Does Mosquito Spray Do More Harm Than Good?
From personal experience, mosquito spray does come in handy when there are tons of Mosquitoes. A couple of months ago I went to Dominican Republic for a week, I felt like I used gallons of it. Out there you had to. There’s so many mosquitoes out there, with some carrying diseases. So you have to protect yourself, whether that be outside, inside, or in bed. From that experience, I understand why people from other countries say that “the higher the percentage of DEET, the better”. I get it, but DEET isn’t the best chemical out there, there are other more natural ways of going about keeping mosquitoes at bay. For this review, I looked at many different journal articles, scholar reports, and professional websites, to determine the effects of mosquito products. There are many different types of mosquito products like lotions, sprays, candles, etc., but I looked specifically at mosquito spray.
First Here’s a Little Background Info.
The American anti-mosquito movement grew out of the discovery of the role of mosquitoes in transferring pathogens and public concern about pest and nuisance mosquitoes in the late 1800s. In the 20th century, organized mosquito control in the United States passed through three eras: mechanical, chemical, and integrated mosquito control. Mosquito control in the 21st century faces the challenge of emerging pathogens, invasive mosquito species, and balancing concerns about the environment with effective control strategies. Research on mosquito chemical repellents continues to advance, along with knowledge of mosquito olfaction and behavior, mosquito–host interactions and chemical structure.
New tools and technologies have revealed information about insect olfactory mechanisms and processing, providing a more complex approach for the interpretation of how chemical repellents influence host‐seeking and feeding behavior. Even with these advances, there is still a large amount of information contained in the early works on insect repellents. Many of the standard test methods and chemicals that are still used for evaluating active repellents were developed in the 1940s. These studies contain valuable references to the activity of different structural classes of chemicals, and serve as a guide to optimization of select compounds for insect repellent effects.
Traditionally, various types of substances have been used to repel mosquitoes. These include such things as smoke, plant extracts, oils, tars, and mud. Since none of the previously available materials were ideal repellents, research into new synthetic materials continued. As insect repellent technology became more sophisticated, individual compounds were discovered and isolated. This allowed the formulation of new, more efficient forms of mosquito repellents. In 1955, scientists synthesized DEET (n-n-diethylnetatoluamide), currently the most widely used active ingredient for mosquito repellents. After its discovery, repellent manufacturers developed many different forms in which to deliver DEET, such as creams, lotions, and aerosols.
So How is the Typical Mosquito Spray Made?
The production of mosquito repellents can be broken down into two steps. First a large batch of the repellent formulation is made, and then the batch is filled into the packaging. Since aerosols are the most common form of mosquito repellent, the following description details their production. Other forms of repellents like creams and lotions are produced in a similar way, except that the filling process is less involved.
First Step: Compounding
· The first step in the manufacturing process is compounding. In the compounding area, raw materials are mixed together in large stainless steel tanks. For an aerosol, the alcohol is pumped into the tank, and the other materials, including DEET, fragrance, and emollients, are manually poured in and allowed to mix. All of the ingredients except the propellant are added at this phase of production. Since some of the materials in this process are flammable, special precautions are taken to prevent explosion, such as using spark-proof electrical outlets and blast-proof walls.
· When the batch is finished, a sample is sent to the quality control lab and tested to make sure it meets the set standards for the product. After passing these tests it is pumped to the filling lines to make the finished product, which is the second step “Filling”.
What are the Active Ingredients in Mosquito Sprays?
Most mosquito sprays are made up of ingredients such as diethyl phthalate, diethyl carbate; N, N-Diethyl-3-Methylbenzamide (DEET), metofluthrin, oil of lemon-eucalyptus, picaridin and ethyl hexanediol. Some mosquito repellents might also have Permethrin in them. But for more than 50 years, DEET has been the gold standard in mosquito repellents. DEET is a chemical used as the active ingredient in many insect repellent products. DEET was developed by the U. S. Army in 1946 and was registered for use by the general public in 1957. It is now widely used, with approximately 30% of the U. S. population using DEET repellents each year. DEET products are currently available in a variety of forms: liquids, lotions, sprays, and even impregnated materials, such as wristbands. Formulations registered for direct application to human skin contain from 4% to 100% DEET. Approximately 230 products containing DEET are currently registered with the U. S. Environmental Protection Agency (EPA).
How Could I Be Exposed?
