Jing-qing Hang

A 20-year follow-up study on chronic respiratory effects of exposure to cotton dust.

In order to evaluate chronic effects of long-term exposure to cotton dust on respiratory health, and the role of dust and endotoxin, longitudinal changes in lung function and respiratory symptoms were observed prospectively from 1981 to 2001 in 447 cotton textile workers, along with 472 silk textile controls. The results from five surveys conducted over the 20-yr period are reported, including standardised questionnaires, pre- and post-shift spirometric measurements, work-area inhalable dust sample collections and airborne Gram-bacterial endotoxin analysis. Cotton workers had more persistent respiratory symptoms and greater annual declines in forced expiratory volume in one second (FEV1) and forced vital capacity as compared with silk workers. After exposure cessation, in the final 5-yr period, the rate of FEV1 decline tended to slow in nonsmoking males, but not in nonsmoking females. Workers who reported byssinotic symptoms more persistently suffered greater declines in FEV1. Chronic loss in lung function was more strongly associated with exposure to endotoxin than to dust. In conclusion, the current study suggests that long-term exposure to cotton dust, in which airborne endotoxin appears to play an important role, results in substantial adverse chronic respiratory effects.

In-home solid fuel use and cardiovascular disease: a cross-sectional analysis of the Shanghai Putuo study

BackgroundAlthough recent research evidence suggests an association between household air pollution from solid fuel use, such as coal or biomass, and cardiovascular events such as hypertension, little epidemiologic data are available concerning such exposure effects on cardiovascular endpoints other than hypertension. We explored the association between in-home solid fuel use and self-reported diagnoses of cardiovascular endpoints, such as hypertension, coronary heart disease (CHD), stroke, and diabetes.MethodsWe analyzed 14,068 Chinese adults, aged 18 years and older. Odds ratios (OR) and the corresponding 95% confidence intervals (CI) were estimated using logistic regression models for the risk of each outcome after adjusting for potential confounders.ResultsThe use of solid fuel in home was significantly associated with an increased risk for hypertension (OR 1.70, 95% CI 1.40 to 2.07), CHD (OR 2.58, 95% CI 1.53 to 4.32), and diabetes (OR 2.48, 95% CI 1.59 to 3.86), after adjusting for potential confounders. Compared with individuals in the lowest tertile of the duration of solid fuel exposure, those in the highest tertile of the duration of solid fuel exposure had an increased odds of hypertension (OR 1.73, 95% CI 1.45 to 2.06), stroke (OR 1.87, 95% CI 1.03 to 3.38), and diabetes (OR 3.18, 95% CI 2.11 to 4.78).ConclusionsOur data suggest that in-home solid fuel exposure maybe associated with increased risk for hypertension, CHD, stroke, and diabetes in the Chinese adult population. Further large-scale longitudinal studies are warranted to confirm these findings.

TLR4 Asp299Gly and Thr399Ile polymorphisms are very rare in the Chinese population.

Endotoxin is an important component of bio-aerosols that contribute to airway inflammation and airflow obstruction. Toll-like receptor 4 (TLR4) mediates the host response to bacterial lipopolysaccharide (LPS), and the Asp299Gly and Thr399Ile polymorphisms have been associated with the development of respiratory diseases. We hypothesized that TLR4 polymorphisms may be associated with a decline of lung function in cotton workers who were exposed continuously to endotoxin. We investigated these two polymorphisms in our 20-year longitudinal cohort of Han Chinese cotton and silk textile workers. The two polymorphisms were genotyped using TaqMan and PCR-restriction fragment length polymorphism methods. No homozygous or heterozygous variant genotypes of the Asp299Gly and Thr339Ile polymorphisms were detected in 491 samples of this population. Our results suggest that the TLR4 Asp299Gly and Thr339Ile polymorphisms are very rare in the Chinese population.

Chronic Lung Function Decline in Cotton Textile Workers: Roles of Historical and Recent Exposures to Endotoxin

Background Long-term occupational exposure to cotton dust that contains endotoxin is associated with chronic respiratory symptoms and excessive decline in forced expiratory volume in 1 sec (FEV1), but the mechanisms of endotoxin-related chronic airflow obstruction remain unclear. Objective In the current study, we examined temporal aspects of the exposure–response relationship between airborne endotoxin exposure, longitudinal change in FEV1, and respiratory symptoms in a cohort of Chinese cotton textile workers. Methods This prospective cohort study followed 447 cotton textile workers from 1981 to 2006.at approximately 5-year intervals. We used a generalized estimating equations approach to model FEV1 level and respiratory symptoms as a function of past exposure (cumulative exposure up to the start of the most recent 5-year survey interval) and cumulative exposure (within the most recent interval) to endotoxins, after adjusting for other covariates. Models were stratified by active versus retired work status and by years employed before the baseline survey (< 5 and ≥ 5 years). Results and conclusions Past exposure to endotoxin was associated with reduced FEV1 level among retired cotton workers. Among all cotton workers, past exposure was more strongly associated with reduced FEV1 for those hired < 5 years before baseline than for those who were hired ≥ 5 years after baseline. Recent endotoxin exposure was significantly associated with byssinosis, chronic bronchitis, and chronic cough.

