Human Health Risk Assessment:World Trade Centre Disaster

Clinton S YoungItza Mendoza Sanchez

Vaishali Kushwaha

World Trade Centre: Introduction

• Seeds of WTC planted after World War II in 1940’s, Dedicated in 1973• City chose to build the WTC instead of building a new tunnel and large

bridge over the Hudson River • 16 acre site in Lower Manhattan• 7 buildings including two 110 storey towers, 8 years of construction

World Trade Centre: Facts

• To create the 16-acre WTC site, 5 streets were closed off and 164 buildings were demolished

• 1.2 million cubic yards of earth was excavated, which was used to create 23.5 acres of Liberty Park along the Hudson River

• More than 200,000 tons (68 miles) of steel, which can make three more Brooklyn Bridges

• 425,000 cubic yards of concrete, enough to build a 5 foot wide sidewalk from New York City to Washington, D.C.

• Combined weight of 2 towers was more than 1.5 million tons• 43,600 windows with over 600,000 square feet of glass window area.• more than 16 miles of staircases.• 60,000 tons of cooling capacity, 49,000 tons of air-conditioning equipment, 239

elevators and 71 escalators • 23,000 fluorescent light bulbs, 12,000 miles of electrical cable, 75,000 telephones

maintained by 19,600 miles of cable, 300 computer mainframes• More than 250,000 cans of paint were needed every year for upkeep of the Towers • More than 50,000 people worked in the twin towers and More than 200,000 people

- half of them tourists - moved through the buildings each day • $110.3 million in gold and 120.7 million in silver were buried in the rubble • It is the first skyscraper in the world destroyed by terrorists

World Trade Centre: Disaster• September 11, 2001, morning 8.45

hijacked 767 commercial jet airplane hit north tower.

• 18 minutes later, 9.03am another plane hit south tower

• S-tower suffered complete structural collapse 1st and then N-tower collapsed

• 47 storey office got damaged, caught fire and later on collapsed totally

• All the seven buildings of WTC collapsed and nearby buildings got significantly damaged

• About 2800 people died• The fires were fed by more than

91,000 L of jet fuel and went on for days

• Airborne dust from the collapse and fumes from burning of the towers blanketed Lower Manhattan with dust containing a complex mixture of PM, asbestos, various metals, dioxins, benzene, glass fiber, PCBs, PAHs, and VOCs

World Trade Centre Disaster: Risk Assessment

The primary goal of this study is to evaluate the potential risk to health of people working or living in the vicinity of the WTC, immediately after the WTC collapse.

The methodology used for the risk assessment

• Hazard Identification and Data evaluation• Exposure Assessment• Toxicity Assessment• Risk Characterization

World Trade Centre Disaster: Data CollectionAir quality in and around New York has been monitored by:• Environmental Protection Agency• New York State Department of Environmental Conservation • New York City Department of Environmental Protection • New Jersey Department of Environmental Protection • Occupational Safety and Health Administration

EPA data has been used for the Analysis• samples of air, dust, water, river sediments and drinking water were tested for

the presence of pollutants• Data collection from more than 20 fixed air monitors in and around ground

zero, regional monitors in the Bronx, Brooklyn, Queens and Staten Island, and more than 20 fixed air monitors at the Staten Island Landfill (where debris from the search and recovery and excavation operations is shifted)

• Data was collected and evaluated for 7 contaminants/contaminant classes:Particulate matter (PM)Metals (lead, chromium, and nickel)Polychlorinated biphenyls (PCBs)Dioxinsvolatile organic compounds (VOCs; benzene and several others)Poly Aromatic Hydrocarbons (PAHs)Asbestos

World Trade Centre Disaster: Data Sampling

• Asbestos in Air

Standard under AHERA, the Asbestos Hazard Emergency Response Act

• Asbestos in Bulk Dust

The 1% definition

• Particulate Matter in Air

Two methods for measuring particulate matter: The filter method , The continuous method

• Drinking Water

Sampled drinking water from 13 water mains, evaluated the samples against federal Maximum Contaminant Levels (MCLs), no contaminants were detected

• Benzene/ VOCs in Air

all measurements were "grab" samples, lasting a few minutes

• Metals in Air

analyzed 20 metals, about a third of these metals: not detected and thirteen metals: detected

World Trade Centre Disaster: Data Evaluation

• very limited data available on the levels of exposure that occurred to individuals due to direct contact with the plume of smoke and dust generated by the WTC collapse on September 11

• earliest reported data are from asbestos monitoring, which began on September 14

• data available is space variable as well as time variable

• the maximum concentration for all the contaminants available has been chosen in order to calculate risk

• comparing a single concentration with the available screening values (which are for average concentrations and for continuous exposure) makes almost all the contaminants Chemical of Concerns (COC’s).

Toxicity Assessment

Toxicity assessment

Exposure assessment

• To evaluate the exposure pathways it is necessary to define:

• a)      Source of contamination

• b)      Media contaminated

• c)      Type of contaminant

• d)      Route of human exposure.

Exposure assessment

• Source of contamination

On-siteOff-site

Exposure assessment• Media contaminated

– air

• Type of contaminants– Asbestos, benzene,dioxin, metals,

PM, PCBs, VOCs

• Route of human exposure– inhalation

Exposure assessment

• Exposure scenarios

Contaminated medium

Exposure route

Contaminant ofpotential concern

Receptor situation

Population

work adult

adultchildadultchild

contaminant inair *on site

work adult

* contaminant in air include asbestos, dust, benzene, chromium,dioxin, lead, metals, particulate matter 2.5, particulate matter 10,PCBs, PAHs, and volatile organic compounds.

air inhalation contaminant inair *off site residential

visitor

Exposure assessment

Ind.

cancer

Ind.

n-canc

Rec

cancer

Rec

n-canc

Res

cancer

Res

n-canc

Exp. freq

15 days/year

15 days/year

1 days/year

1 days/year

15 days/year

15 days/year

Exp time

8 hour/day

8 hour/day

3 hour/day

3 hour/day

6 hour/day

6 hour/day

Ave. time

365 days

15 days

365 days

1 days

365 days

15 days

• Parameter values

WTC Building Exposures

• Four Buildings – North– South– Austin– Building 5

• Carcinogen vs. Non-carcinogen

• Adults Only

• Occupational Exposures

WTC North

• Carcinogens • Non-carcinogens

WTC South

• Carcinogens • Non-carcinogens

WTC Austin

• Carcinogens • Non-carcinogens

WTC Building 5

• Carcinogens • Non-carcinogens

Average Exposures

• Larger sampling area

• Children and Adults

• Different exposures– Industrial– Recreational– Residential

Adult Industrial Exposure

• Carcinogens • Non-carcinogens

Adult Recreational Exposure

• Carcinogens • Non-carcinogens

Child Recreational Exposure

• Carcinogens • Non-carcinogens

Adult Residential Exposure

• Carcinogens • Non-carcinogens

Child Residential Exposure

• Carcinogens • Non-carcinogens

Summary

• Carcinogens– Benzene– chloroform – dichloroethane – vinyl chloride– Dioxane– Bromoform– carbon tetrachloride– hexachlorobutadiene

• Non-carcinogens– Butadiene– vinyl acetate– bromoethane– chromium– chlorobenzene– benzene– MTBE