The comprehensive development plan for the McLean central business district is being challenged by a half dozen proposals seeking to increase the density of existing land uses.

Some of those proposed changes could double the density of buildings in the area, a fact that troubles many local leaders.

Doubling the density could lead to major changes by increasing land costs and eventually bringing about redevelopment of existing single-story shopping centers, said Lilla Richards, chairman of the McLean Citizens Association's transportation committee.

Two public meetings on the proposed changes are scheduled next week. The McLean Planning Committee, which represents the local business community and residents of adjacent neighborhoods, will discuss proposals at a 7:45 p.m. meeting Wednesday at the McLean Community Center.

The McLean Citizens Association's planning and zoning committee has scheduled a town hall meeting on the proposals for 8 p.m. Thursday at the community center's Alden Theatre. Residents will be allowed to ask questions of those seeking the changes, according to Stephen Hubbard, chairman of the planning and zoning committee. He said discussion on proposed changes to the plan will be held, but he said he was not sure if members of his group would be ready to vote because of intense community interest in several of the proposals.

Three of the proposed changes would double the density presently allowed on three sites. If the density is allowed to increase, residents said they fear many local merchants may disappear as a result of rising land values.

"Where are we going to grocery shop?" asked Richards. She said she watched increasing land values drive grocery stores from the Clarendon area of Arlington and from the Tysons Corner area.

Robert Young, head of the planning committee said his group will hear proposals from several applicants. The planning committee deals only with proposals in or adjacent to the business district.

Here are a few of the proposals to be discussed at next week's meeting:

* An application to double the density on land adjacent to McLean House, a high-rise residential building, with frontage on Elm Street and Fleetwood Road near the Dynalectron building.

* An application to allow the construction of town houses surrounding a historic house known as Merryhill. The old home would be preserved, but the owner wants to build town houses at a density of five to eight units per acre on the land that faces Dolley Madison Boulevard next to Madison of McLean, a luxury town-house development.

* Two proposals to change the land plan for town houses to commercial for land in the Lowell Avenue, Emerson Avenue and Laughlin Avenue area because of traffic generated by the Giant Gourmet specialty grocery store and the expected impact of a new fire station that is to be build on Lowell.

* Proposals by residents of portions of Bryn Mawr subdivision to have their land changed from residential because of what the applicants call inconsistencies in the master plan that have allowed commercial development to intrude into their neighborhood.

The entire Bryn Mawr subdivision is not included in the proposal.

Any action by the MCA's planning and zoning committee would be referred to that organization's board for a vote.