Education Cabinet Secretary George Magoha has been asked to step aside overuse of a toxic chemical in the Chemistry practicals during this year's KCSE exams.
Knut officials from the Turkana branch demanded that Prof Magoha takes responsibility after students were exposed to the chemical.
Kenyaman Ariong'oa, the branch chairperson, argued that the Education Ministry head had out the health of candidates at risk.
Fear of going public
"A student has already been confirmed dead. How many people should die for Prof Magoha to accept that the chemical is dangerous?" he asked.
According to the Knut officials, their 'independent investigation' had established that at least 50 examination centers were affected and 15 cases reported so far.
"More than 15 cases, including those of two principals and a police officer from Turkana East sub-county, have been reported. People in Turkana were affected by the chemical (xylene)," he said.
Mr Ariong'oa claimed that school principals feared going public with the issue which has been surrounded in mystery.
Xylene is an aromatic hydrocarbon used in industry and medical laboratory as a solvent.
On exposure, it is rapidly absorbed through the lungs and slowly through the skin.
The State dismissed claims that some teachers and students have been hospitalized after inhaling xylene.