Dust Endotoxin Research Articles

Evaluation of dust and endotoxin exposure among rice mill workers in northeast India

Exposure to particulate matter and endotoxin can lead to acute and chronic respiratory problems in workers. A study was conducted to quantify particulate matter with an aerodynamic diameter of ≤10 μm (PM10) and endotoxin levels in rice mills in northeast India. Sixty-four PM10 dust samples were collected from eight rice mills at two locations: the feeding and polishing sections for two varieties of paddy: Ranjit and Hali. Endotoxin exposures were analyzed using the Limulus Amoebocyte Lysate (LAL) gel clot test. The results showed that the geometric mean of the 8-h time-weighted average (TWA) PM10 dust concentration and endotoxin level in the rice mills were 10.69 mg/m³ and 2.2 EU/m³, respectively. Dust and endotoxin exposure were higher in the feeding section than in the polishing section. Endotoxin exposure in the feeding section during the milling of the Hali variety of paddy was 56.0 % higher than the milling of the Ranjit variety. Additionally, endotoxin exposure during the milling of the Hali variety was 24.2 % higher than that of the milling of the Ranjit variety in the polishing section. The dust exposure in the rice mills was 194.5 % higher than the standards set up by the United States Environmental Protection Agency. However, the exposure to endotoxin in rice mills was approximately 40.10 times below the recommended limit of 90 EU/m3.

Association between house dust endotoxin and kidney injury: findings from the national health and nutrition examination survey (NHANES) 2005-2006.

House dust endotoxin is thought to be associated with systemic inflammatory responses and respiratory diseases. Previous studies have indicated that lung injury and systemic inflammation could lead to kidney damage. However, the potential link between house dust endotoxin and the increased risk of kidney injury remains unexplored. This cross-sectional study and retrospective study aim to investigate the relationship between house dust endotoxin levels and renal markers, specifically the urinary albumin-to-creatinine ratio (UACR) and estimated glomerular filtration rate (eGFR), utilizing data from the NHANES 2005-2006 survey cycle. Proteinuria was assessed using the UACR, with values categorized into negative (UACR ≤ 30mg/g) and positive (UACR > 30mg/g) groups. Significant differences in house dust endotoxin levels were observed between these groups (p value = 0.003). Weighted logistic regression analysis indicated that higher levels of house dust endotoxin were associated with an increased rate of positive UACR (OR [95% CI]: 1.57 [1.20, 2.05]; p value = 0.003). This association remained significant after adjusting for covariates such as age, gender, race, poverty income ratio (PIR), Type 2 Diabetes Mellitus (T2DM), and hypertension (OR [95% CI]: 1.46 [1.08, 1.97]; p-Value = 0.021). However, no significant correlation was found between house dust endotoxin levels and eGFR (Estimate [95% CI]: 1.19 [-1.28, 3.66]; p value = 0.32). Our findings suggest a significant association between house dust endotoxin levels and proteinuria, based on data from the NHANES 2005-2006 survey cycle. This association indicates that elevated levels of house dust endotoxin may be linked to kidney damage. Further research is necessary to elucidate the specific relationship between exposure to house dust endotoxin and the risk of developing kidney disease.

Indoor air quality in remote first nations communities in Ontario, Canada.

A recent study of the health of Indigenous children in four First Nations Communities in remote northwestern Ontario found that 21% of children had been admitted to hospital for respiratory infections before age 2 years. Here we report a detailed analysis of the housing conditions in these communities. We employed a variety of statistical methods, including linear regression, mixed models, and logistic regression, to assess the correlations between housing conditions and loadings of biocontaminants (dust mite allergens, fungal glucan, and endotoxin) and indoor concentrations of PM2.5, CO2, benzene, and formaldehyde. The houses (n = 101) were crowded with an average of approximately 7 people. Approximately 27% of the homes had sustained CO2 concentrations above 1500 ppm. Most homes had more than one smoker. Commercial tobacco smoking and the use of non-electric heating (e.g., wood, oil) were associated with increased fine particle concentrations. Over 90% of the homes lacked working Heat Recovery Ventilators (HRVs), which was associated with increased fine particle concentrations and higher CO2. Of the 101 homes, 12 had mold damage sufficient to increase the relative risk of respiratory disease. This resulted from roof leaks, through walls or around the windows due to construction defects or lack of maintenance. A similar percentage had mold resulting from condensation on windows. Endotoxin loadings were much higher than any previous study in Canada. This work provides evidence for the need for more effort to repair existing houses and to ensure the HRVs are properly installed and maintained.

