Combined exposure to dog and indoor pollution: incident asthma in a high-risk birth cohort.

The impact of single exposures on asthma development is better understood than the effect of multiple exposures. The objective of the present study was to evaluate the effect of combined early exposure to dog allergen (Can-f1) plus indoor nitrogen dioxide (NO2) or environmental tobacco smoke (ETS) on asthma and bronchial hyperreactivity (BHR) in a high-risk birth cohort. We also aimed to assess atopy's impact on the effects of these exposures. Peri-birth ETS exposure was measured using cord blood cotinine (CCot). During year 1, atopy, NO2, Can-f1, and urinary cotinine (UCot) were measured. At 7 yrs of age, 380 children were assessed for asthma and BHR. Exposure effects were determined using stepwise multiple linear regression. Co-exposure to elevated Can-f1 and NO2, or Can-f1 and ETS (CCot), increased risk for asthma, relative to having neither such exposure (OR 4.8 (95% CI 1.1-21.5) and 2.7 (1.1-7.1), respectively); similar risks resulted when substituting dog ownership for allergen. Atopy increased asthma and BHR risk associated with several exposures; notably, atopy with elevated UCot, relative to atopy without such exposure, increased risk of BHR (OR 3.1 (95% CI 1.1-8.6)). In a high-risk birth cohort, early co-exposure to Can-f1 and NO2 or ETS increased the risk of incident asthma. Atopy increased the risk of asthma and BHR associated with ETS.

Geographical variations in the prevalence of atopic sensitization in six study sites across Canada.

BACKGROUND: Geographical variations in atopic sensitization in Canada have not been described previously. This study used the standardized protocol of the European Community Respiratory Health Survey-1 (ECRHS-1) to investigate the distribution and predictors of atopic sensitization in six sites across Canada and to compare the results with some ECRHS-1 centers. METHODS: Adults aged 20-44 years in six study sites across Canada underwent allergy skin testing using 14 allergens (Dermatophagoides pteronyssinus, Dermatophagoides farinae) cat, cockroach, grasses (Timothy grass, Kentucky grass), molds (Cladosporium herbarium, Alternaria alternata, Aspergillus fumigatus, Penicillium), trees (tree mix, birch, Olea europea), and common ragweed. RESULTS: The overall prevalence of atopy (skin test over 0 mm to any allergen) was 62.7%. There was significant geographical variation in the prevalence of atopy in the six study sites (lowest 55.6% [95% C.I.51.3-59.9] in Prince Edward Island, highest 66.0 [61.7-70.3] in Montreal) and of sensitization to each of the allergens tested even after adjustment for confounders. When the first eight of the nine allergens in the ECRHS were used to estimate the prevalence of atopic sensitization, the prevalence of atopy in Canada was 57% compared with 35.2% overall for centers in the ECRHS. The prevalence of atopy in Vancouver (57% [52.3-61.8]) was close to that of Portland, Oregon (52.1% [46.2-58.0]). CONCLUSION: There was a significant variation in atopic sensitization among different study sites across Canada. The prevalence of atopic sensitization is relatively high in Canada compared with sites in the ECRHS and this may, in part, account for the high prevalence of asthma and asthma symptoms in Canada.

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. OBJECTIVE: The purpose of this study was to determine whether 4-H club youth, who have opportunities for contact with livestock through club activities, have reduced risks of respiratory and allergic symptoms according to residence on a farm or exposure to livestock. METHODS: A cross-sectional postal survey was completed by British Columbia 4-H members 8-20 years of age; a subset underwent skin prick testing as well. The association of farm residence and livestock exposure variables with symptoms were evaluated using logistic regression with adjustment for age, sex, cat and/or dog ownership, parental history of allergic disease, parental education, number of older siblings and exposure to smokers at home. RESULTS: Questionnaires were completed by 1158 participants (response rate 50.3%); of these, a subset of 317 had skin prick tests (SPTs) (response rate 64.4%). Current residence on a farm was associated with a lower prevalence of ever having wheeze and asthma, as well as symptoms of atopic dermatitis. Variables relating to residence in a farm or rural area with livestock were more strongly associated with respiratory and allergic symptoms than were the livestock exposure variables such as frequency of contact and hours of barn use. The adjusted odds ratios for living in a farm residence in comparison with a rural non-livestock area were 0.49 (95% confidence interval (CI) 0.27-0.89) for diagnosed asthma, 0.51 (95% CI 0.30-0.85) for allergic rhinitis and 0.45 (95% CI 0.24-0.84) for atopic dermatitis. CONCLUSION: Our findings suggest that some aspects of the farm environment, not just attributable to contact with livestock, were protective for respiratory and allergic conditions among 4-H youth.

