Patrick A. Hessel

Silica, silicosis, and lung cancer: a response to a recent working group report.

The relationship between crystalline silica and lung cancer has been the subject of many recent publications, conferences, and regulatory considerations. An influential, international body has determined that there was sufficient evidence to conclude that quartz and cristobalite are carcinogenic in humans. The present authors believe that the results of these studies are inconsistent and, when positive, only weakly positive. Other, methodologically strong, negative studies have not been considered, and several studies viewed as providing evidence supporting the carcinogenicity of silica have significant methodological weaknesses. Silica is not directly genotoxic and is a pulmonary carcinogen only in the rat, a species that seems to be inappropriate for assessing particulate carcinogenesis in humans. Data on humans demonstrate a lack of association between lung cancer and exposure to crystalline silica. Exposure-response relationships have generally not been found. Studies in which silicotic patients were not identified from compensation registries and in which enumeration was complete did not support a causal association between silicosis and lung cancer, which further argues against the carcinogenicity of crystalline silica.

Evaluation of an Education Program for Elementary School Children with Asthma

To evaluate the effectiveness of a comprehensive asthma management education program for 7- to 12-year-old children with asthma, entitled Roaring Adventures of Puff (RAP), 18 elementary schools in Edmonton were randomized to intervention and control groups. Participating in the program were 76 students with asthma in the intervention schools and 86 in the control schools. Children in the intervention schools had statistically significant improvements in unscheduled doctor visits, missed school days, moderate-to-severe parent rating of severity, severity of shortness of breath, limitations in the kind of play, and correct use of medications. Unscheduled doctor visits and missed school days were the only significant improvements in the control group; however, improvements were about half that of the intervention group. The results showed that a comprehensive, school-based asthma education program is feasible and improves outcomes.

MALE PARTICIPATION IN FAMILY PLANNING: RESULTS FROM A QUALITATIVE STUDY IN MPIGI DISTRICT, UGANDA

The aim of this study was to determine mens perceptions about family planning and how they participate or wish to participate in family planning activities in Mpigi District, central Uganda. Four focus group discussions were conducted with married men and with family planning providers from both the government and private sector. In addition, seven key informants were interviewed using a semi-structured interview guide. The results indicate that men have limited knowledge about family planning, that family planning services do not adequately meet the needs of men, and that spousal communication about family planning issues is generally poor. However, almost all men approved of modern family planning and expressed great interest in participating. The positive change of the beliefs and attitudes of men towards family planning in the past years has not been recognized by family planning programme managers, since available services are not in line with current public attitudes. A more couple-oriented approach to family planning is needed. Measures could include, for example, recruiting males as family planning providers, offering more family planning counselling for couples, and promoting female-oriented methods with men and vice versa.

Silica exposure, silicosis, and lung cancer: a necropsy study

Recent studies of the association between lung cancer and silicosis and silica dust have been inconclusive; some showing positive association and some showing none. The present study matched 231 cases of lung cancer with 318 controls by year of birth. Subjects were selected from the necropsy records of the National Centre for Occupational Health. Data on intensity and duration of exposure to silica dust were obtained from personnel records. Presence or absence of lung cancer and the presence and severity of silicosis of the parenchyma, pleura, and hilar glands were documented from necropsy reports. Smoking data were abstracted from records of routine examinations. No case-control differences were noted for any of the exposure indicators including cumulative dust exposure, total dusty shifts, weighted average intensity of exposure, total underground shifts, and shifts in high dust. Similarly, no association was found between lung cancer and the presence or severity of silicosis and any site. Stratified analyses showed neither significant nor suggestive trends when case-control comparisons for silicosis were examined by level of dust exposure or smoking. Reasons for disparity between these results and those of some other studies may include concomitant exposures to radon daughters, asbestos, diesel emissions, and cigarette smoking; idiosyncracies of the compensation process; and the possibility of a threshold in the relation(s).

Hearing loss among construction workers in Edmonton, Alberta, Canada

Hearing acuity among electricians, plumbers and pipefitters, and boilermakers with > or = 20 years of union membership was compared with that of telephone workers. Automated pure tone audiometry was performed and a questionnaire was administered. Most construction workers were exposed to occupational noise and wore hearing protection. Median thresholds for electricians and telephone workers were comparable. Thresholds of plumbers and pipefitters were higher but comparable to expected values. Boilermakers had high levels of hearing loss. Thresholds at 4000 Hz among older workers were similar for all groups and were above expected values, suggesting a cohort effect. Audiometric screening seems to be warranted for some construction workers.

A nested case-control study of prostate cancer and atrazine exposure.

Elevated prostate cancer incidence was found at a plant producing atrazine that had an intensive prostate screening program. This study tested the relationship among atrazine exposure, prostate cancer, and the screening program. Twelve cases and 130 control subjects were selected from the original cohort. Prostate screening and occupational histories were abstracted from company records and atrazine exposures were estimated. Hire date was comparable for cases and control subjects. Nearly half of the control subjects and no cases left before the prostate-specific antigen (PSA) screening program. Cases had more PSA tests than control subjects (odds ratio for ≥1 test, 8.54; 95% confidence interval, 1.69–82.20). There was no association between atrazine exposure and prostate cancer when those with ≥1 test were compared. There was no evidence for an association between atrazine and prostate cancer.

