Environmental and occupational allergies

Airborne allergens are the major cause of allergic rhinitis and asthma. Daily exposure comes from indoor sources, chiefly at home but occasionally at schools or offices. Seasonal exposure to outdoor allergens, pollens, and molds is another important source. Exposure to unusual substances at work causes occupational asthma, accounting for about 5% of asthma in adults. Indoor and outdoor air pollutants trigger airway inflammation and increase the severity of asthma. Diesel exhaust particles increase the production of IgE antibodies. Identification and reduction of exposure to allergens is a very important part of the management of respiratory allergic diseases. The first section of this chapter discusses domestic allergens, arthropods (mites and cockroaches), molds, and mammals (pets and mice). Indoor humidity and water damage are important factors in the production of mite and mold allergens, and discarded human food items are important sources of proliferation of cockroaches and mice. Means of identifying and reducing exposure are presented. The second section discusses outdoor allergens: pollens and molds. The particular plants or molds and the amount of exposure to these allergens is determined by the local climate, and local pollen and mold counts are available to determine the time and amount of exposure. Climate change is already having an important effect on the distribution and amount of outdoor allergens. The third section discusses indoor and outdoor air pollution and methods that individuals can take to reduce indoor pollution in addition to eliminating cigarette smoking. The fourth section discusses the diagnosis and management of occupational asthma.

Combination treatment with high-dose vitamin C and alpha-tocopherol does not enhance respiratory-tract lining fluid vitamin C levels in asthmatics

Oxidative stress plays a significant role in allergic airway inflammation. Supplementation with alpha-tocopherol (alone or combined with ascorbate/vitamin C) has been assessed as an intervention for allergic airway diseases with conflicting results. Enhancing levels of airway antioxidants with oral supplements has been suggested as an intervention to protect individuals from the effect of inhaled oxidants, although it is unclear whether supplementation changes tocopherol or vitamin C levels in both serum and airway fluids. Our objective was to obtain pilot safety and dosing data from 14 allergic asthmatic volunteers examining the effect of daily combination oral therapy with 500 mg alpha-tocopherol (alpha T) and 2 g vitamin C for 12 wk. We examined serum and airway fluid and cellular levels of alpha- and gamma-tocopherol (gamma T) and vitamin C to plan for future studies of these agents in asthma and allergic rhinitis. Six volunteers completed 12 wk of active treatment with alpha T and vitamin C and 8 completed placebo. Blood and sputum samples were obtained at baseline and at 6 wk and 12 wk of therapy and were analyzed for alpha T, gamma T, and vitamin C levels in the serum, sputum supernatant, and sputum cells. Combination treatment increased serum vitamin C and significantly decreased sputum alpha T and serum gamma T levels. No changes were found in sputum supernatant or sputum cell vitamin C or serum alpha T levels in the active treatment group. In conclusion, supplementation with alpha T and high-dose vitamin C does not augment vitamin C levels in the respiratory-tract lining fluid.

Livestock water productivity in the Blue Nile Basin: assessment of farm scale heterogeneity

A recent study of the livestock water productivity (LWP), at higher spatial scales in the Blue Nile Basin, indicated strong variability across regions. To get an insight into the causes of this variability, we examined the effect of farm households’ access to productive resources (e.g. land, livestock) on LWP in potato–barley, barley–wheat, teff–millet and rice farming systems of the Gumera watershed (in the Blue Nile Basin, Ethiopia). We randomly selected 180 farm households. The sizes of the samples, in each system, were proportional to the respective system’s area. Then we grouped the samples, using a participatory wealth ranking method, into three wealth groups (rich, medium and poor) and used structured and pre-tested questionnaires to collect data on crops and livestock management and applied reference evapotranspiration (ET0) and crop coefficient (Kc) approaches to estimate depleted (evapotranspiration) water in producing animal feed and food crops. Then, we estimated LWP as a ratio of livestock’s beneficial outputs to water depleted. Our results suggest strong variability of LWP across the different systems: ranging between 0.3 and 0.6 US$ m−3 year−1. The tendency across different farming systems was comparable with results from previous studies at higher spatial scales. The range among different wealth groups was wider (0.1 to 0.6 US$ m−3 year−1) than among the farming systems. This implies that aggregating water productivity (to a system scale) masks hotspots and bright spots. Our result also revealed a positive trend between water productivity (LWP and crop water productivity, CWP) and farm households’ access to resources. Thus, we discuss our findings in relation to poverty alleviation and integrated land and water management to combat unsustainable water management practices in the Blue Nile Basin.

