Foiled London Bomb Plot 'Involved Deadly Chemical'

April 6, 2004
By Brian Ross and Christopher Isham

British authorities believe terror suspects arrested last week were planning to make a bomb that would include a highly toxic, easily obtained chemical called osmium tetroxide, ABCNEWS has learned.

Used primarily in laboratories for research, osmium tetroxide is known to attack soft human tissue and could blind or kill anyone who breathed its fumes. According to the New Jersey Department of Health, it is a colorless to pale yellow solid with a strong, unpleasant odor.

"It's a nasty piece of work," said Dave Siegrist, a bioterrorism expert at the Potomac Institute for Policy Studies in Arlington, Va. "It irritates the eyes, lungs, nose and throat. It leads to an asthma-like death, what we call a 'dry-land drowning.' "

Scientists say if, for example, the bomb used in the 1993 World Trade Center attack had produced such fumes, they would have wiped out the first police and rescue workers on the scene.

"They become overwhelmed by fumes," said Jerry Hauer, an expert on biological and chemical terrorism and director of public health preparedness at the Department of Health and Human Services, describing what could have happened. "They can go blind. This is not a benign chemical. It is very nasty."

Eight British citizens of Pakistani descent were arrested and taken into custody when 700 police raided 24 locations in and around London on March 30. Investigators say British authorities moved in when they learned from electronic intercepts the dangerous chemical was involved in the plot. They had been tracking the group's activities for several months.

According to sources, there was some indication the group in custody was targeting Gatwick airport, the British public transportation system and enclosed shopping areas. British authorities feared it had the potential to be one of the worst attacks ever against the United Kingdom.

Even though the arrests were made in the United Kingdom, authorities say the operation was being run out of Pakistan by a suspected al Qaeda figure.

"They are creative in their planning," said Hauer. "They continue to work around our systems."


This is the first time osmium tetroxide has been linked to possible terror use. It's sold, with few questions asked, on Internet sites, as are many industrial chemicals that could be equally as potent.

"You never see the supplier and the supplier never sees you," said Siegrist. "A package arrives on the doorstep a few days later."

U.S. officials say the likelihood of a chemical bomb is much greater than a biological and radiological one. Yet the United States has still not settled how to tighten restrictions on what are known as toxic industrial chemicals, which are well-known to al Qaeda bomb-makers and still easily available.




Osmium tetroxide
(Osmic acid, perosmic oxide, osmium(IV) oxide)
CAS 20816-12-0



Physical Properties

Colorless to pale yellow-green crystals
bp 130 °C (but sublimes at lower temperature), mp 40 °C
Moderately soluble in water (7 g/100 mL)


Acrid, chlorine-like odor detectable at 2 ppm (20 mg/m3)

Vapor Density

8.8 (air = 1.0)

Vapor Pressure

7 mmHg at 20 °C

Toxicity Data

LD50 oral (rat) 14 mg/kg

LCLO inhal (rat) 40 ppm (4 h)

PEL (OSHA) 0.0002 ppm (0.002 mg/m3)

TLV-TWA (ACGIH) 0.0002 ppm (0.002 mg/m3)

STEL (ACGIH) 0.0006 ppm (0.006 mg/m3)

Major Hazards

High acute toxicity; severe irritant of the eyes and respiratory tract; vapor can cause serious eye damage.


The acute toxicity of osmium tetroxide is high, and it is a severe irritant of the eyes and respiratory tract. Exposure to osmium tetroxide vapor can damage the cornea of the eye. Irritation is generally the initial symptom of exposure to low concentrations of osmium tetroxide vapor, and lacrimation, a gritty feeling in the eyes, and the appearance of rings around lights may also be noted. In most cases, recovery occurs in a few days. Concentrations of vapor that do not cause immediate irritation can have an insidious cumulative effect; symptoms may not be noted until several hours after exposure. Contact of the eyes with concentrated solutions of this substance can cause severe damage and possible blindness. Inhalation can cause headache, coughing, dizziness, lung damage, and difficult breathing and may be fatal. Contact of the vapor with skin can cause dermatitis, and direct contact with the solid can lead to severe irritation and burns. Exposure to osmium tetroxide via inhalation, skin contact, or ingestion can lead to systemic toxic effects involving liver and kidney damage. Osmium tetroxide is regarded as a substance with poor warning properties.

Chronic exposure to osmium tetroxide can result in an accumulation of osmium compounds in the liver and kidney and damage to these organs. Osmium tetroxide has been reported to cause reproductive toxicity in animals; this substance has not been shown to be carcinogenic or to show reproductive or developmental toxicity in humans.

Flammability and Explosibility


Reactivity and Incompatibility

Osmium tetroxide reacts with hydrochloric acid to form chlorine gas.

Storage and Handling

Because of its high acute toxicity, osmium tetroxide should be handled in the laboratory using the "basic prudent practices" of Chapter 5.C, supplemented by the additional precautions for work with compounds of high toxicity (Chapter 5.D). In particular, all work with osmium tetroxide should be conducted in a fume hood to prevent exposure by inhalation, and splash goggles and impermeable gloves should be worn at all times to prevent eye and skin contact. Osmium tetroxide as solid or solutions should be stored in tightly sealed containers, and these should be placed in secondary containers.


In the event of skin contact, immediately wash with soap and water and remove contaminated clothing. In case of eye contact, promptly wash with copious amounts of water for 15 minutes (lifting upper and lower lids occasionally) and obtain medical attention. If osmium tetroxide is ingested, obtain medical attention immediately. If large amounts are inhaled, move the person to fresh air and seek medical attention at once.

In the event of a spill, mix osmium tetroxide with an absorbent material such as vermiculite or dry sand (avoid raising dust), place in an appropriate container, and dispose of properly. Evacuation and cleanup using respiratory protection may be necessary in the event of a large spill or release in a confined area.


Excess osmium tetroxide solutions can be rendered safer by reaction with sodium sulfite to produce insoluble osmium dioxide. Ethanol will also react to produce the dioxide. Corn oil or sodium sulfide may also be used to deactivate osmium tetroxide. Osmium-containing waste should be placed in a tightly sealed, labeled container and handled according to your institution's waste disposal guidelines.