become increasingly important hotspots of interspecific transmission for wild ruminants when relative abundance of cattle parasites increases. These results emphasize that livestock have significant potential to alter the level and distribution of parasite exposures across the landscape for wild ruminants.

Economic risk assessment of climate change at the city level. The case of Cape Town, South Africa

ABSTRACTEstimating the economic risks of climate shocks and climate stressors on spatially heterogeneous cities over time remains highly challenging. The purpose of this paper is to present a practical methodology to assess the economic risks of climate change in middle-income cities to inform municipal climate response strategies. Building on a capital-based framework (CBF), spatially disaggregated baseline and future scenario scores for economic wealth and its exposure to climate change are developed for six different classes of capital across 77 major suburbs in Cape Town, South Africa. Capital-at-risk was calculated by combining relative exposure and capital scores across different scenarios, with population impacted for major suburbs and the city’s eight main planning districts. The economic risk assessment presented here provides a generic approach to assist city managers through an enhanced understanding of the relative levels of capital endowment across the city vis-à-vis relative levels of exposure to climate-related hazards over time.

Overview of Adductomics in Toxicology.

Adductomics is epidemiology at the molecular level. Untargeted adductomics compares levels of chemical adducts on albumin, hemoglobin, and DNA between healthy and exposed individuals. The goal is to determine a cause-and-effect relationship between chemical exposure and illness. Chemical exposures are not necessarily due to synthetic chemicals but are often due to oxidation products of naturally occurring lipids, for example, 4-hydroxynonenal and acrolein produced by lipid peroxidation of arachidonic and linoleic acids. The preferred method used in adductomics is ultra-high pressure liquid chromatography coupled to with nanoelectrospray tandem mass spectrometry. The mass of the adduct indicates its structure and identifies the chemical. The advantages of molecular epidemiology include information about the many toxicants to which a person is exposed over a period of weeks or months and the relative exposure levels. The disadvantage is the absence of information about the mechanism of toxicity. Untargeted adductomics examines albumin and hemoglobin adducts, which serve as biomarkers of exposure but do not identify the proteins and genes responsible for the toxicity. Targeted adductomics is used when the origin of the toxicity is known. This can be either an adducted protein, such as the butyrylcholinesterase protein modified by nerve agents, or a toxicant, such as acetaminophen. Untargeted adductomics methods have identified potential protein adduct biomarkers of breast cancer, colorectal cancer, childhood leukemia, and lung cancer. Adductomics is a new research area that offers structural insights into chemical exposures and a platform for the discovery of disease biomarkers. © 2023 The Authors. Current Protocols published by Wiley Periodicals LLC.

Validity of self-reported air pollution annoyance to assess long-term exposure to air pollutants in Belgium

In epidemiological studies, assessment of long term exposure to air pollution is often estimated using air pollution measurements at fixed monitoring stations, and interpolated to the residence of survey participants through Geographical Information Systems (GIS). However, obtaining georeferenced address data from national registries requires a long and cumbersome administrative procedure, since this kind of personal data is protected by privacy regulations. This paper aims to assess whether information collected in health interview surveys, including air pollution annoyance, could be used to build prediction models for assessing individual long term exposure to air pollution, removing the need for data on personal residence address.Analyses were carried out based on data from the Belgian Health Interview Survey (BHIS) 2013 linked to GIS-modelled air pollution exposure at the residence place of participants older than 15 years (n = 9347). First, univariate linear regressions were performed to assess the relationship between air pollution annoyance and modelled exposure to each air pollutant. Secondly, a multivariable linear regression was performed for each air pollutant based on a set of variables selected with elastic net cross-validation, including variables related to environmental annoyance, socio-economic and health status of participants. Finally, the performance of the models to classify individuals in three levels of exposure was assessed by means of a confusion matrix.Our results suggest a limited validity of self-reported air pollution annoyance as a direct proxy for air pollution exposure and a weak contribution of environmental annoyance variables in prediction models. Models using variables related to the socio-economic status, region, urban level and environmental annoyance allow to predict individual air pollution exposure with a percentage of error ranging from 8% to 18%. Although these models do not provide very accurate predictions in terms of absolute exposure to air pollution, they do allow to classify individuals in groups of relative exposure levels, ranking participants from low over medium to high air pollution exposure. This model represents a rapid assessment tool to identify groups within the BHIS participants undergoing the highest levels of environmental stress.

