Contents

Introduction
The Technology of CCP
Exposure
Health Effects
Summary and Conclusions
Recommendations
References
Other Publications Examined

Introduction

1.1 Background

In 1987, the Occupational Safety and Health Administration (OSHA) requested the National Institute for Occupational Safety and Health (NIOSH) to investigate the validity of reported adverse health effects in workers occupationally exposed to chemicals contained in or released from carbonless copy paper (CCP). OSHA also requested that NIOSH publish its findings if health effects were confirmed. The OSHA request was based on one worker’s concern that skin, respiratory problems, and possible brain damage were due to consistent exposure to CCP [52 Fed. Reg.* 22534 (1987)]. In addition, 10 to 12 of the initial complainant’s coworkers who were also exposed to CCP were reported to have suffered adverse health effects.

Thus in 1987, NIOSH issued a Federal Register notice soliciting information about possible adverse health effects from CCP exposure [52 Fed. Reg. 22534 (1987)]. On the basis of information available at that time, no strong conclusion could be reached concerning a consistent link between CCP and major health effects. Between 1987 and 1997, a number of additional incidents were identified as involving health problems potentially related to CCP. Therefore, in 1997 NIOSH issued a second Federal Register notice soliciting new information [62 Fed. Reg. 8023 (1997)].

This report contains a review of the published literature on CCP and the submissions from the two Federal Register notices. NIOSH prefers to use the published literature when investigating the relationship between an occupational exposure and adverse health effects, but some unpublished sources were used in this case because the published literature was limited. The unpublished information was found to be of variable quality, validity, and utility.

1.2 Development and Production of CCP

CCP was introduced in 1954 by the National Cash Register Company as no-carbon-required (NCR) paper—an alternative to separate sheets of carbon paper [Sandberg 1955; Green 1955; Miller and Phillips 1972; Calnan 1979; Buring and Hennekens 1991]. NCR was a patented name, but many of the patents have expired, and several companies have licenses in other countries.

The mechanism of CCP involves coating the under surface of the top sheet of CCP with an emulsion of a colorless dye in a solvent (see Chapter 2). The emulsion is held in microscopic capsules (microcapsules) that are ruptured by firm pressure from a writing instrument. The released dye reacts with a reagent on the surface of the paper and changes the dye to a colored product (generally violet, blue, or black). CCP may also be referred to as one of the following:

• Pressure-sensitive paper
• Reaction-copy paper
• Color-reaction paper
• Self-copying paper

CCP comprises an extremely complex grouping of products. A given CCP can vary greatly as to its constituents, weight and types of paper coatings, paper color, dye colors and combination of dyes used on coatings, solvents and solvent mixtures (including variations from different suppliers), physical form (rolls versus sheets), and final form of the product (i.e, bound with adhesives). To improve quality and performance, the “recipes” used in the manufacture of CCP change frequently. No single product can be identified as a typical formulation of CCP since each product may have its own distinct constituents and different manufacturing processes. Thus the product known as CCP is not a single product but includes thousands of different and often unique products [Mead Corporation 1997 (a NIOSH docket submission)].

Production of CCP grew on an enormous scale after its introduction in 1954. By the 1960s, U.S. sales were about 16,000 tons, and production had started in Europe. In 1962, a Japanese company signed a license agreement with the National Cash Register Company, and by 1970, worldwide production rose to 100,000 tons. In 1991, about 1.8 million tons of CCP (the equivalent of nearly 200 billion 8.5- × 11-in. sheets) [Fetters 1997 (a NIOSH docket submission)] were produced and used [Buring and Hennekens 1991; Murray 1991]. Consumption is divided into three principal regions: North America—800,000 tons, Japan and the Far East—300,000 tons, and Europe— 600,000 tons [Murray 1991]. The Association of European Manufacturers of Carbonless Papers [AEMCP 1985] indicated that in 1985 there were more than 50 manufacturers of CCP throughout the world.

By 1979, four companies in Great Britain, four in Japan, five in other European countries, and five major companies in the United States were manufacturing this paper [Calnan 1979]. Currently, 12 plants (5 manufacturers) in the United States [Fetters 1997 (a NIOSH docket submission)] and more than 50 plants around the world [AEMCP 1985] manufacture CCP. U.S. production averaged nearly 1 million tons during the period 1987–1996 [Graves and Tardiff 1999]. Annual global sales exceed $5 billion [Finch 1990].

