Johny Kongerud

Breastfeeding, maternal smoking and lower respiratory tract infections

The objective of the study was to assess the relationship between breastfeeding and lower respiratory tract infections (LRTIs) during the first year of life, with special reference to maternal smoking. A cohort of 3,754 children born in 1992-1993 in the City of Oslo, Norway was recruited and data were collected at birth, 6 and 12 months of age. Complete information was obtained from 3,238 children (follow-up rate 86%). The main outcome was an episode of a LRTI, such as pneumonia, bronchitis or bronchiolitis, based on a self-administered questionnaire addressed to parents when the child was 6 and 12 months old. The outcome was specified as physician-diagnosed. In logistic regression analysis adjusting for confounding, maternal smoking increased the risk of LRTIs in children breastfed for 0-6 months (odds ratio (AOR) 1.7; 95% confidence interval (95% CI) 1.2-2.4), but not essentially when the child was breastfed for more than 6 months (AOR 1.1; 95% CI 0.7-1.6). Short-term breastfeeding (0-6 months) and no maternal smoking was related to an adjusted AOR of LRTIs of 1.3 (95% CI 1.0-1.7), and short-term breastfeeding combined with maternal smoking was related to an adjusted AOR of 2.2 (95% CI 1.6-3.1), as compared with long-term breastfeeding and no maternal smoking. The present study indicates a protective effect of long-term breastfeeding on the risk of lower respiratory tract infection during the first year of life. The results suggest that the protective effect is strongest in children exposed to environmental tobacco smoke.

Increased risk of heart valve regurgitation after mediastinal radiation for Hodgkin's disease: an echocardiographic study.

OBJECTIVE: To assess by echocardiography the occurrence and degree of late cardiac sequelae after treatment for Hodgkins disease by radiation and chemotherapy. PATIENTS AND METHODS: In Norway from 1980 to 1988, 129 patients < 50 years old with Hodgkins disease had curative treatment with mediastinal radiation, with or without chemotherapy. 116 (90%) of these patients (mean (SD) age 37 (7) years, 67 males) were examined by echocardiography 5-13 years after treatment. 40 healthy individuals (mean (SD) age 40 (11), 20 males) were examined as controls. All those examined were in regular sinus rhythm. RESULTS: Grade > 1 (scale 0-3) aortic and/or mitral valvar regurgitation was found in 24% of the patients (15% aortic, 7% mitral, and 2% aortic+mitral), affecting 46% of the females v 16% of the males (P < 0.001). Female gender was a significant risk factor for aortic and mitral regurgitation (odds ratio 4.7, 95% confidence interval 2.0 to 11.2), whereas age, period of follow up, radiation dose, and chemotherapy were not. Thickened pericardium was diagnosed in 15% of the patients. No risk factors were identified. No cases of pericardial thickening or valvar regurgitation grade > 1 were recorded in the control group. Mean values for measured and calculated indices of systolic and diastolic function were within the normal range for patients and controls. The patients had reduced E/A ratio compared with the healthy controls (E/A 1.1 v 2.0, P < 0.001). CONCLUSIONS: Abnormal left sided valvar regurgitation was detected in one fourth of the patients, affecting the aortic valve in more than half of the cases. Females had an increased risk of valvar regurgitation. Echocardiographic screening after high-dose mediastinal radiation is recommended.

Aluminium potroom asthma: the Norwegian experience

Work-related asthma in aluminium potroom workers, is reviewed and discussed, mainly on the basis of own investigations. The occurrence of work-related asthma has been shown to be associated with the duration of potroom employment, although the prevalence of asthmatic symptoms is not significantly different from that of the general population. Typical manifestations of occupational asthma are described in potroom workers, and a close relationship between the levels of fluoride exposure and work-related asthmatic symptoms has been observed. The existence of occupational asthma in aluminium potroom workers has been confirmed by characteristic patterns of repeated peak flow measurements, supported by changes in methacholine responsiveness in workers with suspected work-related asthma. However, no immunological test is available to establish the diagnosis. Methacholine challenge appears to be inappropriate for screening aluminium potroom workers in order to detect work-related asthma. Current smoking, but not self-reported allergy, is a risk factor for potroom asthma. A family history of asthma and previous occupational exposure may have some effect on the risk of developing symptoms. The prognosis of potroom asthma seems to depend on early replacement to unexposed work. The pathogenetic mechanisms are unknown, although some studies indirectly imply a hypersensitivity reaction. Future studies involving specific bronchial challenge appear to be necessary to find the causal agent(s) of aluminium potroom asthma.

