Neem oil is a naturally occurring pesticide found in seeds from the neem tree. It is yellow to brown, has a bitter taste, and a garlic/sulfur smell. It has been used for hundreds of years to control pests and diseases. Components of neem oil can be found in many products today. These include toothpaste, cosmetics, soaps, and pet shampoos. Neem oil is a mixture of components. Azadirachtin is the most active component for repelling and killing pests and can be extracted from neem oil. The portion left over is called clarified hydrophobic neem oil.
Neem oil and some of its purified components are used in over 100 pesticide products. They are applied to a wide variety of crops and ornamental plants for insect control. Neem oil can be formulated into granules, dust, wettable powders or emulsifiable concentrates.
Neem oil is made of many components. Azadirachtin is the most active. It reduces insect feeding and acts as a repellent. It also interferes with insect hormone systems, making it harder for insects to grow and lay eggs. Azadirachtin can also repel and reduce the feeding of nematodes. Other components of neem oil kill insects by hindering their ability to feed. However, the exact role of every component is not known.
People can be exposed to chemicals by eating them, breathing them in, through skin contact and eye contact. Since neem oil is used on a variety of crops, people are mainly exposed to neem oil in their diet. People who apply neem oil may also be exposed if they inhale the mist or dust, let the product touch their skin, or fail to wash their hands before eating or smoking. However, the label includes directions for keeping exposure low. For example the label might require applicators to wear protective clothing.
Neem oil can be slightly irritating to the eyes and skin. Azadirachtin, a component of neem oil, can be very irritating to the skin and stomach. The remaining portion of neem oil is made of fatty acids, essential oils and other substances that are commonly eaten in a normal diet. These substances are generally recognized as safe (GRAS) by the United States Food and Drug Administration.
In other countries, neem oil has been used on cats for flea control. Some adverse reactions have been reported. Symptoms include feeling sluggish, excessive salivation, impaired movement, trembling, twitching, and convulsions. Some of the cats died. However, most of them recovered within 1 to 5 days.
Clarified hydrophobic neem oil (without azadirachtin) is made of fatty acids and glycerides. These substances are commonly found in food. When they enter the body, they are broken down, used for energy, and incorporated into cells.
In one study, scientists injected insects with azadirachtin. They found 90% of the dose in the insects' feces within 7 hours. The remaining portion lingered in the insects' bodies for 24 days after the injection.
In general, children may be especially sensitive to pesticides compared to adults. When rats were fed neem oil in one study, their pregnancies ended. In another study, rats were fed azadirachtin in their diet throughout their lives. No effects to their offspring were found. Additionally, neem oil is used in toothpaste, cosmetics, soaps and traditional medicines around the world. Therefore, people of all ages are commonly exposed to neem oil. No data were found to show that children are more sensitive than adults to neem oil.
Azadirachtin, a major component of neem oil, is rapidly broken down. Microbes and light break down the pesticide in soil, water and on plants. The half-life of azadirachtin in soil ranges from 3 - 44 days. In water, the half-life ranges from 48 minutes to 4 days. It also rapidly breaks down on plant leaves; the half-life if 1 - 2.5 days. The remaining components of neem oil are broken down by microbes in most soil and water environments.
Neem oil is practically non-toxic to birds, mammals, bees and plants. Neem oil is slightly toxic to fish and other aquatic organisms. Azadirachtin, a component of neem oil, is moderately toxic to fish and other aquatic animals. It is important to remember that insects must eat the treated plant to be killed. Therefore, bees and other pollinators are not likely to be harmed.
For more detailed information about neem oil please visit the list of referenced resources or call the National Pesticide, Monday - Friday, between 8:00am - 12:00pm Pacific Time (11:00am - 3:00pm Eastern Time) at 1-800-858-7378 or visit us on the web at http://npic.orst.edu. NPIC provides objective, science-based answers to questions about pesticides.
Date Reviewed: March 2012
Please cite as: Bond, C.; Buhl, K.; Stone, D. 2012. Neem Oil General Fact Sheet; National Pesticide Information Center, Oregon State University Extension Services. http://npic.orst.edu/factsheets/neemgen.html.
NPIC fact sheets are designed to answer questions that are commonly asked by the general public about pesticides that are regulated by the U.S. Environmental Protection Agency (U.S. EPA). This document is intended to be educational in nature and helpful to consumers for making decisions about pesticide use.
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