In this context, it has also to be discussed whether dust and fiber concentrations in our study are surrogate markers for nondetected exposures at the workplaces. It is well known that in the soft tissue paper-producing industry, a complex exposure situation exists. Moreover lung function impairment has been reported from other work sites with organic dust exposure outside the soft tissue paper-producing industry, eg, among cotton textile workers and poultry workers. Lung function impairment could be unspecifically related to the very high dust concentrations no matter what kind of dust exposure takes place (overload phenomenon).
Searching for the etiologic agent, Rylander et al described that airborne endotoxin and 1-3 (P glucan exposure were responsible for the increased prevalence of respiratory symptoms and for a decreased baseline FEVj and an increased airway responsiveness in a group of 83 workers employed in bark-cleaning units, recycled paper storage, and processing in the paper industry. This exposure is not comparable with soft tissue paper production. Recycled paper and recycled paper dust and fibers have different properties (eg, diminished fiber length) than soft tissue paper dust. Moreover, dust concentrations are higher in the soft tissue paper production. Due to the results of the markers of inflammation determined in the study by Rylander et al, it has to be discussed whether airway inflammation is responsible for the lung function findings. However, the responsible agent still remains unclear. Douwes et al described in their study from saw mills that dust levels were only weakly correlated with endotoxin and 1,3 p glucan levels. Therefore, it is questionable if the dust concentrations detected in our study can serve as a surrogate for endotoxin exposures. All in all, most of the results suggest that the effects detected are unspecific due to the high dust concentrations regardless of its fiber content and probably regardless of other undetected exposures.
Therefore, a reduction of dust exposures is recommended in the soft tissue paper-producing industry. In order to allow specific evidence-based prevention, further investigation is needed to identify the etio-logic agent or agents within the dust fraction.