Considering risks to healthcare workers from glutaraldehyde alternatives in high-level disinfection.

Due to concerns over glutaraldehyde's toxicity, two substitutes have recently been introduced; ortho-phthalaldehyde (OPA), and a mixture of hydrogen peroxide and peracetic acid. There is limited information about the health effects for employees from these products. This study assesses the current practices regarding the use of high-level disinfectants in British Columbian hospitals and predicts the relative toxicities of each product. Industry practices were compiled using a comprehensive survey of current practices and decision processes in all hospitals in British Columbia. Of 95 hospitals, 64 returned surveys; 80% of these used high-level disinfection. Among user hospitals, 49% used glutaraldehyde alone and 51% had introduced alternatives. Concern about staff health was the most common reason for substituting, but this was frequently not considered when choosing specific alternatives. Hospitals that involved occupational health, infection control or regional staff in high-level disinfectant decisions used glutaraldehyde alternatives less often. In most hospitals, it was difficult to find individuals who were knowledgeable about the use of disinfectants. Potential health effects associated with each type of high-level disinfectant were assessed by review of the published literature and available manufacturers' data along with qualitative structure-activity relationship analysis. Results indicated that although all products irritate the skin and respiratory tract, OPA is a potential dermal and respiratory sensitizer but hydrogen peroxide and peracetic acid do not cause allergic reactions. Despite little being known about the risks to employees from glutaraldehyde alternatives, their use is widespread. The potential risks of all high-level disinfectants are serious; thus regulators and users are faced with important risk management decisions before and after they have been introduced into the workplace.

Gender differences in the occurrence of farm related injuries.

AIMS: To use national surveillance data in Canada to describe gender differences in the pattern of farm fatalities and severe injuries (those requiring hospitalisation). METHODS: Data from the Canadian Agricultural Injury Surveillance Program (CAISP) included farm work related fatalities from 1990 to 1996 for all Canadian provinces and abstracted information from hospital discharge records from eight provinces for the five fiscal years of 1990 to 1994. Gender differences in fatalities and injuries were examined by comparison of proportions and stratified by sex, injury class (machinery, non-machinery), and age group. RESULTS: Over the six year period of 1990 to 1996 there were approximately 11 times as many agriculture related fatalities for males compared to females (655 and 61, respectively). The most common machinery mechanisms of fatal injuries were roll-over (32%) for males and run-over (45%) for females. Agricultural machinery injuries requiring hospitalisation showed similar patterns, with proportionally more males over age 60 injured. The male:female ratio for non-machinery hospitalisations averaged 3:1. A greater percentage of males were struck by or caught against an object, whereas for females, animal related injuries predominated. CONCLUSIONS: Gender is an important factor to consider in the interpretation of fatal and non-fatal farm injuries. A greater number of males were injured, regardless of how the occurrence of injury was categorised, particularly when farm machinery was involved. As women increasingly participate in all aspects of agricultural production, there is a need to collect, interpret, and disseminate information on agricultural injury that is relevant for both sexes.

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.

Surveillance of hospitalized farm injuries in Canada.

OBJECTIVE: To provide an overview of hospital admissions for the treatment of farm injuries. 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 8,263 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.

The association between respiratory viruses and symptoms in 2-week-old infants at high risk for asthma and allergy.

