A worker at the quake-damaged Fukushima nuclear power plant in Japan has died, according to Tokyo Electric Power Co. (TEPCO), the facility’s operator.

However, TEPCO noted the passing of the male employee in his 50s was not necessarily linked to radiation leaks.

The man was taken to the hospital on Wednesday after complaining of feeling ill. He died Thursday morning at the hospital.

TEPCO spokeswoman Chie Hosoda told media: He had been exposed to a small amount of radiation. It is difficult to assume that radiation was a cause of his death.

Reportedly, the deceased man worked at the plant for 46 days to help install a tank to be used for processing contaminated water from the damaged reactor units.

He worked every day for three hours and was exposed to a total of 2.02 millisieverts of radiation, according to TEPCO. (An exposure of 100 millisieverts per year is regarded as the lowest level at which there is any risk of cancer).

According to Agence France Presse, the unidentified man was the third Fukushima plant worker to die since the devastating March earthquake-tsunami struck.

The two other men died of heart attack and leukemia, respectively. TEPCO noted neither died from radiation poisoning. Two other employees died during the earthquake itself.