U.S. Environmental Protection Agency officials announced yesterday that extensive tests have revealed only one dioxin "hot spot" at an old wood treating plant near Hollywood in St. Mary's County, Md., but high levels of at least two other suspected carcinogens.

That announcement last night at a public meeting in the Hollywood firehouse came more than six months after EPA officials declared the 10-acre Southern Maryland Wood Treating Corp. plant an emergency Superfund hazardous waste site. Initial tests by EPA last January showed troublesome levels of dioxin, an unwanted byproduct of burning or mixing chemicals, and officials said they would take immediate action since dioxin is considered a serious hazard.

That action -- considered too slow by state and county officials -- has consisted of fencing off the area, adding absorbent material to some polluted areas and additional tests. Some residents of the farm community say the pace has left them more frustrated than relieved, according to local health authorities.

"Whenever you mention the word dioxin, it strikes fear in the hearts of the general public, as well it should," said Dr. William Marek, health officer for the 65,000 people of St. Mary's, a county 50 miles southeast of Washington.

"People want to know what it is, what it means and what they're going to do about it. People tend to think it's taken too long and then they conclude erroneously that EPA officials are covering up something," Marek said in a telephone interview yesterday.

"Communities who are going through this ought to be brought right into the center of this picture and be brought up to date frequently. If there are delays, just say that -- lay the cards on the table."

Last night's meeting at the Hollywood firehouse was attended by about 35 local residents. They heard officials, including ones from EPA and the Maryland Department of Health and Mental Hygiene, explain details of the site cleanup.

EPA officials yesterday stressed that only one sample of dioxin found in soil near the wood treating plant's equipment is "slightly above a level of public health concern" set by the national Centers for Disease Control. They also said that the type of dioxin found was far less toxic than the kind found after a 1983 flood in Times Beach, Mo. Contamination at Times Beach prompted the federal government to resettle the entire town and has made dioxin the latest in a series of buzz words that mark concern over toxic chemical wastes.

The Southern Maryland Wood Treating Corp.'s location in a sparsely populated rural area also lessens its threat to public health, EPA officials said. "If you take our site and put it in downtown Washington, you might have a different action," said Jerry Heston, EPA's on-scene coordinator.

Heston was referring to CDC's recommendation that access to the site continue to be restricted while EPA studies how best to clean up ground water and other contamination there.

Of more concern than the traces of dioxin found at the defunct Hollywood plant, which is nestled above a spring-fed stream amid rolling farmland, are "significant levels" of PCPs, or pentachlorophenols, and creosote, two suspected carcinogens commonly used in wood treating.

Levels of up to 2,000 parts PCP for every billion parts of soil and up to 5,000 parts per million of creosote "pose a direct contact threat to human health as well as a surface and ground water contamination threat to the environment," according to a CDC memo to EPA on the site dated July 30.

Despite the frustration of months of waiting for test results, Marek said the people of St. Mary's are glad that EPA is working on the site. "We're dealing in a whole new era of public health with all these hazardous materials. Maybe we just don't have all the definitive answers people want," Marek said.