San Francisco-based GoodGuide, a consumer group, has said that the holiday season's most popular and fastest selling toys, robotic hamster Zhu Zhu Pets are "unsafe" and kids should be kept away from them.

On Saturday, the "must have toy" of the season was slapped as being dangerous, and the consumer group said that its investigation has led it to believe that the toys contain a higher-than-allowed level of antimony, a chemical which has been linked with various health problems. On a 10 point scale, the group assigned a rating of 5 to the toy.

"If ingested in high enough levels [it] can lead to cancer, reproductive health, and other human health hazards", said Dara O'Rourke, an Associate Professor of Environmental Science at U.C.-Berkeley, and Co-Founder of GoodGuide.com, while stressing that although the company has put in its best effort to keep the toys safe, some units are "slipping between the cracks".

In its defense the toy's maker, St. Louis-based Cepia LLC, has issued a statement asserting that Zhu Zhu Pets are "absolutely safe and has passed the most rigorous testing in the toy industry for consumer health and safety".