Mare Island Naval Shipyard Asbestos Exposure

Mare Island Naval Shipyard, the U.S. Navy's first shipyard on the Pacific Coast, operated continuously from September 16, 1854, until its closure in April 1996. Located on a narrow peninsula in Vallejo, California, it built and repaired hundreds of naval vessels over more than a century. For much of that time, asbestos was woven into nearly every phase of construction, from insulating steam pipes and boilers to fireproofing bulkheads and lining engine rooms. Workers who built, repaired, or served aboard ships at Mare Island were routinely exposed to airborne asbestos fibers, often without any protective equipment or warning.

According to the National Cancer Institute, asbestos exposure is the primary known cause of malignant mesothelioma, an aggressive cancer of the lining surrounding the lungs, abdomen, or heart. Because the disease can take 20 to 50 years to develop after first exposure, many veterans and workers who spent time at Mare Island during the mid-20th century are only now receiving diagnoses. The shipyard's long operational history means the affected population spans multiple generations of U.S. Navy personnel and civilian laborers.

Mare Island is widely recognized by occupational health researchers as one of the highest-risk asbestos exposure sites in the United States. A 2003 study published in the American Journal of Industrial Medicine identified naval shipyards as among the most concentrated sources of occupational asbestos exposure in American history, with workers in insulation, pipefitting, and boiler trades facing the heaviest fiber burdens. Mare Island, given its size and the volume of nuclear submarine construction it handled after World War II, represents a significant portion of that legacy.

If you or someone you love worked at Mare Island or served aboard a vessel built or overhauled there, understanding the specific exposure risks, the diseases that can result, and your legal rights is critically important. The latency of asbestos-related diseases means that diagnoses are still being made today among people whose exposure ended decades ago.

Asbestos exposure at Mare Island did not occur in a single setting or trade. It was pervasive across multiple job categories and work environments, each carrying its own level of risk.

Insulation Workers and Laggers

Insulation workers, sometimes called laggers, applied asbestos-containing insulation to pipes, boilers, turbines, and steam lines throughout ships under construction or repair. This work generated some of the highest airborne fiber concentrations documented in any occupational setting. According to a study by Dr. Irving Selikoff published in the Annals of the New York Academy of Sciences in 1965, insulation workers faced mesothelioma mortality rates dramatically elevated compared to the general population. At Mare Island, laggers worked in confined spaces with poor ventilation, compounding their exposure.

Pipefitters and Boilermakers

Pipefitters and boilermakers routinely cut, shaped, and installed asbestos-wrapped components in engine rooms and fire rooms aboard vessels. Cutting asbestos-wrapped pipe or gaskets released fine respirable fibers into the air. The American Cancer Society notes that any activity that disturbs asbestos-containing materials creates the highest risk of fiber inhalation. These tradespeople often worked directly alongside insulation workers, receiving secondary exposure on top of their own primary risks.

U.S. Navy Veterans

Sailors who served aboard ships built or overhauled at Mare Island faced exposure both during construction periods and while at sea. Engine room personnel, damage control specialists, and machinist's mates worked in spaces where asbestos insulation was present on nearly every surface. The U.S. Department of Veterans Affairs acknowledges that Navy veterans, particularly those who served between 1930 and 1970, represent one of the populations most heavily burdened by asbestos-related disease.

Secondary and Household Exposure

Workers did not leave asbestos at the shipyard gate. Fibers clung to clothing, hair, and skin, and were carried home. Family members, particularly spouses who laundered work clothes, faced what researchers call secondary or para-occupational exposure. The Agency for Toxic Substances and Disease Registry (ATSDR) has documented mesothelioma cases in household contacts of shipyard workers who never set foot in the yard themselves.

Diseases caused by asbestos exposure at Mare Island typically don't announce themselves quickly. That's one of the most dangerous aspects of asbestos-related illness: by the time symptoms appear, the disease is often advanced.

The most serious condition associated with Mare Island asbestos exposure is malignant pleural mesothelioma, which affects the lining of the lungs. According to the Mayo Clinic, symptoms of pleural mesothelioma include persistent chest pain, shortness of breath that worsens over time, a dry or painful cough, unexplained weight loss, and fatigue. These symptoms are often mistaken for less serious conditions like pneumonia or age-related lung changes, which delays diagnosis.

Asbestosis, a chronic scarring of lung tissue, produces symptoms that include progressive shortness of breath, a persistent dry cough, chest tightness, and a characteristic crackling sound in the lungs when breathing, known as bibasilar crackles. The National Heart, Lung, and Blood Institute notes that asbestosis symptoms typically appear 10 to 40 years after exposure and tend to worsen over time, even after exposure has ended.

Lung cancer related to asbestos exposure produces symptoms similar to other forms of lung cancer: a new or changing cough, coughing up blood, chest pain, hoarseness, and recurrent respiratory infections. Workers who also smoked face a dramatically elevated risk. According to the National Cancer Institute, the combination of asbestos exposure and cigarette smoking multiplies lung cancer risk by a factor of up to 50 compared to non-smoking, non-exposed individuals.

