Indoor environment and children's health: recent developments in chemical, biological, physical and social aspects

Much research is being carried out into indoor exposure to harmful agents. This review focused on the impact on children's health, taking a broad approach to the indoor environment and including chemical, microbial, physical and social aspects. Papers published from 2006 onwards were reviewed, with regards to scientific context. Most of publications dealt with chemical exposure. Apart from the ongoing issue of combustion by-products, most of these papers concerned semi volatile organic compounds (such as phthalates). These may be associated with neurotoxic, reprotoxic or respiratory effects and may, therefore, be of particular interest so far as children are concerned. In a lesser extent, volatile organic compounds (such as aldehydes) that have mainly respiratory effects are still studied. Assessing exposure to metals is still of concern, with increasing interest in bioaccessibility. Most of the papers on microbial exposure focused on respiratory tract infections, especially asthma linked to allergens and bio-aerosols. Physical exposure includes noise and electromagnetic fields, and articles dealt with the auditory and non auditory effects of noise. Articles on radiofrequency electromagnetic fields mainly concerned questions about non-thermal effects and papers on extremely low-frequency magnetic fields focused on the characterization of exposure. The impact of the indoor environment on children's health cannot be assessed merely by considering the effect of these different types of exposure: this review highlights new findings and also discusses the interactions between agents in indoor environments and also with social aspects.     

Exposure assessment of residential mould,fungi and microbial components in relation to children's health: Achievements and challenges

Each day we are exposed to a complex mixture of microbial agents and components in indoor environments. A major part of this mixture derives from fungal and bacterial origin. The impact between those microbial agents in the home environment in relation to respiratory health in children is still a major issue in research. There is little known about the causal agents that provoke or arrest the development of allergic respiratory disorders in children. Identification is complicated by the biodiversity and variability of microbial components in indoor air as well as the lack of validated and standardized exposure assessment methods. In this review, we aim to consider all important aspects in terms of research which may encounter an epidemiological study. Apart from the need for standardized exposure assessment methods which consider cost, handling and effort, especially for the participants, we suggest that a combination of different analysis methods such as chemical and molecular methods may have the potential to best describe the microbial milieu in indoor environments at present. Further, the impact of mould and moisture remediation activities on health is still heavily under investigated, especially in larger prospective cohorts of children and should be a topic of future research. Moreover, the exposure to mould and microbial agents might be embedded in a broader spectrum of children's health such as behavior and cognitive development.     

Sensory irritating potency of some microbial volatile organic compounds (MVOCs) and a mixture of five MVOCs.

The authors investigated the ability/potencies of 3 microbial volatile organic compounds and a mixture of 5 microbial volatile organic compounds to cause eye and upper respiratory tract irritation (i.e., sensory irritation), with an animal bioassay. The authors estimated potencies by determining the concentration capable of decreasing the respiratory frequency of mice by 50% (i.e., the RD50 value). The RD50 values for 1-octen-3-ol, 3-octanol, and 3-octanone were 182 mg/m3 (35 ppm), 1359 mg/m3 (256 ppm), and 17586 mg/m3 (3360 ppm), respectively. Recommended indoor air levels calculated from the individual RD50 values for 1-octen-3-ol, 3-octanol, and 3-octanone were 100, 1000, and 13000 microg/m3, respectively-values considerably higher than the reported measured indoor air levels for these compounds. The RD50 value for a mixture of 5 microbial volatile organic compounds was also determined and found to be 3.6 times lower than estimated from the fractional concentrations and the respective RD50s of the individual components. The data support the conclusion that a variety of microbial volatile organic compounds may have some synergistic effects for the sensory irritation response, which constrains the interpretation and application of recommended indoor air levels of individual microbial volatile organic compounds. The results also showed that if a particular component of a mixture was much more potent than the other components, it may dominate the sensory irritation effect. With respect to irritation symptoms reported in moldy houses, the results of this study indicate that the contribution of microbial volatile organic compounds to these symptoms seems less than previously supposed.     

