The Board of Education on Tuesday listened to a plan by an environmental consulting firm to look for possible PCB contamination at the town's schools.

The town hired the company, Woodard & Curran, after PCBs -- a possible carcinogen found in structures built or renovated from the 1950s to the 1970s -- were discovered in several areas at Osborn Hill Elementary School last spring.

Jeff Hamel, a principal with the firm, presented a step-by-step approach to carrying out the review, starting with a study of Osborn Hill and data from four other buildings to create a model of similar building materials and conditions.

"We're going to pull that together to try to understand the kind of probability at different schools and where we should focus," he said, adding that the testing would involve screening for chlorine, a PCB component. "If you don't have chlorine, you can't have PCBs, so it's a good way to do a quick screen," he said.

The firm would then examine and compare the other schools to the model to develop a probability of finding PCBs and potential risks, followed by an outline of next steps based on findings, according to a nine-page handout distributed at the meeting.

If PCBs are found at other schools, then it would be determined if it is necessary to remove the PCB-laden material, depending on whether it is intact, Hamel said.

"We can have a very intact piece of caulking that has PCBs that does not create a risk factor," he said, adding that PCB-laden materials that are deteriorating should be removed or encapsulated to prevent an air-quality issue. "That's something we want to focus in on."

He said three Fairfield schools were built after 1980 after PCBs were banned so those would be taken off the list of schools with potential contamination.

Lisa Camp, another principal with the firm, said the mere presence of PCBs in a building does not necessarily mean it poses a health risk, depending on exposure potential created by location and the condition of the material that the toxin is contained within.

The state Department of Health estimates teachers' risk for getting cancer from 30 years of exposure to PCBs levels in the gym, where levels at Osborn Hill were found to be highest, is 2 in 100,000, the firm states in its handout.

Board member Tim Kery asked why some areas of Osborn Hill with PCB contamination was found to pose a health risk whereas others with PCBs were not. In response, Hamel said conservative health risk levels are set for indoor air down to the nanogram, or one-billionth of a gram per metric cube of air.

The federal Environmental Protection Agency's recommended maximum concentration of PCBs in the air at an elementary school is 300 nanograms per metric cube of air.

"It's a very conservative number," Camp said, adding that it is assumed the children are also exposed to PCBs through fish, soil and other substances as well. "It doesn't mean you have an actual health risk."

The handout also gave several suggestions from the Environmental Protection Agency to reduce possible PCB exposure in buildings erected or redone from 1950 to 1978, such as improving ventilation and using wet cloths or mops to clean surfaces.

Founded in 1979, the company is based in Portland, Maine, with 10 offices in the Northeast, including locations in Windsor Locks and Cheshire. It has 650 employees.

Estimated costs to clean up the toxin at the Stillson Road school, where PCBs have been found in window caulking and a 1968 gym addition due to spray-on fireproofing, have cost more than $720,000 so far. Elevated levels of PCBs were also detected in two classrooms, the foyer floor, library and two lavatories when required testing was done in the spring before a window replacement project.

As a result, a temporary classroom has been rented for $73,448 to take the place of the gym, which is expected to be closed for the entire school year. Furthermore, another nearly $350,000 is expected to be spent on cleanup costs.

The firm is expected to give presentations to the Board of Finance and the Representative Town Meeting as well.; 203-255-4561, ext. 112;