Machinist's Mate: Toxic Exposure and VA Claims

Steam plants were wrapped in asbestos. The National Cancer Institute notes that shipbuilding used asbestos to insulate boilers, steam pipes, and hot water pipes, and Machinist's Mates disturbed that material constantly: stripping lagging to reach a leaking valve, scraping old gaskets off flanges, and repacking pumps and valves with asbestos-containing packing. The work took place in closed machinery spaces where fibers lingered in the air and settled on clothing. VA has recognized in Board decisions that the machinist's mate rating is a probable occupation for asbestos exposure aboard a naval ship, one that would normally place a sailor at high risk of exposure.

Machinist's Mates lived with fuel oil and lubricating oil: transferring and testing fuel, wiping down oily machinery, and clearing bilges where oil and water collected. Exposure came through vapors in hot, poorly ventilated spaces and through direct skin contact. The Agency for Toxic Substances and Disease Registry reports that breathing diesel fuel vapors for long periods may cause kidney damage, and that IARC has determined heavy fuel oils may possibly cause cancer in humans. Used mineral-based lubricating oil contains polycyclic aromatic hydrocarbons, and long-term skin exposure has caused skin cancer in animal studies.

Rebuilding a pump or valve starts with clean metal, and for decades the military's degreaser of choice was trichloroethylene (TCE). The National Cancer Institute notes that the U.S. military used TCE extensively for equipment degreasing. Machinist's Mates used solvent baths, rags, and spray cleaners on bearings, valve internals, and machined parts in engine rooms and machine shops, absorbing solvents through the skin and breathing vapors in confined compartments. NCI links prolonged or repeated TCE exposure to kidney cancer, with some evidence for non-Hodgkin lymphoma and liver cancer.

Engine room fires are fuel fires, and beginning in the 1970s the Department of Defense fought fuel fires with aqueous film forming foam (AFFF), which contains PFAS, the so-called forever chemicals. Machinist's Mates who served after that period may have handled AFFF during shipboard firefighting, damage control drills, and cleanup of foam discharges in machinery spaces. VA notes that PFAS may be associated with kidney and testicular cancer among other effects, although it considers the overall scientific evidence inconclusive, and no PFAS presumptive condition currently exists.