The production industry employs more than 10,000 workers [Fetters 1997 (a NIOSH docket submission)]. Although the total number of workers potentially exposed to CCP in workplaces other than manufacturing (such as offices, laboratories, other businesses, schools, banking, etc.) is unknown [Pedersen 1998], it is likely to be in the millions. Also unknown is the extent to which the general public is potentially exposed to CCP during business transactions, receipt checking, etc.

1.3 Reported Health Effects

About 10 years after the introduction of CCP, medical complaints began to be reported by exposed office workers [North Carolina Medical Journal 1982; Magnusson 1974; Göthe et al. 1981; Buring and Hennekens 1991]. In 1975, OSHA requested information from physicians about any unusual frequency of eye, mucous membrane, or skin irritation associated with CCP similar to the information being reported at that time in Sweden [North Carolina Medical Journal 1982].

Since 1965, various health effects associated with exposure to CCP have been reported in the literature appearing from Denmark, Finland, England, Sweden, Germany, the Netherlands, France, Italy, Belgium, Japan, Norway, and the United States. The National Swedish Board of Occupational Safety and Health [1976] gathered information about the components of CCP and came to the following conclusions:

• None of the substances present in CCP at that time had known irritant or allergenic effects.
• The problems of skin and mucous membrane irritation are most common in the winter when the humidity is low.
• None of the substances gave rise to large amounts of dust.
• None of the substances would lead one to expect vapors to be generated at room temperatures.
• The odor reported by some may originate from the solvents in the adhesives or the inks.

Despite these negative conclusions, the Swedish Board noted that further attention to the question was warranted, "since problems with the skin and mucous membranes are still being reported by persons working with carbonless paper." Thus they also issued advice and instructions related to the handling of CCP [National Swedish Board of Occupational Safety and Health 1976].

In February 1980, the Swedish Trade Union called for a ban on CCP [Göthe et al. 1981], which was claimed to be the cause of numerous conditions including the following [Göthe et al. 1981; Kanerva et al. 1993]:

Government and public concerns have waxed and waned in response to various reports in the literature as well as anecdotal information. The Danish, French, Swedish, and German governments have offered recommendations for reducing exposure to CCP (summarized in Chapter 6) that rely on simple work practices, personal hygiene, substitution, administrative controls, and increased ventilation as preventive measures. The Danish, French, and German governments have also recognized alleged health effects from CCP exposure as compensable according to the seriousness of the worker’s reaction [Norbäck et al. 1983b].

At the first symposium on CCP (which was held in Stockholm and attended by producers, labor, government, and representatives from nine nations), Göthe et al. [1981] commented that strong forces had been mobilized in Sweden 2 years before the meeting to ban CCP or find a substitute for it. They noted that support for such resolutions has "often been anxiousness enhanced by unverified rumors or alarming mass-media reports about dramatic and serious diseases caused by work with carbonless copy papers." On the basis of their field investigations, Göthe et al. [1981] indicated that handling large amounts of CCP might induce dose-related but benign and nonallergic irritative symptoms, particularly in the mucous membranes of the nose and mouth. These authors did not consider these symptoms to be specific for CCP: they could also be elicited by handling large amounts of ordinary paper. But it appeared that a higher percentage of CCP workers might develop these symptoms than workers exposed to ordinary paper. These investigators did not consider the phenomenon to indicate any large health risk, but they noted that CCP seems to be somewhat more irritating than ordinary paper in equivalent amounts.

In Canada, Harris [1983] reported that the symptoms directly associated with use of CCP (and shown to decrease outside of work or at other tasks) develop primarily in office workers who use CCP and less in those who make it. He stated that the symptoms (1) appear to be quickly reversible when exposure ceases, (2) are rarely caused by allergic reactions, and (3) vary greatly from office to office (which may depend on combinations of factors including the brand of CCP, the intensity of use, and office conditions such as ventilation and humidity). He further stated that no individual chemicals such as formaldehyde, oils, or paper dust had been identified as causing the related symptoms and that measurements in the office air were generally too low to account for the symptoms. Harris [1983] concluded that the reported health problems were due to the mixture of chemicals used in CCP and to mechanical irritation by the clay coatings on the paper.

To provide a comparison with the information available on CCP, Brissette and Paquette [1987] summarized the known information about the prevalence of health problems associated with carbon paper in Quebec, Canada. They reported that 34 of 390 cases of industrial dermatitis reported in 1929 and 5 of 5,000 cases reported between 1932 and 1936 were related to carbon paper, but the observations were not based on patch testing. They further reported that at the Finsen Institute in Copenhagen, cutaneous toxicity to carbon paper was evaluated in 40,000 people. Only four cases of allergic contact dermatitis were recorded, and the agents responsible were triorthocresyl phosphate, oleic alcohol, nigrosine, and violet methyl. None of these agents are reported to be used in CCP.

