Helen Dimich-Ward

Respiratory health effects of exposure to environmental tobacco smoke

Abstract:  Tobacco smoke is a major component of indoor air pollution. Exposure to environmental tobacco smoke (ETS) is prevalent worldwide despite growing awareness of its adverse health effects on non‐smokers. ETS contains the same toxic substances as identified in mainstream tobacco smoke. Cotinine (a metabolite of nicotine) can be measured in urine and serum of non‐smokers exposed to ETS and reflects the degree of exposure. In children, exposure to ETS leads to reduced lung function, increased risk of lower respiratory tract illnesses, acute exacerbation of asthma resulting in hospitalization, increased prevalence of non‐allergic bronchial hyperresponsiveness, increased risk for sudden infant death syndrome (SIDS) and possibly increased risk for asthma. Exposure to ETS is responsible for excess cost to the familys financial resources and demands on health services. In adults, exposure to ETS is associated with increased risk of lung cancer, particularly in those with high exposure and acute and chronic respiratory symptoms that improve after the cessation of exposure. Healthcare providers should advocate for non‐smokers’ rights in the community and support legislation to limit tobacco exposure.

Genetic variants of the IL13 and IL4 genes and atopic diseases in at-risk children

We studied a cohort containing 368 children at high risk of developing atopy and atopic disorders and 540 parents of those children to investigate whether the IL13 Arg130Gln and C−1112 T polymorphisms were associated with these outcomes. We also investigated whether haplotypes consisting of any two polymorphisms of IL13 Arg130Gln, IL13 C−1112 T and IL4 C−589 T were associated with these phenotypes. In 288 white children, the IL13 130Gln allele was associated with atopy (RR=1.9, P=0.047), and with atopic dermatitis (RR=2.5, P=0.014). The associations were confirmed using a family-based test of association (P=0.027 and 0.030, respectively) in all subjects. In white subjects there were associations of haplotypes consisting of IL13 Arg130Gln and IL4 C−589 T with atopic dermatitis (P=0.006) and with atopy (P=0.009). Our data suggest that the IL13 Arg130Gln polymorphism and haplotypes consisting of IL13 Arg130Gln and IL4 C−589 T were associated with the development of atopy and atopic dermatitis at 24 months of age.

Analysis of Nicotine and Cotinine in the Hair of Hospitality Workers Exposed to Environmental Tobacco Smoke

The purpose of this study was to determine if hair nicotine and cotinine levels reflect relative exposure to environmental tobacco smoke (ETS) in subjects who worked in the hospitality industry, where public smoking was permitted. Hair samples from 26 subjects were analyzed by gas chromatograph/mass spectrometry techniques for nicotine and cotinine. An exposure gradient was shown for nicotine but not cotinine. Among nonsmokers, those working in bars where there are no public smoking restrictions had the highest hair nicotine levels, which were close to levels found in smokers. Nicotine measured in hair is useful as a biological marker for exposure to ETS from multiple sources. Bar workers in particular are exposed to high levels of ETS, which may adversely affect the health of nonsmokers.

Cord blood IgE: its determinants and prediction of development of asthma and other allergic disorders at 12 months

