The Yangtze delta region has the fastest growing economic development and is the most contaminated region of China. Recent research reveals high levels of toxic compounds in the sediments in this region. This implies many potential adverse consequences for the benthic ecosystem health and services it can provide, benthic species diversity, seafood safety and whole benthic ecosystem stability. This thesis will assess the risk of the benthic pollutants for the marine environmental quality and seafood safety in this region. More specifically, the study aims to study the eco-toxicological effects in the field, develop novel bioassays for monitoring the toxic potency of the sediment and to assess the toxicological risks for seafood originating from this region.