Asbestos Cement (Transite)

Asbestos cement — commonly known by the brand name Transite — is a building material made by combining Portland cement with 10–15% asbestos fibers, typically chrysotile. The addition of asbestos gave ordinary cement extraordinary tensile strength, fire resistance, weather durability, and dimensional stability. This versatile composite was molded into flat sheets, corrugated panels, roofing shingles, water and sewer pipes, electrical conduit, and flue linings, making it one of the most widely used asbestos-containing materials in history.¹

Johns-Manville Corporation introduced the Transite brand in the 1920s, and it quickly became the industry standard for asbestos cement products in North America. James Hardie Industries dominated the Australian market (where asbestos cement was called "fibro"), while the Eternit Group was the largest producer in Europe and South America. At peak production, asbestos cement accounted for approximately 70% of all asbestos consumed worldwide, making it the single largest end-use category for the mineral.²

Unlike friable asbestos insulation products, asbestos cement is classified as non-friable when intact — the asbestos fibers are tightly bound within the cement matrix. However, cutting, drilling, sawing, breaking, or weathering of asbestos cement releases respirable fibers. Workers who manufactured, installed, or cut asbestos cement products faced significant exposure, as did maintenance workers and demolition crews who disturbed these materials without proper controls.³

Asbestos cement remains in place in millions of buildings worldwide. In the United States, production largely ceased by the late 1980s, but asbestos cement pipes still carry water in many municipal systems, and asbestos cement siding, roofing, and panels are present in residential and commercial structures throughout the country. The World Health Organization estimates that 125 million people worldwide continue to be exposed to asbestos in the workplace, with asbestos cement manufacturing remaining active in several countries where chrysotile asbestos has not been banned.⁴

Asbestos cement was manufactured into a wide range of building products:²

• Flat sheets (Transite board) — Used as wall cladding, ceiling panels, partition walls, and laboratory countertops. Common in industrial, commercial, and residential construction
• Corrugated sheets — Used for roofing and wall cladding on agricultural, industrial, and residential buildings. Still widely present in developing countries
• Pipes (AC pipe) — Asbestos cement pipes were widely used for municipal water supply, sewer systems, and agricultural irrigation. Millions of linear feet remain in service in U.S. water systems
• Roofing shingles and slates — Molded to resemble natural slate or wood shakes. Common on residential homes built from the 1930s through the 1970s
• Flue linings — Used inside masonry chimneys to line flue passages for residential heating systems
• Electrical panels and conduit — Used as electrical switch panels and wiring conduit in commercial and industrial buildings

Health effects from asbestos cement exposure follow the same patterns as other asbestos exposures, with a latency period of 15–50 years:³

• Persistent cough and breathlessness — Early signs of pleural or pulmonary asbestos disease
• Chest pain — May indicate pleural thickening, pleural plaques, or developing malignancy
• Recurrent respiratory infections — Compromised lung function increases susceptibility to pneumonia and bronchitis
• Fatigue and weight loss — Systemic symptoms that may signal mesothelioma or lung cancer
• Difficulty breathing when lying flat — May indicate pleural effusion

Asbestos cement releases fibers through mechanical and environmental processes:¹

• Cutting and drilling — Using power saws, drills, or abrasive tools on asbestos cement generates high concentrations of airborne fibers and cement dust
• Breaking and demolition — Smashing or roughly handling asbestos cement panels and pipes releases fibers from fractured surfaces
• Weathering and aging — Decades of exposure to rain, wind, freeze-thaw cycles, and UV radiation erodes the cement matrix, gradually exposing embedded asbestos fibers
• Power washing — High-pressure water cleaning of asbestos cement surfaces can release fibers into the air and surrounding environment
• Manufacturing — Workers in asbestos cement factories were exposed during mixing, molding, cutting, and finishing operations

Groups with elevated exposure risk from asbestos cement include:³

• Asbestos cement factory workers — Highest exposure levels occurred during manufacturing, particularly in mixing and cutting operations
• Construction workers — Carpenters, roofers, and siding installers who cut and fitted Transite panels on job sites
• Plumbers and pipefitters — Workers who cut, joined, and repaired asbestos cement water and sewer pipes
• Municipal water workers — Personnel who maintain and repair aging asbestos cement water distribution systems
• Demolition crews — Workers who break down buildings containing asbestos cement components
• Community members — Residents near asbestos cement factories in countries with active production face environmental exposure

Clinical evaluation of suspected asbestos cement-related disease includes:⁴

• Exposure assessment — Documentation of occupational or environmental contact with asbestos cement products, including job duties and duration
• Imaging — Chest X-ray and high-resolution CT for pleural and parenchymal abnormalities
• Lung function tests — To measure restrictive patterns and gas exchange impairment
• Histopathology — Tissue biopsy for definitive cancer diagnosis when imaging suggests malignancy

Treatment follows standard protocols for the specific asbestos-related condition diagnosed:⁴

• Mesothelioma — Multimodal therapy including surgery, chemotherapy (pemetrexed/cisplatin), immunotherapy, and radiation based on stage and patient fitness
• Lung cancer — Surgical resection, chemotherapy, immunotherapy, targeted therapy, and/or radiation
• Asbestosis — Supportive management with oxygen therapy, pulmonary rehabilitation, and prevention of respiratory infections
• Pleural disease — Monitoring for pleural plaques; drainage or pleurodesis for symptomatic effusions

Health outcomes from asbestos cement exposure depend on exposure intensity and the disease that develops:³

• Factory workers — Epidemiological studies of asbestos cement manufacturing workers show elevated rates of mesothelioma, lung cancer, and asbestosis, though generally lower than rates seen in asbestos insulation workers due to the non-friable nature of the finished product
• Construction workers — Risk correlates with the frequency and duration of cutting and drilling asbestos cement materials without dust controls
• Mesothelioma — Median survival of 12–21 months from diagnosis, consistent across all asbestos exposure sources
• Building occupants — Minimal risk from intact asbestos cement products in good condition that are not disturbed

Managing asbestos cement in buildings and infrastructure requires proper identification and handling:¹

• Identification before work — Test all suspect cement-based materials in pre-1990 buildings before cutting, drilling, or demolishing
• Wet methods — Always wet asbestos cement materials before and during cutting to suppress dust and fiber release
• Hand tools preferred — Use hand tools rather than power tools when possible to minimize fiber generation
• Encapsulation or enclosure — Coating or covering intact asbestos cement products can extend their service life and prevent fiber release without requiring removal
• Professional removal — When removal is necessary, use licensed asbestos abatement contractors following local, state, and federal regulations