Chapter 3 Phytotoxicity, environmental and health hazards of herbicides: challenges and ways forward Mirza Hasanuzzaman 1 , Sayed Mohammad Mohsin 2 , M.H.M. Borhannuddin Bhuyan 3 , Tasnim Farha Bhuiyan 4 , Taufika Islam Anee 1 , Abdul Awal Chowdhury Masud 1 and Kamrun Nahar 4 1 Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, 2 Department of Plant Pathology, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh, 3 Research Wing, Bangladesh Agricultural Research Institute, Joydebpur, Gazipur, Bangladesh, 4 Department of Agricultural Botany, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh 3.1 Introduction Weeds are the greatest threats for crop production and one of the major biotic stresses, which drastically hamper crop growth and productivity. Due to the pernicious nature, weed control becomes a difficult task by the farm- ers, and various tools are used, which includes mechanical, physical, biologi- cal, and chemical control. However, with the emergence of the Green Revolution, the chemical method of weed control has become popular among farmers because of the lower labor cost, higher efficacy, and time-saving advantages of herbicide over conventional methods. However, these herbicides, though controlling weed population very efficiently, sometimes cause hazardous effects on the nontargeted crop species, environment, and animal health too. There are a number of chemical groups introduced till date as herbicides worldwide. Some of these have been identified to cause serious threats to human health and environment when used in excess or without proper knowledge. Evaluating the use of herbicide is a complicated task as it has been changing over time with respect to both positive and negative impacts (Kniss, 2017). To human either high or low, any dose may cause toxicity depending upon 55 Agrochemicals Detection, Treatment and Remediation. DOI: https://doi.org/10.1016/B978-0-08-103017-2.00003-9 © 2020 Elsevier Ltd. All rights reserved.