AsbestosMonitoringWTCrec

By JOE GROSSMAN, UPI Science News

NEW YORK, Sept. 12 (UPI) - - Although apparently extensive asbestos removal programs had been conducted in the World Trade Center towers destroyed yesterday morning by terrorists, it remains unclear what degree of health threat remains from asbestos fiber in the debris. In light of the uncertainty, several experts are recommending continuous monitoring of the site, throughout rescue and cleanup operations.

At the time the two towers were constructed, from 1968 through 1972, inhaled asbestos fiber as a health threat was just beginning to be recognized. Up until that time it was routine for the steel girders of skyscrapers to be sprayed with an asbestos material. After the health threat was recognized, other materials were substituted in the fireproofing spray. Steel will melt in an intense fire. Asbestos slowed the process.

According to Robert Szantner, a principle of Minoru Yamasaki Associates, the architectural firm that designed the World Trade Center, asbestos was used in the construction. "Originally, when the building was built, it did have asbestos in the building. But the Port Authority, once they discovered that asbestos was a problem, put together a remediation program, that through the course of many years was eliminating most of the asbestos in the building. However, there may be some minor areas that hadn't yet been completely upgraded to new fireproofing on the structural steel. So that should be the only remaining asbestos in the building. In proportion it should be fairly nominal," Szantner told United Press International Most of the dust in the air is gypsum board and pulverized concrete, Szantner said.

The structural steel can be accessed to clean off the asbestos and this was done for much of the building, according to Szantner. "Judging from the program the Port Authority had, there shouldn't be much asbestos left in the building," Szantner said.

One person who is close to the construction companies involved in the building of the towers has been involved in trying to determine the extent that asbestos was used. The source told UPI, on the condition of anonymity, that it appears that asbestos had only been used in the first third of the first tower. Emerging health concerns probably halted its use, after that, the source said. "It was being installed for probably the first third of the first tower, but since we were on the cusp of spray fireproofing with asbestos versus spray fireproofing without, because it was when asbestos started to become suspect, the Port Authority stopped its being installed, and the rest of the building was installed without it," the source said. "It's definately safe to say it was not installed in all of both buildings," the source added.

According to Richard Kielar, a spokesperson for Tishman Realty and Construction Company, the general contractor for the construction of the World Trade Center, spray fireproofing would have been sprayed on structural steel, the perimeter columns, the trusses that held up the slabs and also the interior core columns, in those portions of the two buildings where it was indeed used. Kielar said that it was proving difficult to obtain copies of the original plans, which are stored in hundreds of boxes.

Protracted exposure to asbestos fibers can cause scarring of the lung (asbestosis), lung cancer and cancer of the membrane covering the lungs, called mesothelioma.

According to Phillip Harber, professor and chief of occupational and environmental medicine at UCLA Medical School, "When you're looking at relatively low dose exposure, malignant mesothelioma is the thing you worry about," Harbar said, but added that exposure would need to go on for months or longer to cause the disease, which can take 20 to 30 years to appear.

Intense exposure for a brief period of time is not very likely to cause disease. "Asbestosis itself, lung scarring, that's not a real concern for people whose exposure was running out of the building or doing search and rescue operations. . . . That takes a much higher dose," Harber said.

"The important thing is to measure what's there. Go down and measure what's in the air, and go down and stir it up and see if that creates a cloud of it," Harber said. "If there is significant asbestos in the debris then it should certainly be handled appropriately to limit exposures, " he added.

"It's not so much the risk of running down the stairs, being in the area for an hour or five hours, but rather what is going to occur over the next two months or six months or whatever the cleanup is," Harber said. If the buildings had extensive asbestos in them, to do the cleanup safely is going to be more complicated. People doing the clean up would need to be appropriately protected. As the material is stirred up it would be necessary to protect people who work or live in the area, if significant levels of asbestos are detected, he added. According to Harber, "It will be critically important to ascertain whether or not the material was present and secondarily to periodically monitor."

Patrick Breysse, associate professor of environmental health sciences at Johns Hopkins Bloomberg School of Public Health told UPI, "The big challenge in this case is in documenting what the airborne levels are." Occupational standards for traditional workplaces would keep exposures below 100 fibers per liter of air, Breysse said. "I'd get some air samples out there and I'd monitor to see what the asbestos levels are, regardless of how much asbestos was in the building. Clearly some had to have stayed in the buildings," Breysse said. Workers could wear a monitoring device that weighs about a pound, and if recommended levels were exceeded, Breysse recommenced respiratory protection for workers at the site.

(Reported by Joe Grossman in Santa Cruz, California)