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Potential for Carcinogenicity from 
Exposures to VOCs and Metals 

Related to 9/11 

Virginia M. Weaver, MD, MPH 
Environmental Health Sciences 

Key Concepts/Questions 

Cancer risk related to dose (concentration x duration) 

- Generally considered an outcome from chronic exposure 

- What is the shortest exposure duration that results in 
measurable increased risk for cancer? 

• Atomic bomb survivors, despite exposure to one bomb, had 
chronic exposure from internal radiation and persistent 
radioactivity environmentally 

- Steeper exposure rate may result in greater risk 

- Exposure construct for cancer differs from that for pulmonary 

• Collapse versus burning pile/exhaust/persistent carcinogens 
in dust 

Example of Exposure Categorization for 
Cancer (Lorber et al, 2007) 

The data on PAHs sorbed to PM divided into three 

- early group (from Day 12 to Day 50) 

• major WTC fires, activity from diesel engine activity of GZ 
power generation, demolition equipment (cranes, bulldozers), 
and debris removal (trucks) 

- middle group (from Day 51 to Day 100) 

• sporadic fires, some scaled-back rescue activity, and truck 

- late group (from Day 101 to Day 200) 

• Fires officially out, most WTC demolition done, power 
restored, and only truck traffic and background remained as 
PAH sources 

Key Concepts/Questions 


- Cancer outcomes vary by time since exposure onset 

- Traditional teaching 

•4-6 years for radiation induced leukemias 

• 15-20 for most solid tumors 

• 35-40 for asbestos induced mesothelioma 

Mixtures - limited data yet common exposure 

WTC IARC VOCs with Human Cancer 

Group 1 

- Benzene - acute non-lymphocytic leukemia; limited evidence 
that benzene causes acute lymphocytic leukemia, chronic 
lymphocytic leukemia, and multiple myeloma in humans (Baan 
etal. 2009) 

• Supported by Vlaanderen et al meta-analysis EHP 2008 

- 1, 3-butadiene - leukemia and non-Hodgkin lymphoma 

- Formaldehyde - nasopharyngeal, leukemia (strong but not 
sufficient); limited for sinonasal 

- Vinyl chloride - angiosarcoma of the liver 

2A: Benzyl Chloride, ethylene dibromide, 
tetrachloroethylene, trichloroethylene 


Exposure Characteristics 

Exposures present in combustion products 
- burning pile and diesel exhaust 

Not persistent in environment and do not accumulate 
in body 

• So exposures during active generation (fires, diesel) 

Associated with short latency cancer (leukemia) 

Limited VOC Monitoring (Lorber et al 

Samples to characterize VOC emissions within smoldering 
piles on GZ and on other work areas within and bordering GZ 
to determine if the area was safe for entry by rescue workers 
and firefighters 

- When samples showed "extremely high concentrations of VOCs", entry 

Mainly 4 min "grab samples" 

- comprise the bulk of all measurements for VOCs 

4-minute grab samples exceeded screening benchmarks 
outside of GZ but still within restricted zones for: 

- 1,3-butadiene, chloromethane, ethylbenzene, toluene, and acetone 

• limited number 24-hour samples taken from GZ perimeter; 1,3- 
butadiene, ethylbenzene, and toluene ~ 1,000 times lower than 4 
min samples 

Benzene Monitoring (Lorber et al 2007) 

4-minute grab samples exceeded screening benchmarks inside and 
outside restricted zones 

- Actual values not in this publication 

24-hour samples within a factor of 10 of the grab samples 

- suggests that the grab sample concentrations were closer to sustained 

Six of fourteen 24-hour samples were above the detection limit of 
0.0007 ppm 

- three at 0.0007 or 0.0008, and three at 0.002, 0.0025, and 0.005 ppm. 

- ATSDR Intermediate (>14-364 days), MRL of 0.004 ppm (current appears 
to be 0.006 ppm for noncancer health effects ) 

- historic average for New York City of about 0.0005 ppm 

"data suggest that the exposures to benzene at levels that approach 
the Intermediate MRL were not likely to have lasted longer than 45 

VOCs Monitorina Results 

Monitoring of truck drivers (Geyh et al 2005) 

- Highest personal sample = 9 ppb 

Until mid Dec: "airborne particulate levels in lower 
Manhattan continued to decline but rose intermittently at 
night and when the air was still. Transient increases were 
noted also when the pile was disturbed and fires flared. 
Diesel exhaust became an important contaminant" 
(Landrigan 2004) 

"acrid cloud hung over lower Manhattan and areas of 
Brooklyn until the fires were finally extinguished on 20 
December." (Landrigan 2004) 

