Workers in the cotton textile industry may experience both non-specific lung disease (such as chronic bronchitis) and the specific syndrome called byssinosis (3). In extremely rare cases, immediate skin reactions can occur (6). Reactions are more commonly late-onset IgE-dependent asthma (7).
Typically, symptoms of sensitization to cotton include bronchitis, bronchial asthma, or byssinosis (4). Patients with IgE-mediated hypersensitivity to cotton dust or its contaminants may be misdiagnosed as byssinotic (7).
There has been much debate about the cause of reactions to cotton dust. Historically, allergy to cotton has been correlated with multiple factors; occupational asthma, byssinosis due to exposure to aerosolized cotton dust, or obstruction of the airways due to materials resulting from the processing of cotton and the natural contaminants of cotton, such as bacteria, endotoxins and molds (6). This has led to at least three hypotheses of the cause as pharmacological, endotoxin-related, or immunological. In the immunological theory, byssinosis is attributed to a type III immune mechanism, as a consequence of specific antigens in the cotton dust, or bacterial/fungal contaminants. However, it may also be as a result of type I, IgE-mediated immune reactions provoked by mast cells and basophils (3). Another study supported the hypothesis that the key mediator of the immunological response to cotton dust in due to fungal contamination (7). There are many bacterial (including Enterobacter, Pseudomonas, Klebsiella, and Clostridium) and fungal contaminants (Aspergillus, Fusarium and Alternaria) of cotton plants, cotton dust or the air in textile mills (7). There is also a case for irritation caused by the dust (8). While immune reactions such as elevated IgE levels have been identified in textile workers, they correlate poorly with respiratory symptoms and function (9).
Working in the earlier phases of cotton manufacture, compared to the later stages, is correlated with a higher prevalence of lung disease (3). In a study of four cotton mills in the USA, sensitization by skin-prick tests in workers varied depending on the step of cotton processing and production they were primarily involved in. Around 8% of workers in the linter dust category (those who were constantly exposed to cotton fibers during cleaning, baling and hulling of the cotton) had positive skin-prick tests to cotton fibers, whereas those exposed to product dust (including oil extraction, loading or boiler room operations) were positive in approximately 5% of cases and those in the mixed dust (including both groups) had zero positive skin-prick tests. Exposure to the dust, and the presence of atopy correlated with a large mean decline in lung function in those workers exposed to cotton fiber dust who were also atopic (10).
Asthma
A link has been identified between patients with pre-existing nasobronchial allergy and sensitization to cotton dust. In a study of 48 bronchial asthma and allergic rhinitis patients, 6.25% had markedly positive skin-prick tests to cotton mill dust (11).
