Dr. Fu’s research interests include chemical carcinogenesis of pyrrolizidine alkaloids, polycyclic aromatic hydrocarbons (PAHs), and nitro-PAHs as well as structure activity relationships, DNA adducts as biomarkers, herbal dietary supplements, and nanotoxicology. Pyrrolizidine alkaloid-containing plants are widespread in the world and are probably the most common type of poisonous plants affecting livestock, wildlife, and humans. Many pyrrolizidine alkaloids are hepatotoxic and tumorigenic and represent a threat to human health and safety. Regulatory agencies worldwide have issued bans and alerts on products containing pyrrolizidine alkaloids. To date, however, there are no practical analytical methods to quantify the total toxic pyrrolizidine alkaloid content present in herbal plants and products, or in foods, such as herbal dietary supplements, honey, and milk. Therefore, mechanism-based analytical methods must be developed to assess the risk posed by pyrrolizidine alkaloids in herbal plants and herbal products. Dr. Fu’s current research focuses on the quantitation of pyrrolizidine alkaloid-DNA adducts and pyrrolizidine alkaloid-protein adducts as mechanism-based methods for this need. Dr. Fu’s mechanistic studies determined that different types of tumorigenic-pyrrolizidine alkaloids exert tumorigenicity through a common metabolic-activation pathway. These findings are highly significant and strongly imply that a common metabolic mechanism is involved. Furthermore, the consistent type of DNA damage produced correlated with the biological effects of pyrrolizidine alkaloids. Dr. Fu proposes that, upon metabolism of the herbal products in vivo, in vitro, or in the cultured cells, quantitation of the level of the DHP-DNA adducts should be an assessable, reliable, and mechanism-based bioassay. Dr. Fu has also developed an LC/MS analytical method to quantify blood DHP-protein adducts as a noninvasive biomarker of pyrrolizidine alkaloid tumorigenicity and exposure. The levels of DHP-protein adducts in the blood correlated well with the levels of DHP-DNA adducts in the liver. This LC/MS/MS analytical method has the potential to be used for assessing human exposures to pyrrolizidine alkaloids.