In an emotionally charged meeting at W. R. Grace Company's Cambridge plant, more than 20 residents of the area near the chemical manufacturer's principal dumping ground last night demanded to see testing results and expressed concern over plans to build on the site.

Grace held the first of three daily meetings after sending out 800 invitations to members of the North Cambridge community, and took questions from the floor after an hour-long presentation about chemicals in the adjacent dump and plans for building offices on 17 acres of the inactive dump.

Grace spokesmen said none of the chemicals in the ground or in the subsurface water were at dangerous levels, adding that all test results from the area were either on record with public agencies or being compiled for release early next year, before major construction will begin.

Several nearby residents, including members of the community group, North Cambridge Toxic Alert Coalition (NCTAC), however, charged that not enough tests had been run and that they had been unable to get results from the agencies named.

They said the tests, which were conducted by Haley & Aldrich, a consulting firm hired by Grace, might purposefully have avoided particularly suspect areas.

Residents said Haley & Aldrich also did not test for toxic chemicals such as dioxin, which they said is not included on the EPA's list of 129 priority tests which the firm conducted.

Some long-term residents of the site's neighborhood complained of unpleasant odors and said they were afraid for their children who play in the area or swim in nearby Jerry's Bond. They also challenged the image Grace put forward as a "good neighbor" concerned with the well-being of the community.

The Grace officials said none of their tests showed a dangerous level of any chemical, although they added in response to another question that some napthalene had entered the water. They said Haley & Aldrich were taking samples from approximately 25 wells on the development site.

Paul M. Connor of the company's Health, Safety and Toxicology Department said that napthalene, the main ingredient in moth balls, did not cause cancer and that the dump contained a small enough quantity of the chemical so that the only adverse effect might be the odor.

"The record shows we care," said David L. Whiteman, vice-president for administration of the Grace plant. "The relations between Grace and the community were founded on mutual respect, mutual, and proper communication."

Test results for a small area where the first building will be are on file at DEQE, and results for the rest of the ground and water will be filed there before the principal construction begins in a few months, Grace officials said.

Controversy over the dump began several years ago when testing during construction of the MBTA Alewife station revealed napthalene and soil so acidic it had to be removed for fear it would eat through the 18-inch thick concrete walls of the subway tunnel.

Toxic Alert Coalition members and other area residents have stepped up their efforts at getting a full range of tests in the dump this fall. They said they hope to discover which chemicals are present and in what quantity before Grace and Hines Industrial--Grace's partner in the building venture--pave over and build there.

The NCTAC announced plans a month ago for a public meeting to be held Thursday, and invited Grace officials to attend. Last night, NCTAC members accused the company of calling the more select sessions on their own ground in order to avoid addressing the concerns of the public.

But Grace spokesman said they could best express important facts through smaller meetings. Some residents shouted at an NCTAC member who lives in Porter Square, accusing him and other "outsiders" of trying to take over the meeting.