Intake and Uptake of Chemicals Upon Use of Various Tobacco/Nicotine Products: Can Users be Differentiated by Single or Combinations of Biomarkers?

Summary With increasing use of new generation tobacco/nicotine products (TNPs) instead or in addition to conventional cigarettes (CCs), the question arises, whether the user of these new TNPs and CCs can be distinguished on the basis of their exposure in terms of intake and uptake of specific chemicals. For this purpose, the exposure to chemicals for users of 5 product types including CCs, HNB (heat-not-burn products), electronic cigarettes (ECs), oral tobacco products (OT, with the focus on snus), nicotine replacement therapy (NRT) products (only nicotine gum (NG) was considered in this study) was evaluated on the basis of published data. For both intake and biomarker-based uptake, 4 relative exposure levels with the assigned values from 1 (lowest exposure) to 4 (highest exposure) were defined resulting in exposure level patterns. Unique single-biomarker-based exposure levels were found for smokers (11 chemicals), vapers (1 chemical) and non-users (NU, 1 chemical). A few selected biomarkers (usually with relative levels of 3–4) were found to be sufficient for unequivocal differentiation of one user/NU group from the other 5 groups. The impact of dual-product use is also briefly discussed. [Contrib. Tob. Nicotine Res. 30 (2021) 167–198]

Organic Farming Lessens Reliance on Pesticides and Promotes Public Health by Lowering Dietary Risks

Organic agriculture is a production system that relies on prevention, ecological processes, biodiversity, mechanical processes, and natural cycles to control pests and maintain productivity. Pesticide use is generally limited or absent in organic agroecosystems, in contrast with non-organic (conventional) production systems that primarily rely on pesticides for crop protection. Significant differences in pesticide use between the two production systems markedly alter the relative dietary exposure and risk levels and the environmental impacts of pesticides. Data are presented on pesticide use on organic and non-organic farms for all crops and selected horticultural crops. The relative dietary risks that are posed by organic and non-organic food, with a focus on fresh produce, are also presented and compared. The results support the notion that organic farms apply pesticides far less intensively than conventional farms, in part because, over time on well-managed organic farms, pest pressure falls when compared to the levels on nearby conventional farms growing the same crops. Biopesticides are the predominant pesticides used in organic production, which work by a non-toxic mode of action, and pose minimal risks to human health and the environment. Consequently, eating organic food, especially fruits and vegetables, can largely eliminate the risks posed by pesticide dietary exposure. We recommend ways to lower the pesticide risks by increased adoption of organic farming practices and highlight options along organic food supply chains to further reduce pesticide use, exposures, and adverse worker and environmental impacts.

Opportunities and challenges in reducing personal inhalation exposure to air pollution among electronic waste recovery workers in Ghana.

Informal sector electronic waste (e-waste) recovery produces toxic emissions resulting from burning e-waste to recover valuable metals. To identify high-risk worker groups by measuring relative levels of personal inhalation exposure to particulate matter (PM) of fine (≤2.5 µm) and coarse (2.5-10 µm) fractions (PM2.5 and PM2.5-10, respectively) across work activities among e-waste workers, and to assess how wind conditions modify levels of PM by activity and site location. At the Agbogbloshie e-waste site, 170 partial-shift PM samples and time-activity data were collected from participants (N = 105) enrolled in the GeoHealth cohort study. Personal sampling included continuous measures of size-specific PM from the worker's breathing zone and time-activity derived from wearable cameras. Linear mixed models were used to estimate changes in personal PM2.5 and PM2.5-10 associated with activities and evaluate effect modification by wind conditions. Mean (±standard deviation) personal PM2.5 and PM2.5-10 concentrations were 80 (± 81) and 123 (± 139) µg m-3 , respectively. The adjusted mean PM2.5 concentration for burning e-waste was 88 µg m-3 , a 28% increase above concentrations during non-recovery activities (such as eating). Transportation-related and burning activities were associated with the highest PM2.5-10 concentrations. Frequent changes in wind direction were associated with higher PM2.5 concentrations when burning, and high wind speeds with higher PM2.5-10 concentrations when dismantling e-waste downwind of the burning zone.

