| Type of paper | Workers exposed to <150 sheets per day | Workers exposed to ≥150 sheets per day | |||||
|---|---|---|---|---|---|---|---|
| Total number in group | Workers reporting symptoms | Total number in group | Workers reporting symptoms | ||||
| Number | % Total | Number | % Total | ||||
| Paper containing MIPB | 6 | 3 | 50 | 5 | 5 | 100 | |
| Other CCP | 21 | 4 | 19 | 26 | 13 | 50 | |
| Ordinary paper and carbon paper | 7 | 0 | 0 | 15 | 3 | 20 | |
Source: Göthe et al. [1981] and Norbäck et al. [1983b].
- ↑ Note: These values vary slightly in the earlier publication.
(<150 sheets per day). Patients were excluded if they had irritation of the respiratory tract that was not specifically related to work with paper. The data show that throughout, the frequency of complaints was higher in the high-exposure groups than in the corresponding low-exposure groups for all types of paper, including ordinary paper. These data also demonstrated a higher prevalence of work-related respiratory symptoms in patients seen at the clinic and exposed to CCP containing MIPB—a solvent used in the microcapsules. This prevalence rate was 100% in the high-exposure group.
Norbäck et al. [1983b] also investigated whether the dose-response associations might be due to an increased proportion of sensitive workers among those who handle large amounts of paper. They determined whether patients with atopy or nonspecific hyperreactivity of the respiratory tract were concentrated among these highly exposed individuals. Atopy was assumed to be present if the patient had a history of asthma or hay fever or a tendency to develop eczema.
Nonspecific hyperreactivity was assumed to be present if the patient had reported experiencing respiratory tract irritation when exposed to nonspecific irritants such as perfume, cigarette smoke, and vehicle exhaust in the everyday environment. Fewer sensitive patients (P<0.05) were identified among those who handled large volumes of paper than among those who handled small volumes of paper, indicating that confounding by atopy could not explain the observed exposure-response relationships.
These authors also investigated the role of D-inks, which were present in about 20% of the CCP. A significant increase (P=0.00009) occurred in the prevalence of work-related pruritus combined with erythema in those working with CCP treated with D-ink versus those not working with these inks (39% versus 0%).
Analysis of other contributing factors in this population revealed that work involving photocopies or the presence of wall-to-wall carpeting was not significantly correlated with skin or mucous membrane symptoms. The authors concluded that a significant dose-response
