(Updated with information from an FDA conference call.)

CAMBRIDGE, Mass. (

TheStreet

) --The FDA has found garbage floating around in vials of drugs made by

Genzyme

(GENZ)

, the agency warned doctors today.

The news sent Genzyme shares plunging 8% soon after the FDA posted a warning to doctors on its web site. The stock has since recovered somewhat and is now down 5% to $50.09.

Regulators said they have found "foreign particle contamination" in vials of Genzyme drugs, including Cerezyme, Aldurazyme, Fabrazyme and Myozyme. All these drugs treat rare, genetic diseases. For this reason, the FDA decided against forcing Genzyme to recall the contaminated vials.

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The FDA says the contamination affects less than 1% of Genzyme products, but the detritus found floating in the drugs includes stainless steel fragments, non-latex rubber and fiber-like material that could cause serious safety problems for patients.

The affected vials were processed in the fill-finish facility at Genzyme's manufacturing plant located just outside Boston. Genzyme was forced to shut down and sterilize this same manufacturing plant earlier this year due to viral contamination.

The plant shutdown curtailed production of Genzyme's most important drugs, lowering the company's revenue and earnings for the year.

On a conference call, FDA officials said the two manufacturing problems at the same Genzyme plant were unrelated, even though each began around the same time. FDA said Genzyme officials first notified the agency about garbage floating around in its drug vials in early May.

The Alston plant is still under investigation and review by FDA. Officials today would not comment on whether this latest setback would affect the agency's decision to re-authorize the facility, including granting approval for a new Genzyme drug, Lumizyme, made there.

-- Reported by Adam Feuerstein in Boston

Adam Feuerstein writes regularly for TheStreet.com. In keeping with TSC's editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet.com. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback;

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