The central cause of disease among Mare Island workers and veterans is inhalation of asbestos fibers, microscopic mineral strands that the human body cannot break down or expel once they lodge in tissue. Mare Island's construction and repair activities created conditions for fiber release across virtually every department of the shipyard.

Asbestos was used at Mare Island in dozens of products and materials, including pipe insulation, boiler insulation, gaskets, packing materials, deck tiles, ceiling tiles, fireproofing spray, and thermal insulation blankets. The U.S. Navy, like other branches of the military, relied heavily on asbestos through the mid-20th century because of its heat resistance, durability, and low cost. According to the U.S. Department of Veterans Affairs, asbestos was considered a standard and even preferred construction material for naval vessels from the 1930s through the early 1970s.

When asbestos-containing materials are cut, drilled, sanded, or otherwise disturbed, they release respirable fibers into the air. In the enclosed spaces of a ship under construction or repair, those fibers had nowhere to go. Workers breathed them in over years and sometimes decades of employment. The fibers that reach the deepest portions of the lung, called the alveoli, or penetrate the pleural lining, are the ones most associated with mesothelioma and asbestosis.

The specific asbestos types used at Mare Island included chrysotile (white asbestos), amosite (brown asbestos), and crocidolite (blue asbestos). Amosite and crocidolite are considered the most hazardous forms, and both were widely used in naval insulation products. A 1978 study in the Journal of Occupational Medicine found that shipyard workers exposed to amosite-containing insulation products faced particularly elevated rates of mesothelioma compared to workers exposed primarily to chrysotile.

Not everyone who worked at Mare Island faces the same level of risk. Several factors determine how much asbestos exposure a person received and how likely they are to develop an asbestos-related disease.

• Trade and job role: Insulation workers, pipefitters, boilermakers, and sheet metal workers faced the heaviest direct exposure. Electricians, painters, and carpenters working nearby also received significant secondary exposure.
• Duration of employment: Workers who spent many years at Mare Island accumulated higher cumulative fiber doses than those who worked there briefly. However, even short-term exposure can cause mesothelioma, and there is no known safe level of asbestos exposure according to the NCI.
• Era of employment: Workers employed between the 1930s and early 1970s faced the greatest risk, as asbestos use was at its peak and regulatory protections were essentially nonexistent. OSHA did not establish its first asbestos exposure standards until 1972.
• Smoking history: Smoking dramatically increases the risk of asbestos-related lung cancer, though it does not appear to increase mesothelioma risk specifically. Workers who smoked and were exposed to asbestos face the highest lung cancer risk of any occupational group.
• Genetic predisposition: Research published in Nature Genetics in 2011 identified mutations in the BAP1 gene as a factor that increases susceptibility to mesothelioma following asbestos exposure. A small percentage of mesothelioma patients carry this mutation.

Family members of Mare Island workers also carry elevated risk due to secondary exposure. The ATSDR documented that household contacts of heavily exposed shipyard workers have developed mesothelioma at rates above the general population, underscoring the reach of occupational asbestos exposure beyond the workplace itself.

Imagine a 68-year-old retired pipefitter who spent 22 years at Mare Island. He's been experiencing shortness of breath for several months, chalking it up to age. His primary care doctor orders a chest X-ray and finds a pleural effusion, a buildup of fluid around the lung. That finding triggers a cascade of more specialized testing, and weeks later, he receives a mesothelioma diagnosis. This scenario plays out regularly among former Mare Island workers and their physicians.

Diagnosing asbestos-related diseases in former Mare Island workers requires a combination of occupational history, imaging, and tissue analysis. A thorough occupational history is the starting point. Physicians who specialize in occupational medicine or thoracic oncology will ask detailed questions about where you worked, what you did, and during which years, since exposure history directly informs the differential diagnosis.

Imaging studies, including chest X-rays and high-resolution computed tomography (CT) scans, can reveal pleural plaques (calcified thickening of the pleural lining), pleural effusions, interstitial lung changes consistent with asbestosis, or masses suspicious for mesothelioma. The American College of Radiology notes that pleural plaques visible on CT are considered a reliable marker of prior asbestos exposure, even when the patient has no symptoms.

When mesothelioma is suspected, tissue biopsy is required for a definitive diagnosis. This is typically obtained through video-assisted thoracoscopic surgery (VATS), CT-guided needle biopsy, or thoracentesis with cytological analysis of pleural fluid. Pathological examination uses immunohistochemistry to distinguish mesothelioma from lung adenocarcinoma and other malignancies. According to the National Comprehensive Cancer Network (NCCN), markers such as calretinin, WT-1, and D2-40 are used to confirm a mesothelioma diagnosis.

Pulmonary function testing helps assess the degree of lung impairment in patients with asbestosis or pleural disease, and is often used in the context of disability claims and legal proceedings related to Mare Island exposure.

