The government said Saturday that it had vastly underestimated the proportion of the U.S. apple crop that was treated last year with the controversial pesticide Alar.

The proportion of the 1988 apple crop treated with Alar could have been as high as 15 percent - three times its earlier estimate of 5 percent, the Environmental Protection Agency conceded in a printed statement.The environmental agency added that it was moving ahead with plans eventually to remove the pesticide from the market, concluding that exposure "over a lifetime represents a significant carcinogenic risk that outweighs the benefits of use."

But it said Alar traces were nonetheless far below government-set ceilings and posed no undue health risk.

"Although EPA believes that the available data are a cause for concern, the level of risk during the time necessary to complete a cancellation action is not unreasonably high," the agency said.

"Also, exposure is expected to decrease as a result of declining use, which will further reduce risk," the EPA added.

It could take another year and a half for the proposed ban to proceed through the administrative process, an EPA spokesman told Reuters.

"It could be up to 18 months before the ban becomes final," spokesman Alicia Tenuta said.

The EPA announcement preceded by a day a new report on Alar expected from a U.S. television network that apple producers fear will further tarnish the reputation of the popular fruit.

On Sunday evening, the CBS program "60 Minutes" is expected to report that 38 percent of the 1988 apple crop contained Alar traces, government sources told Reuters.

Alarmed by the prospect of the new disclosures, some producers last week had urged the EPA to move more quickly on its plan eventually to remove Alar from the market.