Is Diuron Weed Killer Dangerous in Water Run Off or Air Pollution?

Run-Off Contamination

• Diuron is applied to the soil, and can move into rivers and lakes through run-off, where it bonds to sediment in the water and decomposes. Up to 90 percent of the chemical can degrade in 8 months on organic sediments in water at moderate temperatures. In clear water, sunlight can degrade Diuron in a few days. The largest amounts are found in lakes and rivers after the application of the chemical to nearby areas in the spring, and during the summer when it still is present in the soil. Diuron is moderately to highly toxic to fish, many plants, and algae.

Ground Water Contamination

• Although Diuron usually does not leach more than 4 inches deep in the soil, it has been found in the groundwater in the United States and Canada. Contamination of groundwater is more likely to occur in areas with shallow water tables and porous soil, such as sand. As with run-off contamination, the largest amounts of Diuron in the groundwater are found in the spring and summer.

Air Contamination

• Large amounts of Diuron typically are not released into the air, although it may evaporate when granules lay on the surface of the soil for several days or weeks during hot, dry weather. The Pesticide Action Network does not list Diuron as a hazardous air pollutant, and the material data safety sheet states there are no recorded effects of the chemical on the ozone. Sunlight completely degrades the chemical within five or six days. Direct contact with Diuron spray or dust may irritate a person’s nose, throat, eyes, or skin. Inhaling it can cause coughing and shortness of breath. Diuron is slightly toxic to animals and birds, but is not toxic to bees.

Avoid Contamination

• Do not apply Diuron within 48 hours of rain to reduce the chance of run-off. Avoid applying Diuron to areas with poor drainage or erosion problems, since these areas are more prone to run-off. Do not spray Diuron on windy days to prevent contamination of water from drift. A level buffer strip of vegetation around treated areas or along water banks will reduce contamination from run-off. Avoid applying Diuron to areas with shallow water tables to prevent contamination of ground water. Irrigate areas treated with granules to prevent evaporation of the chemical. Do not inhale Diuron spray or dust. Wash any exposed skin immediately after applying Diuron, and wash clothes separately from other laundry.