Treatment for asbestos-related diseases diagnosed in former Mare Island workers follows the same clinical protocols used for these conditions in the broader population, though treatment decisions are often complicated by the patient's age, overall health, and the advanced stage at which many diagnoses occur.

For malignant pleural mesothelioma, treatment options depend on the disease stage and the patient's performance status. According to the National Cancer Institute, standard treatment approaches include surgery (extrapleural pneumonectomy or pleurectomy/decortication), chemotherapy with the combination of pemetrexed and cisplatin (approved by the FDA in 2004 specifically for mesothelioma), and radiation therapy. Immunotherapy, particularly the combination of nivolumab and ipilimumab approved by the FDA in October 2020, has shown improved survival in some patients with unresectable mesothelioma, according to results from the CheckMate 743 trial published in The Lancet in 2021.

Asbestosis has no curative treatment. Management focuses on slowing progression, relieving symptoms, and preventing complications. Pulmonary rehabilitation, supplemental oxygen, and smoking cessation are the primary interventions. Annual influenza vaccination and pneumococcal vaccination are strongly recommended, as respiratory infections can be particularly dangerous in patients with compromised lung function.

For asbestos-related lung cancer, treatment mirrors that for other non-small cell lung cancers and may include surgery, chemotherapy, targeted therapy, immunotherapy, or combinations depending on the tumor's molecular profile and stage. Given the strong association between asbestos exposure and lung cancer, oncologists treating former Mare Island workers should routinely assess exposure history when planning care.

The prognosis for mesothelioma remains challenging. According to the American Cancer Society, the median survival for pleural mesothelioma is approximately 12 to 21 months from diagnosis, though this varies considerably by stage, cell type, and treatment received. Epithelioid mesothelioma, the most common cell type, generally carries a better prognosis than sarcomatoid or biphasic subtypes. Patients diagnosed at an early stage who are candidates for aggressive multimodal therapy, combining surgery, chemotherapy, and radiation, have achieved median survivals exceeding 24 months in some clinical series.

Asbestosis prognosis depends on the severity of lung scarring at diagnosis and whether exposure has ended. The disease is progressive and irreversible, but its rate of progression varies. Some individuals remain relatively stable for years, while others experience rapid decline in lung function. The National Heart, Lung, and Blood Institute notes that asbestosis increases the risk of lung cancer and mesothelioma, meaning that even patients without an initial cancer diagnosis require ongoing surveillance.

For former Mare Island workers and their families, earlier diagnosis remains the most significant factor affecting outcomes. Individuals with documented occupational asbestos exposure are encouraged to discuss screening options with their physicians, including low-dose CT scanning, which is approved for lung cancer screening in high-risk individuals under current U.S. Preventive Services Task Force guidelines.

Prevention of new asbestos-related disease among former Mare Island workers is no longer possible in the traditional sense, since the exposure has already occurred. What matters now is surveillance, early detection, and avoiding additional exposures that could compound existing risk.

Former workers and veterans should inform their primary care physicians about their Mare Island employment history and the specific trades they worked in. This information should be documented in the medical record so that any respiratory symptoms are evaluated with asbestos exposure in mind. The Occupational Safety and Health Administration recommends periodic medical surveillance, including pulmonary function testing and chest imaging, for individuals with documented occupational asbestos exposure.

Smoking cessation is the single most actionable step that former Mare Island workers who smoke can take to reduce their cancer risk. The combined effect of asbestos and tobacco on lung cancer risk is multiplicative, not merely additive. Quitting smoking, even decades after exposure, reduces lung cancer risk over time, according to the American Cancer Society.

For individuals who may be involved in renovation or demolition of older structures, it's worth knowing that asbestos-containing materials remain present in many buildings constructed before 1980. Disturbing these materials without proper protective equipment creates new exposure risk on top of any historical exposure from Mare Island work.

A diagnosis of mesothelioma or asbestosis connected to Mare Island service or employment brings with it not only medical challenges but also significant emotional, financial, and legal dimensions. You don't have to navigate these alone, and many resources exist specifically for veterans and shipyard workers in this situation.

The U.S. Department of Veterans Affairs provides disability compensation and healthcare benefits to veterans with service-connected asbestos-related diseases. Filing a VA claim requires documenting the connection between your military service, your presence at Mare Island or aboard ships built there, and your current diagnosis. Veterans Service Organizations, including the American Legion and the Disabled American Veterans, can assist with the claims process at no cost.

Many former Mare Island workers and their families have pursued legal claims against the manufacturers of asbestos-containing products used at the shipyard. These civil lawsuits are separate from VA claims and can result in compensation through jury verdicts or settlement. Asbestos litigation has a complex procedural history, and statutes of limitations vary by state, so speaking with an attorney who specializes in asbestos cases is advisable if you're considering this route.

Support groups for mesothelioma patients and their families exist both locally in the Vallejo and San Francisco Bay Area and nationally through organizations like the Mesothelioma Applied Research Foundation. Connecting with others who share similar experiences can provide practical guidance and emotional support during a difficult time.