On February 13, 1986, the National Swedish Board of Occupational Safety and Health decreed that the CCP Announcement No. 1976:2 [National Swedish Board of Occupational Safety and Health 1976] (which recommended actions to be taken when CCP-exposed workers showed symptoms of irritation) was no longer valid: The problems which were previously considered to be caused by carbonless paper are now regarded as being of an extremely complex nature and have been linked directly to the paper only in a small number of cases (see Arbete Och Hälsa [Work and Health] 1983:2, Report on Problems Caused by Carbonless Paper).

1.4 Information Sources and Types

This NIOSH report is based on published and unpublished information. The published information includes case studies and case series, cross-sectional epidemiological studies, patent literature, and some reports of human and animal experimental studies. The unpublished materials were submitted to the NIOSH Docket in response to the Federal Register notices in 1987 and 1997 [52 Fed. Reg. 22534 (1987) and 62 Fed. Reg. 8023 (1997)]. These unpublished materials generally include human repeat insult patch test (RIPT) studies, animal exposure studies, and medical records of workers who indicated that they had exposure to CCP.

The Technology of CCP

2.1 How CCP Works

Athree-part business form (Figure 2–1) illustrates the concept of how CCP works. The first sheet in this three-part example is a coated-back (CB) sheet, the second is a coated-front and -back (CFB) sheet, and the third is a coated-front (CF) sheet. The bottom surfaces of the top and the second sheet are coated with a layer of microcapsules that have a diameter of 3 to 6
m. The coating includes inert spacer particles ("stilts," such as floc, uncooked arrowroot, and/or wheat starch particles) that are larger than the microcapsules and are added to protect the microcapsules from premature rupture. The microcapsules (filled with a colorless solution of 2% to 6% dye dissolved in a high-boiling-point-organic solvent) rupture under pressures encountered in normal handwriting or impact printing. For example, in a three-part form, the released dye solution is transferred from the bottom surfaces of the first and second sheets to the top surfaces of the second and third sheets, respectively, where it reacts with the clay or resin coating to form an image. The capsules and reactive coating can be coated onto the same paper surface. In this case, the product is called self-contained CCP.

2.2 CCP Production

The principles of the CCP production process are similar throughout the industry, but many components are variable and complex. During CCP production, an acid-sensitive dye precursor such as crystal violet lactone (CVL) or N-benzoylleucomethylene blue (N-BLMB) is microencapsulated with a high-boiling-point solvent or oil within a cross-linked gelatin or in synthetic mononuclear microcapsules, including polyamides, polyesters, or polyurethanes. From the origination of NCR paper until 1970, the main solvent for the dyes was polychlorinated biphenyls (PCBs [Arochlor]). Examples of solvents that have replaced PCBs are hydrogenated terphenyls, diarylethanes, alkylnaphthalenes, cyclohexane, and dibutylphthalate (more detailed information about solvent composition, technical requirements, and admixtures is given later in this section). These materials are often diluted with odorless kerosene [Calnan 1979].

CCP production consumes thousands of tons of microcapsules annually. During CCP manufacturing, microcapsules are coated onto the back of the top sheet (referred to as a CB sheet) at a density of several million per cm2 with a binder or suitable adhesive [Certin and Zissu 1983]. Since paper is the usual support, the binders or adhesives are principally paper-coating agents such as the following [Murray 1991; Mathiaparanam 1992]:

• Gum arabic
• Hydroxymethyl cellulose
• Casein
• Methyl cellulose
• Dextrin
• Starch or starch derivatives (wheat or corn) or polymer lattices (e.g., butadiene/styrene copolymers or acrylic homopolymers or copolymers)
• Vinyl acetate and water soluble polymers such as carboxymethyl cellulose
• Polyvinylacetate
• Gelatin
• Polyacrylates
• Polystyrene
• Polyvinyl alcohol

The paper employed comprises not only normal paper made from cellulose fibers, but also paper in which cellulose fibers are replaced (partially or completely) by synthetic polymers [Bedekovic and Fletcher 1986]. (Please refer to Section 2.8 for a listing of brand names and trademarks of CCP.)

The sheet intended to receive the image, the CF sheet, is treated on the front with a clay or resin that is alkaline on the surface but acidic inside, or with an alternative reactive coating [Calnan 1979]. In Europe, the color developer system is typically based on clays, whereas phenolic resins are most commonly used in the United States and Japan [Murray 1991]. The coating is spread in a mixture, dried, and adhered with a styrene-butadiene-latex or one of the binders listed above. When the top sheet is mechanically impacted, the dye capsules rupture and the dye solution is transferred to the receiving sheet, where the acid developer activates the dye as a result of a change in pH or oxidation.

