Deadly chemical reactions

The recent collapse of a Hungarian reservoir filled with waste form aluminum production is tragic, but it’s not the first big chemical accident to make international headlines. Here are some others from the last 50 years.

1976

Seveso, Italy

Following an explosion at a chemical plant 20 km north of Milan, dioxins were released into the atmosphere and surrounding areas.

Almost 200 people suffered from chloracne and other ailments. Thousands of farm animals died and tens of thousands were slaughtered to prevent the toxic chemicals from entering the food chain.

The disaster prompted the European Community to issue a new system of industrial regulation known as the Seveso Directive.

1984

Bhopal, India

The worst industrial accident in history took place in the capital of the central Indian state of Madhya Pradesh, when an employee working at a pesticide-producing plant added a large amount of water to a tank holding a dangerous gas called methyl isocyanate.

The resulting chemical reaction caused a major leak and 41 tonnes of the gas and other toxins travelled from the plant to densely populated communities nearby.

Thousands of people died right away and thousands more fled the area in a panic. Overall, an estimated 20,000 people died and about half a million others suffered the effects of exposure to toxic gas. Many victims developed respiratory ailments or eye problems. Some went blind.

In subsequent years, soil and water contamination led to chronic health problems and high instances of birth defects among local residents.

Investigations later determined the catastrophe had been caused by inadequate operating and safety procedures at the plant, which was owned by a subsidiary of U.S.-based Union Carbide Corporation.

The state of Madhya Pradesh took control of the site in 1998 but only cleared part of the plant. Hundreds of tonnes of toxic chemicals remained scattered around the site.

Today, chemicals continue to leak and pollute the ground and water there. New research shows that groundwater three kilometers from the site contains nearly 40 times more pesticides than the level considered safe. Pesticide levels are 560 times higher around the factory itself.

1986

Schweizerhalle, Switzerland

Within two weeks after a leak was discovered at an agrochemical storehouse, toxins had travelled the length of the Rhine and spilled into the North Sea. The disaster killed half a million fish, eliminating some species altogether.

Public outcry led to the establishment of a program whose aim was to repopulate the Rhine with salmon. To date, officials have reduced nitrates and phosphorus in the Rhine by 50 per cent. Other kinds of pollution have been reduced even more.

Chemical companies in that region have stepped up safety precautions.

1988

Auburn, Indiana

A worker at a metal-plating plant unknowingly combined two common industrial chemicals and created hydrogen cyanide, which prevents the lungs from absorbing oxygen.

As a result, five workers died and 30 people were injured. Even police and firefighters who responded to the emergency had to get medical attention.

The incident is remembered as the worst confined-space industrial accident in U.S. history.

1989

Pasadena, Texas

During regular maintenance operations at a petroleum plastics plant, highly flammable gases were released through an open valve on a polyethylene reactor.

A vapor cloud formed and came into contact with an ignition source. The resulting explosion was so powerful it registered 3.5 on the Richter scale.

A raging fire took 10 hours to bring under control.

In the end, 23 workers died and more than 300 were injured.

The U.S. Occupational Safety and Health Administration issued a report attributing the deadly accident to failure of plant safety management.

2001

Toulouse, France

The explosion at a chemical fertilizer plant in Toulouse rocked southwest France with the force of a 3.4 magnitude earthquake.

Thirty people were killed and more than 2,000 were injured.

The incident also caused significant structural damage to nearby schools and other buildings.

Five years later, investigators released a report blaming the explosion on negligence. They said ammonium nitrate was allowed to come into contact with other chemicals.