Photo/Illutration Akihiro Kobayashi, President of Kobayashi Pharmaceutical Co., second from left, apologizes at a news conference on March 29 in Osaka. (Jin Nishioka)

Embattled Kobayashi Pharmaceutical Co. came under heavy fire for trying to hide the likely cause of its benikoji health crisis as the health ministry confirmed that batches of the benikoji rice dietary supplements were contaminated with “highly toxic” puberulic acid.

Puberulic acid is a natural compound made from blue mold, according to the ministry. It is not yet known how or when the dietary supplements were contaminated.

A fifth death was confirmed March 29 in connection with the growing health crisis that has seen at least 114 people hospitalized.

Puberulic acid has antibiotic properties, making it effective in fighting malaria. But its effects on the kidneys are not known at this time, the ministry said.

Osaka-based Kobayashi Pharmaceutical has since confirmed that only specific lots contained the substance.

It earlier attributed the cause to “unknown ingredients.”

Since it is not yet clear whether puberulic acid is the culprit, the ministry said it will conduct animal experiments to evaluate the substance’s toxicity, among other things.

The health ministry announced the puberulic acid factor while officials of Kobayashi Pharmaceutical were giving a news conference in Osaka.

It was the first time for the company to speak in public since the health crisis surfaced March 22 with its decision to voluntarily recall the dietary supplements.

Akihiro Kobayashi, the company president, stated at the outset: “We have caused anxiety and fear to everyone involved. I deeply apologize for causing serious social problems.”

He said the company was still trying to identify the “unknown ingredients,” adding that it will work with national research organizations to identify them.

“We hope to proceed with the clarification as quickly as possible” but “cannot foresee the time frame,” he said.

It was during the middle of the March 29 news conference that reporters learned the company had reported to the ministry on March 28 that the “unknown ingredient” was most likely puberulic acid.

Questioning immediately shifted to the substance and why the company had not disclosed the information.

Officials scrambled to explain.

“We have yet to formulate a hypothesis that puberulic acid directly causes kidney damage or kidney disease,” said one official. “We have yet to verify even the mechanism of toxicity, and we did not want to confuse the public.”

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