Ground Zero Special Ops Firefighters Took Heavy Chemical Hit

Scientists from the Centers for Disease Control and Prevention, National Center for Environmental Health, National Institute for Occupational Safety and Health, New York City Fire Department Bureau of Health Services, the Department of Pulmonary Medicine at Albert Einstein College of Medicine, and the Montefiore Medical Center conducted the only biomonitoring study performed after the WTC collapse and during rescue operations.

Calling it the most extensive biomonitoring study ever performed on any occupational group during the first weeks of exposure to a major fire, building collapse, or urban disaster, the scientists measured up to 110 chemicals in 368 firefighters.

Thirteen of those chemicals showed statistically significant concentrations in some firefighters. For 11 of the 13 chemicals, firefighters in the Special Operations Command had concentrations that were higher than those of the other firefighter group.

The study was designed to investigate internal dose levels of fire related chemicals and the relationship of those levels with firefighter activities at Ground Zero, the site of the World Trade Center towers hit by two jetliners hijacked by terrorists. Chemical concentrations in blood and urine were compared withfirefighter job task, time of arrival at the site, and number of work days at the site.

For only two of the 13 chemicals -- urinary antimony and urinary cadmium -- levels were higher in firefighters present at the collapse of the towers compared with those who arrived after the collapse during days one and two after the collapse.

Blood and urine specimens were obtained from 321 firefighters responding to the World Trade Center fires. Controls consisted of 47 firefighters not present at the World Trade Center. Sampling occurred three weeks after September 11, while fires were still burning.

Special Operations Command firefighters had more than twice the level of the polycyclic aromatic hydrocarbon (PAH) 1-hydroxypyrene in their urine as did other exposed firefighters or control firefighters. The urinary concentrations of PAHs in the other exposed firefighters were similar to controls.

Heptachlorodibenzodioxins and heptachlorodibenzofurans, chemicals are produced when carbon and chlorine combine at high temperatures, were found in statistically significant concentrations in exposed firefighters when compared with control firefighters.

The metal antimony was found in unexpectedly high concentrations, researchers said. Firefighters present at the collapse of the World Trade Center had urinary antimony levels that were statistically higher than those of firefighters arriving one or two days after the collapse of the buildings or of the control group.

Antimony levels in the urine of the Special Operations Command group was twice as high as that of the other exposed firefighters or controls. Antimony is present in the environment in very low concentrations and has been used in glass as a coloring agent, in nonlead solders, metallurgy, electronics, and the manufacture of plastics.

Lead levels were statistically higher in exposed firefighters than in control firefighters, but the increase was small, far below clinically significant levels.

Mercury levels were not higher in exposed firefighters but were mentioned in the study because of heightened concern about exposure at the World Trade Center.

A major cause of mortality from smoke inhalation at structural fires is cyanide poisoning, but, the scientists said, blood cyanide levels reflect exposure in the 24 hours before testing, so their study shows only that the firefighters were not exposed to significant amounts of cyanide at the time of sampling, three weeks after September 11.

For volatile organic compounds, scientists said some firefighter groups had recent or continual exposures. Because of the variety of sources that could contribute to the low levels measured -- fires, solvents in the debris, indoor air, drinking water, vehicular fuels, and exhausts -- it is difficult to pinpoint a specific source. Only six exposed firefighters had volatile organic concentrations above baseline figures.

Comparison of exposed and control groups indicated that chemical levels in exposed firefighters, although statistically elevated, were generally low compared with reference values in the general population or workplace threshold levels, the scientists said.

Firefighter exposures during the World Trade Center disaster were "unique and extreme," they said. "Our findings should not be generalized to other populations working or living near WTC."