ERS International Congress 2023: highlights from the Epidemiology and Environment Assembly.

In this article, early career members of the Epidemiology and Environment Assembly of the European Respiratory Society (ERS) summarise a selection of four poster and oral sessions from the ERS 2023 Congress. The topics covered the following areas: micro- and macro-environments and respiratory health, occupational upper and lower airway diseases, selected tobacco and nicotine research, and multimorbidity in people with lung diseases. The topics and studies covered in this review illustrate the broad range of the multifaceted research taking place within Assembly 6, from the identification of indoor and outdoor environmental risk factors for the development and worsening of respiratory diseases to the concerningly increasing use of nicotine products and their health consequences beyond respiratory health and comorbidity in respiratory diseases.

Household Use of Green Cleaning Products, Disinfecting Wipes, and Asthma Control Among Adults.

BACKGROUND: The use of household disinfectants and cleaning products (HDCPs) may negatively impact asthma control, but studies remain scarce. Moreover, no study considered green products or wipes, increasingly used during home cleaning. OBJECTIVE: To assess the associations between the use of HDCPs, including disinfecting wipes and green products, and asthma control based on data from the French Web-based NutriNet-Santé cohort. METHODS: Using a standardized questionnaire (2018), we assessed asthma control (never asthma: reference; controlled: Asthma Control Test ≥ 20; uncontrolled: Asthma Control Test < 20) and the use of HDCPs, including 2 types of products (irritants and green products) and 2 application modes (sprays and disinfecting wipes). Cross-sectional associations of the frequency of weekly use of HDCPs at home with asthma control, adjusted for sex, age, smoking status, body mass index, and educational level were assessed by multinomial logistic regressions. RESULTS: Analyses were performed on 37,043 adults (mean age 47 y; 75% women; 62% with a weekly use of at least 1 HDCP). Strong associations were observed between weekly use of HDCPs and uncontrolled asthma. In particular, an almost daily use (4-7 d/wk) of irritants (odds ratio [OR] 2.81; 95% confidence interval [95% CI] 1.97-4.00) and green products (OR 2.40; 95% CI 1.70-3.39) as well as sprays (OR 2.69; 95% CI 1.97-3.68) and disinfecting wipes (OR 3.51; 95% CI 2.31-5.33) was associated with uncontrolled asthma. When not co-used with irritants and sprays, associations remained statistically significant for both disinfecting wipes and green products. CONCLUSIONS: Weekly use of HDCPs, including green products or wipes, was associated with uncontrolled asthma and should be considered by health practitioners in order to improve asthma control.

Longitudinal associations of household use of cleaning agents and asthma symptoms in women: the EGEA study.

OBJECTIVE: To evaluate the associations between the evolution of household use of cleaning products with the asthma symptom score and its evolution over 8 years. METHODS: Our study is based on 509 women participating in the last two surveys of the Epidemiological study on the Genetics and Environment of Asthma (EGEA) study (EGEA2: 2003-2007 (44 years, 19% current smokers) and EGEA3: 2011-2013). We assessed an asthma symptom score and the use of household cleaning products through standardised questionnaires. We studied longitudinal associations of the evolution of weekly use of irritant or spayed cleaning products with (1) the asthma symptom score at EGEA3 and a stable symptom score between EGEA2-EGEA3 (negative binomial models) and (2) the incidence/evolution of asthma symptoms between EGEA2-EGEA3 (logistic/polytomous logistic regressions). Models accounted for familial dependence and were adjusted for age, smoking status, body mass index and occupational exposure to asthmagens. RESULTS: Persistent and increased (40% and 16%, respectively) weekly use of irritants or sprays were associated with a higher risk of asthma symptoms at EGEA3 (Mean Score Ratio (MSR)=1.51 (95% CI 1.06 to 2.14) and 1.33 (95% CI 0.85 to 2.08), respectively). A decreased use (19%) was associated with a lower risk of symptoms at EGEA3, compared with a persistent use (MSR=0.59 (95% CI 0.39 to 0.88)). We also observed an association between an increased use of sprays and the incidence of asthma symptoms (OR=2.30 (95% CI 1.08 to 4.91)), compared with no weekly use of irritants/sprays. CONCLUSIONS: This longitudinal study, with repeated assessment of exposure and respiratory health, supports the hypothesis that a persistent or increased weekly use of sprayed cleaning products over time may have an adverse effect on the evolution of asthma symptoms.