Biomarkers and chemosensory irritations

OBJECTIVES: A literature review on studies in humans, applying physiological methods to monitor environmentally induced reactions in eyes and upper respiratory tract. The focus was on chemical exposures, but other occupational factors and indoor exposures were included. METHODS: Original articles were gathered from Medline until November 2000, combined with peer-reviewed publications from other sources. RESULTS: Ocular methods included measurement of tear film break-up time (BUT), blink frequency, detection of corneal damage, by vital staining, and cells or inflammatory markers in tear fluid. Nasal methods included acoustic rhinometry, rhinostereometry, and nasal peak expiratory flow. In addition, nasal lavage with isotonic sodium chloride solution was applied to measure concentrations of leucocytes, or biomarkers of secretion or inflammation in nasal lavage fluid (NAL). Most occupational studies were on nasal effects of organic or inorganic dust. There were few studies on occupational exposure to organic solvents or chemical irritants. Some studies demonstrated associations between ocular and nasal physiological response and the indoor environment. Finally, there were some exposure-chamber studies on effects of specific volatile organic compounds (VOCs). Little is known about adaptation at repeated ocular or nasal exposure to irritants. CONCLUSION: Physiological measurements can be valuable complements to symptom registration, but there is a need for standardised investigations. There is a lack of studies on ocular and nasal physiological responses in relation to specific chemical compounds. Experimental studies, with repeated exposure and longer follow-up time on biomarkers, are needed. Finally, there is a need for longitudinal epidemiological studies to elucidate if observed effects should be interpreted as variation within normal physiology, or as early signs of impaired ocular and respiratory health.     

Ocular symptoms, tear film stability, nasal patency, and biomarkers in nasal lavage in indoor painters in relation to emissions from water-based paint

Purpose  

Despite the decreased use of solvent-based paint (SBP) and increased use of water-based paints (WBP) with possible risk for microbial growth, few health studies are available. The aim was to study the symptoms and ocular and nasal biomarkers in house painters in relation to paint use and personal exposure to volatile organic compounds (VOC) and microbial VOC (MVOC) during indoor painting with WBP.     

Passive Smoking,Excretion of Metabolites,and Health Effects: Results of the Leipzig's Allergy Risk Study (LARS)

Over a 5-yr period, the Leipzig's Allergy Risk Study (LARS) investigated the influence of typical indoor-contaminant burdens on the development of allergies and upper respiratory tract infections in allergy-prone children. Typical indoor volatile organic compounds (VOCs) and excretion of certain VOC metabolites in urine were measured in children 3 yr of age. Data analyses were based on parent-completed questionnaires, exposure measurements, and medical examinations. Evaluation of passive smoking was of special interest. Generally, residences with a high burden of passive smoking had higher benzene concentrations than residences inhabited by nonsmokers. Obstructive bronchitis was observed more frequently in children exposed to increased concentrations of benzene, as well as toluene, styrene, and m,p-xylene. In addition, atopic symptoms were associated with excretion of certain VOC metabolites. For example, the authors found an association between eczema and exposure to toluene and between eczema and increased excretion of the toluene metabolite S-benzylmercapturic acid. The results suggest that if an association with certain health effects is to be demonstrated, evaluation of external exposures should be supplemented with evaluations of internal exposure.     

Passive smoking,excretion of metabolites,and health effects: results of the Leipzig's Allergy Risk Study (LARS)

Over a 5-yr period, the Leipzig's Allergy Risk Study (LARS) investigated the influence of typical indoor-contaminant burdens on the development of allergies and upper respiratory tract infections in allergy-prone children. Typical indoor volatile organic compounds (VOCs) and excretion of certain VOC metabolites in urine were measured in children 3 yr of age. Data analyses were based on parent-completed questionnaires, exposure measurements, and medical examinations. Evaluation of passive smoking was of special interest. Generally, residences with a high burden of passive smoking had higher benzene concentrations than residences inhabited by nonsmokers. Obstructive bronchitis was observed more frequently in children exposed to increased concentrations of benzene, as well as toluene, styrene, and m,p-xylene. In addition, atopic symptoms were associated with excretion of certain VOC metabolites. For example, the authors found an association between eczema and exposure to toluene and between eczema and increased excretion of the toluene metabolite S-benzylmercapturic acid. The results suggest that if an association with certain health effects is to be demonstrated, evaluation of external exposures should be supplemented with evaluations of internal exposure.     

A healthy home environment?

Over the past seven years, the U.S. Environmental Protection Agency has consistently ranked indoor air pollution among the top five risks to public health. One of the most dangerous indoor air pollutants is carbon monoxide (CO). CO can be lethal, but perhaps more important, many people suffer ill health from chronic, often undetected exposure to low levels of this gas, resulting in fatigue, headache, dizziness, nausea, and vomiting. Another dangerous pollutant is volatile organic compounds (VOCs), which come from sources including building products, cleaning agents, and paints. One VOC, formaldehyde, can act as an irritant to the conjunctiva and upper and lower respiratory tract. Formaldehyde is also known to cause nasal cancer in test animals.     