OBJECTIVES: The role of viral respiratory tract infections in the onset of childhood asthma and allergy is controversial, partly because of limited understanding about postnatal viral exposures. We investigated the prevalence of 3 common respiratory viruses and associated respiratory symptoms in 2-week-old infants at high risk for having asthma and allergy. STUDY DESIGN: Frozen nasal specimens from 2-week-old children at high risk (n = 495) underwent reverse transcription-polymerase chain reaction (RT-PCR) for picornavirus-, parainfluenza-, and respiratory syncytial virus-specific nucleic acid. RT-PCR findings were related to respiratory symptoms (cold, cough, and wheeze) and to characteristics implicated with increased risk for asthma and allergy. RESULTS: Viral RT-PCR was positive in 199 (40.2%) of 495 specimens examined, with picornavirus and parainfluenza significantly associated with respiratory symptoms. Viral prevalence was significantly higher in children born during the winter and summer months. CONCLUSIONS: A high percentage (40.2%) of infants at high risk for asthma and allergy had been exposed to common respiratory viruses at 2 weeks of age. RT-PCR is a powerful diagnostic method that can be used in epidemiologic studies examining the role of viral respiratory tract infections in the pathogenesis of pediatric asthma and allergy.

Prevalence of asthma symptoms among adults aged 20-44 years in Canada.

BACKGROUND: Reported prevalence rates of asthma vary within and between countries around the world. These differences suggest environmental factors in addition to genetic factors in the cause of the disease and may provide clues for preventive strategies. We examined the variability of asthma-related symptoms and medication use among adults in 6 sites across Canada (Vancouver, Winnipeg, Hamilton, Montreal, Halifax and Prince Edward Island) and compared our findings with those from sites that had participated in a recent European survey. METHODS: We used the same sampling strategy and standardized questionnaire as those used in the European Community Respiratory Health Survey (ECRHS). The 6 Canadian sites were selected to represent different environments with respect to climate, air pollution and occupational exposure. Community-based samples of 3000 to 4000 people aged 20-44 years were randomly selected in each site. Subjects were asked to complete the questionnaire by mail between March 1993 and November 1994. Prevalence rates (and 95% confidence intervals [CIs]) of asthma symptoms, self-reported asthma attacks and use of asthma medication were compared across the Canadian sites and with sites that had participated in the ECRHS. RESULTS: The overall response rate of those selected to receive the questionnaire was 86.5% (range 74.5%-92.8%). The prevalence rates of most asthma symptoms varied significantly among the Canadian sites. For instance, 21.9% (Montreal) to 30.4% (Halifax) of the men and 24.0% (Vancouver) to 35.2% (Halifax) of the women reported wheezing in the year before the survey. Depending on the site, 4.4% to 6.3% of the men and 5.2% to 9.5% of the women reported an asthma attack in the last year, and 4.0% to 6.1% of the men and 4.9% to 9.7% of the women were currently using asthma medication. Prevalence rates of symptoms, asthma attacks and medication use did not change with age, but they were higher among women than among men. Compared with the results from the ECRHS sites, those from the Canadian sites were among the highest. INTERPRETATION: Significant variation in the prevalence of asthma symptoms, asthma attacks and use of asthma medication between Canadian sites and international sites suggests environmental influences. Different combinations of factors in different sites may be responsible for the high prevalence rates and should be the subject of further research to guide clinical management and public health intervention.

Occupational asthma in adults in six Canadian communities.