Wood dust and asthma.

Review recent developments on asthma associated with wood dust, given the increasing scale of wood handling and processing activities globally. Work in wood industries is associated with a significantly increased risk of respiratory symptoms, rhinitis and asthma. This can be attributed to traditional processing techniques and newer technologies producing complex bioaerosol exposures, which may include chemicals. Meta-analysis studies indicate strong evidence for wood dusts as occupational sensitizers for asthma, but the underlying mechanisms remain poorly understood. The global prevalence of asthma in wood workers ranges between 6-18% and for rhinitis 16-33%. Exposure estimates show wide variation. Risk factors include atopy and exposure to certain wood species, elevated current and cumulative particulate exposures. Future studies should focus on better characterization of wood dust allergens and other bioaerosol components, specific immunoglobulin E responses to different wood species, pathophysiological mechanisms underlying asthma, and modelling dose-response relationships using refined exposure metrics for dust particulate and other bioaerosol components. There is a need for improved health-based international exposure standards and effective workplace control measures to reduce exposures to wood dust particulate (hard and soft woods), endotoxin and β-glucan, to reduce the risks of asthma in wood workers.

Environmental determinants of household microbial and allergen levels in the Greater Taipei Area

People spend most of their time indoors, where they may be exposed to various microorganisms and allergens. In this cross-sectional study, we investigated the relationship between indoor microbial and allergen levels and indoor and outdoor household environmental characteristics. Participants were recruited from an ongoing cohort study in the Greater Taipei Area. Questionnaire administration and environmental sampling were conducted during home visits. Samples were collected from children's bedrooms, living rooms, kitchens, and outdoor areas (balconies) and analyzed for fungal spores, house dust mite allergens (Der p 1 and Der f 1), endotoxin, and cockroach allergens (Bla g 1). Indoor temperature and relative humidity were also measured, and the land-use characteristics and points of interest surrounding the residences were evaluated within specified radii. The mean levels of outdoor air pollutants were then estimated, and multiple regression analysis was performed to investigate the predictors of indoor microbial and allergen levels. In total, 136 homes were analyzed. The results indicated that dog ownership, air purifier use, and floor cleaning frequency were major predictors of indoor microbial and allergen levels. Moreover, proximity to parks, roads, and forests was associated with elevated levels of indoor microorganisms and allergens. Our results demonstrated that indoor concentrations of certain microorganisms and allergens tended to increase in households located within neighborhoods with particular characteristics. Overall, our research findings contribute to housing intervention protocols and policies aimed at reducing exposure to indoor microorganisms and allergens. Future studies should longitudinally investigate the health effects of indoor microorganisms and allergens.

Fungi, mites/ticks, allergens, and endotoxins in different size fractions of house dust from long-term uninhabited houses and inhabited houses

Considering the necessity of countermeasures against microbial contamination in long-term uninhabited houses after the Fukushima accident, fungi, mites/ticks, allergens, and endotoxins in house dust from long-term (6–7 years) uninhabited houses (N = 37) and inhabited houses (N = 17) were investigated. In addition, the particle size dependence of microbial concentrations was evaluated to know what sieving size is desirable for microbial hazard and exposure assessments in dust. No difference in particle size distribution was observed between the two types of houses. Fungal concentrations were much higher in the long-term uninhabited houses than those in the inhabited houses, with the values decreasing with increase in particle size. Aspergillus spp. was dominant in 78% of the long-term uninhabited houses but in only 31% of the inhabited houses. Mite concentrations were not different between long-term uninhabited and inhabited houses; in both, the highest mite concentrations were observed in 63–180 μm dust particles while the highest Der 1 and Der 2 concentrations were observed in 20–63 μm dust particles. In inhabited houses, Dermatophagoides were predominant, whereas they represented <50% of mite population in long-term uninhabited houses. Endotoxin concentrations were lower in inhabited houses than in long-term uninhabited houses. The endotoxin concentration in the long-term uninhabited houses increased with increasing particle size. In conclusion, residents should reduce fungal and mite concentrations through careful cleaning prior to occupancy. The dependence of microbial concentration on particle size varied with microbial species and location, confirming that sieving size deserves attention in microbial hazard and exposure assessment.