Wi-Fi Technology and Human Health Impact: A Brief Review of Current Knowledge

An enormous increase in the application of wireless communication in recent decades has intensified research into consequent increase in human exposure to electromagnetic (EM) radiofrequency (RF) radiation fields and potential health effects, especially in school children and teenagers, and this paper gives a snap overview of current findings and recommendations of international expert bodies, with the emphasis on exposure from Wi-Fi technology indoor devices. Our analysis includes over 100 in vitro, animal, epidemiological, and exposure assessment studies (of which 37 in vivo and 30 covering Wi-Fi technologies). Only a small portion of published research papers refers to the “real” health impact of Wi-Fi technologies on children, because they are simply not available. Results from animal studies are rarely fully transferable to humans. As highly controlled laboratory exposure experiments do not reflect real physical interaction between RF radiation fields with biological tissue, dosimetry methods, protocols, and instrumentation need constant improvement. Several studies repeatedly confirmed thermal effect of RF field interaction with human tissue, but non-thermal effects remain dubious and unconfirmed.Key words: exposure to RF fields, e-school, radiofrequency, SAR     

Evaporative gasoline emissions and asthma symptoms

Attached garages are known to be associated with indoor air volatile organic compounds (VOCs). This study looked at indoor exposure to VOCs presumably from evaporative emissions of gasoline. Alaskan gasoline contains 5% benzene making benzene a marker for gasoline exposure. A survey of randomly chosen houses with attached garages was done in Anchorage Alaska to determine the exposure and assess respiratory health. Householders were asked to complete a health survey for each person and a household survey. They monitored indoor air in their primary living space for benzene, toluene, ethylbenzene and xylenes for one week using passive organic vapor monitoring badges. Benzene levels in homes ranged from undetectable to 58 parts per billion. The median benzene level in 509 homes tested was 2.96 ppb. Elevated benzene levels in the home were strongly associated with small engines and gasoline stored in the garage. High concentrations of benzene in gasoline increase indoor air levels of benzene in residences with attached garages exposing people to benzene at levels above ATSDR's minimal risk level. Residents reported more severe symptoms of asthma in the homes with high gasoline exposure (16%) where benzene levels exceeded the 9 ppb.     

Exposure to airborne fungi, MVOC and mycotoxins in biowaste-handling facilities

Health impacts due to fungi in indoor air can only be estimated reliably, if both fungal propagules and fungal secondary metabolites are qualified and quantified. In the present study, the fungal species composition in a compost facility is compared to the spectrum of microbial metabolites in the air with regard to the physiological properties of different fungal species. A number of relevant fungi was tested for the production of both volatile and non-volatile metabolites on different substrata. The profiles of mycotoxins and microbial volatile organic compounds (MVOC) turned out to be specific for certain species in pure culture. Consequently, the fungi may have different toxicological health impacts, though information on the relevance of microbial volatiles is still limited.     

Asthmatic symptoms and volatile organic compounds, formaldehyde, and carbon dioxide in dwellings.

OBJECTIVES--As a part of the worldwide European Community respiratory health survey, possible relations between symptoms of asthma, building characteristics, and indoor concentration of volatile organic compounds (VOCs) in dwellings were studied. METHODS--The study comprised 88 subjects, aged 20-45 years, from the general population in Uppsala, a mid-Swedish urban community, selected by stratified random sampling. Room temperature, air humidity, respirable dust, carbon dioxide (CO2), VOCs, formaldehyde, and house dust mites were measured in the homes of the subjects. They underwent a structured interview, spirometry, peak expiratory flow (PEF) measurements at home, methacholine provocation test for bronchial hyperresponsiveness, and skin prick tests. In addition, serum concentration of eosinophilic cationic protein (S-ECP), blood eosinophil count, and total immunoglobulin E (S-IgE) were measured. RESULTS--Symptoms related to asthma were more common in dwellings with house dust mites, and visible signs of dampness or microbial growth in the building. Significant relations were also found between nocturnal breathlessness and presence of wall to wall carpets, and indoor concentration of CO2, formaldehyde, and VOCs. The formaldehyde concentration exceeded the Swedish limit value for dwellings (100 micrograms/m3) in one building, and CO2 exceeded the recommended limit value of 1000 ppm in 26% of the dwellings, showing insufficient outdoor air supply. Bronchial hyperresponsiveness was related to indoor concentration of limonene, the most prevalent terpene. Variability in PEF was related to two other terpenes; alpha-pinen and delta-karen. CONCLUSION--Our results suggest that indoor VOCs and formaldehyde may cause asthma-like symptoms. There is a need to increase the outdoor air supply in many dwelling, and wall to wall carpeting and dampness in the building should be avoided. Improved indoor environment can also be achieved by selecting building materials, building construction, and indoor activities on the principle that the emission of volatile organic compounds should be as low as reasonably achievable, to minimise symptoms related to asthma due to indoor air pollution.     

