Scott Cohen, recently retired staff director of the Senate Foreign Relations Committee, has opened a new political consulting firm in Washington specializing in government and public relations and foreign affairs. Cohen was foreign affairs advisor to former Sen. Charles H. Percy (R-Ill.) for 18 years and worked earlier as a foreign news correspondent.

R. Sarah Compton, formerly deputy assistant administrator for the U.S. Environmental Protection Agency, has left her position at the law firm of Collier, Shannon, Rill & Scott to become a partner at McDermott, Will & Emery in its Washington office. Kurt J. Olson, an associate at Collier, joins her at the law firm.

William J. Sargis, formerly president of the interior design division of Eisinger/Kilbane & Associates, and Andrew G. Jones, previously a national operations manager for Booz, Allen & Hamilton, have formed a new interior design consulting firm. Sargis & Jones will offer management services in all phases of interior planning and construction for commercial space.

Bon Secours Health System Inc., a Columbia health services and outreach organization, has named Jerry L. Rutherford senior vice president. An accountant, Rutherford was formerly southeast regional coordinator for Peat, Marwick's health-care audit services.

Gregory E. Hand, a professional engineer and past president of the Potomac chapter of the Maryland Society of Professional Engineers, has been named an associate of Loiederman Associates Inc., an engineering and land surveying firm in Rockville.

The MITRE Corp. in McLean has promoted Lawrence M. Kushner to consulting scientist, a special position that serves as a major resource for technical advice to be drawn upon by any department in the company. Kushner, who is the second person to hold the position, was with the National Bureau of Standards for 25 years before joining MITRE in 1980 as a staff member in its energy, resource and environmental systems division.

Metrocom Productions Inc., a film and video production firm, has hired Meg Mullery to manage marketing and promotion. Mullery, following stints with the Office of Public Liaison and then the Senate Liaison Office during the Carter administration, ran a government and public relations consulting practice.

The Carter Cos., a 5-year-old building maintenance firm, has appointed William Carter as chairman of the board, his son, Michael Carter, as president and Al Plotnick as president of the marketing division.

Creative Associates Inc., a government contracting firm specializing in the social sciences, information systems and private enterprise development, has appointed Ralph Arosemena as its chief financial officer.