Long-term effects of work cessation on respiratory health of textile workers: a 25-year follow-up study.

RATIONALE The degree to which chronic respiratory health effects caused by exposures to cotton dust and endotoxin is reversible after cessation of textile work is unknown. OBJECTIVES To investigate changes in lung function and respiratory symptoms after cessation of textile work and to determine whether past exposure to cotton dust and endotoxin or smoking history modify the associations. METHODS We performed a prospective cohort study consisting of 447 cotton textile workers exposed to cotton dust and 472 unexposed silk textile workers, with a 25-year follow-up. Spirometry testing and respiratory questionnaires were conducted at 5-year intervals. Generalized estimated equations were used to model the average 5-year change in FEV(1) and odds ratios of respiratory symptom prevalence. MEASUREMENTS AND MAIN RESULTS Years since cessation of textile work was positively associated with 11.3 ml/yr and 5.6 ml/yr gains in 5-year FEV(1) change for cotton and silk workers, respectively. Among male cotton workers, smokers gained more FEV(1) per year after cessation of exposure than did nonsmokers, and the risk of symptoms of chronic bronchitis and byssinosis was larger for smoking than for nonsmoking male cotton workers. CONCLUSIONS Cessation of textile work was significantly associated with improvement in lung function and respiratory symptoms. The positive effect of work cessation was greater for cotton workers than for silk workers. For cotton workers, the improvement in lung function loss after cessation of textile work was greater among smokers, but no differences were observed for silk workers.

The changing epidemiology of asthma in Shanghai, China

Abstract Objective: To investigate the prevalence of bronchial asthma in Putuo district in Shanghai, China. Methods: Cross-sectional, community-based study was performed with random sampling of a district with a population of one million. The subjects were residents of the district and six or more years of age. Questionnaire and spirometry were completed in all subjects. Asthma was defined as physician-diagnosed asthma. The results were compared with the asthma study of 40 000 population completed by the same team in Pudong area of Shanghai in 1997. Results: We surveyed 27 042 participants. The prevalence of asthma was 1.8% (488/27 042), much higher than the 0.41% (163/40 000) found in the 1997 survey in Pudong area of Shanghai. In subjects with asthma, current smoking, obesity, gender distribution and the combination of allergic diseases between the two studies had no differences. The most prominent causes of asthma exacerbation were cold air, respiratory infection and dust inhalation. Pulmonary function for 428 asthma patients in Putuo survey was analyzed: 228 (53.3%) patients had FEV1%pred lower than 80%. Asthmatics older than 65 years had lower FEV1%pred than other age groups (p < 0.01). Conclusions: The prevalence of physician-diagnosed asthma in urban of Shanghai has increased in recent years. The most important causes of asthma exacerbations were cold air, respiratory infection and dust exposure. The proportion of individuals with decreased percent predicted forced expiratory volume of first second increased with age. Strengthening the prevention and treatment of asthma, especially in children with asthma, may decrease the health burden of asthma in the urban Chinese population.

TNF Polymorphisms Modify Endotoxin Exposure Associated Longitudinal Lung Function Decline

Objectives: Endotoxin exposure induces airway inflammation, hyper-responsiveness and higher expression of tumour necrosis factor (TNF). This study was conducted to investigate whether TNF polymorphisms modify the effect of endotoxin exposure on chronic declines in lung function. Methods: Associations between TNF and LTA polymorphisms, endotoxin exposure and lung function were analysed in 263 cotton workers and 230 silk workers as a reference group, who were prospectively followed for 20 years. Multiple linear regression models were used to assess the association, with adjustment for smoking and other covariates. Results: Endotoxin exposure was associated with faster lung function decline among genotypes associated with higher TNF expression levels, with estimates of annual FEV1 change in relation to endotoxin exposure of –2.9 ml and –6.8 ml in the G/G and G/A+AA genotypes, respectively, for the TNF polymorphism; and –2.0 ml, –4.0 ml and –3.6 ml in A/A, A/G and G/G genotypes, respectively, for the LTA polymorphism. When joint effects of endotoxin exposure and smoking were considered, the effect modification of TNF and LTA polymorphisms was prominent in never smokers. Conclusions:TNF and LTA polymorphisms may modify the association between occupational endotoxin exposure and longitudinal lung function decline, which was more clearly observed in never smokers.

