4 Health Effects
4.1 Introduction
During the early 1970s, manufacturers, employers, and occupational safety and health organizations received numerous complaints of skin and mucous membrane symptoms related to handling or working in close proximity to CCP [Calnan 1979; Göthe et al. 1981; Parmeggiani 1983]. The association of CCP with cases of occupational contact dermatitis was first investigated by Calnan [1979], who also reviewed reactions to ordinary carbon paper, which CCP has largely replaced. According to Calnan, proven allergic contact dermatitis from carbon paper was a rarity. Four early outbreaks of CCP health effects were described by Calnan [1979] and Göthe et al. [1981] at a scientific symposium in Stockholm in 1981. Although skin-patch tests were negative and therefore did not support allergic contact dermatitis as the mechanism of CCP health effects, five pieces of evidence indicated an occupational origin for the CCP symptoms:
- The reporting of symptoms from several workers in a number of unrelated and unconnected companies
- The receipt of customer complaints by all of the CCP manufacturers
- The similarity of reported symptoms and signs
- The similarity of complaints from different countries
- The absence of reported symptoms before the introduction of CCP
Calnan [1979] concluded that the reactions appeared to be toxic (i.e., irritant) rather than allergic because the affected workers were able to continue working in the same general environment without immediate recurrence of their symptoms and because many of the workers related their symptoms to periods of intensive work handling large amounts of CCP.
Calnan [1979] noted that the CCP manufacturers had reported an absence of skin, oral, ocular, or respiratory tract symptoms among their own workers employed in packing large quantities of CCP. However, subsequent investigations identified health problems in these groups as well. Calnan also pointed out that all CCP complaints were associated with used CCP paper, indicating that the rupture of the microcapsules containing the color formers and solvents may be important—even though only a small proportion of capsules in each sheet of paper are broken. Ultimately, Calnan concluded that the eye, nose, mouth, and throat symptoms were caused not by the color former chemicals but rather by the encapsulated solvents, which would presumably have to evaporate to cause other than dermal symptoms.
In a review of the evidence, Buring and Hennekens [1991] found most of the available studies on CCP health effects to be critically lacking epidemiologically and difficult to interpret. They were able to find no "analytic studies" of CCP health effects for review. However, they concluded that unequivocal evidence was not likely ever to be available, even with great expenditure of effort and resources.