Exposure to House Dust Mite Allergen and Endotoxin in Early Life and Sensitization and Allergic Rhinitis: The JECS.

The association between endotoxin and allergic rhinitis (AR) is not conclusive. The aim of this study was to determine the association between endotoxin and house dust mite (HDM) allergens in dust, and HDM sensitization and AR among Japanese infants. This study included 4188 participants in the Sub-Cohort Study of the Japan Environment and Children's Study. Dust was collected from children's mattresses at age 18 months and endotoxin and HDM allergen levels were measured. A logistic regression model was used to analyze the association between endotoxin or HDM allergen and the sensitization to HDM (specific-IgE) at age 2 and AR at age 3. The median (interquartile range) endotoxin level was 375.1(186.9-826.5) EU/m2 and the Der 1 (Der p 1 + Der f 1) level was 51.2 (14.8-168.6) ng/m2. There were significant positive associations between endotoxin and HDM sensitization (Der f 1, adjusted odds ratio [aOR] quartile [Q] 4 vs. Q1, 1.44, 95% CI, 1.04-2.00; Der p 1, aOR Q4 vs. Q1, 1.56, 95% CI, 1.12-2.16). There were also significant positive associations between Der 1 exposure and HDM sensitization (Der f 1, aOR Q3 vs. Q1, 1.75, 95% CI, 1.26-2.44; aOR Q4 vs. Q1, 2.98, 95% CI, 2.15-4.13; Der p 1, aOR Q3 vs. Q1, 1.91, 95% CI, 1.37-2.66; aOR Q4 vs. Q1, 2.91, 95% CI, 2.09-4.05). There were, however, no associations between endotoxin or Der 1 and AR. In the population residing mostly in non-farming settings, both endotoxin and HDM allergens in dust were associated with an increased risk of HDM allergen sensitization, but not with AR.

Exposure to Endotoxins as a Risk Factor for Decreased Lung Function in Workers in the Cotton-Based Textile Industry

Dust particles that enter the body through inhalation and into the lungs can cause disturbances in the respiratory tract. Dust particles produced from cotton fibers can contain endotoxin biological agents, inhalation of endotoxins can also cause other diseases namely, flu, bronchitis, chronic obstructive pulmonary and decreased lung function. This study was conducted for the analysis of endotoxin exposure in cotton dust as a risk factor for decreasing lung function of workers in the textile industry. The method used in writing this article is a literature review using ten scientific articles to analyze the level of endotoxins in cotton dust, the characteristics of workers and the decline in lung function in workers. The study found that the highest levels of endotoxins were found in cotton mills in Shanghai with annual endotoxin levels of 1,730-65,204 EU/m3. Endotoxins in cotton dust are found most abundantly in spinning and weaving units. Factors such as age, length of service and smoking status are risk factors for workers experiencing a decrease in lung function, while the influence of Personal Protective Equipment (PPE) still needs to be studied further.

An unequal endotoxin distribution in typical house types of Ho Chi Minh city.

Endotoxin exposure may cause asthma exacerbations and contribute to non-atopic respiratory diseases. Viet Nam, a country with multiple house types, is lacking data on indoor contamination by endotoxin in regard with house types. The comparison of measured settled dust endotoxin levels among house types in Ho Chi Minh city will allow to classify the house types regarding health risks. This study is a cross-sectional study. Five identified house types were selected: apartment (APA), rental (REN), rural (RUR), slum (SLU) and tube house (TUB). One hundred house's endotoxin contamination was evaluated by questionnaire and dust sampling. Endotoxin concentration was measured by kinetic chromogenic Limulus assay. dotoxin concentration (geometric mean 126.0 EU/mg, 95%CI 118.3-133.7) is particularly high in settled house dust compared to western countries and is significantly associated with the house type. The highest level was found in RUR in each room (p = 0.002 for living room; p < 0.0001 for bedrooms and for kitchens). Concerning levels in the different rooms, APA and TUB form a low group while REN and SLU (p < 0.001) form a median group and RUR the highest (p < 0.001). Differences in endotoxin levels were associated to the presence of dog, chicken and farm animals, wood cooking, air-conditioning usage. Further understanding of the relevant factors to endotoxin levels would contribute to prevent asthma exacerbations and chronic respiratory diseases. Public health interventions to reduce exposure to endotoxin include improving housing conditions, eliminating risk factors and a priority to high-risk house types.