Household solid fuel use and pulmonary function in an urban population in Shanghai, China

Objectives We examined the association between household solid fuel exposure and lung function in a densely populated district in urban Shanghai, China. Methods Spirometry was performed in 12 506 subjects, aged 18 and over, residing in the Putuo District in Shanghai, China, in a cross-sectional survey. Exposure to solid fuel use at home was assessed by an administered questionnaire, estimating duration and total amount of solid fuel use at home during the lifetime. Results After adjusting for confounders, the subjects with exposure to household solid fuel had a 1.3% (95% CI 0.57 to 2.02) decrease in forced expiratory volume in 1 s (FEV1) percent predicted and 3.5% (95% CI 2.74 to 4.18) decrease in forced vital capacity (FVC) percent predicted, respectively. Trends towards decreased pulmonary function measures were seen for longer duration and greater amount of household fuel use at home, in the highest compared with lowest tertile (p values for trend <0.001). We observed decrease in FEV1 and FVC percent predicted across increase in tertile of body mass index in association with in-home solid fuel exposure. Conclusions This study suggests that in-home solid fuel exposure is associated with reduced lung function in an urban population.

Endotoxin and gender modify lung function recovery after occupational organic dust exposure: a 30-year study

Objectives The purpose of this study is to determine the trajectory of lung function change after exposure cessation to occupational organic dust exposure, and to identify factors that modify improvement. Methods The Shanghai Textile Worker Study is a longitudinal study of 447 cotton workers exposed to endotoxin-containing dust and 472 silk workers exposed to non-endotoxin-containing dust. Spirometry was performed at 5-year intervals. Air sampling was performed to estimate individual cumulative exposures. The effect of work cessation on forced expiratory volume in 1 s (FEV1) was modelled using generalised additive mixed effects models to identify the trajectory of FEV1 recovery. Linear mixed effects models incorporating interaction terms were used to identify modifiers of FEV1 recovery. Loss to follow-up was accounted for with inverse probability of censoring weights. Results 74.2% of the original cohort still alive participated in 2011. Generalised additive mixed models identified a non-linear improvement in FEV1 for all workers after exposure cessation, with no plateau noted 25 years after retirement. Linear mixed effects models incorporating interaction terms identified prior endotoxin exposure (p=0.01) and male gender (p=0.002) as risk factors for impaired FEV1 improvement after exposure cessation. After adjusting for gender, smoking delayed the onset of FEV1 gain but did not affect the overall magnitude of change. Conclusions Lung function improvement after cessation of exposure to organic dust is sustained. Endotoxin exposure and male gender are risk factors for less FEV1 improvement.

Cotton dust, endotoxin and cancer mortality among the Shanghai textile workers cohort: a 30-year analysis

Background Although occupational exposure to cotton dust and endotoxin is associated with adverse respiratory health, associations with cancer are unclear. We investigated cancer mortality in relation to cotton dust and endotoxin exposure in the Shanghai textile workers cohort. Methods We followed 444 cotton textile and a reference group of 467 unexposed silk workers for 30 years (26 777 person-years). HRs for all cancers combined (with and without lung cancer) and gastrointestinal cancer were estimated in Cox regression models as functions of cotton textile work and categories of cumulative exposure (low, medium, high), after adjustment for covariates including pack-years smoked. Different lag years accounted for disease latency. Results Risks of mortality from gastrointestinal cancers and all cancers combined, with the exclusion of lung cancer, were increased in cotton workers relative to silk workers. When stratified by category of cumulative cotton exposure, in general, risks were greatest for 20-year lagged medium exposure (all cancers HR=2.7 (95% CI 1.4 to 5.2); cancer excluding lung cancer HR=3.4 (1.7–7.0); gastrointestinal cancer HR=4.1 (1.8–9.7)). With the exclusion of lung cancer, risks of cancer were more pronounced. When stratified by category of cumulative endotoxin exposure, consistent associations were not observed for all cancers combined. However, excluding lung cancer, medium endotoxin exposure was associated with all cancers and gastrointestinal cancer in almost all lag models. Conclusions Cotton dust may be associated with cancer mortality, especially gastrointestinal cancer, and endotoxin may play a causative role. Findings also indirectly support a protective effect of endotoxin on lung cancer.