In the late 1970s, Cash worked with BRAC (presently the world's largest NGO in terms of programs and personnel) on their OTEP (Oral Therapy Extension Programme), which taught over 13 million mothers and caregivers how to prepare and use ORT in the home using the "pinch and scoop" method.

For demonstrating how inexpensive and simple-to-use oral rehydration therapy (ORT) could treat cholera and other diarrheal diseases, then by promoting in the developing world customized applications of oral rehydration therapy (ORT) developed by Cash and David R. Nalin (at Merck in Vaccine Development from 1983 to 2002), Cash, David Nalin, and Dilip Mahalanabis became joint recipients of the 2006 Prince Mahidol Award in public health for "exemplary contributions in the field of public health" and for their contributions "to the application of the oral rehydration solution in the treatment of severe diarrhea worldwide, including Thailand.

After the breakup of the Soviet Union, Cash served (beginning in 2003) with the Russian Academy of Sciences project on development of bioethics capacity in the Commonwealth of Independent States.

For eleven years, as Director of the Program on Ethical Issues in International Health Research and in line with his deep commitment to capacity building in growing nations, he has conducted training workshops based on this research in at HSPH, and in 18 nations in South America, Africa, India, and the Middle East, covering issues of informed consent, confidentiality, conflict of interest, investigator responsibilities to study populations, research in resource poor environments, and the development of ethical review committees.

Richard Cash had been interviewed intermittently (often in remote meetings) to comment on the legacy of work he had done in the Middle East, India, and Himalayas.