Livestock water productivity: implications for sub-Saharan Africa

Water is essential for agriculture including livestock. Given increasing global concern that access to agricultural water will constrain food production and that livestock production uses and degrades too much water, there is compelling need for better understanding of the nature of livestock–water interactions. Inappropriate animal management along with poor cropping practices often contributes to widespread and severe depletion, degradation and contamination of water. In developed countries, diverse environmental organisations increasingly voice concerns that animal production is a major cause of land and water degradation. Thus, they call for reduced animal production. Such views generally fail to consider their context, applicability and implications for developing countries. Two global research programs, the CGIAR ‘Comprehensive Assessment of Water Management and Agriculture’ and ‘Challenge Program on Water and Food’ have undertaken studies of the development, management and conservation of agricultural water in developing countries. Drawing on these programs, this paper describes a framework to systematically identify key livestock–water interactions and suggests strategies for improving livestock and water management especially in the mixed crop–livestock production systems of sub-Saharan Africa. In contrast to developed country experience, this research suggests that currently livestock water productivity compares favourably with crop water productivity in Africa. Yet, great opportunities remain to further reduce domestic animals’ use of water in the continent. Integrating livestock and water planning, development and management has the potential to help reduce poverty, increase food production and reduce pressure on the environment including scarce water resources. Four strategies involving technology, policy and institutional interventions can help achieve this. They are choosing feeds that require relatively little water, conserving water resources through better animal and land management, applying well known tools from the animal sciences to increase animal production, and strategic temporal and spatial provisioning of drinking water. Achieving integrated livestock–water development will require new ways of thinking about, and managing, water by water- and animal-science professionals.

Factors affecting livestock water productivity: animal scale analysis using previous cattle feeding trials in Ethiopia

Availability and access to fresh water will likely constrain future food production in many countries. Thus, it is frequently suggested that the limited amount of water should be used more productively. In this study we report the results of our investigation on effects of feed, age and weight on livestock water productivity (LWP). The main objective is to identify technologies that will help enhance LWP. We combined empirical knowledge and literature values to estimate the amount of water depleted to produce beef, milk, traction power and manure. We estimated the LWP as the ratio of livestock products and services to the depleted water. In the feeding trials, various combinations of maize and oat stover, vetch, lablab and wheat bran were combined in different proportions to make 16 unique rations that were fed to the experimental animals of different age and weight groups. We observed differences of LWP across feed type, age and weight of dairy cows. The value of LWP tended to increase with increasing age and weight: the lowest LWP (0.34 US$/m3) for cows less than five years whereas the highest LWP value was 0.41 US$/m3 for those cows in the age category of 8 years and above. Similarly, there was an increase in LWP as weight of the animal increased, i.e. LWP was lowest (0.32 US$/m3) for lower weight groups (300–350 kg) and increased for larger animals. There were apparent impacts of feed composition on LWP values. For example, the highest LWP value was observed for oat, vetch and wheat bran mixes. Taking livestock services and products into account, the overall livestock water productivity ranged from 0.25 to 0.39 US$/m3 and the value obtained from a cow appeared to be higher than for an ox. In conclusion, some strategies and technological options such as improved feeds, better herd management, appropriate heard structure can be adapted to enhance LWP.

Sublingual-oral administration of standardized allergenic extracts: phase 1 safety and dosing results

BACKGROUND

European studies provide a preponderance of evidence for sublingual allergen immunotherapy (SLIT) safety and efficacy, but they use allergen products that differ from those expected to be approved in the United States.

OBJECTIVE

To determine the safety and tolerability of 4 US-licensed standardized SLIT allergenic extracts.

METHODS

Adults 18 to 50 years old with allergic rhinitis with or without asthma due to timothy grass pollen, short ragweed pollen, house dust mite, or cat hair allergy completed a single-session dose escalation followed by an 8-week, open-label daily course of SLIT. Participants documented the presence and severity of adverse effects and adherence using a daily electronic diary.

RESULTS

Ninety-one participants initiated treatment, and 77 completed the phase 1 testing. Maximum tolerable doses ranged from 50 to 2,090 BAU for cat hair and dust mite extract, 31 to 91 Amb a 1 Units for short ragweed pollen extract, and 50 to 21,090 BAU for timothy grass pollen extract. During the 8-week treatment course, 98.9% of participants reported at least 1 mild, 70.4% at least 1 moderate, and 13.6% at least 1 severe adverse effect. Most adverse effects (94.6%) were rated as mild, 5.2% as moderate, and 0.1% as severe; nasal and oral-mucosal adverse effects were most commonly reported. No life-threatening adverse reactions occurred in more than 4,500 administered doses.