Effects of early‐life exposure to dust mite allergen and endotoxin on the development of asthma and wheezing: The Japan Environment and Children's Study

BackgroundThe effects of early‐life exposure to house dust mite allergen and endotoxin on the development of asthma are unclear in the literature. We investigated the association of early‐life exposure (0–36 months old) to house dust mite allergen and endotoxin with asthma incidence.MethodsIn this novel, large‐scale, nationwide birth cohort study, 5017 participants were randomly selected from those who met the eligibility criteria. House dust was vacuum‐sampled from the children's mattresses within homes and assayed for the presence of dust mite allergen (Der 1) and endotoxin. The participants were classified into four quartiles (Q1–Q4) according to exposure levels. We defined the incidence of asthma and wheezing using questionnaires at 12, 24, and 36 months old. Odds ratios (ORs) of the incidence of asthma and wheezing by age in Der 1 and endotoxin exposure level were estimated using logistic regression.ResultsThe cumulative incidence rates of asthma and wheezing during 0–36 months were 10.4% and 38.1%, respectively. Significant ORs were observed in asthma onset during 12–24 months old, asthma onset during 24–36 months old, and wheezing onset during 0–12 months old in the Q4 Der 1 group. In the Q4 endotoxin group, significant positive associations between endotoxin exposure and asthma (OR 2.00, 95% confidence interval [CI]: 1.03–3.85) and wheezing (OR 1.78, 95% CI: 1.01–3.12) onset during 24–36 months old were found.ConclusionsOur results indicated that high levels of early‐life exposure to Der 1 and endotoxin in mattresses may be involved in the development of asthma.

Interaction between Genetic Risk Scores for reduced pulmonary function and smoking, asthma and endotoxin

RationaleGenome-wide association studies (GWASs) have identified numerous loci associated with lower pulmonary function. Pulmonary function is strongly related to smoking and has also been associated with asthma and dust endotoxin....

Dust exposure and pulmonary inflammation in Standardbred racehorses fed dry hay or haylage: A pilot study

Respirable dust exposure is linked to airway inflammation in racehorses. Feeding haylage may reduce dust exposure by 60–70%. The objective of this study was to compare dust exposure, airway cytology, and inflammatory cytokine concentrations between horses fed haylage or hay over 6 weeks while in training. Seven healthy Standardbred horses were randomly assigned to be fed alfalfa hay (n = 3) or grass-alfalfa mix haylage (n = 4) for six weeks while training on a treadmill. Dust exposure was measured gravimetrically at the breathing zone. Endotoxin and β-glucan concentrations in respirable dust were measured. Bronchoalveolar lavage fluid (BALF) cytology was determined at baseline and after 2, 4, and 6 weeks. Cytokine concentrations (interferon-γ, tumor necrosis factor-α, and interleukin-4) were measured in BALF at baseline and week 6. The effect of forage on exposure, airway cytology and cytokines were evaluated using generalized linear mixed models.Respirable dust and β-glucan exposures were lower in horses fed haylage than hay (0.02 ± 0.001 mg/m3 vs. 0.06 ± 0.01 mg/m3; P = 0.03, and 69 ± 18 pg/m3 vs. 160 ± 21 pg/m3; P = 0.02, respectively). In horses eating haylage, BALF neutrophil proportion decreased between baseline (2.2 ± 0.5%), week 2 (0.8 ± 0.3%; P = 0.01) and week 6 (0.7 ± 0.2%; P = 0.03). By week 6, horses fed haylage had lower BALF neutrophilia than horses fed hay (4.0 ± 0.7 %; P = 0.0004). Interleukin-4 concentration in BALF was higher at week 6 (14.4 ± 4.6 pg/mL) in horses fed hay compared to baseline (2.9 ± 4.6 pg/mL; P = 0.007). In conclusion, feeding haylage instead of hay to horses in training can reduce exposure to respirable irritants and mitigate airway neutrophilia.

Assessment of airborne endotoxin in sandstorm dust and indoor environments using a novel passive sampling device in Al Zulfi city, Saudi Arabia - Establishing threshold exposure levels.

