Any use of tobacco products is bad for you, regardless if you have a SCI or not. Chewing tobacco and snuff use is highly correlated with oral and throat cancer (baseball great Tony Gwynn died from this...he regretted chewing during his career and worked hard to get the word out as he was dying). Nicotine, in any form, constricts your blood vessels in your heart and skin as well, and makes you more likely to have pressure ulcers. So this includes smoking, chewing, dipping, and vaping.