Variable risk of atopic disease due to indoor fungal exposure in NHANES 2005-2006

BACKGROUND

Exposure to damp indoor environments is associated with increased risk of eczema, allergy and asthma. The role of dampness-related exposures and risk of allergic diseases are yet to be fully explored in the US population.

OBJECTIVE

We assess whether exposure to fungi, house dust mites and endotoxin increases the risk of eczema, allergy and asthma in children and adults participating in NHANES 2005-2006.

METHODS

A total of 8412 participants (2849 were children aged between 6 and 17 years) were recruited in the 2005-2006 survey. We used multiple logistic regression to investigate whether mildew/musty odour and increased concentrations of Alternaria alternata allergen, Aspergillus fumigatus antigens, house dust mite and endotoxin antigens increase the risk of eczema, allergy and asthma. We stratified models by total IgE < 170 and ≥ 170 KU/L to assess allergic and non-allergic asthma outcomes. Exposure to multiple biological agents and risk of reporting eczema, allergy and asthma were also investigated.

RESULTS

Reporting of a mildew/musty odour was associated with increased risk of childhood asthma (OR 1.60; 95% CI 1.17-2.19), and adult eczema, allergy and asthma (OR 1.92; 95% CI 1.39-2.63, OR 1.59 95% CI 1.26-2.02 and OR 1.61 95% CI 1.00-2.57, respectively). Risk of asthma was associated with total IgE ≥ 170 KU/L in children (OR 1.81; 95% CI 1.01-3.25) and total IgE < 170 KU/L in adults (OR 1.91; 95% CI 1.07-3.42). Children and adults exposed to more than eight biological agents present in the home were at reduced risk of eczema (OR 0.17; 95% CI 0.04-0.77) and asthma (OR 0.49; 95% CI 0.25-0.97), respectively.

CONCLUSION

Exposure to a mildew/musty odour, as a proxy for exposure to fungus, was implicated in an increased risk of atopic diseases. Sensitisation may play a different role in children and adults, and exposure to multiple allergens may reduce the risk of atopic disease.

Coastal climate is associated with elevated solar irradiance and higher 25(OH)D level

INTRODUCTION

There is evidence that populations living close to the coast have improved health and wellbeing. Coastal environments are linked to promotion of physical activity through provision of safe, opportune, aesthetic and accessible spaces for recreation. Exposure to coastal environments may also reduce stress and induce positive mood. We hypothesised that coastal climate may influence the vitamin D status of residents and thus partly explain benefits to health.

MATERIALS AND METHODS

Ecological and cross-sectional analyses were designed to elucidate the connection between coastal residence and vitamin D status. We divided residential data, from developed land use areas and the Lower Super Output Areas or Data Zones (Scotland) of the 1958 Birth Cohort participants, into the following coastal bands: <1 km, 1-5 km, 5-20 km, 20-50 km and over 50 km. In the ecological analysis we used a multiple regression model to describe the relationship between UV vitd and coastal proximity adjusted for latitude. Subsequently, using the residential information of the participants of the 1958 Birth Cohort we developed a multiple regression model to understand the relationship between serum 25(OH)D (a marker of vitamin D status) and coastal proximity adjusted for several factors related to vitamin D status (e.g. diet, outdoor activity).

RESULTS

We found that coastal proximity was associated with solar irradiance; on average a 99.6 (96.1-103.3)J/m(2)/day regression coefficient was recorded for settlements <1 km from the coast compared with those at >50 km. This relationship was modified by latitude with settlements at a lower latitude exhibiting a greater effect. Individuals living closer to the coast in England had higher vitamin D levels than those inland, particularly in autumn.

CONCLUSION

Geographic location may influence biochemistry and health outcomes due to environmental factors. This can provide benefits in terms of vitamin D status but may also pose a risk due to higher skin cancer risk. We provide further evidence in support of the claim that coastal environments can provide opportunities for health and wellbeing.

Modifiable factors governing indoor fungal diversity and risk of asthma

Exposure to dampness and fungi in the home is a known risk factor for individuals with allergic asthma. Inadequate heating and ventilation may lead to dampness and concomitant increased exposure to spores of allergenic fungi such as Aspergillus and Penicillium. These fungi have been cultured from sputum of asthmatic and non-asthmatic individuals, and implicated in the initiation or exacerbation of asthma. Indoor environmental factors influence the presence and concentrations of fungal propagules and, in turn, risk of asthma outcomes. This review aims to identify modifiable risk factors in the built environment that have been shown to influence fungal composition indoors, and to examine this association with the risk of asthma development and/or exacerbation. A complex interaction between residential characteristics, the built environment and the behaviour of people regulate the diversity and concentrations of indoor fungi. Modifiable factors include build age, architectural design, level of maintenance, variations in construction materials, presence of pets, heating and ventilation patterns. Risk of fungal contamination and asthma outcomes are also influenced by low occupant awareness concerning potential health effects and socio-economic factors. Addressing these factors provides an opportunity to improve future housing interventions, though it is not clear how the built environment and occupant behaviours interact to modify the diversity of indoor fungi and resultant risk of asthma. A combination of housing improvements combined with awareness programmes and the alleviation of fuel poverty can be used to lower the allergen burden associated with damp homes. Further research is needed to identify factors that regulate the concentration and diversity of indoor fungi and how this may act as a modifier for asthma outcomes.

