Swimming pool exposure is associated with autonomic changes and increased airway reactivity to a beta-2 agonist in school aged children: A cross-sectional survey

Swimming was associated with rhinitis and pollinosis in a duration-dependent manner

BACKGROUND

Previous studies have reported conflicting results regarding the effects of childhood swimming on respiratory allergic symptoms. We investigated the relationship between swimming and respiratory allergic symptoms in schoolchildren.

METHODS

A questionnaire regarding participation in sports club activities and respiratory allergic symptoms in schoolchildren was distributed to the parents of all 6853 public school students (aged 6-14 years) in Omihachiman City, Shiga, Japan. The relationships between participation in sports club activities and the prevalence of respiratory allergic symptoms were analyzed by multivariable logistic regression analyses.

RESULTS

Questionnaires were returned for 4991 schoolchildren (response rate: 72.8%). Logistic regression analysis revealed significant positive associations between swimming and rhinitis (42.9% vs. 38.9%; adjusted odds ratio, 1.26; 95% confidence interval, 1.10-1.44), and swimming and pollinosis (32.1% vs. 28.1%; adjusted odds ratio, 1.28; 95% confidence interval, 1.11-1.47). The duration of participation in swimming activities was also significantly positively associated with the prevalence of rhinitis and pollinosis. Those who had participated in swimming activities for 6 years or more showed significantly higher prevalences of rhinitis and pollinosis (46.3% and 36.4%, respectively) than those without swimming activities (38.9% and 28.1%, respectively) and those who had participated in swimming activities for 5 years or less (40.1% and 28.5%, respectively).

CONCLUSIONS

Swimming was associated with the prevalence of rhinitis and pollinosis in schoolchildren, especially among those who had participated in swimming activities for 6 years or more. Preventive measures and early interventions for rhinitis and pollinosis should be recommended to these children.

Pooling the evidence: A review of swimming and atopic dermatitis

Swimming is an excellent form of aerobic exercise and is an essential life skill. Many children with atopic dermatitis (AD) are advised not to swim because of concerns about negative impacts on their skin disease, and some children with AD do not swim because they are self-conscious about the appearance of their skin. We aimed to perform a narrative review of the available literature on swimming and AD and scientifically analyze the potential impact of all components of swimming in AD-water, skin barrier, swimming gear, and exercise. Studies examined the impact of swimming on the skin barrier and the relative contraindications to swimming. Constituents of water which may affect AD include hardness, pH, temperature, antiseptics, and other chemicals. Potential interventions to reduce damage included emollient application, special swim gear, and showering post-submersion. The benefits of swimming as a form of exercise in AD included reduced sweating, cardiorespiratory fitness, and maintenance of healthy weight. Drawbacks of swimming as a form of exercise in AD included the limited benefit on bone mineral density. Future research should examine the impact of swimming on flares of AD using noninvasive biomarkers as well as clinical severity assessment and assess the role for different types of emollient as an intervention for optimal eczema control. This review highlights gaps in the scientific literature on swimming and AD and provides evidence-based guidance on interventions to minimize deleterious effects on skincare and maximize opportunities for children with AD to swim.

Blood trihalomethane concentrations and allergic sensitization: A nationwide cross-sectional study

BACKGROUND

Exposure to disinfection by-products has been associated with several allergic diseases, but its association with allergen-specific immunoglobulin E (IgE) antibodies remains inconclusive.

METHODS

We included 932 U.S. adolescents and 2187 adults from the National Health and Nutrition Examination Survey 2005-2006 who had quantified blood THM concentrations [chloroform (TCM), bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform (TBM)] and 19 allergen-specific IgE antibodies. The odds ratios (ORs) of allergen-specific sensitization per 2.7-fold increment in blood THM concentrations were estimated by multivariable logistic regression models.

RESULTS

Blood THM concentrations were unrelated to any allergen-specific sensitization in adults. Among adolescents, however, we found positive associations between blood TCM and chlorinated THMs (Cl-THMs: sum of TCM, BDCM, and DBCM) concentrations and the odds of pet sensitization [OR = 1.28 (95 % CI: 1.05, 1.55) and 1.38 (1.15, 1.65), respectively, per each 2.7-fold increment], between blood BDCM concentrations and the odds of mold [OR = 1.47 (1.24, 1.74)], plant [OR = 1.25 (1.09, 1.43)], pet [OR = 1.27 (1.07, 1.52)], and food sensitization [OR = 1.18 (1.03, 1.36)], and between blood brominated THM (Br-THMs: sum of BDCM, DBCM, and TBM) and total THM (TTHMs: sum of 4 THMs) concentrations and the odds of mold [OR = 1.52 (1.30 1.78) and 1.30 (1.03, 1.65), respectively], dust mite [OR = 1.39 (1.06, 1.82) and 1.45 (1.06, 1.98), respectively], and pet sensitization [OR = 1.42 (1.05, 1.92) and 1.54 (1.19, 1.98), respectively].

CONCLUSION

Higher blood concentrations of THMs were associated with a greater risk of allergic sensitization among U.S. adolescents but not in adults.

Health effects of exposure to chlorination by-products in swimming pools

Concerns have been raised regarding the potential negative effects on human health of water disinfectants used in swimming pools. Among the disinfection options, the approaches using chlorine-based products have been typically preferred. Chlorine readily reacts with natural organic matter that are introduced in the water mainly through the bathers, leading to the formation of potentially harmful chlorination by-products (CBPs). The formation of CBPs is of particular concern since some have been epidemiologically associated with the development of various clinical manifestations. The higher the concentration of volatile CBPs in the water, the higher their concentration in the air above the pool, and different routes of exposure to chemicals in swimming pools (water ingestion, skin absorption, and inhalation) contribute to the individual exposome. Some CBPs may affect the respiratory and skin health of those who stay indoor for long periods, such as swimming instructors, pool staff, and competitive swimmers. Whether those who use chlorinated pools as customers, particularly children, may also be affected has been a matter of debate. In this article, we discuss the current evidence regarding the health effects of both acute and chronic exposures in different populations (work-related exposures, intensive sports, and recreational attendance) and identify the main recommendations and unmet needs for research in this area.

