Domestic exposure to volatile organic compounds in relation to asthma and allergy in children and adults

Abstract

Over the past decades, the prevalence of asthma, allergic disease and atopy has increased significantly and in parallel with the increased use of products and materials emitting volatile organic compounds (VOCs) in the indoor environment. The purpose of this review is to examine the evidence of the relationship between quantitatively measured domestic exposure to VOCs and allergic diseases and allergy in children and adults. Sources, potential immune-inflammatory mechanisms and risks for development and severity of asthma and allergy have been addressed. Available evidence is based on studies that have mainly used observational designs of variable quality. Total, aromatic, aliphatic, microbial VOCs and aldehydes have been the most widely investigated VOC classes, with formaldehyde being the most commonly examined single compound. Overall, the evidence is inadequate to draw any firm conclusions. However, given indicative evidence from a few high-quality studies and significant potential for improvements in asthma outcomes in those with established disease, there is a need to consider undertaking further investigation of the relationship between domestic VOC exposure and asthma/allergy outcomes that should encompass both high-quality, robust observational studies and ultimately clinical trials assessing the impact of interventions that aim to reduce VOC exposure in children and adults with asthma.

Keywords::

• allergic rhinitis
• asthma
• atopic eczema/dermatitis
• atopy
• formaldehyde
• immune responses
• indoor air pollutants
• residential exposure
• VOC

Financial & competing interests disclosure

The authors were funded by Chief Scientist’s Office of the Scottish Government (CZG/2/573). The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. No writing assistance was utilized in the production of this manuscript.

Key issues

• Recent dramatic changes in the prevalence of allergic disease and allergy coincide with the changes in the indoor environment manifested by elevated indoor levels of pollutants emitted from plastics, synthetic materials and household chemicals.

• Evidence concerning the exposure to volatile organic compounds (VOCs) in domestic environment and asthma and allergy gathered mostly from cross-sectional and case–control studies.

• The research is focused primarily on asthma, children and the prevalence of conditions; aromatics and aldehydes are most commonly investigated VOCs.

• Research findings are, in general, supportive of the association between exposure and asthma and allergy, mainly in those with established disease and mechanistic pathways for the association have also been demonstrated.

• Most evidence should be viewed as suggestive of the association rather than definitive, owing to the observational nature of the studies.

• There is a lack of robust evidence: poor methodological and exposure assessment quality of the studies raise concerns about the reliability and validity of the findings.

• Studies that demonstrated and did not demonstrate the exposure–outcome relationship do not differ in terms of design, sample size and methods of exposure assessment.

• There is a need for repeated measurements of VOC concentrations in the domestic environment to provide a valid indicator for actual long-term exposure.

• There is a need for a long-term assessment of the domestic exposure to VOCs in relation to the development of allergic disease and allergy, requiring a large birth cohort study.

• There is a need for well-designed intervention studies with an adequate sample size and high-quality exposure assessment to evaluate the effectiveness of reducing exposure to improve asthma and allergy outcomes.

• Proven relationship between exposure and allergic diseases will offer the real possibility of disease prevention and improvement of outcomes and is likely to become a part of their management.