2.3 Microcapsule Production

Three processes can be used to microencapsulize the dyes for the size requirements of CCP: complex coacervation, interfacial polymerization, or in situ polymerization [Kroschwitz and Howe-Grant 1979, 1995; Sliwka 1975]. The complex coacervation process produces a shell material of gelatin and gum arabic (treated with glutaraldehyde); the chemical class is a protein-polysaccharide complex. Interfacial polymerization produces a shell of polyurea or polyamide and is chemically classed as a cross-linked polymer. The in situ process results in a shell material of aminoplasts and is also considered to be in the cross-linked polymer chemical class. Microcapsules have a wide range of geometries and structures. These range from a continuous core shell that surrounds the core material to a multinuclear capsule in which a number of cells of core material are distributed uniformly throughout the matrix of shell material and a continuous core capsule with two different shells. Examples of other synthetic resins used for the microencapsulation process are urea-formaldehyde, melamine-formaldehyde, polyamide, and polyurethane resins [Asano et al. 1983]. Maggio et al. [1978] stated that urea-formaldehyde capsules are more resistant to pressure than those made of gelatin.

2.4 CCP Production Process

Apol and Thoburn [1986] described the process of CCP manufacturing. The plant they investigated made paper from pulp and then applied the appropriate coatings to the paper to make CCP. The paper itself is usually produced in a continuous sheet from a pulp slurry to form a wet web of paper as it exits on a screen, such as in a Fourdrinier paper machine. Apol and Thoburn [1986] describe a process in which the CF and CB coatings are applied to the wet web. The CF coating can also be applied as the paper exits from the paper machine. As the coating is applied, the paper passes through a dryer and is wound on a roll. The CB coating may be applied in a separate plant area to the paper as it passes through a series of dryers and is rewound on a roll.

The CF and CB coatings are prepared in the coater preparation area. The phenolic resins (1- to 10-
mor 1- to3-
msize range is preferred [Mathiaparanam 1992]) may be prepared by grinding the resins to specific-size particles, or they may be purchased already prepared. The already prepared resin reduces exposure to phenol among workers who handle the coating preparation and is the preferred option for today’s technology.

A typical coating composition for the CF component is shown in Table 2–1. The CF is dried in a high-velocity air oven at 93 °C [Kroschwitz and Howe-Grant 1995]. Miller and Phillips [1972] stated that suitable amounts of the various materials per unit of paper are as follows: chromogenic dyes, 0.03 to 0.075 lb/ream (one ream is 500 sheets of 25- × 38-in. paper totaling 3,300 ft2), with the preferred amount being 0.05 lb/ream; solvent, 1 to 3 lb/ream; polymer, 0.5 to 3 lb/ream.

CF, CB, and CFB coated papers are produced in large rolls weighing up to several tons. These are subsequently cut down by machines to a variety of smaller reel and sheet sizes. This cutting means that the contents of the microcapsules will be ruptured and released. Although many of the sheeting, reeling, and packing operations are automated, some of the paper still needs to be hand-sorted. The workers who hand sort these papers are potentially exposed to the components, particularly the contents of the ruptured capsules that have been cut in previous mechanical operations. Some of these workers sort paper at the rate of 90 kg/hr (or more than 2 tons/week [600,000 sheets]) [AEMCP 1985].

2.5 Forms Production

CCP is converted into forms for a variety of applications—for example, business forms, invoices, computer paper, and Telex rolls. This process is normally performed by printers with appropriate forms design using conventional printing inks as well as specialized desensitizing inks. The latter are applied to the CF surface to prevent the color former from developing into an image on certain areas of the paper [AEMCP 1985].

CCP may be collated into business form sets that are glued along one edge. The glues (called edge-padding, edge-tipping, or "fanapart" glues) are similar to those used for ordinary paper writing pads. Manifold forms using pressure-sensitive CCP are produced using conventional printing press techniques. For some applications, the production of the multipart form by photocopying or laser printer operations is preferred—especially in short-run for production, emergencies, and experimental or individualized forms. The manifold forms are bound with an adhesive containing gum resins such as abietic acid. More recently, Moore Business Forms, Inc., was granted a patent [McIntyre and Greig 1989] for the use of a repositionable adhesive pad on the CF (such as is found on money wrappers). Bodmer and Peters [1984] and Bodmer and Miller [1985, 1986] noted that CF coating components can accumulate on the heated fuser roll of the copier or the laser printer, which becomes tacky and can lead to poor copy quality. A phenolic polymeric film material, diolefinic alkylated or alkenylated cyclic hydrocarbons (cyclic terpene derivatives such as limonene), and/or an oil-soluble metallic salt (primarily zinc) of a phenol- formaldehyde novolak resin can be used to overcome the fuser roll contamination problem, which may or may not result in slower print speeds.

