A 2021 longitudinal study conducted among populations of HIV-positive and HIV-negative adults found that smoke-related carcinogenic toxicants and biomarkers detected in tobacco smokers were also detected in exclusive marijuana smokers, including carbon monoxide (CO), polycyclic aromatic hydrocarbons (PAHs), aldehydes (such as acrolein), acrylonitrile and acrylamide metabolites, but exposures are lower compared with tobacco or dual smokers. Increased levels of acrolein exposure by tobacco smoking but not exclusive marijuana smoking were detected both in HIV-positive and HIV-negative adults, and contribute to increased diagnoses of cardiovascular diseases and respiratory diseases among tobacco smokers.Cannabis smoke contains thousands of organic and inorganic chemical compounds. This tar is chemically similar to that found in tobacco smoke or cigars. Over fifty known carcinogens have been identified in cannabis smoke. These include nitrosamines, reactive aldehydes, and polycylic hydrocarbons, including benz[a]pyrene. Marijuana smoke was listed as a cancer agent in California in 2009. A study by the British Lung Foundation published in 2012 identifies cannabis smoke as a carcinogen and also finds awareness of the danger is low compared with the high awareness of the dangers of smoking tobacco particularly among younger users. Other observations include possible increased risk from each cigarette; lack of research on the effect of cannabis smoke alone; low rate of addiction compared to tobacco; and episodic nature of cannabis use compared to steady frequent smoking of tobacco. Professor David Nutt, a UK drug expert, points out that the study cited by the British Lung Foundation has been accused of both "false reasoning" and "incorrect methodology".
Fractures of the scapular body with displacement may heal with malunion, but even this may not interfere with movement of the affected shoulder. However, displaced fractures in the scapular processes or in the glenoid do interfere with movement in the affected shoulder if they are not realigned properly. Therefore, while most scapular fractures are managed without surgery, surgical reduction is required for fractures in the neck or glenoid; otherwise motion of the shoulder may be impaired. Epidemiology
Scapular fracture is present in about 1% of cases of blunt trauma and 3–5% of shoulder injuries. An estimated 0.4–1% of bone fractures are scapular fractures.The injury is associated with other injuries 80–90% of the time. Scapular fracture is associated with pulmonary contusion more than 50% of the time. Thus when the scapula is fractured, other injuries such as abdominal and chest trauma are automatically suspected. People with scapular fractures often also have injuries of the ribs, lung, and shoulder. Pneumothorax (an accumulation of air in the space outside the lung), clavicle fractures, and injuries to the blood vessels are among the most commonly associated injuries. The forces involved in scapular fracture can also cause tracheobronchial rupture, a tear in the airways. Fractures that occur in the scapular body are the type most likely to be accompanied by other injuries; other bony and soft tissue injuries accompany these fractures 80–95% of the time.