The cartilage rings are C-shaped because the back of the trachea presses against the esophagus. The cartilage opens at the esophagus and is replaced by connective tissue and muscle. This gives the esophagus space to allow food to be swallowed easily. The rings of the trachea are stacked one on top of the other, with a small space between them.
In 2014, a survey of the Australian working population revealed that the most common carcinogenic exposures in the workplace were solar ultraviolet radiation, diesel engine exhaust, environmental tobacco (second-hand) smoke, benzene, lead and silica.
Workplace exposures. Lead poisoning in adults is usually due to lead exposures in the workplace. Workers can inhale lead dust or fumes, or swallow dust while eating, drinking, or smoking through hand-to-mouth contact.Workers who perform certain jobs and activities are at a higher risk for lead poisoning. simple blood lead test is the only way to find out if an adult has lead poisoning. The test, known as a blood lead level (BLL), measures how much lead is in your body. If you think you are exposed to lead at work or at home, as your employer or family physician for a blood lead test.