2.6 Other Forms and Variations of CCP Technology

Forms sometimes combine CCP with carbon paper to become a "two-write" system [Mead Corporation 1992]. The Branch Safety Council for Offices and Administrations [1988] also reported on another type of CCP that is pressure sensitive and is called "mechanical" paper. The CB sheet is coated with zinc chloride and covered by a thin layer of wax. Pressure created on the top side of the form causes the zinc chloride to break through the wax and adhere to the sheet below that is coated with an absorbing layer of color generators, polyvinyl acetate, and clay. The Mead Corporation was granted a patent that incorporated a microencapsulated, photosensitive material that cured to a stable image when heat-activated in the presence of a developer such as an organic peroxide [Sanders 1984]. The Mead Corporation was also granted a patent on a novel system that uses a self-contained imaging sheet to produce images on plain paper using a photosensitive *, photocurable, image-forming agent and a developer material on the surface of the paper support [Feldman et al. 1994].

The NCR Corporation (formerly the National Cash Register Company) was granted a patent [Marinelli 1985] for the addition of an aqueous wax emulsion to the CB coating to act as a barrier between the reactants in the CB coating and in the CF coating in multiple-copy printing operations. The technology prevents precolor formation caused by reactants seeping into the CF and can withstand on-press CF coating (presumably with desensitizing inks). Formulations included the use of Jonwax™ 120 (an emulsion of polyethylene and paraffin wax), Jonwax 26 (a wax emulsion of polythene wax), and Jonwax 22 (a water-based wax compound). The wax emulsion also replaces some of the microcapsules on the substrate. (Jonwax™ is a registered trademark of S.C. Johnson and Son, Inc., of Racine, Wisconsin.) According to Graves and Tardiff [1999], this process was never commercialized.

2.7 Desensitizing Inks

Frequently, information entered on the top form must be unreadable on certain sections of the form or forms beneath. If the areas on the forms beneath are not needed for other data, two types of obscuring methods can be used. The most common is the "masking" blockout, which entails the printing of a solid block of blue ink over the appropriate areas. The second type of blockout method calls for printing a dense pattern of random lines and blotches suggestive of Chinese characters ("Chinese blockout"). Both methods use the same color ink as the carbonless image color. When the blocked-out areas must remain clear to allow data entry on lower plies, the manufacturer must print a special clear "desensitizing" ink on that area. This desensitizing ink deactivates the carbonless imaging system by not allowing the CF side to react with the color former encapsulated on the CB surface [Mead Corporation 1993]. Desensitizing inks may contain a variety of solvents such as white spirits, kerosene, toluene, alcohols, glycols, ketones, and plasticizers such as dibutyl phthalate, etc. [AEMCP 1985]. Desensitizing inks are sold to industrial printers much like other printing inks [Graves and Tardiff 1999].

Chang [1978] described a patented method of desensitizing CCP when the color developer is a combination of acid clay, phenolic novolac resin, and metal salt of an organic carboxylic acid coated with 10 to 35 parts N-vinylpyrrolidone and about 65 to 90 parts of a free-radical, co-polymerizable compound of a photoinitiator having at least one terminal ethylenic group per molecule. The paper is then subjected to ultraviolet radiation.

Some CCP originates from printing shops that may use different manufacturing sources of CCP in the same manifold. Thus it is extremely difficult to trace the origin of a particular paper. For example, the CF sheet could come from one manufacturer and the remainder of the form from another supplier or manufacturer. In addition, the printer can apply the desensitizing inks to the form [Danish Branch Safety Council for Offices and Administration 1988].

2.8 Summary of Chemical Components of CCP

This section lists the known components of CCP classified as to the microcapsule, color developer, CF coating, etc. The compilation was taken from the scientific literature, patent applications, and manufacturers’ submissions.

Adhesives for Binding the Various Coatings to the paper

Color Developers for Dye-Formers on CF and other Associated Agents

Agents Connected with the Coatings on the CB

2.9 Brand Names or Trademarks for CCP

Brand names or trademarks for CCP were obtained from the following sources: Calnan [1979], CHIP [1988], Levy and Hanoa [1982], Olsen and Mørck [1985], Paper Europe [1993], and Dady [1998]. The brand names or trademarks are listed as follows:

Technology of CCP