BACKGROUND The value of cord blood IgE in predicting the development of asthma and other IgE-mediated allergic diseases is unclear. OBJECTIVE The purpose of this study is twofold: (1) to determine factors affecting cord blood IgE level and (2) to determine whether cord blood IgE predicts the development of asthma and other IgE-mediated allergic diseases in high risk (defined as those with at least one first degree relative with asthma or 2 first degree relatives with other IgE-mediated allergic diseases) infants at 12 months. METHODS The study utilized cord blood obtained from a group of high risk infants who took part in a randomized controlled trial to assess the effectiveness of an intervention program in the primary prevention of asthma and other IgE-mediated allergic diseases. Total IgE and cotinine in the cord blood were measured. Assessment of the infants was done at 12 months for these diseases. RESULTS Sixty-four (17.8%) infants had detectable total IgE in cord blood >0.5 kU/L. The proportion of infants with elevated cord blood IgE was significantly higher among nonwhites, birth during winter months, and those with a maternal history of asthma. There was no correlation between cord blood IgE and cord blood cotinine level. Cord blood IgE was found to be a significant predictor for the development of urticaria due to food allergy but not for other outcomes. CONCLUSION Both genetic and environmental risk factors play a role in determining the level of IgE in cord blood. Cord blood IgE was a significant risk factor for the development of urticaria due to food allergy at 12 months of life. As urticaria due to food allergy is a prodrome for anaphylaxis, measurement of IgE in cord blood may be indicated in infants at high risk for developing allergic diseases so that preventive measures can be applied.

Surveillance of hospitalized farm injuries in Canada

Objective—To provide an overview of hospital admissions for the treatment of farm injuries. Methods—Design: descriptive analysis of data from the Canadian Agricultural Injury Surveillance Program (CAISP). Population: persons experiencing a farm injury requiring hospitalization, April 1991 to March 1995. Access to hospital separation data was negotiated within Canadian provinces. Individual cases were verified by medical records personnel and supplemental data describing injury circumstances were obtained. Analysis: descriptive analyses characterizing farm injuries by: persons involved, mechanisms, primary diagnoses, and agents of injury. Results—Data from 8/10 Canadian provinces representing 98% of the farm population were obtained. A total of 8263 farm injuries were verified. Adults aged 60 years and older were over-represented in these injuries. Leading external causes of agricultural machinery injury included entanglements, being pinned/struck by machinery, falls, and runovers. Non-machinery causes included falls from heights, animal related trauma, and being struck/by against objects. Leading diagnoses varied by age group, but included: limb fractures/open wounds, intracranial injuries, skull fractures, and spinal/truncal fractures. Conclusions—CAISP is a new agricultural injury surveillance program in Canada. Data from this system are actively used to inform prevention initiatives, and to indicate priorities for etiological and experimental research in the Canadian agricultural setting.

House dust mite allergen levels in two cities in Canada: effects of season, humidity, city and home characteristics

The homes of 120 patients with asthma, 57 in Vancouver and 63 in Winnipeg, were studied. The characteristics of the homes were assessed by a questionnaire. Dust samples were collected and the indoor relative humidity was measured four times during the year covering all four seasons in both cities. Mite allergen levels were determined using monoclonal antibodies against Der p I and Der f I by the ELISA method. The mean levels of both mite allergens in mattress and floor samples in the homes in Vancouver and in Winnipeg were relatively low for all seasons. Mite allergen levels were found to be associated with city, season and individual home differences. They were significantly higher in Vancouver than in Winnipeg. Der p I and Der f I in mattress samples in both cities and Der f I in floor samples in Vancouver, varied by season. The indoor relative humidity level in the homes in Vancouver were also significantly higher than those in Winnipeg. There was, however, no significant association between the levels of indoor relative humidity and the levels of mite allergens after adjusting for variations in city, season and individual home. Although individual home differences were highly associated with mite allergen levels, only a few home characteristics were found to be related to mite allergen levels such as the type and the age of the home, the type of heating, the use of feather pillows and the number of occupants in the homes. Whether low levels of mite allergens are partially responsible for the relatively low prevalence of childhood asthma in Canada remains to be investigated.

Mortality and cancer incidence among sawmill workers exposed to chlorophenate wood preservatives.

