Malathion is an insecticide in the chemical family known as organophosphates. Products containing malathion are used outdoors to control a wide variety of insects in agricultural settings and around people’s homes. Malathion has also been used in public health mosquito control and fruit fly eradication programs. Malathion may also be found in some special shampoos for treating lice. Malathion was first registered for use in the United States in 1956.
Friday, April 20, 2012
HOW DOES MALATHION WORK?
Malathion kills insects by preventing their nervous system from working properly.When healthy nerves send signals to each other, a special chemical messenger travels from one nerve to another to continue the message. The nerve signal stops when an enzyme is released into the space between the nerves. Malathion binds to the enzyme and prevents the nerve signal from stopping.This causes the nerves to signal each other without stopping.The constant nerve signals make it so the insects can’t move or breathe normally and they die.
People, pets and other animals can be affected the same way as insects if they are exposed to enough malathion. About the same amount of malathion will be taken into the body whether you breathe it in or you swallow it. Malathion is also readily taken into the body through skin, though the amount absorbed will depend on where the exposure occurs on the body. Malathion can become more toxic if it has been sitting for a long time, especially in a hot place.
BACKYARD SOLUTIONS FOR MOSQUITOES
- Set up large fans for home barbeques or other outdoor gatherings.
- Use citronella candles or yellow outdoor light bulbs to repel mosquitoes.
- Some botanicals such as garlic or pepper are used as barriers around property.
- Encourage natural predators - stock closed, ornamental ponds with mosquito-eating fish (Gambusia holbrooki). Do not allow ornamental ponds to enter waterways, G. holbrooki are not native to all parts of the U.S. Whenever possible, nurture natural mosquito predators such as bats, birds, dragonflies, beetles, frogs and snails (pesticide use adversely effects predators).
- Carbon dioxide mosquito traps and attractants
- Fill holes or depressions in trees with sand or mortar, or drain after each rain.
- Microbial Insecticides (Bti - Bacillus thuringiensis israelensis) (Cinnamon Oil) to kill larvae.
- Botanical Yard Repellents (Scented Geranium, citrusy or lemon-scented plants such as Lemon Grass, and herbs like Oregano, Catnip, or sweet and holy basil [see Dave's Garden plant database], Garlic barriers, Dr. T's Nature Products);
(Any mention of product names is for informational purposes and does not constitute an endorsement.)
WHAT ARE THE HEALTH EFFECTS OF PESTICIDES?
Health effects of pesticides can cause both acute and chronic problems. Acute health effects appear shortly after exposure to these pesticides and can include: skin and eye irritations, headaches, dizziness and nausea, weakness, difficulty breathing, mental confusion and disorientation, seizures, coma, and death. Chronic health effects may not be apparent until months or years after exposure. Such health aliments include nervous, reproductive, and immune system disorders, and cancer.
Children can be particularly sensitive to exposure to chemicals due to their small body size, immature immune systems and rapid growth cycles. Although everyone is at risk from exposure, the most vulnerable groups are children, pregnant women, the elderly, patients undergoing chemotherapy, and people with compromised immune systems.
All pesticides are associated with some risk of harm to human health and the environment. Every pesticide on the market must be registered with the Environmental Protection Agency (EPA). This registration does not guarantee the safety of the product even when used as directed. In fact, the EPA has officially stated that no pesticide can be considered safe and federal law prohibits manufacturers from making claims that EPA registration of their products means they are safe.
STUDY: Children's Vulnerability to Organophosphates 1. David Wallinga, M.D.; MPA; Linda Greer, Ph.D.
SOURCE: Natural Resources Defense Council, November 2000, p.57 (74).
This report discusses children’s risks to the toxic effects of organophosphates. "It is now widely accepted that among a child’s developing organs, the brain - as well as the developing immune, reproductive and endocrine systems – are particularly sensitive to chemical injury". Recent studies propose the nature of adverse affects induced by organophosphate in young developing brains. "Exposure to even a single, low-level dose of organophosphates, during particular times of early brain development, can cause permanent changes in brain chemistry as well as changes in behavior, such as hyperactivity".