Occupational Exposures to Irritants and Sensitizers, Asthma and Asthma Control in the Nutrinet-Santé Cohort.

BACKGROUND: The role of chronic occupational exposures to irritants in asthma remains not well-defined. Few studies have examined their associations with asthma and its control. OBJECTIVE: To study the associations of occupational exposures with asthma and its control, with specific interest for irritants, including disinfectants and cleaning products (DCPs) and solvents. METHODS: Analyses included 4,469 adults (3,792 with neither asthma nor respiratory symptoms, 677 with current asthma; 75.9% women, mean age 54 years) of a case-control study (2018) from the French NutriNet-Santé cohort. Current asthma was defined by ever asthma with symptoms, medication or asthma attacks in the past 12 months, adult-onset asthma by age at first asthma attack older than 16 years, and uncontrolled asthma was defined by an Asthma Control Test score less than 20. Ever/current exposures were assessed with the Occupational Asthma-specific Job Exposure Matrix. Associations were evaluated by multinomial logistic regressions adjusted for sex, age, smoking status, and body mass index. RESULTS: Ever exposures to sensitizers (high molecular weight [HMW]: OR 1.53, 95% CI 1.18-2.00; and low molecular weight [LMW]: OR 1.42; 95% CI 1.09-1.87), irritants (OR 1.32; 95% CI 1.03-1.68), and DCPs (OR 1.43; 95% CI 1.10-1.85) were associated with current adult-onset asthma. Significant associations between ever exposures and uncontrolled adult-onset asthma were observed for high molecular weight (OR 2.69; 95% CI 1.52-4.78) and low molecular weight (OR 2.27; 95% CI 1.24-4.37) sensitizers, irritants (OR 2.32; 95% CI 1.36-3.95), and DCPs (OR 2.59; 95% CI 1.48-4.54). Results were similar for current exposures, with higher ORs. No association was observed with solvents. CONCLUSIONS: Occupational exposures to both sensitizers and irritants were associated with current adult-onset asthma and uncontrolled asthma. Irritant and sensitizing agents should be carefully considered in asthma management.

Household use of green and homemade cleaning products, wipe application mode, and asthma among French adults from the CONSTANCES cohort.

While exposure to irritant and sprayed cleaning products at home is known to have a harmful role in asthma, the potential health effect of other categories or forms has not been investigated. We studied the associations of household use of cleaning products, including green, homemade products, and disinfecting wipes, with asthma based on data from the large French population-based CONSTANCES cohort. Participants completed standardized questionnaires on respiratory health and household use of cleaning products. Cross-sectional associations of cleaning products with current asthma, adjusted for gender, age, smoking status, BMI, and educational level, were evaluated by logistic regressions. Analyses were conducted in 41 570 participants (mean age: 47 years, 56% women, weekly use of the six specific products/forms studied varied from 11% to 37%). Weekly use of irritants (OR = 1.23 [1.13-1.35]), scented (OR = 1.15 [1.06-1.26]), green (OR = 1.09 [1.00-1.20]), and homemade products (OR = 1.19 [1.06-1.34]), as well as sprays (OR = 1.18 [1.08-1.29]), disinfecting wipes (OR = 1.21 [1.09-1.34]) were significantly associated with asthma, with significant trends according to the frequency of use. When they were not co-used with irritants/sprays, associations were reduced and persisted only for disinfecting wipes. Weekly use of disinfecting wipes at home was associated with current asthma, but fewer risks were observed for the use of green and homemade products.

Association between household cleaning product profiles evaluated by the Ménag'Score® index and asthma symptoms among women from the SEPAGES cohort.