Assessing exposure to air toxics relative to asthma

Asthma is a respiratory disease whose prevalence has been increasing since the mid 1970s and that affects more than 14.6 million residents of the United States. Environmental triggers of asthma include air pollutants that are respiratory irritants. Air toxics emitted into the ambient air are listed in the 1990 Clean Air Act Amendments as hazardous air pollutants (HAPs) if they can adversely affect human health, including the respiratory tract. HAPs include particulate and gaseous-phase pollutants, individual organic compounds and metals, and mixtures. Associations between asthma exacerbation and both particles and indoor volatile organic compounds (VOCs), often referred to as indoor air quality, have been reported. Studies conducted in the United States, Canada, and Europe over the past two decades have shown that most people living in the developed countries spend the majority of their time indoors and that the air concentrations of many air toxics or HAPs are higher indoors than in the ambient air in urban, suburban, and rural settings. Elevated indoor air concentrations result from emissions of air toxics from consumer products, household furnishings, and personal activities. The Relationship of Indoor, Outdoor and Personal Air (RIOPA) study was designed to oversample homes in close proximity to ambient sources, excluding residences where smokers lived, to determine the contribution of ambient emissions to air toxics exposure. The ratios of indoor to outdoor air concentrations of some VOCs in homes measured during RIOPA were much greater than one, and for most other VOCs that had indoor-to-outdoor ratios close to unity in the majority of homes, elevated ratios were found in the paired samples with the highest concentration. Thus, although ambient emissions contribute to exposure of some air toxics indoors as well as outdoors, this was not true for all of the air toxics and especially for the higher end of exposures to most volatile organic air toxics examined. It is therefore critical, when evaluating potential effects of air toxics on asthma or other adverse health end points, to determine where the exposure occurs and the source contributions for each air toxic and target population separately and not to rely solely on ambient air concentration measurements.     

Airway symptoms among house painters in relation to exposure to volatile organic compounds (VOCS)—a longitudinal study

The increased use of water-based paint (WBP) for indoor application during the last decade has drastically changed the exposure conditions for Swedish house painters. WBP has a lower emission of volatile organic compounds (VOCs) than solvent-based paint (SBP), but contains more reactive compounds, such as biocides, glycol ethers, and other high molecular solvents. The aim of this study was to compare the incidence of airway symptoms and self-reported asthma in house painters with a different degree of use of WBP and SBP. The incidence of seven general airway symptoms, and three work-related symptoms, was analysed by means of a self-administered questionnaire, in a cohort of 207 house painters followed from 1989 to 1992. Different airway symptoms were compared with clinical information obtained by a methacholine challenge test and dynamic spirometry in a selected subgroup of 44 painters. Information on the degree of use of SBP and WBP was used to estimate the total exposure to volatile organic compounds (TVOC) for each individual. In total, 175 men in the cohort worked as painters during the study period. No increase of asthma or respiratory symptoms was observed among those 50 painters with a pure exposure to WBP (estimated TVOC 1–3mgm⁻³). Most painters (N = 125) had a mixed exposure to SBP and WBP, the main source of the TVOC being the limited use of SBP. WBP was perceived as less irritative than SBP, but complaints on airway irritation from WBP increased during the study period. The most pronounced increase of airway irritation in relation to both SBP and WBP, was observed among those 35 painters with the highest solvent exposure (estimated TVOC 100–380 mgm⁻³). An increase of respiratory symptom index and shortness of breath, in relation to estimated TVOC exposure was also observed. Selection effects were detected. Painters leaving their job during the study period had more non-specific hyper-reactivity symptoms, and more airway irritation from WBP-as compared to painters remaining at their occupation. Our study indicates that VOC emissions from SBPs may contribute to the development of respiratory symptoms and airway irritation. We found no increase of respiratory symptoms among painters exposed only to WBPs. There were, however, indications that VOC exposure from WBPs may cause airway irritation in some subjects. Because of selection effects, cross-sectional studies on respiratory symptoms in relation to occupational exposure to paint emissions may be inconclusive.     

