*Review* **Toxic Metals in a Paddy Field System: A Review**

**Yuanliang Duan, Qiang Li, Lu Zhang, Zhipeng Huang, Zhongmeng Zhao, Han Zhao, Jun Du and Jian Zhou \***

Fisheries Institute, Sichuan Academy of Agricultural Sciences, Chengdu 611731, China; duan9104@126.com (Y.D.); liq7920@126.com (Q.L.); zhanglu425@163.com (L.Z.); h3392078@163.com (Z.H.); 18227552594@163.com (Z.Z.); zhaohan232323@163.com (H.Z.); dujun9100@126.com (J.D.)

**\*** Correspondence: zhoujian980@126.com; Tel./Fax: +86-028-87955015

**Abstract:** The threat of toxic metals to food security and human health has become a high-priority issue in recent decades. As the world's main food crop source, the safe cultivation of rice has been the focus of much research, particularly the restoration of toxic metals in paddy fields. Therefore, in this paper, we focus on the effects of toxic metals on rice, as well as the removal or repair methods of toxic metals in paddy fields. We also provide a detailed discussion of the sources and monitoring methods of toxic metals pollution, the current toxic metal removal, and remediation methods in paddy fields. Finally, several important research issues related to toxic metals in paddy field systems are proposed for future work. The review has an important guiding role for the future of heavy metal remediation in paddy fields, safe production of rice, green ecological fish culture, and human food security and health.

**Keywords:** toxic metals; health risk; paddy field; bioremediation; rice–fish co-culture system