OBJECTIVE: Considering household disinfectants and cleaning products (HDCP) as mixture of ingredients, rather than each ingredient individually, might help in characterizing their role in asthma. We investigated the association between HDCP and asthma, using the recently developed Ménag'Score®, a health risk assessment score based on exhaustive ingredient lists of HDCP. METHODS: The study is based on 103 female volunteers of the SEPAGES cohort (2014-2019), with repeated data (up to 3 collection times, 200 observations). HDCP use was assessed from a barcode-based smartphone application linked with an ingredient database. The Ménag'score® risks for health and environment were computed for each weekly used HDCP from their exhaustive ingredient data (from A: no known risk to E: highest risk). The association between the use of HDCP with a poor Ménag'score® (D or E; overall, health, environment scores) and asthma symptoms, was estimated by generalized estimating equations models adjusted for age, BMI and smoking status. RESULTS: Participants were on average 33 years old, 11% smoked and 20% had at least one asthma symptom. The Ménag'score® was computed for 540 HDCP scanned by participants. Weekly use of HDCP with a poor Ménag'score®-health (around 60% of the participants) was associated with a higher risk of asthma symptoms (OR 3.13, 95% CI [1.32-7.43]). No association was observed for the Ménag'score®-environment. CONCLUSION: The use of HDCP with a poor Ménag'score®-health was associated with asthma symptoms. The results support the use of the Ménag'score®-health to further evaluate the health risks of HDCP in observational studies and as a potential public health tool.

An adverse outcome pathway for lung surfactant function inhibition leading to decreased lung function.

Inhaled substances, such as consumer products, chemicals at the workplace, and nanoparticles, can affect the lung function in several ways. In this paper, we explore the adverse outcome pathway (AOP) that starts when inhaled substances that reach the alveoli inhibit the function of the lung surfactant, and leads to decreased lung function. Lung surfactant covers the inner surface of the alveoli, and regulates the surface tension at the air-liquid interface during breathing. The inhibition of the lung surfactant function leads to alveolar collapse because of the resulting high surface tension at the end of expiration. The collapsed alveoli can be re-opened by inspiration, but this re-opening causes shear stress on cells covering the alveoli. This can damage the alveolar-capillary membrane integrity, allowing blood components to enter the alveolar airspace. Blood components, such as albumin, can interact with the lung surfactant and further inhibit its function. The collapse of the alveoli is responsible for a decrease in the surface area available for blood oxygenation, and it reduces the volume of air that can be inhaled and exhaled. These different key events lead to decreased lung function, characterized by clinical signs of respiratory toxicity and reduced blood oxygenation. Here we present the weight of evidence that supports the AOP, and we give an overview of the methods available in vitro and in vivo to measure each key event of the pathway, and how this AOP can potentially be used in screening for inhalation toxicity.

Molecular and biophysical basis for the disruption of lung surfactant function by chemicals.

With the intention to move away from animal testing for the toxicological evaluation of chemicals comes the need to develop new approach methodologies which are mechanism-anchored and target relevant key events leading to an adverse outcome. To date, no validated alternative methods are available for studying the acute inhalation toxicity potential of airborne chemicals but the constrained drop surfactometer measuring the surface tension of a drop of lung surfactant presents as a promising candidate. Indeed, the correlation of the increase in minimum surface tension of lung surfactant in vitro with changes in the breathing patterns of mice after inhalation of test compounds has been shown in multiple studies. However, the causal factors leading to lung surfactant inactivation remain speculative. This paper combines molecular and biophysical methods (constrained drop and captive bubble surfactometers, Langmuir-Blodgett balance, epifluorescence microscopy, cryogenic transmission electron microscopy, and differential scanning calorimetry) applied to purified porcine lung surfactant and dipalmitoylphosphatidylcholine interfacial films to gain insights into the disruption of lung surfactant function by three chemicals known to show acute inhalation toxicity (trimethoxyoctylsilane, methyl 3-oxo-2-pentylcyclopentaneacetate, and diisopentyl ether). The results of this study suggest that the test chemicals intercalate between the phospholipids at the air-liquid interface, reduce the stability of the films, and decrease the cohesivity of interface-associated multilayered structures thereby perturbing the lung surfactant surface activity. These findings contribute to a better understanding of chemically-induced lung surfactant function disruption.

