About 60,000 pounds of ammonium nitrate, a chemical used as a fertilizer and in explosives, went missing on a rail shipment from Wyoming to California in April and has still not been found, officials said.
Dyno Nobel, an explosive manufacturing company, notified the federal government of the loss and said in a statement that it was investigating what happened during the nearly two-week journey.
The company said the rail car with the material was sealed when it left a manufacturing site in Cheyenne, Wyo., and the seals “were still intact” when it arrived in Saltdale, Calif.
“The initial assessment is that a leak through the bottom gate on the rail car may have developed in transit,” the statement said.
A report made on May 10 to the National Response Center, a federal emergency call center for railroad incidents, said that the rail car left Wyoming on April 12 and arrived in California empty.
Dyno Nobel said that the rail car was transported back to Wyoming for further investigation and that it had “limited control” of the train’s activity while the cargo was being transported.
Kristen South, a spokeswoman for the rail carrier, Union Pacific, said in a statement that the company’s investigation was in its “early stages.”
“The fertilizer is designed for ground application and quick soil absorption,” Ms. South said. “If the loss resulted from a rail car leak over the course of transportation from origin to destination, the release should pose no risk to public health or the environment.”
The company said it does not suspect any criminal or malicious activity was involved in the disappearance of the cargo.
The Federal Railroad Administration and the California Public Utilities Commission were also investigating, KQED, a San Francisco radio station, reported. The agencies could not be reached for comment on Sunday.
Ammonium nitrate is used mainly as a fertilizer. It is also used to manufacture first aid products, such as cold packs, and as an explosive in mining and construction, according to the Department of Homeland Security.
The chemical by itself is relatively harmless, but it can explode if it is added to a fuel source and subjected to heat and pressure.
“Ammonium nitrate is certainly a well-known disaster risk,” said Fred Millar, an independent chemical disaster expert.
Ammonium nitrate was used to bomb the Alfred P. Murrah Federal Building in downtown Oklahoma City in 1995, killing 168 people.
In 2013, 15 people were killed and more than 260 others were injured in West, Texas, after ammonium nitrate exploded at a fertilizer plant. Federal investigators said in 2016 that the fire that set off the explosion had been intentionally set.
In August 2020, more than 2,000 tons of ammonium nitrate stored in a warehouse in the port of Beirut, Lebanon, exploded, killing more than 200 people, injuring another 6,000 and causing widespread damage to the city.