CONCLUSIONS

Daily sublingual-oral dosing of standardized allergenic extracts at maximum tolerable doses was generally well tolerated. These results are a first step toward establishing the safety of US-licensed SLIT extracts when appropriately self-administered and monitored.

Circulating neutrophil CD14 expression and the inverse association of ambient particulate matter on lung function in asthmatic children

BACKGROUND

Identifying baseline inflammatory biomarkers that predict susceptibility to size-specific particulate matter (PM) independent of gaseous pollutants could help us better identify asthmatic subpopulations at increased risk for the adverse health effects of PM.

OBJECTIVE

To evaluate whether the association between lung function and exposure to ambient levels of PM less than 2.5 microm in diameter (PM2.5) (fine) and 10 to 2.5 microm in diameter (PM(10-2.5)) (coarse) in children with persistent asthma differed across baseline measures of inflammation and innate immune activation.

METHODS

We performed a panel study on a local population of 16 children with persistent asthma and evaluated daily pulmonary function (percentage of predicted peak expiratory flow and forced expiratory volume in 1 second) while concurrently measuring daily PM2.5 and PM(10-2.5) exposure from a central site in Chapel Hill, North Carolina. The children underwent a baseline medical evaluation that included assessment of several immunoinflammatory biomarkers in peripheral blood.

RESULTS

Children without measurable CD14 expression on circulating neutrophils had significantly reduced pulmonary function (forced expiratory volume in 1 second and peak expiratory flow) with each interquartile range (IQR) increase in PM2.5 (IQR = 8.5 microg/m3) and PM(10-2.5) (IQR = 4.1 microg/m3) concentration, unlike children with measurable CD14 expression (P < .001 for interaction).

CONCLUSIONS

Asthmatic children with muted surface expression of CD14 on circulating neutrophils may have a decreased capacity to respond to bacterial components of PM.

Nasal responses in asthmatic and nonasthmatic subjects following exposure to diesel exhaust particles

Asthma rates have been increasing worldwide, and exposure to diesel exhaust particles (DEP) may be implicated in this increase. DEP may also play a role in the increased morbidity and mortality associated with ambient airborne particulate matter (PM) exposure. Two types of nasal responses have been reported for human subjects nasally instilled with one type of DEP: alterations in cytokines responses, and an increase in immunoglobulin E (IgE) production. Since DEP composition can vary depending on several factors, including fuel composition and engine load, the ability of another DEP particle and ozone-treated DEP to alter nasal IgE and cytokine production was examined. Nonasthmatic and asthmatic subjects were intranasally instilled with 300 microg NIST 1650 DEP per nostril, NIST 1650 DEP previously exposed to ozone (ozDEP; 300 microg/nostril), or vehicle. Subjects underwent nasal lavage before DEP exposure, and 4 and 96 h after exposure. Nasal cell populations and soluble mediators in the nasal lavage fluid were characterized. Total cell number, cell types, cell viability, concentrations of soluble mediators (including interleukin [IL]-8, IL-6, IgE, and granulocyte-macrophage colony-stimulating factor [GM-CSF]) were not altered by either DEP or ozDEP exposure. NO levels were not altered by either particle exposure. These findings suggest that DEP can be relatively noninflammatory and nontoxic, and that the physicochemical characteristics of DEP need to be considered when assessing the health effects of exposure to diesel exhaust.

The influence of variation in type and pattern of symptoms on assessment in pediatric asthma

OBJECTIVE

We conducted a national, population-based survey to examine the asthma-related health burden of US children.

METHODS

A telephone-based survey was conducted in 2004 of children 4 to 18 years of age with current asthma in the United States. In 41,433 households screened, 1089 children reported current asthma; 801 interviews were completed by parents of children aged 4 to 15 years and by children themselves aged 16 to 18 years. The survey included questions about symptoms, perceived level of control, activity limitations, health care use, medicines, disease management, and knowledge. Global asthma symptom burden, derived from the National Asthma Education and Prevention Program guidelines, was composed of 3 components: short-term symptom burden (4-week recall), long-term symptom burden (past year), and functional impact (activity limitation).