We examined the prevalence, population attributable risk (PAR), and clinical characteristics of occupational asthma (OA) in a randomly selected population in six communities in Canada. Our study followed the European Community Respiratory Health Survey protocol. A randomly selected population of 18,701 (87% response rate) persons from the study communities, ranging in age from 20 to 44 yr, completed an initial questionnaire, of whom 2,974 (39% response rate) attended the laboratory and completed supplementary questionnaires. Of these latter individuals, 383 had asthma. Asthma was defined as physician-diagnosed asthma, and adult-onset asthma was defined as a first attack at age 15 yr or older. We used several methods for estimating OA as follows: (1) reporting of a high-risk job (occupation and industry) for OA at the time of asthma onset (Probable OA); (2) reporting of exposure to a substance that may cause OA (Possible OA) while not in a high-risk job at the time of asthma onset; and (3) combination of the PAR for high-risk jobs and exposures. The prevalence (95% confidence interval [CI]) of Probable OA and Possible OA combined was 36.1% (31.3 to 41.0%) among subjects with adult-onset asthma. The occupations most commonly reported in association with OA were nursing in the Probable OA group and clerical and food preparation in the Possible OA group. The clinical characteristics and exposures reported by both groups were similar. The PAR for adult-onset asthma in high-risk jobs and exposures was 18.2%. The assessment of occupation and industry alone, rather than of exposures, may underestimate the contribution of occupational exposures to asthma prevalence.

A randomized controlled study on the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants.

BACKGROUND: The prevalence of asthma has increased in developed countries in the past 2 decades. The effectiveness of intervention measures on the primary prevention of asthma has not been well studied. OBJECTIVE: To assess the effectiveness of a multifaceted intervention program in the primary prevention of asthma in high-risk infants (in this study, infants are defined as persons from birth to the age of 1 year). DESIGN: Prospective, prenatally randomized, controlled study with follow-up through the age of 1 year. SETTING: University hospital-based settings at 2 Canadian centers: Vancouver, British Columbia, and Winnipeg, Manitoba. PARTICIPANTS: A total of 545 high-risk infants (at least 1 first-degree relative with asthma or 2 first-degree relatives with other IgE-mediated allergic diseases) identified before birth. INTERVENTIONS: Avoidance of house dust mite and pet allergens and environmental tobacco smoke, encouragement of breastfeeding, and supplementation with a partially hydrolyzed formula. MAIN OUTCOME MEASURES: Probable or possible asthma, rhinitis without apparent colds, and a prick skin test result positive for common inhalant allergens. RESULTS: Thirty-eight (15.1%) of the 251 infants available for assessment in the intervention group and 49 (20.2%) of the 242 infants available for assessment in the control group fulfilled the criteria for possible or probable asthma (adjusted relative risk, 0.66; 90% confidence interval, 0.44-0.98). Also, 16.7% of the infants in the intervention group and 27.3% of the infants in the control group developed rhinitis without colds (adjusted relative risk, 0.51; 90% confidence interval, 0.35-0.74). The incidence of positive skin test results to 1 or more inhalant allergens was similar in both groups (4.4% in the intervention group and 4.6% in the control group). CONCLUSIONS: Our multifaceted intervention program resulted in a modest but significant (P= .04) reduction in the risk of possible or probable asthma and rhinitis without apparent colds at the age of 12 months in high-risk infants. In the absence of a validated definition of asthma at the age of 12 months, follow-up studies are needed to determine the effectiveness of the intervention program in the primary prevention of asthma in high-risk infants.

Distribution of DRB1 and DQB1 HLA class II alleles in occupational asthma due to western red cedar.

Occupational asthma caused by western red cedar is a common problem in sawmill industries. The objective of this study was to examine a possible association of human leukocyte antigen (HLA) class II genetic markers with susceptibility or resistance to western red cedar induced asthma. The distribution of DRB1 and DQB1 HLA class II alleles and DRB1-DQB1 haplotypes was studied in 56 Caucasian patients with proven red cedar asthma and 63 healthy Caucasian control subjects exposed to red cedar dust. DRB1 and DQB1 high resolution typing was performed by the polymerase chain reaction-based method. Patients with red cedar asthma had a higher frequency of HLA DQB1*0603 and DQB1*0302 alleles compared to a group of healthy exposed control subjects and a reduced frequency of DQB1*0501 allele. The frequency of the DRB1*0401-DQB1* 0302 haplotype was increased and the DRB1*0101-DQB1*0501 haplotype was reduced. These findings suggest that genetic factors such as human leukocyte antigen class II antigens may be associated with susceptibility or resistance to development of red cedar asthma.