The role of passive smoking in the development of bronchial obstruction during the first 2 years of life

We assessed the effect of exposure to environmental tobacco smoke on the risk of developing bronchial obstruction in a 2‐year cohort study of 3,754 children born in Oslo, Norway, during a period of 15 months in 1992–1993. We collected questionnaire information on the childs health and environmental exposures at birth and when the child was age 6 months (follow up rate = 95%), 12 months (92%), 18 months (92%), and 24 months (81%). The outcome of interest was defined as two or more episodes of bronchial obstruction or one obstruction lasting more than 1 month, and it was verified by a specialist group evaluating data from questionnaires, clinical examinations, and health records. The risk of bronchial obstruction was increased in children exposed to environmental tobacco smoke (cumulative incidence = 0.109) compared with unexposed children (0.071), with an adjusted odds ratio of 1.6 [95% confidence interval (CI) = 1.3–2.1]. The effect was seen for maternal smoking alone (odds ratio = 1.6; 95% CI = 1.0–2.6), paternal smoking alone (odds ratio = 1.5; 95% CI = 1.1–2.2), and both parents smoking (odds ratio = 1.5; 95% CI = 1.0–2.2). There was no clear exposure‐response pattern. The findings indicate that exposure to environmental tobacco smoke such as is experienced in Norwegian housing increases the risk of developing bronchial obstruction during the first 2 years of life.

Respiratory symptoms and ventilatory function in workers exposed to Portland cement dust

The healthy worker effect and incomplete exposure information have been problems in former studies regarding the association between exposure to Portland cement dust and respiratory effects. We included former workers and made an individual estimation of particle exposure to reduce the selection bias in this controlled cross-sectional study on the effects of cement dust exposure on respiratory symptoms and ventilatory function in long-term exposed Norwegian cement plant workers. A total of 119 workers from the largest cement plant in Norway and 50 workers from a nearby control plant, born 1918 to 1938, performed spirometry and gave information on respiratory symptoms in 1998 and 1999. The prevalence of symptoms and mean pulmonary function indices were similar for exposed workers and controls. There was no dose–response-related increase in symptoms or decrease in lung function indices. The estimated power to detect a true difference between forced expiratory volume in one second (FEV1) in the two groups of 0.3l was 0.90, assuming 95% significance level. The prevalence of chronic obstructive pulmonary disease was 14.3% in the exposed group and 14.0% among the controls. These findings do not support the hypothesis that cement dust exposure has a negative impact on lung function or gives an increase in respiratory symptoms.

Cumulative exposure to dust causes accelerated decline in lung function in tunnel workers

OBJECTIVES To examine whether underground construction workers exposed to tunnelling pollutants over a follow up period of 8 years have an increased risk of decline in lung function and respiratory symptoms compared with reference subjects working outside the tunnel atmosphere, and relate the findings to job groups and cumulative exposure to dust and gases. METHODS 96 Tunnel workers and a reference group of 249 other heavy construction workers were examined in 1991 and re-examined in 1999. Exposure measurements were carried out to estimate personal cumulative exposure to total dust, respirable dust, α-quartz, oil mist, and nitrogen dioxide. The subjects answered a questionnaire on respiratory symptoms and smoking habits, performed spirometry, and had chest radiographs taken. Radiological signs of silicosis were evaluated (International Labour Organisation (ILO) classification). Atopy was determined by a multiple radioallergosorbent test (RAST). RESULTS The mean exposure to respirable dust and α-quartz in tunnel workers varied from 1.2–3.6 mg/m3 (respirable dust) and 0.019–0.044 mg/m3 (α-quartz) depending on job task performed. Decrease in forced expiratory volume in 1 second (FEV1) was associated with cumulative exposure to respirable dust (p<0.001) and α-quartz (p=0.02). The multiple regression model predicted that in a worker 40 years of age, the annual decrease in FEV1 would be 25 ml in a non-exposed non-smoker, 35 ml in a non-exposed smoker, and 50–63 ml in a non-smoking tunnel worker (depending on job). Compared with the reference group the odds ratio for the occurrence of new respiratory symptoms during the follow up period was increased in the tunnel workers and associated with cumulative exposure to respirable dust. CONCLUSIONS Cumulative exposures to respirable dust and α-quartz are the most important risk factors for airflow limitation in underground heavy construction workers, and cumulative exposure to respirable dust is the most important risk factor for respiratory symptoms. The finding of accelerated decline in lung function in tunnel workers suggests that better control of exposures is needed.

Increased risk of obstructive pulmonary disease in tunnel workers

BACKGROUND Tunnel workers are exposed to gases and particles from blasting and diesel exhausts. The aim of this study was to assess the occurrence of respiratory symptoms and airflow limitation in tunnel workers and to relate these findings to years of exposure. METHODS Two hundred and twelve tunnel workers and a reference group of 205 other heavy construction workers participated in a cross sectional investigation. Exposure measurements were carried out to demonstrate the difference in exposure between the two occupational groups. Spirometric tests and a questionnaire on respiratory symptoms and smoking habits were applied. Atopy was determined by a multiple radioallergosorbent test (RAST). Radiological signs of silicosis were evaluated. Respiratory symptoms and lung function were studied in relation to years of exposure and adjusted for smoking habits and atopy. RESULTS Compared with the reference subjects the tunnel workers had a significant decrease in forced vital capacity (FVC) % predicted and forced expiratory volume in one second (FEV1) % predicted when related to years of exposure. Adjusted FEV1 decreased by 17 ml for each year of tunnel work exposure compared with 0.5 ml in outdoor heavy construction workers. The tunnel workers also reported significantly higher occurrence of respiratory symptoms. The prevalence of chronic obstructive pulmonary disease (COPD) was 14% in the tunnel workers compared with 8% in the reference subjects. CONCLUSION Exposure to dust and gases from diesel exhaust, blasting, drilling and rock transport in tunnel work enhances the risk for accelerated decline in FEV1, respiratory symptoms, and COPD in tunnel workers compared with other heavy construction workers.

