health effects (symptoms) was generally identified by surveys of workers using a questionnaire. A major concern with studies based on questionnaires is the potential for overreporting of symptoms, particularly when the study subjects are already concerned about the exposure being studied.
This concern is greater for the CCP studies than for the indoor air quality studies because the CCP studies were generally conducted at facilities where complaints of symptoms were allegedly related to CCP. The indoor air quality studies were not conducted in facilities where complaints were related to CCP, and thus they are generally considered to provide better information than the CCP cross-sectional studies. The indoor air quality studies and the CCP studies are considered separately below.
4.2.3.1 Cross-Sectional Studies of Indoor Air Contaminants
A number of studies on indoor air quality have associated CCP exposure (and other factors) with workers’ symptoms (Table 4-3). Three indoor air quality studies—Knave et al. [1985], Reinikainen et al. [1990], and Thompson [1996]—are not included in this review because they were judged to be largely uninformative with respect to potential health effects associated with CCP exposure. One common limitation of the studies described below is that they generally include only two or at most three categories of CCP exposure and thus provide a very limited assessment of exposure-response.
Skov et al. 1987, 1989. Skov et al. [1987] conducted a cross-sectional survey of office workers and indoor climates in 14 town halls and other affiliated buildings in Copenhagen. Researchers administered a questionnaire to 4,369 workers and measured indoor climate factors in town halls. The return rate for the questionnaire was 80%. Measurements of the many indoor climate factors yielded values considered acceptable or within a typical range for office buildings as previously reported. The analysis showed that the following tasks were significantly correlated with the presence of mucosal and general symptoms: photocopying, working at video display terminals (VDTs), and handling CCP. However, in this univariate analysis the potential exists for confounding between CCP, photo-copying, and VDT exposures.
Subsequently, Skov et al. [1989] described the influence of personal characteristics as well as job-related and psychosocial factors on indoor air quality complaints in the same population. Of the 3,507 respondents (2,347 women), the CCP-exposed included 1,102 women and 424 men. For the 19 buildings studied, numbers were sufficient for multi-variate analyses. The questionnaire provided information about work activity, previous and present diseases, the presence of mucous membrane and general symptoms (headache, fatigue, and malaise), indoor climate, family and housing conditions, exercise habits, smoking, and consumption of alcohol and other beverages. Thirty-six percent (397) of these women reported complaints, as did 26% (110) of the men. In logistic regression analyses, sex, type of job, and the following job activities were significantly related to mucous membrane symptoms: handling CCP (P<0.0001), handling carbon papers (P<0.0001), photo-copying (P<0.0001), working at VDT's (P<0.0001), dissatisfaction with one’s superiors (P<0.0001), and work overload (P<0.0001). Crude prevalence rates showed a dose-response between frequency of CCP exposure and mucous membrane symptoms:
| % | |
| Monthly or less frequent use | 24 |
| Weekly use of 25 sheets or fewer | 32 |
| Weekly use ofmore than 25 sheets | 43 |
