Bentazon is a herbicide used in agriculture for selective post-emergence control of many broad leaf weeds in soybeans, rice, corn, peanut, mint, dry bean, dry peas and succulent lima bean plantations.
Bentazon is expected to enter surface water by run of from application sites. It has a moderate water solubility of 500 mg/l and a low tendency to adsorb to soils and sediments. In water it can be rapidly broken down by sun light (photodegradation). Its environmental half-life varies between 24 hours and 4 months, depending on the environmental conditions. It can also be biodegraded.  
It has a very low a tendency to bioaccumulate.
Bentazon has a low toxicity to most aquatic animals. Concentrations above 100 mg/l are necessary to cause acute toxicity to fishes. Invertebrates are most vulnerable; mussels die at concentrations above 20 mg/l. Concentrations above 5 mg/l might affect phytoplankton. 
Environmental standards and legislation