The impact of sandstorm dust events affects local air quality and public health. These issues are becoming of greater concern in Saudi Arabia. There is a significant lack of research on airborne endotoxin exposure and analysis in the Middle East countries and no coherent body of research exists focusing on sandstorm dust in worldwide. In this study, we used a novel design of an aluminum foil plate (AFP) electrostatic dust cloth (EDC) for the passive air sampling of sandstorm dust. A total of 38 sandstorm dust samples were collected during sandstorm episodes occurring between January and April 2020 in both indoor (7 days, n = 20) and outdoor environments (24 h, n = 18). After exposure, and following an extraction procedure, bacterial endotoxin levels were measured using the Limulus Amoebocyte Lysate (LAL) gel clot method. The study highlights that the airborne endotoxin level observed was between 10 and 200 EU/m2 in both indoor and outdoor environments, during a sandstorm event. Agricultural activities and farmhouses observed higher airborne endotoxin levels. In general, increased endotoxin levels were related to the severity of the sandstorms. Given that the observed values were high as per existing guidelines for respiratory health, we recommend the setting an occupational airborne exposure limit for bacterial endotoxin. This is the first report and further studies across various sandstorm-hit regions will need to be undertaken, together with various sampling methods, in order to assess for seasonal and geographic trends.

Endotoxin, Food Allergen Sensitization, and Food Allergy: A Complementary Epidemiologic and Experimental Study

A Tsuang, A Grishin, G Grishina. Allergy. 2020;75(3):625–635 The epidemiologic aspect of the study aimed to describe the association between exposure to house dust endotoxin and sensitization to food allergens, while the experimental component compared the measurement of cytokines secreted from peripheral blood mononuclear cells (PBMCs) after stimulation with endotoxin in allergic and nonallergic children. 6963 participants, ages 1 to 84 years, from the 2005–2006 NHANES were included in the epidemiologic study. Twenty-one children (ages 1–19 years) from pediatric clinics at the Mount Sinai Health System with food allergy to either egg, milk or peanut, and healthy controls were included in the experimental study. Dust endotoxin measurement in the household was …

Occurrence of extended-spectrum beta-lactamase-producing Enterobacteriaceae, microbial loads, and endotoxin levels in dust from laying hen houses in Egypt

BackgroundPoultry houses are often highly contaminated with dust, which might contain considerable amounts of microorganisms and endotoxins. The concentrations of microorganisms and endotoxins in dust from laying hen houses in Egypt are unknown. However, to estimate the risks for birds, the environment, and people working in laying hen houses, it is important to gather information about the composition of these dusts. Here we report the microbial loads, the occurrence of antimicrobial-resistant bacteria, and endotoxin concentrations in dust samples from 28 laying hen farms in Dakahliya Governorate, Egypt, and discuss the results relevant to the literature.ResultsPooled settled dust samples (n = 28) were analyzed for total viable counts of bacteria and fungi (CFU/g), the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, Salmonella spp., and methicillin-resistant Staphylococcus aureus (MRSA), and endotoxin concentrations (ng/g). The means and standard deviations of total viable counts were 7.10 × 108 ± 2.55 × 109 CFU/g for bacteria and 5.37 × 106 ± 7.26 × 106 CFU/g for fungi. Endotoxin levels varied from 2.9 × 104 to 6.27 × 105 ng/g. None of the tested samples contained Salmonella spp. or MRSA. In contrast, by direct plating, Enterobacteriaceae were found frequently (57%; n = 16), and suspected ESBL-producing Enterobacteriaceae occurred in 21% (n = 6) of the sampled barns. Using an enrichment method, the detection of Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae increased to 20 and 16 positive barns, respectively. Taking results from both methods into account, Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae were detected in 23 barns Overall, 100 ESBL suspected isolates (Escherichia coli, n = 64; Enterobacter cloacae, n = 20; and Klebsiella pneumoniae n = 16) were identified to species level by MALDI-TOF MS. Isolates from 20 barns (71% positive barns) were confirmed as ESBL producing Enterobacteriaceae by the broth microdilution test.ConclusionsDust in Egyptian laying hen houses contains high concentrations of microorganisms and endotoxins, which might impair the health of birds and farmers when inhaled. Furthermore, laying hens in Egypt seem to be a reservoir for ESBL-producing Enterobacteriaceae. Thus, farmers are at risk of exposure to ESBL-producing bacteria, and colonized hens might transmit these bacteria into the food chain.

