Ok, sulfuric acid causes cancer. It's an IARC group one classification https://www.osha.gov/dts/chemicalsampling/data/CH_268700.html Nitric and phosphoric are not known to cause cancer. Only the workers that inhaled sulfuric acid got cancer. All inorganic acids are dangerous. Just because our bodies need sulfur, doesn't mean that all of the different physical forms of sulfur are compatible with our physiology. (Like sulfuric acid, or sulfur dioxide) Chloride is necessary for the chemical reaction that causes stomata to open and close. It's found in all plant tissue.