Childhood cancer in the offspring of male sawmill workers occupationally exposed to chlorophenate fungicides.

The objective of this study was to determine whether paternal occupational exposure to chlorophenol fungicides and their dioxin contaminants is associated with childhood cancer in the offspring of sawmill workers. We used data from 23,829 British Columbian sawmill workers employed for at least 1 continuous year between 1950 and 1985 in 11 sawmills that used chlorophenates. Probabilistic linkage of the sawmill worker cohort to the provincial marriage and birth files produced an offspring cohort of 19,674 children born at least 1 year after the initiation of employment in the period 1952-1988. We then linked the offspring cohort to the British Columbia Cancer Registry. We included all malignancies in cases younger than 20 years of age that appeared on the cancer registry between 1969 and 1993. We calculated standardized incidence ratios (SIRs) using the British Columbia population as a reference. A nested case-control analysis assessed the effects of paternal cumulative exposure and windows of exposure on the risk of developing cancer in the offspring. We identified 40 cases of cancer during 259,919 person-years of follow-up. The all-cancer SIR was 1.0 [95% confidence interval (CI), 0.7-1.4]; the SIR for leukemia was 1.0 (CI, 0.5-1.8); and the SIR for brain cancer was 1.3 (CI, 0.6-2.5). The nested case-control analysis showed slightly increased risks in the highest categories of chlorophenol exposure, although none was statistically significant. Our analyses provide little evidence to support a relationship between the risk of childhood cancer and paternal occupational exposure to chlorophenate fungicides in British Columbian sawmills.

Polymorphisms of the IL-4, TNF-alpha, and Fcepsilon RIbeta genes and the risk of allergic disorders in at-risk infants.

Polymorphisms in the TNF-alpha (A-308G), IL-4 (C-589T), and Fcalpha RIbeta (E237G) genes have been associated with asthma and related phenotypes. To determine the predictive value of these polymorphisms we have assessed their relative risk (RR) for the development of atopy, asthma, and rhinitis in a high-risk infant population that is being followed longitudinally from birth. DNA was extracted and genotyped for 373 infants and 572 parents for each polymorphism. Phenotypic data were collected for atopy and allergic diseases in the infants at 12 mo of age. The prevalence of these phenotypes in the 281 white infants was compared in each genotypic group. There were no differences in the prevalence of any phenotype between genotypes of the TNF-alpha and Fcalpha RIbeta polymorphisms. However, we found that the IL4-589*T allele was associated with "probable" asthma (RR = 4.1) and that homozygotes for the IL4-589*T allele had an increased risk for the development of rhinitis (RR = 2.4). Using the transmission disequilibrium test, an association of IL4-589*T with atopy was found. We conclude that IL-4-589*T, but not TNF-alpha-308*2 or Fcalpha RIbeta*G, is a risk factor for the development of atopy, asthma, and rhinitis by 12 mo of age.

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.

Umbilical cord blood mononuclear cell proliferative response to house dust mite does not predict the development of allergic rhinitis and asthma.

BACKGROUND: Cord blood mononuclear cells (CBMNCs) have been found to proliferate when stimulated with food or inhalant allergens. The significance of this finding is not known. OBJECTIVES: We sought to determine the factors associated with proliferation of CBMNCs when stimulated with house dust mite (HDM) allergen and to determine whether proliferation of CBMNCs is associated with subsequent development of HDM sensitization and development of allergic rhinitis and asthma. METHODS: Cord blood was taken from infants at high risk for having asthma and allergic diseases who were recruited for a primary prevention study in which infants were randomized into the intervention or the control group. CBMNCs were stimulated with HDM allergen and PHA as a positive control. Infants were assessed at 12 and 24 months for health outcome. RESULTS: When stimulated with HDM allergen, 29.7% of infants had a stimulation index (SI) of 2 or greater. There were no differences in the levels of cord blood IgE and cotinine, maternal smoking, immediate skin test reactivity, maternal IgE, and maternal exposure to HDM allergen between those with an SI of 2 or greater and those with an SI of less than 2. Infants with an SI of less than 2 had a significantly higher proportion of mothers with a history of asthma. No differences in the incidence of "asthma" and rhinitis without cold at 12 months and cumulative prevalence at 24 months were seen between the 2 groups. None of the infants had skin test reactions to HDM allergen. CONCLUSION: The negative association between HDM allergen-induced proliferation of CBMNCs and maternal mite allergen exposure and health outcomes at 12 and 24 months raises the issue of the significance of CBMNC proliferation.