Context-sensitive ecological momentary assessments; integrating real-time exposure measurements, data-analytics and health assessment using a smartphone application

IntroductionModern sensor technology makes it possible to collect vast amounts of environmental, behavioural and health data. These data are often linked to contextual information on for example exposure sources which is separately collected with considerable lag time, leading to complications in assessing transient and/or highly spatially variable environmental exposures. Context-Sensitive Ecological Momentary Assessments11CS-EMA: Context-Sensitive Ecological Momentary Assessment. (CS-EMAs) could be used to address this. We present a case study using radiofrequency-electromagnetic fields (RF-EMF) exposure as an example for implementing CS-EMA in environmental research. MethodsParticipants were asked to install a custom application on their own smartphone and to wear an RF-EMF exposimeter for 48h. Questionnaires were triggered by the application based on a continuous data stream from the exposimeter. Triggers were divided into four categories: relative and absolute exposure levels, phone calls, and control condition. After the two days of use participants filled in an evaluation questionnaire. Results74% of all CS-EMAs were completed, with an average time of 31s to complete a questionnaire once it was opened. Participants reported minimal influence on daily activities. There were no significant differences found between well-being and type of RF-EMF exposure. ConclusionsWe show that a CS-EMA based method could be used in environmental research. Using several examples involving environmental stressors, we discuss both current and future applications of this methodology in studying potential health effects of environmental factors.

Comparative Bioavailability of Tizanidine in Three Dosage Forms (6-MG Delayed-Release Tablets, Sirdalud Preparation, and 2-MG Tablets)

Valenta Pharm Co. compared the pharmacokinetic parameters in healthy volunteers of three prototype tizanidine dosage forms (delayed-release 6-mg tablets) and the reference drug sirdalud (2-mg tablets for a total dose of 6 mg, three tablets). This allowed the relative bioavailability of the three prototype tizanidine forms relative to sirdalud to be assessed. All three prototypes showed signs of delay based on MRT parameters of (2.217 ± 0.441) h for the sirdalud instant-release form and (6.529 ± 1.990), (5.951 ± 1.295), and (6.384 ± 2.339) h for prototypes T1, T2, and T3, respectively. High relative exposure levels of prototypes T1, T2, and T3 [AUC 103.80% (73.69 – 146.20), 124.14% (88.14 – 174.86), and 131.93% (93.66 – 185.82), respectively] with a significant decrease of C max (to 35.83, 38.78, and 40.79%, respectively) were demonstrated by analyzing the comparative bioavailability. A model pharmacokinetic study of the forms produced secondary modeling parameters that were similar to those obtained by an off-model method (89.19 – 122.71%). This confirmed that the developed model was acceptable for planning future clinical tests of these drugs.

Capturing the Active Ingredients of Multicomponent Participatory Organizational Stress Interventions Using an Adapted Study Design

Adapted study designs use process evaluation to incorporate a measure of intervention exposure and create an artificial control and intervention groups. Taking into account exposure levels to interventions combines process and outcome evaluation and strengthens the design of the study when exposure levels cannot be controlled. This study includes longitudinal data (two assessments) with added process measures at time 2 gathered from three complex participatory intervention projects in Canada in a hospital and a university. Structural equation modelling was used to explore the specific working mechanisms of particular interventions on stress outcomes. Results showed that higher exposure to interventions aiming to modify tasks and working conditions reduced demands and improved social support, but not job control, which in turn, reduced psychological distress. Exposure to interventions aiming to improve relationships was not related to psychosocial risks. Most studies cannot explain how interventions produce their effects on outcomes, especially when there are multiple concurrent interventions delivered in several contexts. This study advances knowledge on process evaluation by using an adapted study design to capture the active ingredients of multicomponent interventions and suggesting some mechanisms by which the interventions produce their effects on stress outcomes. It provides an illustration of how to conduct process evaluation and relate exposure levels to observed outcomes. Copyright © 2016 John Wiley & Sons, Ltd.

