(Beyond Pesticides, November 2, 2010) A new study published in the American Chemical Society’s bi-weekly journal Industrial & Engineering Chemistry Research shows that nicotine could be used as an effective natural pesticide on a large scale, however the article fails to discuss the health and environmental hazards of tobacco production. Conventional tobacco production is heavily reliant on pesticides and synthetic fertilizers, and nicotine poisoning, called green tobacco sickness, is common among farmworkers in tobacco fields. The new study, “Experimental Investigations into the Insecticidal, Fungicidal, and Bactericidal Properties of Pyrolysis Bio-oil from Tobacco Leaves Using a Fluidized Bed Pilot Plant,” was published online September 14, 2010.
According to lead researcher Cedric Briens, PhD from the University of Western Ontario, concerns about the health risks of tobacco have reduced demand and hurt tobacco farmers in some parts of the world. Scientists are looking for new uses for tobacco. One potential use is as a natural pesticide, due to tobacco’s content of toxic nicotine. For centuries, gardeners have used home-made mixtures of tobacco and water as a natural pesticide to kill insect pests. A “green” pesticide industry based on tobacco could provide additional income for farmers, and as well as a new eco-friendly pest-control agent, the scientists say.
They describe a way to convert tobacco leaves into pesticides with pyrolysis, a process that involves heating tobacco leaves to about 900 degrees Fahrenheit in a vacuum to produce an unrefined substance called bio-oil. The scientists tested tobacco bio-oil against a wide variety of insect pests, including 11 different fungi, four bacteria, and the Colorado potato beetle, a major agricultural pest that is increasingly resistant to current insecticides. The oil killed all of the beetles and blocked the growth of two types of bacteria and one fungus. Even after removal of the nicotine, the oil remained a very effective pesticide. The ability of the oil to block some but not all of the microorganisms suggests that tobacco bio-oil may have additional value as a more selective pesticide than those currently in use, according to the study’s authors.
Some environmentalists criticize the widespread production of a nicotine-based pesticide as short sighted for not examining the full cradle-to-grave impacts of tobacco production. According to the World Health Organization, environmental degradation results from the tobacco plant leaching nutrients from the soil, as well as pollution from pesticides and fertilizers. The World Wildlife Fund says that tobacco leaches phosphorus, nitrogen and potassium from the soil at a rate higher than any other major crop and frequent applications of pesticides are required to protect the plant from insects and disease. Some management guides call for as many as 16 applications of pesticides during the three-month growing period before the plants even leave the greenhouse.
Additionally, farmworkers in tobacco fields face risks from green tobacco sickness (GTS), a type of nicotine poisoning caused by the dermal absorption of nicotine from the surface of wet tobacco plants. Tobacco harvesters, whose clothing becomes saturated from tobacco wet with rain or morning dew, are at high risk of developing GTS. Symptoms of GTS include nausea, vomiting, headache, dizziness, and severe weakness. These symptoms may be accompanied by fluctuations in blood pressure or heart rate. Abdominal cramping, chills, increased sweating, salivation and difficulty breathing are also common. A National Institute for Occupational Safety and Health (NIOSH) study indicates that a startling number of tobacco workers are becoming afflicted with this illness, which may require hospital care.
Tobacco dust has been historically used as a plant-based pesticide, but is prohibited in organic agriculture.
For more information on natural and organic methods for controlling pests, contact Beyond Pesticides.