Optimising testing strategies for classification of human health and environmental hazards - A proof-of-concept study.

This paper outlines a new concept to optimise testing strategies for improving the efficiency of chemical testing for hazard-based risk management. While chemical classification based on standard checklists of information triggers risk management measures, the link is not one-to-one. Toxicity testing may be performed with no impact on the safe use of chemicals . Each hazard class and category is not assigned a unique pictogram and for the purpose of this proof-of-concept study, the level of concern for a chemical for the population and the environment is simplistically considered to be reflected by the hazard pictograms. Using active substances in biocides and plant protection products as a dataset, three testing strategies were built with the boundary condition that an optimal approach must indicate a given level of concern while requiring less testing (strategy B), prioritising new approach methodologies (strategy C) or combining the two considerations (strategy D). The implementation of the strategies B and D reduced the number of tests performed by 6.0% and 8.8%, respectively, while strategy C relied the least on in vivo methods. The intentionally simplistic approach to optimised testing strategies presented here could be used beyond the assessment of biocides and plant protection products to gain efficiencies in the safety assessment of other chemical groups, saving animals and making regulatory testing more time- and cost-efficient.

Acute Inhalation Toxicity After Inhalation of ZnO Nanoparticles: Lung Surfactant Function Inhibition In Vitro Correlates With Reduced Tidal Volume in Mice.

People can be exposed to zinc oxide (ZnO) by inhalation of consumer products or during industrial processes. Zinc oxide nanoparticle (NP) exposure can induce acute inhalation toxicity. The toxicological mechanisms underlying the acute effects on the lungs have long focused on the phagolysosomal dissolution of ZnO NPs in macrophages followed by the release of free Zn2+ ions. However, we postulate an alternative mechanism based on the direct interaction of ZnO NPs with the lung surfactant (LS) layer covering the inside of the alveoli. Therefore, we tested the effect of ZnO NPs and Zn2+ ions on the function of LS in vitro using the constrained drop surfactometer. We found that the ZnO NPs inhibited the LS function, whereas Zn2+ ions did not. To examine the role of lung macrophages in the acute toxicity of inhaled ZnO NPs, mice were treated with Clodrosome, a drug that depletes alveolar macrophages, or Encapsome, the empty carrier of the drug. After macrophage depletion, the mice were exposed to an aerosol of ZnO NPs in whole body plethysmographs recording breathing patterns continuously. Mice in both groups developed shallow breathing (reduced tidal volume) shortly after the onset of exposure to ZnO NPs. This suggests a macrophage-independent mechanism of induction. This study shows that acute inhalation toxicity is caused by ZnO NP interaction with LS, independently of NP dissolution in macrophages.

Pre-conceptional exposure to multiwalled carbon nanotubes suppresses antibody production in mouse offspring.

Prenatal particle exposure has been shown to increase allergic responses in offspring. Carbon nanotubes (CNTs) possess immunomodulatory properties, but it is unknown whether maternal exposure to CNTs interferes with offspring immune development. Here, C57Bl/6J female mice were intratracheally instilled with 67 of µg multiwalled CNTs on the day prior to mating. After weaning, tolerance and allergy responses were assessed in the offspring. Offspring of CNT-exposed (CNT offspring) and of sham-exposed dams (CTRL offspring) were intranasally exposed to ovalbumin (OVA) once weekly for 5 weeks to induce airway mucosal tolerance. Subsequent OVA sensitization and aerosol inhalation caused low or no OVA-specific IgE production and no inflammation. However, the CNT offspring presented with significantly lower OVA-specific IgG1 levels than CTRL offspring. In other groups of 5-week-old offspring, low-dose sensitization with OVA and subsequent OVA aerosol inhalation led to significantly lower OVA-specific IgG1 production in CNT compared to CTRL offspring. OVA-specific IgE and airway inflammation were non-significantly reduced in CNT offspring. The immunomodulatory effects of pre-gestational exposure to multiwalled CNTs were unexpected, but very consistent. The observations of suppressed antigen-specific IgG1 production may be of importance for infection or vaccination responses and warrant further investigation.