Exhaled breath condensate pH determinants in school-aged children: A population-based study

BACKGROUND

Exhaled breath condensate (EBC) pH is a promising biomarker of airway inflammation. Lack of method standardization and interstudy variability precludes its use in clinical practice. While endogenous determinants have been described, underlying mechanisms for variability are mostly unknown. Thus, we aimed to assess the association between asthma and EBC pH in children, while studying potential environmental factors for interstudy variability.

METHODS

A cross-sectional analysis of exhaled breath condensates from 613 children, aged 7-12 years, was conducted. Assessments included lung function and airway reversibility, exhaled nitric oxide, allergic sensitization, and body mass index (BMI). Indoor air quality (IAQ) was assessed in children's classrooms during 5 school days. Post-deaeration EBC pH showed a bimodal distribution, and the sample was split into acidic and alkaline groups. Regression models were constructed to assess the effects of asthma and asthma adjusted to IAQ parameters on EBC pH.

RESULTS

Following adjustment to gender and BMI, asthma was significantly associated with a lower EBC pH in the acidic group. The effect of asthma on EBC pH was independent of IAQ, in both groups. In the acidic group, EBC pH was significantly affected by temperature [β = -0.09 (-0.15, -0.02)] and PM 2.5 concentration [β = -0.16 (-0.32, -0.01)], and in the alkaline group by relative humidity [β = 0.07 (0.02, 0.13)] and concentration of endotoxins [β = -0.06 (-0.1, -0.01)].

CONCLUSION

Our study shows that in addition to individual determinants such as asthma, environmental factors may influence and should be taken into consideration when interpreting EBC pH level in children.

Development and validation of exhaled breath condensate microRNAs to identify and endotype asthma in children

Detection and quantification of microRNAs (miRNAs) in exhaled breath condensate (EBC) has been poorly explored. Therefore we aimed to assess miRNAs in EBC as potential biomarkers to diagnose and endotype asthma in school aged children. In a cross sectional, nested case control study, all the asthmatic children (n = 71) and a random sample of controls (n = 115), aged 7 to 12 years, attending 71 classrooms from 20 local schools were selected and arbitrarily allocated to the development or validation set. Participants underwent skin-prick testing, spirometry with bronchodilation, had exhaled level of nitric oxide determined and EBC collected. Based on previous studies eleven miRNAs were chosen and analyzed in EBC by reverse transcription-quantitative real-time PCR. Principal component analysis was applied to identify miRNAs profiles and associations were estimated using regression models. In the development set (n = 89) two clusters of miRNAs were identified. After adjustments, cluster 1 and three of its clustered miRNAs, miR-126-3p, miR-133a-3p and miR-145-5p were positively associated with asthma. Moreover miR-21-5p was negatively associated with symptomatic asthma and positively associated with positive bronchodilation without symptoms. An association was also found between miR-126-3p, cluster 2 and one of its clustered miRNA, miR-146-5p, with higher FEF25-75 reversibility. These findings were confirmed in the validation set (n = 97) where two identical clusters of miRNAs were identified. Additional significant associations were observed between miR-155-5p with symptomatic asthma, negative bronchodilation with symptoms and positive bronchodilation without symptoms. We showed that microRNAs can be measured in EBC of children and may be used as potential biomarkers of asthma, assisting asthma endotype establishment.

Exhaled nitric oxide as a marker of chlorine exposure in young asthmatic swimmers

BACKGROUND

Swimming is recommended for people with asthma. However, the inevitable exposure to chlorine and its disinfectant byproducts in indoor swimming pools could be responsible for bronchial inflammation and asthma development. Fractional exhaled nitric oxide (FeNO) is a noninvasive marker of airway inflammation that predicts asthma exacerbations.

OBJECTIVES

To evaluate pretraining and posttraining FeNO levels in young swimmers with asthma attending an indoor chlorinated pool compared with a set of healthy swimmers and to examine the potential risk of exposure to chlorine as a factor associated with bronchial inflammation.

METHODS

A total of 146 children (8-18 years old) constantly attending an indoor chlorinated swimming pool were enrolled. Spirometry and FeNO measurements were performed 30 minutes after their arrival at the pool and immediately after exercise. Pre-exercise and postexercise spirometric and FeNO levels were assessed in a random subgroup of 14 swimmers (10 with asthma and 4 without) who performed cardiopulmonary exercise testing.

RESULTS

Asthma was detected in 23 swimmers. In swimmers with asthma, preswimming FeNO values were significantly elevated compared with swimmers without asthma and their FeNO values measured before cardiopulmonary exercise testing. Postexercise FeNO values were significantly decreased by approximately one-third in healthy children and children with asthma in all sporting backgrounds. However, postswimming FeNO values remained significantly higher in swimmers with asthma compared with those without asthma. Forced expiratory volume in 1 second (FEV₁), forced vital capacity (FVC), and FEV₁/FVC ratio values showed no significant difference before and after 2 types of activity.

CONCLUSION

Elevated FeNO levels before and after swimming were recorded in swimmers with asthma not observed in a different exercise field. The presence of chlorine in the indoor swimming pool seems to explain this finding.