Chemical giant Syngenta has admitted health and safety failings after a potentially deadly form of weedkiller was released by accident at its Huddersfield plant.
At least three-and-a-half tons of highly-toxic paraquat leaked out after a worker opened a valve on a tanker.
Swallowing just 50 grams of the substance is enough to cause death or serious injury.
Kirklees Magistrates’ Court heard that while no worker was harmed in the incident, the paraquat could have spread across the site to road users had the wind been blowing in a different direction.
The company now faces a huge fine after a district judge said that his maximum penalty of £40,000 was inadequate.
Syngenta, which is based at Leeds Road, Deighton, pleaded guilty to two charges of contravening a health and safety regulation.
These were failing to ensure that work equipment was maintained in an efficient state and failing to take all measures necessary to prevent a major accident.
The incident at the site occurred on December 12, 2014.
Engineer Daniel Morris accidentally opened a valve on top of a tanker used to transport the paraquat between sites to be purified.
That resulted in the release of between 3.5 to 3.8 tons of paraquat dichloride solution being ejected from the valve into the air.
This continued to erupt for 30 minutes until it was safe for staff wearing hazard protection clothing to enter the area and close the valve.
Mr Morris had to use a decontamination shower but was not harmed by the release of the paraquat as he did not swallow or inhale it.
Also at risk of exposure to the herbicide was Philip Parkinson who was standing on a gantry behind Mr Morris.
Angus Robbins, prosecuting on behalf of the Health and Safety Executive, said: “This is a very toxic substance.
“Fifty grams would kill you if you consume it and if you inhale it will cause significant lung damage the result of which will probably be fatal.
“The wind direction blew this material into the area and it’s good fortune that the wind was in this direction.
“The internal roadway next to the plant is used as an access road and if they had been unlucky other people could have been exposed on the adjacent roadway.”
The court heard that Syngenta acted quickly to contain the risk and sounded the toxic gas alarm to keep people out of the area.
But the company admitted failing to ensure that work equipment, namely the dry-disconnect couplings including those on the export tanker, was maintained and in an efficient state.
Mr Morris shouldn’t have been able to open the valve while some documentation used by staff was inadequate and failed to identify all of the valves in use on the equipment.
District Judge Michael Fanning accepted that Syngenta - which in 2014 made a profit after tax of £48m - was a responsible company with a good reputation.
He acknowledged that while it had not shown a gross disregard for health and safety, a combination of smaller failings had led to the incident occurring.
Judge Fanning said: “I accept no harm was caused to the health of the operative or anybody else in close proximity.
“This is nasty stuff and there was a very real risk of death of the operative or at least the risk of serious injury.
“I cannot consider that a fine of £40,00 could adequately address the seriousness of this offence.”
Judge Fanning committed Syngenta for sentencing to Leeds Crown Court on February 1.
A spokesperson for Syngenta said after the hearing: “Syngenta has manufactured Paraquat safely in Huddersfield for more than 20 years and greatly regrets this incident.
"After the incident, the correct emergency procedures were followed and there was no harm caused to the environment.
"As a responsible operator, the Company immediately notified the HSE, admitting to the offence at the first opportunity. Syngenta has acted quickly to address issues identified by the investigation to guard against a similar incident ever happening again."