Exposure to hydrogen fluoride: an experimental study in humans of concentrations of fluoride in plasma, symptoms, and lung function.

OBJECTIVES: To study the absorption of inhaled hydrogen fluoride (HF) by measuring plasma fluorides and HF concentrations in the breathing zone during exposure to HF. A possible dose-effect relation was investigated by following airway symptoms and lung function-that is, forced expiratory volume in one second (FEV1) and forced vital capacity (FVC)-during and after exposure to HF. METHODS: 20 healthy, male volunteers were exposed for one hour to constant HF concentrations that ranged from 0.2 to 5.2 mg/m3; these concentrations are known to occur among potroom workers in the primary aluminium industry. Plasma fluorides were analysed before, during, and after exposure. Symptoms from the eyes and the upper and lower airways were registered and graded from 1 to 5 with a standardised questionnaire. RESULTS: The total symptom score was significantly increased at the end of exposure for all the subjects as a group (P < 0.01) and for the group exposed to HF below the present Norwegian standard for total fluorides 0.6 mg/m3 (P = 0.05). No change was detected in FEV15 although a significant decrease was found in FVC in the group exposed to fluorides below the hygienic standard (n = 9) and for the entire group (n = 23). Almost all the symptoms had disappeared four hours after the end of exposure. Symptom scores from the upper airways were significantly correlated with the HF concentration (r = 0.62, P = 0.002), the change in plasma fluoride concentration (delta C) (r = 0.51, P = 0.01), and the maximum plasma fluoride concentration (Cmax) (r = 0.42, P = 0.05). A significant correlation was also found between the total symptom score for airways and the HF concentration. CONCLUSIONS: The present study showed a strong relation between inhaled HF and concentrations of fluoride in plasma. Upper airway and eye symptoms occurred after one hour of exposure to HF even when below the Norwegian hygienic standard for fluorides.

Weight gain during the first year of life in relation to maternal smoking and breast feeding in Norway.

OBJECTIVE: To assess the weight gain during the first year of life in relation to maternal smoking during pregnancy and the duration of breastfeeding. DESIGN: This was a one year cohort study. SETTING: The city of Oslo, Norway. PARTICIPANTS: Altogether 3020 children born in Oslo in 1992-93. Children were divided into three groups as follows: 2208 born to non-smoking mothers, 451 to mothers who were light smokers (< 10 cigarettes per day), and 261 to mothers who were heavy smokers (> or = 10 cigarettes per day). MAIN RESULTS: The mean birth weights were 3616 g, 3526 g, and 3382 g and 1 year body weights were 10,056 g (gain 6440 g per year), 10,141 g (6615 g), and 10,158 g (6776 g) in children of non-smoking and light and heavy smoking mothers respectively. Cox regression analysis showed that children of heavy smokers were 2.0 (95% confidence interval, 1.7, 2.3) times and children of light smokers 1.3 (1.2, 1.5) times more likely to have stopped breast feeding during their first year of life compared with children whose mothers were non-smokers. Linear regression analysis, adjusting for confounders, showed that weight gain was slower in breast fed children than in those who were not breast fed (-38 g (-50, -27) per month of breast feeding). Compared with children of non-smokers, the adjusted weight gain was 147 g (40, 255) per year greater in children of light smokers and 184 g (44, 324) per year in children of heavy smokers. CONCLUSION: Children catch up any losses in birth weight due to maternal smoking, but some of the catch up effect is caused by a shorter duration of breast feeding in children of smoking mothers.

Relation between exposure to fluoride and bronchial responsiveness in aluminium potroom workers with work-related asthma-like symptoms.

BACKGROUND--The relation between plasma fluoride levels and bronchial responsiveness was investigated in a longitudinal study in aluminium potroom workers who reported work-related asthmatic symptoms. METHODS--From a cross-sectional respiratory survey, 26 men who reported work-related asthmatic symptoms on a validated questionnaire were selected for repeated measurements of bronchial responsiveness to methacholine. Regular analyses of plasma fluoride levels were performed. Exposure to fluoride and total particulates was assessed from routine surveillance of the workplace. Bronchial responsiveness was expressed as the dose-response slope of the line through the origin and last data point. RESULTS--A positive association was found between bronchial responsiveness and plasma fluoride levels, such that an increase in the plasma fluoride level of 10 ng/ml was associated with an increase in the dose-response slope by a factor of 1.11 (95% confidence interval 1.05 to 1.17). Plasma fluoride levels were associated with the total atmospheric fluoride concentration in mg/m3 (beta = 28.1), but not with total particulates in the environment. CONCLUSIONS--Bronchial responsiveness in aluminium potroom workers reporting work-related asthmatic symptoms appears to be related to plasma levels of fluoride. The underlying mechanism is, however, unknown.