House dust endotoxin, asthma and allergic sensitization through childhood into adolescence.

BackgroundHouse dust endotoxin may have beneficial effects on allergic sensitization and asthma in children. Evidence is scarce for adolescents and most studies so far have been cross‐sectional and limited to a single exposure measurement.ObjectiveWe assessed associations of house dust endotoxin with asthma and allergic sensitization from birth to age 17 years longitudinally taking into account exposure early in life and at primary school age.MethodsWe used data of 854 participants of the prospective Dutch PIAMA birth cohort study with house dust endotoxin measurements at 3 months and/or 5‐6 years and data on asthma and/or allergic sensitization from at least one of 11 follow‐ups until age 17. We assessed overall and age‐specific associations of the prevalence of asthma and sensitization with mattress and living room floor dust concentrations (per gram of dust) and loads (per m2 of sampling surface).ResultsHigher living room floor dust endotoxin concentrations at 3 months were associated with lower odds of asthma until age 4 [odds ratio (95% confidence interval) ranging from 0.70 (0.51‐0.97) at age 1 to 0.76 (0.57‐1.00) at age 3 per interquartile range increase], but not thereafter in children of allergic mothers. Higher living room floor dust endotoxin at 5‐6 years was associated with higher odds of sensitization at 8‐16 years [eg odds ratio (95% confidence interval) 1.70 (1.17‐2.47) per interquartile range increase in endotoxin load].Conclusions and clinical relevanceHouse dust endotoxin may have beneficial effects on asthma in preschool children of allergic mothers, which do not persist into adolescence. Beneficial associations with allergic sensitization could not be confirmed.

Endotoxin clustering with allergens in house dust and asthma outcomes in a U.S. national study

BackgroundEndotoxin is ubiquitous in the environment, but its clustering with indoor allergens is not well characterized. This study examined the clustering patterns of endotoxin with allergens in house dust and their association with asthma outcomes.MethodsWe analyzed data from 6963 participants of the 2005–2006 National Health and Nutrition Examination Survey. House dust sampled from bedroom floor and bedding was evaluated for endotoxin and allergens from fungi, cockroach, dog, cat, mites, and rodents. Two-step cluster analysis and logistic regressions were performed to identify the clustering patterns and their associations with current asthma and wheeze in the past 12 months, adjusting for covariates.ResultsOf the homes, 17.8% had low endotoxin and allergen levels in house dust (Cluster 1). High endotoxin level clustered with Alternaria and pet allergens in the homes of participants with a high socioeconomic status who own pets (Cluster 2) (48.9%). High endotoxin clustered with Aspergillus, dust mites, cockroach, and rodent allergens in the homes of participants with low socioeconomic status (Cluster 3) (33.3%). Compared to Cluster 1, Cluster 2 was associated with higher asthma prevalence (OR 1.42, 95% CI: 1.06–1.91) and wheeze (OR 1.32, 95% CI: 1.07–1.63). Cluster 3 was positively associated with wheeze only in participants sensitized to inhalant allergens (OR 1.42, 95% CI: 1.06–1.91) or exposed to tobacco smoke (OR 1.72, 95% CI: 1.15–2.60).ConclusionsThe clustering of endotoxin with allergens in dust from homes with pets or of people with low socioeconomic status is associated with asthma and wheeze.

Household endotoxin reduction in the Louisa Environmental Intervention Project for rural childhood asthma.

Endotoxin exacerbates asthma. We designed the Louisa Environmental Intervention Project (LEIP) and assessed its effectiveness in reducing household endotoxin and improving asthma symptoms in rural Iowa children. Asthmatic school children (N=104 from 89 homes) of Louisa and Keokuk counties in Iowa (aged 5-14years) were recruited and block-randomized to receive extensive (education+professional cleaning) or educational interventions. Environmental sampling collection and respiratory survey administration were done at baseline and during three follow-up visits. Mixed-model analyses were used to assess the effect of the intervention on endotoxin levels and asthma symptoms in the main analysis and of endotoxin reduction on asthma symptoms in exploratory analysis. In the extensive intervention group, dust endotoxin load was significantly reduced in post-intervention visits. The extensive compared with the educational intervention was associated with significantly decreased dust endotoxin load in farm homes and less frequent nighttime asthma symptoms. In exploratory analysis, dust endotoxin load reduction from baseline was associated with lower total asthma symptoms score (Odds ratio: 0.52, 95% confidence interval: 0.29-0.92). In conclusion, the LEIP intervention reduced household dust endotoxin and improved asthma symptoms. However, endotoxin reductions were not sustained post-intervention by residents.

