Herbal teas and toxins: novel aspects of pyrrolizidine poisoning in the United States

This article reviews the discovery of pyrrolizidine alkaloid poisoning in United States caused by the drinking of herbal tea and describes some of the difficulties involved in establishing a causal relationship between exposure to these alkaloids and the delayed appearance of toxic symptoms. In addition, some of the more general problems presented by the widespread use of herbs in various forms are addressed. First, however, a brief overview is given of the toxicity of this class of alkaloids. (AU)