Short-term health effects in the general population following a major train accident with acrylonitrile in Belgium

BackgroundFollowing a train derailment, several tons of acrylonitrile (ACN) exploded, inflamed and part of the ACN ended up in the sewage system of the village of Wetteren. More than 2000 residents living in the close vicinity of the accident and along the sewage system were evacuated. A human biomonitoring study of the adduct N-2-cyanoethylvaline (CEV) was carried out days 14–21 after the accident. Objectives(1) To describe the short-term health effects that were reported by the evacuated residents following the train accident, and (2) to explore the association between the CEV concentrations, extrapolated at the time of the accident, and the self-reported short-term health effects. MethodsShort-term health effects were reported in a questionnaire (n=191). An omnibus test of independence was used to investigate the association between the CEV concentrations and the symptoms. Dose-response relationships were quantified by Generalized Additive Models (GAMs). ResultsThe most frequently reported symptoms were local symptoms of irritation. In non-smokers, dose-dependency was observed between the CEV levels and the self-reporting of irritation (p=0.007) and nausea (p=0.007). Almost all non-smokers with CEV concentrations above 100pmol/g globin reported irritation symptoms. Both absence and presence of symptoms was reported by non-smokers with CEV concentrations below the reference value and up to 10 times the reference value. Residents who visited the emergency services reported more symptoms. This trend was seen for the whole range of CEV concentrations, and thus independently of the dose. Discussion and conclusionThe present study is one of the first to relate exposure levels to a chemical released during a chemical incident to short-term (self-reported) health effects. A dose-response relation was observed between the CEV concentrations and the reporting of short-term health effects in the non-smokers. Overall, the value of self-reported symptoms to assess exposure showed to be limited. The results of this study confirm that a critical view should be taken when considering self-reported health complaints and that ideally biomarkers are monitored to allow an objective assessment of exposure.

Cancer Risk from Exposure to Low to Moderate Level of Arsenic Using Meta-Analysis of Flexible Regression Models

These meta-analysis studies on arsenic exposure and disease risk assume linear exposure-response models. The linearity assumption for the logarithm of relative risks and levels of exposure to arsenic is overly simplified and is not adequate to capture the local structure accurately. This article applies fractional polynomial and cubic spline regression models in order to capture the shapes of the exposure-response relationships between both bladder and lung cancer risk and exposure to low to moderate dose arsenic. We consider low to moderate dose levels with concentrations from near 0 to 300µg/l. We also consider more recent studies on low to moderate dose exposure to arsenic and the risk of bladder and lung cancer. These flexible models are used to identify a combined general exposure-response relationship for the logarithm of relative risk and the levels of exposure to arsenic. The primary objective of this study is to predict overall risks of bladder and lung cancers by combining findings from systematically selected studies on these cancers under both linear and non-linear modeling assumptions. We predict overall risks of bladder and lung cancers for a series of exposure levels from the best fitting models.

Place effects on noise annoyance: Cumulative exposures, odour annoyance and noise sensitivity as mediators of environmental context

Previous research suggests there may be combined effects of outdoor air pollution and traffic noise on noise annoyance, but it is not known how environmental context can moderate these effects. Physical attributes of the environment can influence relative levels of exposure, while sociocultural contexts can moderate environmental perceptions. Noise sensitivity is an important factor in appraisal, but previous research has not linked levels of sensitivity to contextual factors. The objectives of this study were to understand how a high-volume traffic corridor and pollution hotspot could influence co-exposures to air pollution and traffic noise and consequent levels of noise annoyance. Data from a community survey (n = 610) along with modelled estimates of residential traffic noise and nitrogen dioxide exposure were utilized for the analyses. The effective loudness function for noise annoyance and an ordinal location-scale model showed that varying levels of co-exposure to traffic noise and air pollution along with odour annoyances in the corridor and a control area had strong effects on the noise annoyance dose–response. The results also indicated that there was a significantly higher level of error in predicting noise annoyance in the corridor area. There appeared to be neighbourhood-level differences in the effect of noise sensitivity on noise annoyance. The findings have important implications for our understanding of multiple exposures along with the influence of environmental context on noise annoyance. In particular, this study demonstrates that research on the effects of traffic noise across large urban areas may conceal important phenomena occurring at the neighbourhood level.

