Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Beware of Arsenic and other impurities

I've been on this protein powder for a couple months and I have to admit that I have gained strength and muscle mass when compared to not using it. Taste is good and it dissolves fairly quickly with milk. The problem I'm worried about is I recently saw something on consumer reports with respect to the level of impurities of a particular EAS chocolate shake. Not sure about the accuracy of the report, whether it is this product, or even if the numbers really make a difference (maybe that much arsenic has no real impact). Anyways, just thought I'd share.[...]