Breast-feeding and environmental tobacco smoke exposure.

BACKGROUND: Exposure to environmental tobacco smoke is associated with adverse effects in infants and children. OBJECTIVE: To explore whether an increase in urinary cotinine fumarate level is caused by ingested nicotine and cotinine in breast-feeding infants. METHODS: We studied newborns at risk for developing asthma and allergies based on a strong family history. We measured urinary cotinine levels in the infants as a measure of environmental tobacco smoke exposure and cotinine levels in the breast milk of breast-feeding mothers. RESULTS: Of 507 infants, urinary cotinine levels during the first 2 weeks of life were significantly increased in infants whose mothers smoked. Breast-fed infants had higher cotinine levels than non-breast-fed infants, but this was statistically significant (P<.05) only if mothers smoked. Urinary cotinine levels were 5 times higher in breast-fed infants whose mothers smoked than in those whose mothers smoked but did not breast-feed. CONCLUSIONS: Mothers should be encouraged to not smoke, and parents must be advised of the potential respiratory and systemic risks of environmental tobacco smoke exposure to their child, including the potential for future addiction to smoking.

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.

Work-related mortality among older farmers in Canada.

OBJECTIVE: To describe the frequency and circumstances of work-related, fatal injuries among older farmers in Canada (1991 to 1995). DESIGN: Descriptive, epidemiologic analysis of data from the Canadian Agricultural Injury Surveillance Program. SETTING: Canada. PARTICIPANTS: Farmers aged 60 and older who died from work-related injuries from 1991 through 1995. METHOD: Age-adjusted mortality rates were calculated using the Canadian farm population as a standard for people involved, mechanism of injury, and place and time of injury. MAIN FINDINGS: The 183 work-related fatalities observed produced an overall mortality rate of 32.8 per 100,000 population per year. Higher fatality rates were observed in Quebec and the Atlantic Provinces. Almost all of those who died (98%) were men. Farm owner-operators accounted for 82.8% of the deaths (where the relationship of the person to the farm owner was reported). Leading mechanisms of fatal injury included tractor rollovers, being struck or crushed by objects, and being run over by machinery. Many older farmers appeared to be working alone at the time of injury. CONCLUSIONS: The data suggest that older farmers died while performing tasks common to general farm work, that most were owner-operators, and that many were working alone at the time of death. Innovative ways to reduce work-related injuries in this population must be found.

Opportunities for a broader understanding of work and health: multiple uses of an occupational cohort database.

Occupational cohort studies conducted to study cancer incidence and mortality require extensive data gathering about workers' job histories, exposures, and health outcomes. Although this process is expensive, the database created can be looked upon as a resource for broad investigations of the relationship between work and health. This paper presents the example of a retrospective cohort study which began in the traditional way, examining the link between a specific pesticide exposure and mortality and cancer incidence. The cohort register has since been used to investigate whether infertility, adverse reproductive outcomes, and childhood cancers might be associated with this exposure. It is also being used as the basis for studying other sawmill exposures including noise and wood dust as well as socioeconomic factors including job strain, job mobility, unemployment, and retraining. This approach allows both the efficient use of occupational cohorts as well as providing the opportunity for investigators to develop a more comprehensive perspective on the determinants of the health status of workers and their families.