Working Group report 4: exposure assessment for biological agents

This Working Group was assembled to review and evaluate methods currently used to estimate work site exposures to biological agents and to present recommendations on suitable measurement strategies. The current state of exposure assessment was evaluated for environments with organic dust including agriculture, composting, sewage and waste treatment processing, peat moss harvesting and handling, cotton and textile processing, greenhouse work, and grass seed processing. Methods for measurement of microbial contaminants in indoor environments were also considered. Important methods are emerging that use quantitative PCR for assessment of microbial agents. Difficulties exist with optimization of extraction to yield contaminant-free DNA without significant DNA loss. Advances in assays for microbial agents (e.g., endotoxin and glucans) as well as allergens have increased the utility of exposure assessment for these agents. A crucial area for further development is international harmonization of methodologies to reduce interlaboratory variability and to facilitate establishment of exposure guidelines. Endotoxin exposure assessment using the Limulus amebocyte lysate method is a high priority for harmonization because of its importance as a pulmonary inflammatory agent in many occupational settings.     

挥发性有机污染物在室内环境中的化学反应及其健康影响

室内环境中存在大量的挥发性有机污染物(VOCs),在O3和NO2存在的情况下,各污染物之间可能发生各种各样的化学反应,这些反应严重地影响了室内空气质量,造成室内人员的健康损害。该文论述了室内可能存在的主要化学反应,以及其带来的健康问题,并概括了相关研究的内容和存在的问题。对室内环境中VOCs的化学反应进行研究对于人体健康非常重要,有助于改进室内空气质量标准和建立建筑材料“生态标志”。     

Indoor climate, air pollution, and human comfort.

The term sick building syndrome (SBS) is frequently used to describe a set of symptoms often reported by occupants of certain buildings. The symptoms are supposed to be direct or indirect consequences of an inadequate indoor climate. Typically, a majority of the occupants in these buildings complain, and the most frequent complaint is irritation of eyes, nose, and throat. Many different factors are known to be potential agents for the symptoms and no definitive causality has been identified yet. In consequence authors of publications on indoor air quality have been using the SBS term in different ways. A review of literature indicates that in supposed "sick buildings" only the prevalence of irritation of mucosal membranes and headaches seems to differ significantly from the prevalence in buildings considered to have a normal indoor climate. Volatile organic compounds (VOC) are known to have a potency to cause symptoms like those included in SBS. A dose-response relation for sensory reactions and mucosal irritation caused by volatile organic air pollutants is discussed, and a tentative guideline at 3 mg/m3 (about 0.9 PPM toluene equivalent) for the total volatile organic compounds (TVOC) is suggested for the nonindustrial indoor climates.     

International trends in the study of room air quality and conclusions for East Germany

The international literature is analyzed in order to recognize recent developments in the field of investigations of indoor air quality. Special attention is paid to the papers of the 4th International Conference on Indoor Air Quality and Climate, held in Berlin (West) August 1987. It is noticed that a certain emphasis is put on the investigation of volatile organic compounds and of radon and their effects on human health. General conclusions are drawn for the research on these problems in the GDR.     

装修后居室空气中甲醛和总挥发性有机物污染现状

目的了解目前室内装修后空气中挥发性有机物（TVOC）污染水平、特征、原因和所致健康效应。方法于2003年6-9月在上海市徐汇区选取23户新装修居民住宅,分为有家具和无家具2组,另外选9户为对照组,进行室内空气中甲醛和TVOC浓度监测,同时进行居民主观症状问卷调查。结果新装修后有家具住宅空气中甲醛超标率为47．1％,最大超标5．56倍;TVOC超标率为76．5％,最大超标4．03倍;新装修后无家具住宅空气中甲醛无超标,TVOC超标率为100％。装修后空气中甲醛和TVOC浓度均以储藏室最高,其中甲醛浓度分别是客厅和卧室的7．2倍和3．6倍。装修后3个月后甲醛和TVOC浓度都大大降低,其中TVOC超标率从最初的76％下降到0％。主观症状中仅异嗅发生率差异具有统计学意义（P〈0．01）。结论本研究发现目前装修所致TVOC污染水平有所下降,但装修后室内甲醛污染仍比较严重和普遍,污染原因主要在于不合格板材的使用。居民在入住新装修住房后眼睛和上呼吸道刺激症状发生率增加。     

Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational,indoor, and community air pollution research

Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass. Community studies should focus on air toxics expected to have adverse respiratory effects based on biological mechanisms, particularly irritant and immunological pathways to asthma onset and exacerbation.