Improving Media Measurement: Evidence From the Field

In light of a recent exchange between Prior (2013a) and Dilliplane, Goldman, and Mutz (2013), we evaluate the new American National Election Study program-count measures of news exposure using a unique dataset that tracks self-reports as well as actual exposure to news collected via passive tracking devices. We bring these data to bear on concerns raised by Prior (2013a) about the construct and convergent validity of the new ANES measures. Our results add nuance to previous findings showing respondents’ propensity to overreport exposure to news, and also demonstrate that on average, self-reported measures reflect relative levels of exposure quite well. Additionally, we show that the more unique news programs a person watches, the more total time he or she is exposed to political news. Very few people watch only one program but watch it repeatedly. The data also reveal an increase in the number of programs watched leading up to election day, and a concomitant increase in the amount of time per capita spent with political news as elections approach. We conclude, however, that the program-count measure is not without its weaknesses. Shortening the list of programs affects construct validity by introducing noise into the low end of the scale. Expanding the list of programs in the survey to include local news and special reports will improve fidelity at the low end of this new measure.

Acoustic scene metrics for spatial planning

Potential effects of anthropogenic underwater sounds on marine mammals are usually assessed on the basis of exposure to one sound source. Recently published research modeling underwater noise exposure and assessing its impact on marine life has extended the typical single source/single species absolute received level approach to defining exposure in a variety of ways including: relative levels of exposure, such as loudness, signal to noise ratio, and sensation level; metrics for evaluating chronic elevation in background noise; cumulative exposure to multiple and dissimilar sound sources, as well as the potential for animals to selectively avoid a particular source and other behavioral changes. New approaches to managing the overall acoustic scene that account for these issues requires a more holistic and multi-dimensional approach that addresses the relationships among the noise environment, animal hearing and behavior, and anthropogenic sound sources. We present a layered acoustic scene concept that considers each facet of the extended problem. Our exemplar is a seismic survey in the Gulf of Mexico with layers for ambient oceanographic and meteorological noise, shipping, and distant anthropogenic sources in which the exposure is filtered by the animal’s hearing filter, sensation level, and nominal loudness of the signal.

Systemic and cerebral exposure to and pharmacokinetics of flavonols and terpene lactones after dosing standardized Ginkgo biloba leaf extracts to rats via different routes of administration

Flavonols and terpene lactones are putatively responsible for the properties of Ginkgo biloba leaf extracts that relate to prevention and treatment of cardiovascular disease and cerebral insufficiency. Here, we characterized rat systemic and cerebral exposure to these ginkgo compounds after dosing, as well as the compounds' pharmacokinetics. Rats received single or multiple doses of ShuXueNing injection (prepared from GBE50 for intravenous administration) or GBE50 (a standardized extract of G. biloba leaves for oral administration). Brain delivery of the ginkgo compounds was assessed with microdialysis. Various rat samples were analysed using liquid chromatography/mass spectrometry. Slow terminal elimination features of the flavonols counterbalanced the influence of poor oral bioavailability on their systemic exposure levels, which also resulted in significant accumulation of the compounds in plasma during the subchronic treatment with ShuXueNing injection and GBE50. Unlike the flavonols, the terpene lactones had poor enterohepatic circulation due to their rapid renal excretion and unknown metabolism. The flavonol glycosides occurred as major forms in plasma after dosing with ShuXueNing injection, while the flavonol aglycone conjugates were predominant in plasma after dosing with GBE50. Cerebral exposure was negligible for the flavonols and low for the terpene lactones. Unlike the significant systemic exposure levels, the levels of cerebral exposure to the flavonols and terpene lactones are low. The elimination kinetic differences between the two classes of ginkgo compounds influence their relative systemic exposure levels. The information gained is relevant to linking ginkgo administration to the medicinal effects.

