Powder at New York Times negative for anthrax, officials say

NEW YORK (CNN) -- Preliminary tests of a white powder that sprinkled on a reporter for The New York Times when she opened an envelope containing the substance proved negative, health officials said.

A preliminary test of the substance itself by the New York Department of Health "has found the culture negative for dangerous biological materials, including anthrax," Times spokeswoman Christine Mohan said.

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"This was the third biological test that has been negative," Mohan said. "The CDC are conducting additional tests to confirm this result."

Results from the Centers for Disease Control and Prevention in Atlanta, Georgia, are expected by Tuesday.

The envelope was addressed to reporter Julie Miller, who has written books on biological weapons and the Middle East, where she had been posted for several years. Miller, who newspaper officials said showed no ill effects from the incident, and 30 other Times employees have been tested and given antibiotics as a precaution, Mohan said.

After being informed of the incident Friday, the New York Police Department cordoned off West 43rd Street between Seventh and Eighth avenues, off Times Square, for a short time, said Kathy Park, a spokeswoman for the newspaper.

In addition to tests on the substance itself, the air in the newsroom was "tested for radioactive and chemical substances," said New York Times spokesman Toby Usnik. "These tests were negative."

The paper's newsroom was open and functioning normally Saturday, according to Park.

A postal official told CNN the letter to the newspaper had no return address but was postmarked from St. Petersburg, Florida. However, the official said it was not possible to tell from what post office or other collection point within the city the letter was mailed.