The prevalence and socio-demographic risk factors of clinical eczema in infancy: a population-based observational study

BACKGROUND

Socio-demographic predictors for the development of clinically observed, infantile eczema have not been formally examined in a large population-based study. Few studies of eczema risk factors have included current, objective eczema outcomes as well as parent-reported history.

OBJECTIVES

We aimed to measure the population prevalence of infantile eczema using novel sampling methodology, and identify socio-demographic risk factors for eczema in the first year of life.

METHODS

A population-based cross-sectional study of infantile allergy (the HealthNuts study, n = 4972, response rate 74.1%) was conducted from 2008-2011 in Melbourne, Australia. Infants were examined for current eczema at age 12 months (mean 12.7, SD 0.7). Parents provided information about the infants' history of eczema and demographic factors. Factors associated with eczema were modelled using multinomial logistic regression.

RESULTS

The population prevalence of observed eczema at 12 months was 20.3% (95% CI 19.0, 21.5), while cumulative prevalence for parent-reported eczema was 28.0% (95% CI 26.7, 29.4). The strongest predictors of eczema were maternal eczema and asthma (multinomial (M)-OR 1.7, P < 0.001, and M-OR 1.4, P = 0.007), male sex (M-OR 1.4, P < 0.001), and East Asian ethnicity (M-OR 1.6, P < 0.001) with over 80% of infants with all risk factors exhibiting eczema. East Asian parents, particularly recent migrants, reported fewer allergies than other parents.

CONCLUSIONS AND CLINICAL RELEVANCE

Approximately, one in three infants developed eczema by 12 months of age. East Asian infants are at increased risk of eczema despite their parents having lower rates of allergy than non-Asian parents. Gene-environment interactions may explain the differential effect seen in this minority group.

Environmental and demographic risk factors for egg allergy in a population-based study of infants

BACKGROUND

Although egg allergy is the most common food allergy in infants and young children, risk factors for egg allergy remain largely unknown. This study examined the relationship between environmental and demographic factors and egg allergy in a population-based infant cohort.

METHODS

In a study of 5276 infants (HealthNuts), infants underwent skin prick testing (SPT) to egg white at 12 months of age. Questionnaire data on relevant exposures were obtained. 699/873 (80%) infants eligible for oral food challenge (detectable wheal on SPT) attended for formal assessment of egg allergy status; 453 had confirmed egg allergy (positive challenge and SPT ≥ 2 mm). Associations between environmental and demographic factors and egg allergy were investigated using multivariable logistic regression.

RESULTS

Children with older siblings and those with a pet dog at home were less likely to develop egg allergy by 1 year of age (adjusted OR [aOR], 0.72; 95% CI, 0.62, 0.83 per sibling; and aOR, 0.72; 95% CI, 0.52, 0.99, respectively). Caesarean section delivery, antibiotic use in infancy, childcare attendance and maternal age were not associated with egg allergy. History of allergic disease in an immediate family member and having parents born in East Asia were strong risk factors for infantile egg allergy (aOR, 1.82; 95% CI, 1.40, 2.36; and aOR, 3.30; 95% CI, 2.45, 4.45, respectively).

CONCLUSIONS

Exposure in the first year of life to siblings and dogs may decrease the risk of subsequent egg allergy. Infants with a family history of allergy and those with parents born in East Asia are at increased risk of egg allergy.

Carbimazole embryopathy: implications for the choice of antithyroid drugs in pregnancy

Maternal thyrotoxicosis, predominantly secondary to Graves' disease, affects 0.2% of all pregnancies. The Endocrine Society guidelines recommend the use of propylthiouracil as a first-line drug for thyrotoxicosis in pregnancy because of associations between carbimazole or methimazole and congenital anomalies. However, recent studies have highlighted the risk of severe liver injury with propylthiouracil. Here, we report another case with multiple congenital anomalies following in utero exposure to carbimazole and review the literature to consider the risks and benefits of available pharmacological treatments for thyrotoxicosis in pregnancy.

The HealthNuts population-based study of paediatric food allergy: validity, safety and acceptability

BACKGROUND

The incidence of hospital admissions for food allergy-related anaphylaxis in Australia has increased, in line with world-wide trends. However, a valid measure of food allergy prevalence and risk factor data from a population-based study is still lacking.

OBJECTIVE

To describe the study design and methods used to recruit infants from a population for skin prick testing and oral food challenges, and the use of preliminary data to investigate the extent to which the study sample is representative of the target population.

