Research on the safety and effectiveness of using ultrasound treatments to kill sperm has undergone since the idea originally came about following experiments in the 1970s by Mostafa S. Fahim who noticed ultrasound killed microbes and decreased fertility.[48] As of 2012 a study conducted on rats found that two 15-minute treatments of ultrasound delivered 2 days apart in a warm salt bath effectively lowered their sperm count to below fertile levels.[6][48] Another small study involved dogs, and found that after three ultrasound applications the dogs' ejaculate contained no sperm.[5] Further experiments on its effectiveness on humans, the longevity of the results, and its safety have yet to be conducted.[48]