RESULTS

The majority of children were classified with mild intermittent disease on the basis of recent daytime symptoms alone (80%); yet, when report of nighttime symptoms was included, the proportion of children classified as having mild intermittent symptoms decreased (74%). When asthma burden was assessed on the basis of the global symptom burden construct, only a minority (13%) of individuals was classified as having an asthma symptom burden consistent with mild intermittent disease; the majority (62%) was classified as having moderate/severe disease. In addition, the impact of asthma on the daily activities is substantial; avoiding exertion (47%) and staying inside (34%) are common approaches to improve control of asthma symptoms.

CONCLUSIONS

The goals of therapy for asthma, based on the National Asthma Education and Prevention Program guidelines, have not been achieved for the majority of children. In addition, parents and children overestimate the child's asthma control and commonly restrict activities to control asthma symptoms. Deficiencies in the control of asthma may be related to the underestimation of the burden of disease.

How exposures to biologics influence the induction and incidence of asthma

A number of environmental factors can affect the development and severity of allergy and asthma; however, it can be argued that the most significant inhaled agents that modulate the development of these conditions are biologics. Sensitization to environmental allergens is an important risk factor for the development of asthma. Innate immune responses are often mediated by receptors on mononuclear cells whose primary ligands arise from microorganisms. Many pathogens, especially viruses, target epithelial cells and affect the host immune response to those pathogens. The acquired immune response to an allergen is influenced by the nature of the innate immune system. Products of innate immune responses to microbes promote T(H)1-acquired responses. In the absence of T(H)1 responses, T(H)2 responses can dominate. Central to T(H)1/T(H)2 balance is the composition of contaminants that derive from microbes. In this review we examine the biology of the response to allergens, viruses, and bacterial products in the context of the development of allergy and asthma.

Incidence of allergy and allergy symptoms among workers exposed to laboratory animals

BACKGROUND AND AIMS

Few studies have described relations between exposure to laboratory animals and the incidence of laboratory animal allergy (LAA). Studies that have found exposure-response relations have been cross sectional in design or have focused on exposure to rats and mice. This study used longitudinal data collected over a 12 year period to describe the relations between indices of exposure to laboratory animals and the development of LAA and LAA symptoms.

METHODS

Data were obtained from questionnaires and serological laboratory results from a dynamic cohort of workers exposed to a variety of laboratory animals in a pharmaceutical manufacturing company. Poisson regression was used to model the incidence rate ratios of species specific and general LAA and LAA symptoms at different levels of exposure.

RESULTS

The 12 year incidence rates of LAA symptoms and LAA for all workers were 2.26 (95% CI 1.61 to 2.91) and 1.32 (95% CI 0.76 to 1.87) per 100 person-years, respectively. Higher rate ratios were seen with increasing reported hours of exposure to tasks that required working with animal cages or with many animals at one time. The most common symptoms were related to rhinitis rather than to asthma.

CONCLUSIONS

This study suggests that the risk of LAA increases with duration of exposure to animals and work in animal related tasks. Incidence might be reduced by limiting hours per week of exposure to laboratory animals.

Progression of self-reported symptoms in laboratory animal allergy

BACKGROUND

Laboratory animal allergy is a common illness among workers exposed to laboratory animals and can progress to symptoms of asthma.

OBJECTIVES

This study evaluates the continuum of disease from allergy symptoms to asthma symptoms in a dynamic cohort of workers exposed to animals in a pharmaceutical company.

METHODS

Data arose from annual questionnaires administered to workers in a surveillance program established to monitor exposure to animals and the development of allergy. The life-table method was used to compare asthma-free survival between workers with and without symptoms of allergy. A Cox proportional hazards model was used to examine the effects of covariates on the development of asthma.

RESULTS

A total of 603 workers contributed 2527.4 person-years to the study over the 12.3-year period. The probabilities of experiencing asthma symptoms by the 11th year of follow-up were 0.367 for workers with allergy symptoms and 0.052 for those without allergy symptoms. The hazard ratio for asthma symptoms when comparing workers with and without allergy symptoms was 7.39 (95% CI, 3.29-16.60) after adjustment for sex and family history of allergy. Female subjects developed asthma at a rate 3.4 times that of male subjects.

CONCLUSIONS

This study supports the hypothesis that laboratory animal allergy symptoms are a major risk factor for the development of asthma. It also suggests a heightened risk of asthma for women who work with laboratory animals, a finding that has not been previously reported.