Endotoxin, food allergen sensitization, and food allergy: A complementary epidemiologic and experimental study

Household endotoxin levels have been variably associated with risk for asthma and atopy. We studied participants from the 2005-2006 National Health and Nutrition Examination Survey (NHANES, n=6963), a large cohort representative of the US population (aged 1-84years). We built logistic regression models to test for associations between house dust endotoxin and sensitization to specific foods (milk, egg, and peanut). To experimentally explore the detected epidemiologic associations, peripheral blood mononuclear cells (PBMCs) were collected from 21 children (aged 1-19years) mono-food allergic (ie, sensitized and clinically reactive) to milk, egg, or peanut and nonallergic controls for stimulation with endotoxin and secreted cytokine measurement. For each food allergy, linear mixed-effects models were built to test the association between endotoxin stimulation and cytokine level. Among NHANES subjects, the geometric mean household endotoxin level was 15.5EU/mg (GSE 0.5). Prevalence of food allergen sensitization (sIgE≥0.35kUA /L) varied by food: milk 5.7%, egg 4.0%, and peanut 7.9%. In models adjusted for potential confounders (age, race, country of birth, total people per household, US region, and history of wheezing in the past year), household endotoxin level was associated with sensitization to milk (OR 1.7, 95% CI 1.2-2.1) and egg (OR 1.4, 95% CI 1.01-1.9), but not peanut (OR 0.98, 95% CI 0.8-1.2). Interferon-γ levels of endotoxin-stimulated PBMCs from children allergic to milk or egg, but not peanut, were significantly lower compared to controls in linear mixed-effects models adjusted for repeated measures, experimental variables, age, and inter-individual variability (P-values .007, .018, and .058, respectively). Higher household endotoxin is associated with increased odds of milk and egg sensitization. Altered cytokine responsiveness to endotoxin is also observed in PBMCs from individuals with milk and egg allergy.

Sensitization to Pets and Pet Ownership Modify the Association Endotoxin with Asthma and Wheeze

OPS 08: Biological contaminants and respiratory health, Room 117, Floor 1, August 26, 2019, 4:30 PM - 5:30 PM Background: Pets are important sources of endotoxin. Exposure to endotoxin as well as exposure to dog and cat allergens have each been associated with asthma and wheeze. However, it has been difficult to separate the impact of these exposures and whether they interact with each other to affect respiratory outcomes. Methods: We examined whether exposure and sensitization to dog and cat influence the association of house dust endotoxin with asthma and wheeze in 6051 children and adults in the U.S. National Health and Nutrition Examination Survey. Exposure to pets was assessed using both pet ownership and pet allergens measured in bedroom dust. Endotoxin was quantified using the LAL assay. Allergic sensitization status was determined from serum levels of specific immunoglobulin-E. Administered questionnaires assessed current asthma and wheeze and associated morbidities. Results: The study confirmed the prevalence of dog (48.3%) and cat (37.5%) ownership and endotoxin concentration in dust was significantly greater in homes with pets. Exposure to endotoxin as well as exposure and sensitization to dog and cat allergens were each independently associated with a higher prevalence of current asthma and/or wheeze, especially in adults. The association of endotoxin with the respiratory outcomes was significantly altered by exposure to pet allergens and sensitization status. In participants not sensitized to dog, exposure to high levels of dog allergen enhanced the association of endotoxin with wheeze, while in participants sensitized to cat, exposure to high levels of cat allergen heightened the odds of current asthma associated with endotoxin. The concurrent exposure to high levels of both dog and cat allergens augmented the association of endotoxin with both current asthma and wheeze in the past 12 months. Conclusions: We conclude that measures to reduce the levels of endotoxin as well as dog and cat allergens may help prevent active asthma and wheeze.