There are a ton of ways to be exposed to DEET. The Agency for Toxic Substances & Disease Registry (ATSDR) says, it can be released from common showering and laundering practices and eventually may enter waste water treatment facilities. It can also enter surface water from recreational activities such as swimming. DEET has been detected at very high levels in streams, surface water and groundwater systems, and sewage treatment plant effluents throughout the United States. Although it is considered a pesticide, it is only registered by the EPA as a repellent. Therefore, applications to crops or agricultural products do not typically occur and detections in soils are infrequent. Limited data suggest that DEET is rarely detected in food; however, the transfer of DEET from one’s hands to food products or contamination of nearby foods from spraying a DEET repellent is possible. The most important route of exposure to the general population is through dermal contact from intentional application to human skin and clothing of consumer products containing DEET. It might also get into your eyes if sprayed improperly. It can be released into the air, water, and soil at places where it is produced or used. It is most often released into surface waters following its incomplete removal at waste water treatment facilities, and to a lesser extent released into the air when applying DEET-containing repellents. You will be exposed to DEET if you use water containing it for drinking or bathing. However, the levels of DEET detected in water and air, however, are low. Scientists have not yet studied whether DEET in the air can be absorbed into your lungs after inhalation. It is absorbed through the skin and digestive tract, so it is likely that it can also be absorbed through the lungs and into the blood. DEET in the lungs can be coughed up and swallowed, if it is not absorbed first. DEET in water or food can be absorbed from the digestive tract; studies in animals suggest that most of the ingested DEET will be absorbed. The ATSDR suggest that small quantities of DEET (less than 10–20%) can be absorbed through your skin. In addition, if your skin contacts water with DEET in it, you may absorb some DEET through your skin. Although rarely found in soil, if you accidentally eat soil contaminated with DEET, some of it will enter your body through the digestive tract. In addition, if you touch soil contaminated with DEET, some of the DEET may enter your body through the skin.
So is DEET Good For Me? Not Really.
The health effects of DEET depend on how much of this substance you are exposed to and the length of that exposure. When products containing DEET get into the eyes, they may cause irritation, pain and watery eyes. Scientific America has concluded, through their own studies, that people who have left DEET products on their skin for extended periods of time have experienced irritation, redness, a rash, and swelling (EarthTalk). People that have swallowed products containing DEET have experienced upset stomach, vomiting, and nausea. Very rarely, exposure to DEET has been associated with seizures in people. A study conducted in the late 1980s on Everglades National Park employees to determine the effects of DEET found that one-quarter of the subjects experienced negative health effects from it — e.g., rashes, skin irritation, numb or burning lips, nausea, headaches, dizziness and difficulty concentrating (Barnard, 2002). Environmental monitoring data suggest that any DEET levels that the public might encounter in the environment are much lower than levels causing effects in animal studies, and at much lower levels than people are exposed to when using insect or acarid repellents. Considering the intentional extensive consumer use of products containing DEET on the skin, the risk of health effects due to exposure to DEET appears to be quite low. There have been sporadic reports over the last several decades of an association between excessive use of repellents containing DEET and adverse neurological effects including seizures, uncoordinated movements, agitation, aggressive behavior, low blood pressure, and skin irritation. Duke University pharmacologist Mohamed Abou-Donia, in studies on rats, found that frequent and prolonged DEET exposure led to diffuse brain cell death and behavioral changes, and concluded that humans should stay away from products containing it (EarthTalk). Looking at the health effects of DEET exposure in humans from when they’re first conceived to 18 years of age. ScienceDaily explains how some children exposed to insect repellents or lotions containing DEET have experienced similar types of neurological effects observed in adults (agitation, hypertonia, seizures, ataxia, restlessness, and uncontrolled limb movements) (Center, 2002). The US National Library of Medicine National Institutes of Health says that in the specific case of seizures, it should be noted that because a relatively high percentage (23–29%) of children are exposed to DEET in North America and because seizure disorders occur in (3–5%) of children, it would not be unexpected to see an association just by chance (Koren, 2003).
DEET isn’t the only chemical we need to worry about, there’s also Permethrin. Permethrin is an insecticide in the pyrethroid family. Pyrethroids are synthetic chemicals that act like natural extracts from the chrysanthemum flower. Permethrin is used in a number of ways to control insects. Products containing permethrin may be used in public health mosquito control programs. Permethrin can affect insects if they eat it or touch it. Permethrin affects the nervous system in insects, causing muscle spasms, paralysis and death. Permethrin is more toxic to insects than it is to people and dogs. This is because insects can’t break it down as quickly as people and dogs. Cats are more sensitive to permethrin than dogs or people because it takes their bodies a long time to break it down. Permethrin was first registered with the United States Environmental Protection Agency (U.S. EPA) in 1979, and was re-registered in 2006.
What’s the exposure?
Permethrin may be used on food and feed crops, on ornamental lawns, on livestock and pets, in structures and buildings, and on clothing. Permethrin may also be used in places where food is handled, such as restaurants. Permethrin-containing products (Permanone) are recommended for use only on clothing, shoes, bed nets and camping gear, never on skin. Permethrin does kill mosquitoes and ticks and is highly effective. Permethrin-treated clothing repels and kills ticks, mosquitoes and other arthropods. It remains effective even after repeated laundering. Permethrin-treated clothing should be safe when label directions are followed. Permethrin products should never be applied to the skin. It is often helpful to use spray repellents on outer clothing as well as the skin. Protection times vary. Permethrin products sprayed on clothing generally may be expected up to 6 hours following application.