1. Information adapted from Appendix A: Children’s Vulnerability to Organophosphates.
STUDY: Child Leukemia and Aplastic Anemia After DDVP Exposure. Drs. Jerry D. Reeves; David A. Driggers; Vincent A. Kiley. Department of Pediatrics, David Grant Medical Center, Travis Air Force Base, California.
SOURCE: The Lancet, August 8, 1981, p.300.
This study reviews the cases of seven children with bone marrow disorders that have been observed by physicians at Travis Air Force Base Medical Center in California. The physicians believe that organophosphate pesticides caused the blood disorders, in all cases. "All blood disorders occurred shortly after exposure to the pesticides DDVP/propoxur and malathion. Six of the patients had aplastic anemia and one had acute lymphoblastic leukemia".
STUDY: Intestinal Disorders in Children Born After California Spraying. Department of Preventative Medicine, University of Southern California, Los Angeles.
SOURCE: Epidemiology, January 1992, vol.3, p.32 (8).
This study shows evidence of harm to human health after aerial sprayings of Malathion over human populations. It was found that "children who had been exposed to Malathion during the second trimester of pregnancy were showing over two and a half times more gastrointestinal disorders (affecting the stomach and small intestines) in comparison to children not exposed to Malathion during pregnancy".
STUDY: Human Birth Defect Suspected from Malathion. Department of Clinical Genetics, Erasmus University, Rotterdam. Department of Child Neurology, University Hospital, Utrecht.
SOURCE: Teratology, 1987, vol.36, p.7 (3).
Malathion has been shown to cause birth defects in a variety of animals and at lower levels than other pesticides. Researchers suspect that Malathion caused the birth defect known as "amyoplasia", which is "a disorder characterized by almost total absence of skeletal muscle", in an infant girl who died soon after birth. The main researcher, Dr. D Lindhout, suspects this because "the mother used a malathion head lice shampoo during the 11th and 12th week of her pregnancy". Dr. Lindhout stated that malathion was a suspect in this birth defect because "when administered to adult animals, malathion and related thiophosphonates stimulate, and subsequently inhibit, the nicotinic sites in skeletal muscle, resulting in muscle weakness and paralysis. Neonates (newborn babies) are far more sensitive to these agents than adults, mainly because of a slower rate of detoxification of the metabolite (the metabolite in this case would be the liver breakdown of malathion which has been shown to be far more toxic than malathion itself)". Furthermore, "there was no genetic history of this problem in the mother or the father’s family and there was no evidence of drug use by the mother", except for the use of Malathion head lice shampoo during early pregnancy.
STUDY: Immune System Weakens After Malathion Exposure. University of Virginia.
SOURCE: The Journal of Immunology, vol.140, p.564 (7).
According to the Journal of Immunology, Malathion contains chemical impurities which have been found to weaken immune system function, including a weakening of a type of white blood cell called “cytotoxic lymphocytes” (which attack cancer cells and virus infected cells). These lymphocytes can also attack viruses in the body. Malathion has been shown to significantly weaken the cytotoxic lymphocyte’s ability to perform their job effectively. Since it has been shown that people with weakened immune systems are more likely to develop encephalitis, paradoxically, it must be considered that malathion has the potential in itself to increase encephalitis cases as the spraying of malathion can weaken a person’s immune system, thereby making them more vulnerable to the disease.
STUDY: Malathion. Loretta Brenner.
SOURCE: Journal of Pesticide Reform, Winter 1992, vol.12, no.9, p.29 (9).
This article examines the health effects of Malathion in human and animal studies. Malathion is detrimental because it effects the nervous system by inhibiting the enzyme, acetylcholinesterase (AchE), that breaks down acetylcholine, a chemical essential in transmitting nerve impulses across junctions between nerves. Without functioning AchE, acetylcholine accumulates to produce rapid twitching of voluntary muscles, incoordination, convulsions, paralysis, and ultimately death. Acute toxicity reactions in humans include headaches, nausea...blurred vision and pupil constriction, slowed heartbeat, respiratory depression, paralysis, coma, as well as muscular damage (after inhalation). Birth defects, reproductive problems, and genetic damage have been associated with alathion exposure in humans and animals. Furthermore, Malathion has the potential to contaminate ground and surface water. In California, five of twenty-eight county water systems tested were contaminated with malathion1 and storm drains in Santa Clara County (where aerial sprays of malathion had been used for eradication programs) concentrated Malathion and malaoxon, eventually draining into San Francisco Bay.2 Drift and aerial spray mosquito control programs can expose people to levels of Malathion that can cause the aforementioned health effects.
