Yesterday, a judge in the District Court of Delta County, Colorado issued a permanent injunction prohibiting a farmer from fogging for mosquitoes within 150 feet of his neighbor’s property and ever allowing pesticides to drift onto the property. The case involved drift of Fyfanon™—a mosquito adulticide containing 96% malathion—onto a neighboring property where the owners were trying to get their land certified for organic production.
The injunction upholds the rights of the defendants to apply a mosquito control pesticide, but only if it does not drift onto the neighbors’ property. Specifically, the judge noted:
The [Defendants] intend to spray Fyfanon on their property. This they have a right to do. What they do not have a right to do is to allow the Fyfanon, and the malathion contained in that product, to intrude onto Plaintiffs’ property. Because the application of Fyfanon is likely to drift onto Plantiffs’ property unless it is applied properly, Plaintiffs will be irreparably harmed if the [Defendants] do not comply with certain restrictions.
The threatened injury to Plaintiffs outweighs any harm that an injunction will cause to the [Defendants]. Plaintiffs have an interest, shared by the public in general, in not having their property invaded by third persons or things. Plaintiffs also have a specific interest in not having pesticides invade their property because such invasions will delay or negate their efforts to have their property certified for the production of organic crops. The [Defendants] will suffer no injury because they can continue to apply Fyfanon to their property.
Finally, issuing the injunction is in the public interest. The public has a strong interest in protecting and preserving property rights from invasions by others. The public also has an interest in insuring that pesticides are applied safely and in accordance with legal requirements. (Download the entire permanent injunction order.)
This decision reaffirms a fundamental principle on which the U.S. legal system is based—that people have a right to use their property as they wish, as long as that use does not break the law or violate the rights of others. In this case, the defendant’s chemical trespass interfered with the plaintiffs’ right to use their property as they wished, in this case, to create an organic farm.
Certification of a farm as organic requires that no pesticides be used on the property for three years. Delta County, Colorado is a center for organic farming, but with every drift incident, the plaintiffs’ 3-year certification clock was reset to zero. Because the drift incidents were so frequent, it was impossible for the plaintiffs to use their property as an organic farm. Indeed, in one sample that was taken on the property, the concentration of malathion on their crop was higher than FDA’s allowable level (the tolerance) on some foods.
In one way, this result is surprising, since mosquito adulticides are applied at rates of just ounces per acre. In contrast, most applications of malathion to crops are on the order of 1-2 pounds per acre. So how is it that the measured residues were so high? There are two possibilities here: 1) Overapplication of the adulticide; and/or 2) The application equipment aerosolized all of the applied pesticide by creating very fine droplets. Although the defendant’s fogging equipment was mis-calibrated, and overapplication was a part of the problem, a more significant issue was the small droplets generated by the fogger. This is the way mosquito adulticides are supposed to work—a fog of pesticide kills mosquitoes when the fine suspended droplets intercept flying mosquitoes. But because the spray droplets are so small, they do not fall to the ground quickly; drift from mosquito fogging can travel hundreds to thousands of feet or more, depending on wind speed.
The figure below, extracted from a University of Nebraska, Lincoln (UNL) Extension publication, shows the experimental results of drift distance as a function of droplet size. Larger droplets fall to the ground much more quickly than small droplets. Mosquito fogging equipment generates spray droplets that are 10–20 microns in diameter. Based on the data in the UNL publication, a 10 micron droplet takes 17 minutes to fall to the ground in still air. If the wind is blowing just 3 miles per hour, those droplets can travel 0.85 miles. Over that distance, they will also collide with plants, structures, people, beehives, and whatever else is in their path, depositing pesticide residues.
