Britney Spears' drugs fears caused her baldness!

According to brand new reports, Britney Spears chopped off her hair back a few months ago for one plain reason: she was worried she would fail a drugs test.

An insider told the Daily Mirror that the 'Hit Me Baby One More Time' star had the chop at a Los Angeles salon. Apparently traces of marijuana could be found in her hair, which was warned by her ex-husband, Kevin Federline.

"Kevin taunted Britney that even his smoking marijuana near her would leave traces that could be picked up by drug testing," an insider is quoted by The Mirror as saying. "He threatened to use that against her in a custody battle."

The confidante added that Britney later instructed her mother to return the hair clippings from the salon, in fear that they would fall into the wrong hands.