Per- and polyfluoroalkyl substances (PFASs) modify lung surfactant function and pro-inflammatory responses in human bronchial epithelial cells.

The toxicity of some per- and polyfluoroalkyl substances (PFASs), such as perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) has been studied thoroughly, showing that systemic PFASs targets the lungs. However, regulators lack data to assess the impact of other PFASs on the lungs and alternative methods to test substances for lung toxicity are needed. We combined two in vitro models to assess toxicity to the respiratory system; i) a lung surfactant (LS) function assay to assess the acute inhalation toxicity potential, and ii) a cell model with human bronchial epithelial cells to study pro-inflammatory potential and modulation of inflammatory responses. We tested salts of four PFASs: perfluorobutane sulfonate (PFBS), perfluorohexane sulfonate (PFHxS), PFOS, and PFOA as well as the fluorotelomer 8:2 FTOH. The results show that PFHxS, PFOA and PFOS can inhibit LS function. High PFOS concentrations induced a pro-inflammatory response, measured as increased IL-1α/ß release. Moderate concentrations of PFOS suppressed release of the chemokines CXCL8 and CXCL10, whereas both PFOS and PFOA stimulated the release of the pro-inflammatory cytokine IL-1ß in immune stimulated human bronchial epithelial cells. These findings support the concern that some PFASs may increase the risk of acute lung toxicity and of airway infections.

Data supporting the investigation of interaction of biologically relevant proteins with ZnO nanomaterials: A confounding factor for in vitro toxicity endpoints.

Test materials, like manufactured nanomaterials (MN), may interact with serum proteins, interleukins (IL) and lactate dehydrogenase (LDH) and cause measurement artefacts as a result of e.g., physical adsorption and electrostatic forces, and/or interaction with dissolved species or conditional chemical changes during testing. In this article, data are given on the zeta-potentials of two manufactured ZnO nanomaterials (NM-110 and NM-111) dispersed in 0.05% w/v Bovine Serum Albumin (BSA) water batch dispersions and in Ham's F12 nutrient mixture added Fetal Bovine Serum (FBS), penicillin, and streptomycin and particle free mediums (cHam's F12). Data on the Zeta-potential and the iso-electrical point of lactate hydrogenase in pure Ham's F12 nutrient mixture is also provided. The percentage of added IL-6, IL-8 and LDH remaining after 24-h incubation in cHam's F12 are given as function of MN concentrations. Finally data from thermodynamic chemical reaction modeling of changes in pH and Zn-speciation during dissolution of ZnO or dissolved ZnCl2 additions to Ham's F12 using Geochemist Workbench® are given. For further information, data interpretation and discussion please refer to the research article "Interaction of biologically relevant proteins with ZnO nanomaterials: a confounding factor for in vitro toxicity endpoints" (E. Da Silva et al. 2019).

Interaction of biologically relevant proteins with ZnO nanomaterials: A confounding factor for in vitro toxicity endpoints.

The results of in vitro toxicological studies for manufactured nanomaterials (MNs) are often contradictory and not reproducible. Interference of the MNs with assays has been suggested. However, understanding for which materials and how these artefacts occur remains a major challenge. This study investigated interactions between two well-characterized ZnO MNs (NM-110 and NM-111) and lactate dehydrogenase (LDH), and two interleukins (IL-6 and IL-8). Particles (10 to 640 µg/mL) and proteins were incubated for up to 24 h in routine in vitro assays test conditions. LDH activity (ODLDH), but not interleukins concentrations, decreased sharply in a dose-dependent manner within an hour after exposure (ODLDH < 60% of ODref for both MNs at 10 µg/mL). A Freundlich adsorption isotherm was successfully applied, indicating multilayer adsorption of LDH. ZnO MNs and LDH had neutral to slightly negative surface charges in dispersion, precluding electrostatic attachment. Particle sedimentation was not a limiting factor. Fast dissolution of ZnO MNs was shown and Zn2+ could play a role in the ODLDH drop. To summarize, ZnO MNs quickly reduced ODLDH due to concentration-dependent adsorption and LDH inhibition by interaction with dissolved Zn. The control of particle interference in toxicological in vitro assays should become mandatory to avoid misleading interpretation of results.