Transfer Efficiency of Bacteria and Viruses from Porous and Nonporous Fomites to Fingers under Different Relative Humidity Conditions

Fomites can serve as routes of transmission for both enteric and respiratory pathogens. The present study examined the effect of low and high relative humidity on fomite-to-finger transfer efficiency of five model organisms from several common inanimate surfaces (fomites). Nine fomites representing porous and nonporous surfaces of different compositions were studied. Escherichia coli, Staphylococcus aureus, Bacillus thuringiensis, MS2 coliphage, and poliovirus 1 were placed on fomites in 10-μl drops and allowed to dry for 30 min under low (15% to 32%) or high (40% to 65%) relative humidity. Fomite-to-finger transfers were performed using 1.0 kg/cm(2) of pressure for 10 s. Transfer efficiencies were greater under high relative humidity for both porous and nonporous surfaces. Most organisms on average had greater transfer efficiencies under high relative humidity than under low relative humidity. Nonporous surfaces had a greater transfer efficiency (up to 57%) than porous surfaces (<6.8%) under low relative humidity, as well as under high relative humidity (nonporous, up to 79.5%; porous, <13.4%). Transfer efficiency also varied with fomite material and organism type. The data generated can be used in quantitative microbial risk assessment models to assess the risk of infection from fomite-transmitted human pathogens and the relative levels of exposure to different types of fomites and microorganisms.

An Updated Algorithm for Estimation of Pesticide Exposure Intensity in the Agricultural Health Study

An algorithm developed to estimate pesticide exposure intensity for use in epidemiologic analyses was revised based on data from two exposure monitoring studies. In the first study, we estimated relative exposure intensity based on the results of measurements taken during the application of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) (n = 88) and the insecticide chlorpyrifos (n = 17). Modifications to the algorithm weighting factors were based on geometric means (GM) of post-application urine concentrations for applicators grouped by application method and use of chemically-resistant (CR) gloves. Measurement data from a second study were also used to evaluate relative exposure levels associated with airblast as compared to hand spray application methods. Algorithm modifications included an increase in the exposure reduction factor for use of CR gloves from 40% to 60%, an increase in the application method weight for boom spray relative to in-furrow and for air blast relative to hand spray, and a decrease in the weight for mixing relative to the new weights assigned for application methods. The weighting factors for the revised algorithm now incorporate exposure measurements taken on Agricultural Health Study (AHS) participants for the application methods and personal protective equipment (PPE) commonly reported by study participants.

The sociolinguistic competence of former immersion students at the post-secondary level: the case of lexical variation

This paper examines two sociolinguistic lexical variables, ‘work’ and ‘to dwell,’ in the spoken French of former immersion students in their first or fourth year at a bilingual university in Ontario, Canada. Their patterns of use are compared to those of non-immersion graduates in the same institution, to Ontario high school immersion students, to former immersion students living in daily contact with French in Montreal, Canada, and to native speakers of Canadian French. The results suggest that, while under-performing in relation to the Montreal learners and the native speakers, the former immersion university students are at an advantage over their non-immersion university and their high school immersion counterparts in mastering socially stratified lexical variants, but that this advantage does not extend to socially neutral variants. The results are discussed in light of the relative levels of exposure to ‘naturalistic’ French experienced by the various speaker groups.

Otitis, rhinitis, and atopy in relation to domestic endotoxin and β-glucan exposure among children in Singapore

Exposure to microbial cell wall agents (MCWAs) has been related to the risk for atopy, otitis, and rhinitis. To relate domestic exposure to two important MCWAs-β-glucan and endotoxin-to the risk for otitis, rhinitis, atopy, and allergy in a sample of children from Singapore. Subjects (n=98) were recruited from July 2006 to December 2008. Blood samples were taken to determine nonspecific IgE and skin prick tests were performed. Dust samples were collected from the bedrooms of the subjects and analyzed for the content of β-glucan and endotoxin, using the Limulus method. Levels of IgE were significantly higher among children with rhinitis, and these children also had a larger proportion of atopics. There were no differences in β-glucan values between children with otitis, children with rhinitis, and controls. Endotoxin levels were lower in the homes of children with otitis, with a tendency for the levels to be lower in those with rhinitis. Among children with a high level of β-glucan, there was a higher proportion of those with high IgE values and atopy. The results suggest that a low level of endotoxin is a risk factor for otitis and that a high level of β-glucan is a risk factor for atopic sensitisation. Reactions to domestic indoor exposure are determined by several indoor agents and their relative exposure levels.