Gene-environment interactions in asthma and other respiratory diseases

It is generally agreed that many lung diseases such as asthma and chronic obstructive pulmonary disease (COPD) have polygenic inheritance, and that the association of a specific genotype or genotypes with the disease is likely to vary between populations. Furthermore, it is recognized that the etiology of many lung diseases involves a complex interplay between genetic background and exposure to multiple environmental stimuli, and understanding the mechanisms through which genes and environment interact represents a major challenge for pulmonary researchers. We discuss experimental approaches and challenges that must be overcome to identify disease genes for asthma, COPD and chronic bronchitis, and occupational lung diseases. In particular, common polymorphisms in CD14, glutathione S-transferase, and tumor necrosis factor alpha have been found to be important in gene-environment interaction and asthma pathogenesis. An understanding of gene-environment interactions in complex lung diseases is essential to the development of new strategies for lung disease prevention and treatment.

Efficacy and safety of fluticasone propionate/salmeterol HFA 134A MDI in patients with mild-to-moderate persistent asthma

The objective of this study was to compare the efficacy and safety of fluticasone propionate (FP) (44 microg)/salmeterol (21 microg) delivered as two inhalations twice daily via a single hydrofluoroalkane (HFA 134a) metered dose inhaler (MDI) (FSC) with that of placebo HFA 134a (PLA), fluticasone propionate 44 microg chlorofluorocarbon (CFC) alone and salmeterol 21 microg CFC alone (S) in patients (n=360) with persistent asthma previously treated with beta2-agonists (short- or long-acting) or inhaled corticosteroids (ICS). After 12 weeks of treatment, patients treated with FSC had a significantly greater increase (p < or = 0.006) in mean FEV1 AUC(bl) compared with PLA, FP, or S. At end point, mean change from baseline in morning predose FEV1 for FSC (0.58 L) was significantly (p < or = 0.004) greater than PLA (0.14 L), FP (0.36 L), and S (0.25 L). Patients treated with FSC also had a significantly higher probability of remaining in the study without being withdrawn due to worsening asthma (2%) compared with those in the PLA (29%) and S (25%) groups (p < 0.001). Finally, treatment with FSC resulted in significantly (p < or = 0.007) greater improvements in morning and evening peak expiratory flow, need for rescue albuterol, and asthma symptom scores compared with FP, S, and PLA. The safety profile of FSC was also similar to FP or S alone. Initial maintenance treatment of the two main components of asthma, inflammation, and smooth muscle dysfunction (e.g., bronchoconstriction), with FSC results in greater overall improvements in asthma control compared with treatment of either individual component alone.

Health effects of air pollution

The general public, especially patients with upper or lower respiratory symptoms, is aware from media reports that adverse respiratory effects can occur from air pollution. It is important for the allergist to have a current knowledge of the potential health effects of air pollution and how they might affect their patients to advise them accordingly. Specifically, the allergist-clinical immunologist should be keenly aware that both gaseous and particulate outdoor pollutants might aggravate or enhance the underlying pathophysiology of both the upper and lower airways. Epidemiologic and laboratory exposure research studies investigating the health effects of outdoor air pollution each have advantages and disadvantages. Epidemiologic studies can show statistical associations between levels of individual or combined air pollutants and outcomes, such as rates of asthma, emergency visits for asthma, or hospital admissions, but cannot prove a causative role. Human exposure studies, animal models, and tissue or cellular studies provide further information on mechanisms of response but also have inherent limitations. The aim of this rostrum is to review the relevant publications that provide the appropriate context for assessing the risks of air pollution relative to other more modifiable environmental factors in patients with allergic airways disease.

Health consequences associated with frequent wheezing in adolescents without asthma diagnosis

Using questions from the International Study of Asthma and Allergies in Childhood, this study evaluated the association between undiagnosed frequent wheezing and health consequences in adolescents. The North Carolina School Asthma Survey provided self-reported questionnaire data on respiratory health from 122,829 children aged 12-14 yrs. The frequency of health consequences were compared among undiagnosed frequent wheezers, diagnosed asthmatics, and children with no wheezing symptoms or diagnosed asthma. The odds of wheezing-related sleep disturbances, limited activities, and missed school were higher among undiagnosed frequent wheezers, relative to diagnosed asthmatics. The frequency of emergency room visits and hospitalisations did not differ substantially between the undiagnosed wheezing and diagnosed asthma groups, though the undiagnosed group was less likely to have visited a physician for wheezing in the past year. Children with frequent wheezing symptoms but no asthma diagnosis experience substantial illness-related morbidity similar to that of diagnosed asthmatics. Undiagnosed frequent wheezers require more recognition from primary care physicians and need active disease management to reduce health consequences.