Four technical studies have been conducted so far. Behavioral studies have also been conducted on hikers themselves. However, clinical trials have not been conducted. Additional surveys are now being conducted throughout the region. Therefore, further research is being conducted. By 2007, it had conducted 75 such investigations. Mortality is higher in men in studies conducted in China and Italy. During 1942, high altitude experiments were conducted. Besides that, Data Folha has also conducted research on this subject. In reality, those experiments cannot be conducted. Human testing has not been conducted. In May 2004, two polls were conducted statewide. Some major reform efforts have been conducted. After graduating, Stevenson conducted research in biochemistry. Soil tests were conducted by Greenpeace in 1999.