Respiratory health and dust levels in cottonseed mills

Respiratory effects of bioaerosols: exposure-response study among salmon-processing workers

OBJECTIVES

The aim of the study was to determine exposure-response relationships in salmon-processing workers.

METHODS

Cross-shift FEV1, acute respiratory symptoms, and exposure to total protein, parvalbumin and endotoxin were main variables measured during one workweek. Exposure-response relationships were analyzed by Generalized Estimation Equations of cross-week data and by multiple regressions of day-to-day data.

RESULTS

Exposure levels were higher in those workers who reported use of water hose. GEE showed negative coefficients for interaction between TP exposure and time (days) on cross-week change of FEV1. Multiple regressions showed significant associations between TP levels and cross-shift change of FEV1 and symptoms (cough, chest tightness) only for Monday shifts.

CONCLUSIONS

A tolerance effect during the course of a workweek is suggested. Use of water hose is a risk process with regard to the liberation of measured components of bioaerosols.

Natural history and risk factors of early respiratory responses to exposure to cotton dust in newly exposed workers

OBJECTIVE

A prospective study of newly exposed cotton workers was performed to investigate the natural history of respiratory symptoms and lung function changes.

METHODS

A total of 157 workers naive to cotton dust exposure were investigated by questionnaire, spirometry, and skin tests. They were examined before employment (baseline) and at the end of the first week, and the first, third, sixth, and 12th month after starting work. Acute airway response was defined as either a cross-first-shift or a cross-week fall in forced expiratory volume in one second (FEV1). The longitudinal change of lung function over the year was also calculated. Five hundred seventy-two personal dust sampling and 191 endotoxin measurements were performed to assess the exposure.

RESULTS

Forty percent of workers reported work-related symptoms in the first week of the study. Smoking, endotoxin, and dust concentrations were risk factors for all work-related symptoms. Acute airway responses were witnessed after immediate exposure. Female status was the only factor found to be predictive of acute airway response. The mean longitudinal fall in FEV1 at 1 year was 65.5 mL (standard error = 37.2). Age, early respiratory symptoms, and early fall in cross-week FEV1 were found to predict the 12-month fall in FEV1. Cross-first-shift and cross-week falls in FEV1 reduced in magnitude during the course of the study.

CONCLUSIONS

This study of workers naive to cotton dust exposure has demonstrated that respiratory symptoms and acute airway responses develop early following first exposure, and a tolerance effect develops in those workers with the continued exposure. Current smoking and increasing exposure predicts the development of work-related lower respiratory tract symptoms, while early symptoms and acute airway changes across the working week predict the longitudinal loss of lung function at 1 year.

Across-shift lung function variation in cottonseed oil workers

BACKGROUND

The effects of cotton dust on pulmonary function among workers employed in cotton-spinning mills are well known. However, little data exist on the prevalence of this disorder in 'non-textile' cotton industries, including cottonseed oil mills, where high levels of exposure to dust have been demonstrated.

AIMS

This study was performed in order to determine the across-shift and across-week decline of FEV(1) and respiratory symptoms among workers in a cottonseed oil mill.

METHODS

Sixty-six exposed and 48 unexposed workers of a cottonseed oil mill in Turkey were investigated by questionnaire and lung function test (LFT). LFTs were performed before and after shift on all the working days of the week. Acute airway response was defined as an across-shift decline in FEV(1) of 5% or more on the first working day.

RESULTS

Smoking was the only risk factor for having respiratory symptoms. Acute airway response was more frequently observed in the exposed group as compared to the unexposed group (OR = 6.2, 95% CI = 2.3-16.7). The median across-shift decline in FEV(1) on the first day (120 ml) significantly improved on the following days (10, 50, 60 and -30 ml).

CONCLUSION

Smoking appears to be the main risk factor for having respiratory symptoms. Cottonseed dust may cause an acute pulmonary function decline on the first working day, but not on the following days of the week. This decline is associated with respiratory symptoms in exposed workers.

Occupational exposure to cotton dust in cottonseed oil mills

Air samples were collected at breathing height in the hulling-separation department of a modern cottonseed oil mill in Uzbekistan. The average elutriated mass concentration measured by standard cotton dust samplers was 4.6 mg/m3, much lower than the average total dust concentration measured by stationary personal samplers, 12.49 mg/m3, and by personal samplers attached to workers, 14.53 mg/m3. Differences in readings among the vertical elutriators, stationary personal samplers, and roving personal samplers are attributed to the distinct sampling nature and dynamics of these samplers. The data suggest that most of the dust consisted of particles larger than 15 microm, the particle size cutoff of the vertical elutriator. Differences in readings among stationary and roving personal samplers are statistically significant, presumably representing biased sampling by the roving personal samplers of regions characterized by high dust concentration (due to machines malfunctioning), the nonstatic nature of the sampling, and the interaction between the sampler and the worker (the personal cloud). Cotton dust concentrations in the hulling-separation room were nonuniform, peaking in front of and between the huller-separator pairs. The high total mass readings show that workers were exposed to very high levels of nonthoracic airborne dust, which upon inhalation tends to deposit in the extrathoracic airways. The high elutriated mass concentrations suggest that workers were exposed to respirable cotton dust at levels higher than 1 mg/m3 mean concentration, the current Occupational Safety and Health Administration (OSHA) Permissible Exposure Limit (PEL) for cotton dust. Regressions between dust concentrations measured by stationary vertical elutriators and by personal samplers attached to workers serve for estimating the potential occupational exposure to cotton dust of workers in the hulling-separation room.

Interaction of atopy and exposure to cotton dust in the bronchoconstrictor response

A survey of 255 workers in four cottonseed crushing mills included a respiratory health questionnaire, allergy skin testing, and measurements of lung function over the Monday working shift. Atopy was defined as having two or more positive weal reactions to common inhalant antigens. Categories of exposure to dust were based on the stage of milling, and one category contained workers with continuous exposure to cotton dust derived from linters, the cotton fibres adherent to cottonseed. Atopy and exposure to dust were found to have significant interaction: large mean declines in FEV1 and FEF 25-75 occurred only in the workers exposed to linter dust who were also atopic. Skin-testing surveys in cotton textile mills have concentrated on specific cotton antigen reactivity and its first-order relations to symptoms. Our results indicate a need to identify atopic workers, and to search for interactions between atopy and other variables that may influence acute changes in expiratory flow rates.