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 medical problems. On the basis of the available assays of irritant or allergenic potency, the authors were unable to conclude that a specific chemical was common to CCP complaints. Two patients had probable allergic reactions to components in the synthetic resins (one to melamine formaldehyde and one to resorcin), but those reacting to resins or solvents did not react in patch tests to their own CCP. Other contributing factors were mentioned, such as the handling of paper generally (i.e., carbon paper, plain paper, CCP, etc.) and atopy. The authors asserted that there were no differences by CCP brand; however, because of the design of the study (only symptomatic workers were included) differences in prevalence or incidence of symptoms across CCP brands could not be assessed. The authors concluded (based on the absence of a causal agent) that CCP was not the leading suspect responsible for symptoms in most of the patients exposed to CCP.

Morgan and Camp 1986. Morgan and Camp [1986] conducted an experiment in the United States under controlled laboratory conditions to quantify upper respiratory congestion in clerical workers reporting prior sensitivity when exposed to CCP. Seventy percent of the subjects reported having symptoms associated with CCP use. These symptoms included dryness, light-headedness, headache, dry mouth, burning sinuses, dizziness, sore throat, tickle in throat, sneezing, irritation, itching nose, congestion in throat, and flushed face. The symptoms reportedly increased with increased use of CCP and tended to dissipate rapidly when the worker was removed from the exposure. The authors used an objective measure of nasal congestion—measurement of the nasal contribution to the work of breathing (nasal impedence) by posterior rhinomanometry. The subjects were 28 clerical workers who reported handling 1 to 200 CCP forms per day, with an average of 90 forms per day. These workers were subjected in random, single-blind fashion to controlled exposures of vapors from two sets of three-page, blue-dye CCP forms and to vapors from plain bond paper. Any particles released by the paper were removed by a 0.3-µm particle filter. Total hydrocarbon concentration during CCP exposure averaged 1 ppm. Nasal impedance increased 34% after exposure to CCP forms (P<0.025) and 8% after exposure to plain paper (P>0.10). However, frequency of symptoms did not differ between exposure to CCP and plain paper, and they were not correlated with the nasal measurements. The authors concluded that quantitation of nasal congestion by this technique may be a sensitive measure of short-term reaction to inhalation of irritants. In subjects with a history of allergy, changes in nasal function were reported after exposure to both paper types, but only the change after CCP exposure was statistically significant (paired t-test, P<0.05). In these patients, nasal aerodynamic response to CCP vapor was significant even with low concentrations of hydrocarbon exposure, and objective changes were measured in the absence of consistent subjective complaints.

RIPT Studies. NIOSH reviewed all of the industry-sponsored laboratory studies in humans submitted to its docket as a result of the Federal Register notices in 1987 and 1997. Most of these studies were RIPT studies, which are summarized in Table 4–12. The RIPT is a test method designed to evaluate the potential of a material to induce and elicit type IV skin sensitization reactions (allergic contact dermatitis) in humans [ASTM 1999]. In general, these tests were performed by administering multiple potentially sensitizing doses of study material as occlusive patch tests over a several-week period. After 2 to 3 weeks, subjects were challenged with an additional diagnostic patch test and evaluated for responses consistent with allergic contact dermatitis.