OBJECTIVES This study examined the association between exposure to chlorophenates and the risk of soft tissue sarcoma; non-Hodgkins lymphoma; Hodgkins disease; and cancers of the lung, nose, and nasopharynx. METHODS A retrospective cohort study was conducted of 26487 workers employed for at least 1 year between 1950 and 1985 in 11 chlorophenate-using and 3 non-using sawmills in British Columbia, Canada. Exposures by job were ascertained with interviews of senior employees. RESULTS Probabilistic record linkage to the Canadian Mortality Data Base and the British Columbia Cancer Registry found 4710 deaths between 1950 and 1990, and 1547 incident cases of cancer between 1969 and 1989. None of the cancers of interest had elevated mortality related to chlorophenate exposure. Non-Hodgkins lymphoma incidence (n = 65) increased with increasing chlorophenate exposure hours, yielding the following standardized incidence ratios: less than 120 hours 0.68; 120 to 1999 hours, 0.59; 2000 to 3999 hours, 1.04; 4000 to 9999 hours, 1.02; and 10000 or more hours, 1.30. CONCLUSIONS These results are consistent with the borderline positive associations seen in other recently reported studies of chlorophenate-exposed workforces.

Atopic dermatitis in a high-risk cohort: natural history, associated allergic outcomes, and risk factors.

BACKGROUND Atopic dermatitis (AD) is commonly associated with asthma and other atopic disorders in childhood. OBJECTIVE To evaluate the natural history of AD and its association with other allergic outcomes in a high-risk cohort through the age of 7 years. METHODS A total of 373 high-risk infants, who had undergone a randomized controlled trial with intervention measures for primary prevention of asthma applied during the first year of life, were assessed for asthma, AD, and allergic sensitization at 1, 2, and 7 years. RESULTS The multifaceted intervention program did not reduce AD despite reducing the prevalence of asthma significantly. Sixty-two children (16.6%) had AD during the first 2 years (early-onset AD); of these, 26 continue to have AD at the age of 7 years (persistent), whereas 36 no longer had the disease (nonpersistent) at the age of 7 years. Twenty-three children (6.2%) developed AD only after the age of 2 years (late-onset AD). Early-onset AD, persistent or nonpersistent, was associated with increased risk of allergic sensitization to food allergens within the first 2 years of life and asthma diagnosis at year 7. However, only persistent AD was associated with an increased risk of other atopic diseases and allergic sensitization to food and aeroallergens at year 7. Late-onset AD was not associated with atopic diseases or allergic sensitization at year 7 with the exception of Alternaria alternans. CONCLUSION In this cohort of infants at high risk of asthma, early-onset persistent AD, which was highly associated with atopic sensitization, increased the risk of atopic diseases in later childhood and thus appears to be part of the atopic march.

Exposure and sensitization to cat dander: Asthma and asthma-like symptoms among adults☆☆☆★

BACKGROUND Several pets, such as cats, dogs, and rodents, are known to produce allergens. Despite the clinical and laboratory evidence that exposure to pets can cause bronchoconstriction in sensitized subjects, the results of population studies have been contradictory. OBJECTIVES The purpose of this study was to investigate the relationship between cat ownership and the prevalence of asthma, asthma-like symptoms, and bronchitic symptoms among subjects 20 to 44 years of age in Vancouver, Canada and to determine whether sensitization is responsible for such an association. METHODS Two thousand nine hundred ninety-nine (88%) randomly selected subjects responded to a mail questionnaire. Of these, 504 participated in laboratory examination, including allergy skin testing. RESULTS One thousand nineteen study responders (34%) were pet owners at the time of the study (current owners). Current pet owners were found to have a higher prevalence of current asthma, asthma-like symptoms, and bronchitic symptoms compared with those without pets. Cat owners had significantly higher risk of having current asthma and asthma-like symptoms. In the subset who had allergic skin tests, we found that those who were allergic to cat dander had a significantly higher risk of current asthma than those not allergic to cat dander and not owning a cat. CONCLUSION This study provides evidence that sensitization to cat dander is a more important risk factor for current asthma and asthma-like symptoms than cat ownership itself.

Contact with livestock – a protective effect against allergies and asthma?

Background A ‘protective farm factor’ possibly related to livestock exposure is hypothesized to reduce the risk for allergic sensitization.