Factors associated with poor asthma control in children aged five to 13 years

BACKGROUND Most children with asthma should be able to achieve acceptable control. However, are there differences between those with acceptable and poor control, and if so, how can health care approaches be modified accordingly? OBJECTIVE To examine the characteristics of elementary school children aged five to 13 years with acceptable and poor levels of asthma control. METHODS The present cross-sectional study of children with asthma used five indicators of control, as outlined by the Canadian Asthma Consensus Report, to categorize acceptable and poor asthma control. RESULTS Of 153 children, 115 (75%) were rated as having poorly controlled asthma. Of those with poor control, 65 (64%) children were currently using inhaled corticosteroids, and 65% of those reported using inhaled corticosteroids daily versus as needed. Fifty-one per cent of the children with poorly controlled asthma had exposure to tobacco smoke, whereas 79% of the children with asthma under acceptable control were from households with no smokers (P=0.002). The poor control group also had significantly worse parental perceptions of the psychosocial impact of asthma on their child. No significant difference was found in the percentage of those who had written action plans in the poor control group (28%) compared with the acceptable control group (26%), and similar percentages in each group stated that they used the plans. CONCLUSIONS Despite the high use of inhaled corticosteroids, the majority of children had poorly controlled asthma. The poor control group had more exposure to tobacco smoke and a worse psychosocial impact due to asthma. Few children had past asthma education and action plans, suggesting that there is a need to improve access to and tools for education.

Respiratory Consequences of Exposure to Wood Dust and Formaldehyde of Workers Manufacturing Oriented Strand Board

A cross-sectional study was performed at a plant in which 99 workers were employed in the manufacture of oriented strand board. This group was compared with 165 unexposed workers from the petroleum industry. Both groups were assessed, using a questionnaire, spirometry, and skin prick tests to common environmental antigens. Environmental studies showed a low dust level of 0.27 mg/m3, consisting of particles of a mass median aerodynamic equivalent diameter of 2.5 microns. There were variable concentrations of formaldehyde, up to 0.27 ppm. A significant difference between the oriented strand board workers and oil field workers was noted for the forced expiratory volume in 1 s/forced vital capacity ratio, without significant differences in either the forced expiratory volume in 1 s or the forced vital capacity. Oriented strand board workers who were current smokers were three times as likely to have a forced expiratory volume in 1 s/forced vital capacity ratio of less than 75% of that found in the currently smoking oil field workers. Significant reductions in forced expiratory volume in 1 s (p = .044) and forced vital capacity (p = .022) in oriented strand board workers were noted across the work shift. The oriented strand board workers complained of self-reported asthma and of lower respiratory tract symptoms significantly more frequently than did oil workers for all of the symptoms examined. The prevalence of atopy was not different in the two groups. Lung function was significantly better in oriented strand board workers who had no symptoms, compared with oriented strand board workers who were symptomatic.(ABSTRACT TRUNCATED AT 250 WORDS)

The epidemiology of childhood asthma in Red Deer and Medicine Hat, Alberta

OBJECTIVES To document the prevalence of asthma among school-aged children in two Alberta communities, to understand host and indoor environmental factors associated with asthma, and to compare these factors between the two communities. DESIGN A cross-sectional study with a nested, case-control follow-up. SETTING Red Deer and Medicine Hat, Alberta. PATIENTS AND METHODS Questionnaires were sent to families of children aged five to 19 years in Red Deer (n=5292) and Medicine Hat (n=5372) to identify children with current asthma. A random sample of 592 children with current asthma and 443 with no history of asthma constituted a case-control population; they were followed up by telephone to obtain responses to the European Respiratory Health Survey and, in children with current asthma, the Pediatric Quality of Life Questionnaire. RESULTS Cross-sectional response rates were 84% and 73% for Red Deer and Medicine Hat, respectively. The prevalence of asthma was higher in Medicine Hat (17.0%) than in Red Deer (12.8%). In the follow-up study, factors associated with the presence of asthma were parental asthma or allergies, number of siblings, presence of cats, serious respiratory illnesses before five years of age, sex, age, presence of mould and/or mildew and use of a gas cooking stove. The presence of mould and/or mildew was a significant risk factor in Red Deer but not in Medicine Hat. CONCLUSIONS Asthma prevalence among school children in Red Deer was consistent with recently published Canadian data; the prevalence in Medicine Hat was higher than expected, especially given the low relative humidity. Risk factor data are consistent with other studies in that parental asthma, especially maternal asthma, was a significant predictor of childhood asthma. Cats in the house (both communities) and environmental tobacco smoke (Medicine Hat only) were significantly less common among children with asthma, suggesting that preventive actions may have been taken in the homes of some children with asthma.

Pulmonary effects of simultaneous exposures to MDI formaldehyde and wood dust on workers in an oriented strand board plant

A study was undertaken in a plant producing oriented strand board (OSB) from aspen and balsam wood, bonded by methylene diisocyanate (MDI) and phenol formaldehyde. A group of 127 production workers in the plant was compared to 165 oil workers from the same geographic area. Measurements of MDI ranged from 6 to 33 μg/m3 (0.001–0.003 ppm), of respirable dust ranged from 0.05 to 0.5 mg/m3, and of formaldehyde were 0.05 ppm or less. The ratio of forced expiratory volume in 1 second to forced vital capacity (FEV1/FVC) was significantly lower among the OSB workers compared to the oil workers, and this was more pronounced for ex-smokers and current smokers. A number of respiratory symptoms suggestive of airway reactivity were significantly more common among the OSB workers. It was known that changes to reduce worker exposure had been made in the plant before the study, and it is unclear whether the health effects documented were the result of these low levels or if previous, probably higher levels were responsible.