Trophic magnification of organic chemicals: A global synthesis

Production of organic chemicals (OCs) is increasing exponentially, and some OCs biomagnify through food webs to potentially toxic levels. Biomagnification under field conditions is best described by trophic magnification factors (TMFs; per trophic level change in log-concentration of a chemical) which have been measured for more than two decades. Syntheses of TMF behavior relative to chemical traits and ecosystem properties are lacking. We analyzed >1500 TMFs to identify OCs predisposed to biomagnify and to assess ecosystem vulnerability. The highest TMFs were for OCs that are slowly metabolized by animals (metabolic rate k_M < 0.01 day^–1) and are moderately hydrophobic (log K_OW 6–8). TMFs were more variable in marine than freshwaters, unrelated to latitude, and highest in food webs containing endotherms. We modeled the probability that any OC would biomagnify as a combined function of K_OW and k_M. Probability is greatest (∼100%) for slowly metabolized compounds, regardless of K_OW, and lowest for chemicals with rapid transformation rates (k_M > 0.2 day^–1). This probabilistic model provides a new global tool for screening existing and new OCs for their biomagnification potential.