METHODS

The study sampling frame design comprises 12-month-old infants presenting for routine scheduled vaccination at immunization clinics in Melbourne, Australia. We compared demographic features of participating families to population summary statistics from the Victorian Perinatal census database, and administered a survey to those non-responders who chose not to participate in the study.

RESULTS

Study design proved acceptable to the community with good uptake (response rate 73.4%), with 2171 participants recruited. Demographic information on the study population mirrored the Victorian population with most the population parameters measured falling within our confidence intervals (CI). Use of a non-responder questionnaire revealed that a higher proportion of infants who declined to participate (non-responders) were already eating and tolerating peanuts, than those agreeing to participate (54.4%; 95% CI 50.8, 58.0 vs. 27.4%; 95% CI 25.5, 29.3 among participants).

CONCLUSION

A high proportion of individuals approached in a community setting participated in a food allergy study. The study population differed from the eligible sample in relation to family history of allergy and prior consumption and peanut tolerance, providing some insights into the internal validity of the sample. The study exhibited external validity on general demographics to all births in Victoria.

Health effects of recreational exposure to Moreton Bay, Australia waters during a Lyngbya majuscula bloom

A survey of residents in an area subject to annual toxic cyanobacterial blooms was undertaken to examine potential health effects of cyanobacteria toxins. The survey assessed the health of marine recreational water users in Deception Bay/Bribie Island area in northern Moreton Bay, Queensland, which is exposed to blooms of the nuisance and potentially harmful cyanobacterium Lyngbya majuscula. A postal survey was mailed to 5000 residents with a response rate of 27%. High numbers of people (78%) responding to the survey reported recreational water activity in Moreton Bay. Of those having marine recreational water activity, 34% reported at least one symptom after exposure to marine waters, with skin itching the most reported (23%). Younger participants had greater water exposure and symptoms than older participants. Participants with greater exposures were more likely to have skin and eye symptoms than less exposed groups, suggesting agents in the marine environment may have contributed to these symptoms. Of those entering Moreton Bay waters 29 (2.7%) reported severe skin symptoms, 12 of whom attended a health professional. Six (0.6%) reported the classic symptoms of recreational water exposure to L. majuscula, severe skin symptoms in the inguinal region. Participants with knowledge of L. majuscula were less likely to report less skin, gastrointestinal and fever and headache symptoms. In conclusion, high numbers of participants reported symptoms after exposure to waters subject to L. majuscula blooms but only a small number appeared to be serious in nature suggesting limited exposure to toxins.

The toxins of Lyngbya majuscula and their human and ecological health effects

Lyngbya majuscula is a benthic filamentous marine cyanobacterium, which in recent years appears to have been increasing in frequency and size of blooms in Moreton Bay, Queensland. It has a worldwide distribution throughout the tropics and subtropics in water to 30m. It has been found to contain a variety of chemicals that exert a range of biological effects, including skin, eye and respiratory irritation. The toxins lyngbyatoxin A and debromoaplysiatoxin appear to give the most widely witnessed biological effects in relation to humans, and experiments involving these two toxins show the formation of acute dermal lesions. Studies into the epidemiology of the dermatitic, respiratory and eye effects of the toxins of this organism are reviewed and show that Lyngbya induced dermatitis has occurred in a number of locations. The effects of aerosolised Lyngbya in relation to health outcomes were also reported. Differential effects of bathing behaviour after Lyngbya exposure were examined in relation to the severity of health outcomes. The potential for Lyngbya to exhibit differential toxicologies due to the presence of varying proportions of a range of toxins is also examined. This paper reviews the present state of knowledge on the effects of Lyngbya majuscula on human health, ecosystems and human populations during a toxic cyanobacterial bloom. The potential exists for toxins from Lyngbya majuscula affecting ecological health and in particular marine reptiles.

Perturbation of paracetamol urinary metabolic ratios by urine flow rate

The effects of high and low urine flow rates on the urinary metabolic ratios for paracetamol glucuronidation, sulphation and oxidation were determined at steady-state in seven healthy young adult volunteers. Metabolic partial clearances were unaffected by urine flow rate, but individual paracetamol metabolic ratios varied 2.5- to 3.2-fold over a 7.4-fold range of urine flow rates (0.81-6.00 ml min-1). The change in metabolic ratios was due entirely to a 2.5-fold change in renal clearance of unchanged paracetamol. These data emphasise the limitations of the metabolic ratio as a measure of intrinsic clearance for compounds which undergo some degree of tubular reabsorption.

Interethnic differences in drug glucuronidation: a comparison of paracetamol metabolism in Caucasians and Chinese

Paracetamol disposition following a single oral 1 g dose of the drug was compared in groups (n = 12) of healthy young adult male Caucasians and Chinese. There was no difference between the groups in terms of paracetamol oral clearance, elimination half-life, or partial metabolic (glucuronidation, sulphation, oxidation) and renal clearances. The results demonstrate that drug glucuronidation is not universally impaired in Chinese and, together with previously published data, that paracetamol glucuronidation is minimally affected by race.