1. Howard, P.H. (ed.) 1991 Handbook of environmental fate and exposure data for organic chemicals. Volume III. Pesticides. Chelsea, MI: Lewis Publishers.
2. Oshama, R.J. et al. 1982. A characterization of sequential aerial Malathion applications in Santa Clara Valley of California, 1981. California Department of Food and Agriculture Environmental Hazards Assessment Program. (April.) p.12. Cited in Residents Against Spraying Pesticides. 1984. Environmental concerns. Unpublished report. Los Angeles, CA.
STUDY: The Five Worst Environmental Health Threats to Children’s Health
SOURCE: Journal of Environmental Health, May 1998, vol.60, no.9, p.46 (2).
This article contains information cited from a eport entitled "Our Childen at Risk" published by the Natural Resources Defense Council (NRDC, 1997) which discusses environmental exposures that threaten children’s health. Pesticides are one of the five worst threats to children's health. The other four are lead, air pollution, environmental tobacco smoke, and drinking-water contamination.
According to the Journal of Environmental Health, "Pesticides have been associated with the development of certain cancers in children, including leukemia, sarcomas, and brain tumors. Many classes of pesticides have been shown to adversely affect the developing nervous system of experimental animals. Parental exposure to pesticides has been linked with birth defects in children. New studies suggest that pesticides may compromise the immune system of infants and children".
ADULTICIDING
Adulticiding is the use of chemicals to reduce adult mosquitoes by ground or aerial applications. Adulticiding should only be used when all other less invasive control measures have failed to reduce mosquito populations to an acceptable tolerance and there is documented evidence to sufficiently support the measure. Feelings, perceived threats and public hysteria are NOT considered acceptable documented evidence to support adulticiding measures. See page 1 for additional information. Possible adulticides of use are pyrethroids and malthion (organophosphate). All application sites should be monitored before and after treatment to ensure proper placement and effective control.
Recommendations for Mosquito Control Programs, Kristy Gottfried, Medical Entomologist
ALTERNATIVES TO MOSQUITO REPELLANT
Some Least-Toxic Mosquito Sprays Include:
Oil of Lemon Eucalyptus- CDC recommends lemon eucalyptus oil repellents as a good alternative to DEET. The scented oil of lemon eucalyptus masks both carbon dioxide and lactic acid exhalations that alert mosquitoes to our presence, essentially hiding humans from detection. According to CDC, this plant-based mosquito repellent provides protection time similar to low concentration DEET products.(Repel Lemon Eucalyptus Insect Repellent-www.repel.com).
Essential oils- Pesticides made with essential oils are derived from plants that are known to have insecticidal properties. Some essential oils used in repellents include Cedarwood, Soybean Oil (www.biteblocker.com), and Geraniol (MosquitoGuard- www.wildroots.com, Bite Stop- www.bitestop.com, Bugband- www.bugband.net) When compared against products like Citronella, Geraniol proved to be 100% more effective. Against products containing 10% Deet, Geraniol proved to be more effective.
Picaridin (KBR 3023), dervived from pepper, is a newly registered repellent that CDC claims provides comparable protection as DEET products with similar concentrations (Cutter Advanced- www.cutterinsectrepellent.com/). The limited data available on this product suggest that it has low potential for toxicity.
Citronella sprays- The same ingredient in the candles that repels mosquitoes also is in some mosquito sprays, including the repellent Natrapel (www.tendercorp.com).
Some repellents include many of these ingredients, including: Quantum Buzz Away Mosquito Repellent (www.quantumhealth.com), All Terrain (http://www.allterrainco.com/), Avon Skin-So-Soft, and Herbal Armour.These recommendations are based on what is known about the relative toxicity of the active ingredient. The inert ingredients, which often makes up the largest portion of the product, is not disclosed, and therefore cannot be evaluated.