VOCs Potential Implications 

Workers on pile are potential risk group 

Was dose enough to cause measurable increase in 

- Highest 24 hour sample = 5 ppb but OSHA benzene std = 
1000 ppb; NIOSH REL = 100 ppb 

• based on for 40 hours per week x 40 years 

- Levels potentially higher than measured values but still for 
limited time period 

IARC Group 1 Metals with Major Human 
Cancer Sites 

Arsenic - urinary bladder, lung, skin, liver, and kidney 

Beryllium - Lung cancer 

Cadmium - Lung cancer; prostate with Cd chloride 

Chromium - Lung and sinonasal cancer 

Nickel - lung and nasal cancers 

Inorganic lead - 2A 



Acknowledgement: Thank you to Susan Sidel 

- WTC metal exposures complex 

- my expertise is metals and kidney 

Metals: Cahill Incinerator Hypothesis 

"simultaneous presence of finely powdered (circa 5 pm) 
and highly basic (pH 11 to 12) cement dust and high 
levels of very fine (< 0.25 |jm) sulfuric acid fumes" 

"unprecedented levels of several metals in the very fine 
mode aerosols" 

- "liberation of those metals that are both present in elevated 
concentrations in the debris and have depressed volatility 
temperatures caused by the presence of organic materials and 
chlorine under anaerobic conditions." 

- "Health concerns focus on the workers at the site, as plume 
lofting protected most of New York City." 

Cahill et al. Chap. 9 Very Fine Aerosols from the World Trade Center Collapse Piles: Anaerobic 
Incineration? Urban Aerosols and Their Impacts: Lessons Learned from the World Trade Center 

Metals: Cahill Incinerator Hypothesis 

Very fine metals were routinely seen, but while most 
were at low concentrations, some metals (V, Ni, Cu, 
As, Se, Br, and Hg) occurred at unprecedented levels 
in the very fine size range (Cahill, 2004) 

"The concentrations of very fine silicon, sulfur, and 
many metals, as well as coarse anthropogenic 
metals, decreased markedly during October, probably 
in association with the cooling of the collapse piles. 
Values of very fine elements seen in May, 2002 at the 
WTC site were only a few percent of October values." 
(Cahill 2004) 


"Calcium and sulfate are the most soluble 
components in the dust, but many other elements are 
also readily leached, including metals such as Al, Sb, 
Mo, Cr, Cu, and Zn." 

"interpret health effects resulting from the short-term 
exposure to the initial dust cloud and the longer-term 
exposure to dusts resuspended during cleanup." 

Plumlee et al. Chap. 12 Inorganic Chemical Composition and Chemical Reactivity of Settled Dust 
Generated by the World Trade Center Building Collapse. Urban Aerosols and Their Impacts: Lessons 
Learned from the World Trade Center Tragedy 


"The smaller particles, which can penetrate into the 
deep lung and would have been generated by 
burning materials, were probably not captured in 
these samples (dust samples)." Samet 2007 

"Airborne lead levels were elevated in the first days 
after 11 September, but never highly." Landrigan, 

Lioy EHP 2002 

Because of the large mass of material deposited 
within rehabitable buildings throughout lower 
Manhattan, surface loading could enhance potential 
nondietary exposures [to lead] 

Concentrations of arsenic and cadmium were 
relatively low, but in the micrograms/gram (parts per 
million) concentration range. 

Metals: Lorber 2007 

"Samples evaluated for total Cr at GZ and at sites 
surrounding GZ never exceeded the NIOSH REL of 0.5 
mg/m 3 or the OSHA PEL of 1 mg/m 3 for Cr metal and 
insoluble salts, or the ATSDR Intermediate MRL of 1 
|jg/m 3 for Cr VI particulates. 

Ni samples evaluated at GZ and at sites surrounding GZ 
never exceeded the NIOSH REL of 0.015 mg/m 3 or the 
OSHA PEL of 1 mg/m 3 for Ni metal. The ATSDR 
Intermediate MRL for Ni of 0.2 pg/m 3 was exceeded only 
once, on November 10, 2001, by a measurement of 0.49 
pg/m 3 . Overall, monitored levels were rarely above 

Metals Implications 

Metals are persistent in environment 

- ? Risk for toddlers from persistent metals in dust in 
residential areas 

Deposited in lungs 

- ? Increased half-life from high initial load 

- Some metals bioaccumulate (lead, cadmium) 

- ?lnteraction with high pH 

•Although "Alkalinity decreased with decreasing particle 
size, and PM2.5 had a more nearly neutral pH (Lioy et 
al. 2002; McGee et al. 2003)." Landrigan 2004