A chemicals company is under fire after one of its truck drivers was found dead in his cab after he was allegedly exposed to cyanide while cleaning his vehicle.

In a scathing statement, the Transport Workers’ Union on Tuesday called for “urgent action and accountability” following the death of the driver who was employed by Coogee Chemicals.

The TWU allege the driver was exposed to a diluted amount of the dangerous substance while cleaning his truck at a mining site in Western Australia; just two days later, he was dead.

The union claimed the driver was found dead by police near the town of Pithara having pulled over, despite being medically assessed at the site and “inexplicably given the all-clear”.

The TWU said the driver’s death was a “stark reminder of the grave risks our drivers face daily and the critical importance of rigorous safety protocols and proper medical assessments”.

“This truck driver was someone’s son, brother, father, and mate. Every worker has the right to be safe at work and return home safe”, TWU State Secretary Tim Dawson said.

“It is unacceptable that a driver can be exposed to such risks and left to fend for themselves on a long-haul journey without proper care or consideration for their wellbeing.

“The TWU will not stand by while the safety of transport workers are compromised. The TWU is calling on WorkSafe and the coroner for a full inquiry into this incident.”

The TWU said it would demand answers from Coogee Chemicals and the relevant mine operators, including how a worker exposed to a toxic substance could be cleared to drive.

In a statement, WorkSafe WA said it had been notified and had “initiated an investigation … with a view to ensuring compliance and preventing future incidents of a similar nature.”

“At present, WorkSafe is awaiting further evidence from the Coroner in relation to the work relatedness of the incident,” a spokesperson for the agency said on Tuesday.

Coogee Chemicals could not be contacted for comment, but in a statement to the West Australian said it was “deeply saddened” by the passing of one of its “valued drivers and members”.

“At that time the employee came into contact with other chemicals. The incident was self-reported and the mine site provided medical care and the driver was subsequently declared fit for work,” a Coogee spokesman said.

“Our heartfelt sympathy and condolences have been extended to our employee’s family, friends, and colleagues. We all feel for their loss at this time.”

Northern Star Resources, which operates the Thunderbox mine site, told the WA paper it too was “deeply saddened” by the man’s passing.

The company said the truck driver was given “immediate medical care”, including a consultation with a doctor after he sustained his chemical burns, after which he was declared fit to drive.