For those in a hurry
- In November 2014, a massive leak of methyl mercaptan, a chemical used to make insecticides and fungicides, occurred at a DuPont plant in La Porte, Texas.
- The leak killed four workers who were trying to clear a blocked pipe or respond to a distress call.
- The leak also released a foul odor that smelled like rotten eggs and garlic and could be detected from miles away.
- The leak was caused by a flawed engineering design, inadequate safeguards, and poor safety management at the plant.
- The leak exposed the weaknesses in DuPont’s safety culture and prompted federal investigations and fines.
What is methyl mercaptan and why does it stink?
Methyl mercaptan is a colorless gas with a strong smell. It is naturally found in some foods, such as cheese, onions, and garlic. It is also produced by bacteria in the human gut and contributes to bad breath and flatulence.
Methyl mercaptan is used in the chemical industry to make insecticides and fungicides. It is also added to natural gas as an odorant, so that people can detect gas leaks.
Methyl mercaptan is toxic if inhaled, ingested, or absorbed through the skin. It can cause eye irritation, headache, nausea, vomiting, dizziness, coma, and death. It can also explode if mixed with air or oxygen.
How did the leak happen?
The leak happened at the DuPont plant in La Porte, Texas, on November 15, 2014. The plant produced an insecticide called Lannate and a fungicide called Vydate. Both products contained methyl mercaptan as a raw material.
The leak occurred when two workers opened two valves in a poorly ventilated manufacturing building. They were trying to drain liquid from a pipe that was connected to a vent system. They did not know that the pipe was also connected to another pipe that contained liquid methyl mercaptan.
The liquid methyl mercaptan drained from the open valves and vaporized in the building. The two workers were overcome by the toxic gas and died. One of them made a distress call before collapsing.
Four other workers responded to the distress call and entered the building. Two of them also died from exposure to the gas. The other two survived but suffered injuries.
What caused the leak?
The leak was caused by a combination of factors, including:
- A flawed engineering design that allowed liquid methyl mercaptan to accumulate in the vent system and connect to other pipes without proper isolation or labeling.
- A lack of adequate safeguards, such as alarms, ventilation, emergency shutdown systems, or personal protective equipment, to prevent or mitigate the release of methyl mercaptan.
- A poor safety management system that failed to identify and correct the hazards of methyl mercaptan, conduct proper training and supervision of workers, or follow standard operating procedures.
- A weak safety culture that did not foster a sense of responsibility or accountability for safety among workers and managers.
What were the consequences of the leak?
The leak had several consequences, such as:
- Four workers lost their lives and two others were injured.
- The plant was shut down permanently and about 300 employees lost their jobs.
- The plant released about 24,000 pounds of methyl mercaptan into the air, creating a foul odor that smelled like rotten eggs and garlic and could be detected from miles away.
- The plant violated several federal and state environmental and safety regulations and was fined by various agencies.
- The plant faced lawsuits from the families of the deceased workers, as well as from nearby residents who claimed health problems or property damage from the leak.
- The plant damaged DuPont’s reputation as a safety leader in the chemical industry and raised questions about its safety practices at other facilities.
How can such leaks be prevented in the future?
To prevent such leaks in the future, chemical plants should:
- Follow good engineering practices and design systems that minimize the risk of leaks or explosions of hazardous chemicals.
- Install adequate safeguards and emergency systems that can detect, contain, or stop leaks or explosions of hazardous chemicals.
- Implement effective safety management systems that can identify and control hazards, train and supervise workers, audit and correct deficiencies, and enforce safety rules.
- Foster a strong safety culture that can encourage workers and managers to report problems, learn from mistakes, communicate openly, and act responsibly for safety.
