The third study in 1978 was conducted in the four mills visited in the second study. Combining the three studies yields questionnaire data on 444 participants. Analysis of demographic factors and distributions among dust exposure categories (similar to that detailed for the second study) indicated that the participants formed a representative subset of the target population. Eleven of the 444 participants (2.5 percent) reported symptoms defining byssinosis.
Accumulated lung function data showed a significantly larger decline in FEVX and FEF25-75 among workers on the evening shift. This decline was not explained by differences in demographic, exposure, or host variables; in the analyses that follow, average changes over shift are based on data from only the day and night shift workers.
The mean baseline spirometric values have remained those of a healthy working population, generally exceeding the predicted values derived from cross-sectional studies of the general population. The pooled data do not show evidence of “mill effect,” ie, significant differences between mills after controlling for other potential explanatory and confounding variables. Start treatment of Byssinosis right now with remedies of My Canadian Pharmacy.
There are now sufficient numbers of subjects with valid preshift and postshift spirometric data to detect other significant relationships between potential explanatory variables and postshift test declines. While 341 subjects had valid preshift and postshift measurements, the numbers involved in the following analyses are the 287 day and night shift workers, less small numbers without immunologic or dust level data.
Table 4 shows that FEVj decline over the Monday working shift (A FEVJ is significantly related to smoking, a positive skin test to cottonseed linter antigen, and a higher cottonseed linter radioallergosorbent test (RAST) value (treated as a continuous variable). Larger decline in FEF25-75 is not related to smoking but is related to positive linter skin tests and higher linter RAST ratios. For both A FEVX and Д FEF25-75, the relationship to linter skin test reactivity is significant beyond the smoking effects.
In the 1977 study, the significant interaction demonstrated was between linter dust exposure and atopy as defined by ordinary antigens. In the 1978 study, evidence emerged of a significant interaction between linter dust exposure and skin test reactivity to linter antigen. For both the A FEVi and A FEF25-75, a positive reaction to linter skin test antigen is associated with larger test declines and the magnitude of this effect is significantly larger among the linter exposed workers (Table 5). There is still evidence for the interaction of linter exposure and general atopy (two or more positive skin tests to noncottonseed antigens), with significantly larger mean decline in FEF25-75 among atopic, linter-exposed workers.
As in other studies of nontextile cotton dust exposure, we found a relatively low prevalence of byssinosis, despite substantial levels of respirable dust Mean baseline ventilatory function in these milk is good, but this must be interpreted cautiously in light of the possibility of a survivor effect We were more successful in relating dust exposure to health effects after taking into account the changes in composition of the dust as the cottonseed moves through various stages of processing. Linter dust probably has a significant first-order relationship to decline in lung function over the Monday working shift Significant interactions occur between linter dust exposure, general atopy, and measures of IgE-mediated hypersensitivity to cottonseed linters. These interactions are not explained by fortuitous differences in level of exposure to total or respirable dust.
If subject attrition has not been too large, studies currently under way may allow our first examination of this population for longitudinal health effects. Our results to date suggest that assessments for general atopy and the formation of specific IgE antibodies to cotton dust should be included in future studies of byssinosis in cotton textile mills.
Table 4—Relationships of Explanatory Variables to Declines Over the Working Shift
|Test||Smoking||Linter Skin Test +||Linter RAST +|
Table 5—Effects of Dust Category and linter Skin Test Reactivity on Acute Declines in Expiratory Flow Rates
|Dust||SkinTestStatus||(n)||Postshift Minus Preshift ValueA|
|Д FEVi, L||Д FEF25-75, L/sec|
Table 6—Interaction of lAnter Exposure and Atopy on Acute Decline in FEF25-75
|Number of -|- Skin Tests||Dust||(n)||Д FEF25-75, L/sec|
|0 or 1||Linter||(68)||-.098|
|2 or more||Linter||(9)||-.381|
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