With all these repellents, be sure to reapply often (following the directions on the label) to repel the mosquitoes most effectively.
http://www.beyondpesticides.org/mosquito/documents/LesstoxRepellents.pdf
RECOMMENDATIONS FOR MOSQUITO CONTROL PROGRAMS. Kristy Gottfried, Medical Entomologist
To view the entire article: http://www.beyondpesticides.org/mosquito/documents/Nashville%20advice%20TNDOHCountyDirsMtngGottfriedvm.pdf
Adulticiding as the only control source is ineffective for the following reasons:
1. There are approximately 170 different mosquito species found in the US and approximately 50 mosquito species found in Tennessee. All mosquito species found in Tennessee are not pests nor do they feed on humans nor are they WNV vectors. Even though there is a list of mosquito species that have been found with evidence of WNV contact in the US, very few of those species are biologically capable of serving as effective WNV vector species.
There are three primary mosquito species in Tennessee that are involved in WNV transmission to humans and are all in one genus: Culex. If a program is designed specifically to reduce the mosquitoes that are involved in WNV transmission, then the program must be specific and targeted for the mosquitoes in the genus Culex. I say this to convey the critical point that an effective program must specifically target the species present in the area. Since, eradicating mosquitoes is not possible, an acceptable level of mosquitoes must be determined. Once the mosquito species are identified, the knowledge of flight, biting and breeding behavior will allow the program to apply adulticides effectively. The bottom line is that the application of adulticides without regular mosquito surveillance (knowledge of the target species) may look pleasing to the average citizen, however, it is ineffective and can potentially lead to serious consequences.
2. Adulticides are designed to break down fast in the environment; there are NO residual effects of the product. Product droplets that land and dry on surfaces will not kill mosquitoes landing on that surface. Adulticides must come in direct contact with a flying mosquito to kill; mosquitoes that are in inaccessible habitats will not be affected. The appropriate timing of the adulticidal application is based on knowing the mosquito species present in the area as well as the behavioral (feeding, breeding) characteristics.
3. Adulticides will only kill flying adult mosquitoes that are in the area at the time of application and may supply short-term relief (3-4 days). The immature stage (larvae) found in water sources will NOT be affected. When the next generation of mosquitoes emerges from the water surfaces, there is an entire new population that will need to be treated. In addition, some mosquito species are capable of flying long distances in search of a blood meal; treatment in one area will not prevent searching mosquitoes from another area entering the treatment area after application.
4. Overuse and non-regulated use of chemical products used for adulticiding or larviciding have the potential to increase the resistant individuals in a population. Once resistant individuals increase in a resident mosquito population, killing the adults becomes increasingly difficult. Resistance occurs when a mosquito population is treated with a chemical product and although a substantial proportion may die, there will be a few that have the capability of reducing the chemical to inert compounds with no biological effects. Survivors will be capable of passing on these favorable genetic characteristics to their progeny and essentially an artificial selection process will produce a resistant population.
Since adulticidal products are expensive, the natural thought would be to most operators to decrease the concentration for the purpose of reducing cost. This is a great mistake and actually results in encouraging the development of a resistance mosquito population. The application of less concentrated products will not provide a lethal dose and will result in a mosquito population with resistant individuals. Resistant individuals will build up in a population with each additional application of decreased concentration. There are very few EPA registered adulticidal products on the commercial market. Promoting resistant populations in a region will only decrease the effectiveness of these few products. Then during an unfortunate time if/when a critical public health situation arises, the products of choice will be limited and success questionable.
5. There are non-chemical strategies available for use in many situations and the EPA recommends considering using these methods as part of an overall pest management strategy, IPM. Therefore, adulticides should play only a small roll in the overall mosquito control program.
IF A REGION IS GOING TO INVEST LOCAL FUNDS INTO A MOSQUITO ABATEMENT PROGRAM-THEN THE PROGRAM SHOULD BE FUNDED SUFFICIENTLY TO ENSURE COMPLIANCE WITH PROFFESSIONALLY ACCEPTED MOSQUITO CONTOL STANDARDS.
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