Bile salt enhancers for inhalation: Correlation between in vitro and in vivo lung effects.

The lungs have potential as a means of systemic drug delivery of macromolecules. Systemic delivery requires crossing of the air-blood barrier, however with molecular size-dependent limitations in lung absorption of large molecules. Systemic availability after inhalation can be improved by absorption enhancers, such as bile salts. Enhancers may potentially interfere with the different constituents of the lungs, e.g. the lung surfactant lining the alveoli or the lung epithelium. We used two in vitro models to investigate the potential effects of bile salts on lung surfactant function (with the constrained drop surfactometer) and on the epithelium in the proximal airways (with the MucilAir™ cell system), respectively. In addition, we measured direct effects on respiration in mice inhaling bile salt aerosols. The bile salts inhibited lung surfactant function at different dose levels, however they did not affect the integrity of ciliated cells at the tested doses. Furthermore, the bile salt aerosols induced changes in the breathing pattern of mice indicative of pulmonary irritation. The bile salts were ranked according to potency in vitro for surfactant function disruption and in vivo for induction of pulmonary irritation. The ranking was the same, suggesting a correlation between the interference with lung surfactant and the respiratory response.

Prediction of acute inhalation toxicity using in vitro lung surfactant inhibition.

Private consumers and professionals may experience acute inhalation toxicity after inhaling aerosolized impregnation products. The distinction between toxic and non-toxic products is difficult to make for producers and product users alike, as there is no clearly described relationship between the chemical composition of the products and induction of toxicity. The currently accepted method for determination of acute inhalation toxicity is based on experiments on animals; it is time-consuming, expensive and causes stress for the animals. Impregnation products are present on the market in large numbers and amounts and exhibit great variety. Therefore, an alternative method to screen for acute inhalation toxicity is needed. The aim of our study was to determine if inhibition of lung surfactant by impregnation products in vitro could accurately predict toxicity in vivo in mice. We tested 21 impregnation products using the constant flow through set-up of the constrained drop surfactometer to determine if the products inhibited surfactant function or not. The same products were tested in a mouse inhalation bioassay to determine their toxicity in vivo. The sensitivity was 100%, i.e., the in vitro method predicted all the products that were toxic for mice to inhale. The specificity of the in vitro test was 63%, i.e., the in vitro method found three false positives in the 21 tested products. Six of the products had been involved in accidental human inhalation where they caused acute inhalation toxicity. All of these six products inhibited lung surfactant function in vitro and were toxic to mice.

A Proposed In Vitro Method to Assess Effects of Inhaled Particles on Lung Surfactant Function.

The lung surfactant (LS) lining is a thin liquid film covering the air-liquid interface of the respiratory tract. LS reduces surface tension, enabling lung surface expansion and contraction with minimal work during respiration. Disruption of surface tension is believed to play a key role in severe lung conditions. Inhalation of aerosols that interfere with the LS may induce a toxic response and, as a part of the safety assessment of chemicals and inhaled medicines, it may be relevant to study their impact on LS function. Here, we present a novel in vitro method, based on the constrained drop surfactometer, to study LS functionality after aerosol exposure. The applicability of the method was investigated using three inhaled asthma medicines, micronized lactose, a pharmaceutical excipient used in inhaled medication, and micronized albumin, a known inhibitor of surfactant function. The surfactometer was modified to allow particles mixed in air to flow through the chamber holding the surfactant drop. The deposited dose was measured with a custom-built quartz crystal microbalance. The alterations allowed the study of continuously increasing quantified doses of particles, allowing determination of the dose of particles that affects the LS function. The tested pharmaceuticals did not inhibit the function of a model LS even at extreme doses--neither did lactose. Micronized albumin, however, impaired surfactant function. The method can discriminate between safe inhaled aerosols--as exemplified by the approved inhaled medicines and the pharmaceutical excipient lactose--and albumin known to impair lung functionality by inhibiting LS function.