The Health Effects.
Health effects from permethrin will depend on how someone is exposed to it. Dogs and cats that have permethrin on their skin may act strangely, and flick their paws, twitch their skin or ears, or roll on the ground. Animals that have licked treated skin may drool a lot or smack their lips. Toxicology Brief found that cats that have been exposed by accident to products with high (45–65%) levels of permethrin may seem anxious and can’t walk normally (Merola, 2006). They may also have muscle tremors and seizures and they may die from the exposure. The NCBI found that when people get permethrin on their skin, they may have irritation or tingling, burning and itching at that spot. If permethrin gets in the eyes it can cause redness, pain or burning. If people eat permethrin it could cause sore throat, abdominal pain, nausea and vomiting. People that have breathed in permethrin have had irritation in the nose and lungs, difficulty breathing, headaches, dizziness, nausea and vomiting. Permethrin was classified by the International Agency for Research on Cancer (IARC) as “not classifiable as to its carcinogenicity to humans” in 1991. This means that IARC could not decide whether or not permethrin can cause cancer. The U.S. EPA decided that permethrin was “likely to be carcinogenic to humans” if it was eaten.
Watch Out! It Lingers
This decision was based on the structure of permethrin, what happens to it in the body, laboratory tests that caused tumors in mice and evidence of tumors in rats. If permethrin gets into the soil, it is broken down by microorganisms. Sunlight may also break down permethrin on the soil surface and on the surface of water. Permethrin does not mix well with water. When permethrin gets into surface water like lakes or streams, it sticks very strongly to sediment and can stay there for more than a year. Since permethrin sticks to sediment and does not mix well with water, it won’t usually contaminate groundwater. Permethrin does not evaporate very easily when it is applied to surfaces. Permethrin was applied indoors near a window in an experiment where it was exposed to daylight. After 20 days, 60% of the permethrin that was applied was still on the surface. If permethrin is applied to plants, it may stay on the leaves for between 1 and 3 weeks. Scientists applied permethrin to soil and then planted sugar beets, wheat, lettuce and cotton in the soil. Scientists found trace amounts of the permethrin residue in the edible parts of the plants at 30 and 120 days after planting. Trace amounts of permethrin have been found in foods including bananas, collard greens, squash and watermelon. However, less than 1% of the more than 1,700 food samples tested had detectable levels of permethrin.
Do Low Doses Matter?
It’s been the official mantra of pesticide companies for decades: “The dose makes the poison.” While it makes intuitive sense, you’d think that the more of a chemical you’re exposed to, the sicker you’ll get. The science has, in fact, been saying otherwise for years. Scientists have released reports calling on EPA to completely revamp the way they evaluate chemicals, to better reflect this now fully understood reality: Tiny amounts of certain chemicals can have devastating effects on human health. For example looking at the Food chain. As you go up the food chain the dosages accumulate. Scientific American says, it’s all about the hormones. Our systems are largely regulated by these powerful chemical messengers, and the intricate process of fetal development is all but completely orchestrated by them. The bad news is, some synthetic chemicals look a lot like our natural hormones to the “hormone receptor” trigger cells that turn many functions on and off in our bodies (Cone, 2012). Particularly for the developing systems of infants and children, it’s often the timing, not the dose that matters most.
Looking at DEET. The long-term low dose affects are more harmful to children or those still in the womb, than adults. In children, the most frequently reported symptoms of DEET toxicity reported to poison control centers including headaches, tremors, lethargy, seizures, involuntary movements, and convulsions. Experts also say that frequent and long-term use of this chemical, especially in combination with other chemicals or medications, could cause brain deficits in vulnerable populations, especially children. Just about every expert agrees that children, as well as those with weakened immunity and seniors, should be extra cautious and that it should never be used on infants younger than two months of age. Canada’s federal health department goes further, stating that no child under six months old should be using DEET, and that those who are six months through 12 years old should avoid products that contain more than 10 percent DEET, though that certainly should make one take note as to how potentially dangerous this substance can be (Insect repellents, 2016).
A 2008 study out of the Institute of Development Research in France, published in the journal BMC Biology, discovered that DEET can interfere with the activity of enzymes that are crucial in order for the nervous system to function like it should (Corbe, 2009). The researchers found that DEET blocked the enzyme cholinesterase, which is required for transmitting messages from the brain to the muscles in insects. They noted that DEET may also affect the nervous systems of mammals and that more research was needed, but it certainly causes for concern. The study also showed that chemicals that interfere with the action of cholinesterase can cause excessive salivation and eye-watering in low doses, followed by muscle spasms and ultimately death.
For Permethrin, there weren’t many studies on humans looking at its long term effects. The studies that I could find were similar to that of the effects of DEET. There were many studies done on animals though.
References
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