Nonylphenol ethoxylates (NPE), surfactants commonly used in many agricultural emulsion systems such as pesticides, industrial processes, and industrial and household cleaning products, are perceived by some users as hazardous to the environment. The producers of NPE have a great deal of information on NPE environmental fate and effects which gives reassurance to the agricultural emulsifier industry and water quality regulators that they pose minimal risk to the environment and human health. NPE, which have been tested thoroughly for effects toward mammals and aquatic life, exhibit toxicity patterns similar to other widely used surfactants. They are highly treatable in aerobic biological treatment plants; studies in U.S. wastewater plants have shown up to 99.8% removal. Monitoring of a random selection of U.S. rivers judged most likely to receive NPE showed that water and sediment concentrations are very low or undetectable. One NPE metabolite, nonylphenol (NP), poses a potential risk since it is very toxic to aquatic organisms. Evidence indicates, however, that NP is rapidly removed by biological action and is not formed under aerobic conditions. Wastewater treatment plant effluents, river waters, and sediments do not contain levels of NP that would suggest accumulation to toxic thresholds in the aquatic environment. NP and NPE degrade in soil and are not taken up by growing plants. More work is underway by NPE producers to elucidate better the dynamics and mechanisms of NPE biodegradation.