Pesticides & Mosquito Control: Dangers & Safe Management
As our climate continues to change, mosquito-borne diseases will be an increasing public health challenge for which we must prepare. Pesticides – applied from trucks or aerially to try to address mosquito-borne illnesses – also themselves pose serious public health risks.
Pesticides used for mosquito control do not eliminate mosquito larvae and may kill other species that are mosquito predators. Moreover, pesticide drift can impact pollinators, birds, fish and amphibians. During the height of West Nile Virus in Baltimore City in 2002-2003, Baltimore City’s Health Commissioner Peter Beilenson, M.D., decided to focus on educating all City employees and residents regarding non-chemical practices to eliminate mosquitoes. This effort proved effective.
2021 Update: ‘Forever chemical’ PFAS found in mosquito pesticide widely used in Maryland
Three of the products that were found to be contaminated by PFAS are listed for use in the State’s mosquito control program, serving 2100 Maryland communities.
PFAS are not supposed to be in mosquito control products but it was found in testing Permanone 30-30. PFAS pose significant risk to public health and environment. PFAS are associated with liver damage, thyroid disease, developmental issues, reduced fertility, obesity, hormone suppression, and cancer.
Managing Mosquitoes Without Pesticides
There are ways to minimize the chance of mosquito bites while also eliminating exposure to toxic pesticides.
Download Managing Mosquitoes Without Pesticides fact sheet.
Maryland Pesticide Education Network supports a least-toxic approach to managing mosquitoes both for preventing mosquito-borne disease and for nuisance control.
To protect yourself and your family from a mosquito-related health threat or simply for nuisance control, consider taking these steps:
Get Rid Of Mosquito Breeding Grounds Around Your Home
“Standing water left alone keeps mosquitoes close to home (download poster)”: Eliminate pooled or stagnant waters from containers, gutters, drains, and anywhere that pools water. Even a bottle cap can become a breeding site. Fix leaky faucets.
- Stock ponds and other ornamental ‘standing water’, with mosquito larvae eating fish
- Fix outdoor leaks from water faucets and clear and enhance drainage where needed.
- For standing water, you can’t drain, use Mosquito Dunks or Mosquito Bits with BTI, a least toxic biological control. BTI is toxic only to mosquito larvae and lasts 30 days, treating 100 square feet of surface water. Simply apply Mosquito Dunks® or Mosquito Bits to any standing water, or water garden. Mosquito Bits work well for moist areas that can also be a mosquito breeding site. They are available at local hardware and home and garden stores and are an effective least-toxic biological control. The dunks are ingested by feeding larvae and kills them.
- Citronella candles help to repel mosquitos
- Wear long sleeves and long pants and use least-toxic mosquito repellents when outdoors such as oil of lemon eucalyptus and Picaridin, both registered by the US EPA or essential oil-based repellents sold in health food stores.
- Try to avoid being outside at dusk when mosquitoes are most active.
- Fans will also keep mosquitoes away.
- If looking for a vendor to hire for mosquito management, consider hiring an organic lawn care company that uses safer products.
Pesticides Used For Mosquitoes Control in Maryland
- Synthetic Pyrethroids, the class of pesticides applied by trucks in Maryland, are considered possible endocrine disruptors and carcinogens by US EPA. They are also known to worsen asthma. People with compromised immune systems, chemically sensitive people, pregnant women, and children with respiratory problems, such as asthma, are especially vulnerable to these pesticides.
- Naled is an organophosphate pesticide aerially sprayed in some parts of Maryland. This class of pesticides, derived from World War II nerve agents, is neurotoxic and affects the cardiovascular and respiratory systems.
In the event state and local officials deem pesticide applications are necessary to address the presence of Zika in your community, U.S. Department of Health and Human Services has recommended the following action in its Toxicological Profile for Synthetic Pyrethroids:
Remain indoors and closing your windows while your neighborhood is being sprayed will lessen your exposure”.
Turn off air conditioners and swamp coolers and keep family pets indoors during.
Because Permethrin is odorless and weather conditions vary, individuals must use their judgment in deciding how long after spraying to keep these precautions in place.”
Additionally, HHS recommends bringing toys and other outdoor items indoors. Permethrin can remain on items and persists in soil and on plants for a significant period of time beyond the actual application.
Larvicides are used to kill mosquito larvae: Bacillus thuringiensis (Bt): Bt is a naturally occurring soil bacterium. While EPA considers Bt to be among the safer pesticides, the Agency is still requiring additional data on ecological effects. Bt is completely biodegradable. We do support an expanded use of this larvicide to effectively reduce mosquito populations with the least risk to human health. However, Bt formulations can contain anywhere from 0-99+% ‘inert’ ingredients (see more on inerts below).
Methoprene: Methoprene is an insect growth regulator, which mimics an insect growth regulation hormone. It is slightly toxic to birds and slightly too moderately toxic to fish. Methoprene may have severe developmental effects on frogs. It was found to be a possible cause of a sharp rise in the incidence of frog deformities throughout North America. Methoprene also has a moderate toxicity towards both warm and cold water, freshwater fish, although exposure of these organisms is limited due to Methoprene’s rapid degradation in unshaded water. It is highly acutely toxic to estuarine and marine invertebrates, which play an important role in the delicate estuarine ecosystem.
Adulticides: used to eliminate adult mosquitoes: the three pesticides used by the state of Maryland to combat West Nile are two synthetic pyrethroid pesticides, ANVIL 10 +10 (Sumethrin) and BIOMIST (Permethrin) and an organophosphate — TRUMPET (Naled). The two synthetic pyrethroid pesticides are mixed with Piperonyl Butoxide, a synergist that enhances the killing power of the active ingredients and are sprayed from trucks. TRUMPET (Naled) is aerially sprayed.
Pesticides Related Injury
If you suspect you may be suffering from exposure to the pesticides used to reduce mosquito populations, we suggest you visit the nearest emergency room or contact your physician – and ask the health care provider to report the case to your county’s Department of Health. Health care provider reporting of suspected pesticide injury is mandatory under Maryland law! Your health care provider should report suspected pesticide-related injury online here.
Possible Acute Symptoms of Pesticides Poisioning
ANVIL (Sumethrin) and BIOMIST (Permethrin):
Effects on the nervous system such as itching, numbing, burning or tingling
Respiratory problems (synthetic pyrethroids are known to worsen respiratory illnesses such as asthma)
Irritation of the eyes
Irritability to sound and touch
Abnormal facial sensation
Abnormal facial sensation
Mild nervous system depression
Very high doses may result in unconsciousness, incontinence, and convulsions or fatality. This chemical also adversely affects birds and aquatic life.
Possible Long-Term Effects Of Exposure – Synthetic Pyrethoids
TALSTAR (Bifenthrin) and BIOMIST (Permethrin), synthetic pyrethroids are considered possible endocrine disruptors (EDs) by the U.S. EPA. Some synthetic pyrethroids already have been banned for their endocrine disrupting impacts. EPA has only recently begun a safety review of synthetic pyrethroids to evaluate this class of pesticides for its effects on children and the endocrine system. EDs are linked to cancer, obesity, infertility, neurobehavioral disorders and immune dysfunction. According to Dr. Linda Birnbaum, Director of the National Institute of Environmental Health Sciences, recent research underscores that EDs can have effects at external doses that are often considered safe by the regulatory community. Permethrin is also classified as a possible carcinogen by the U.S. EPA.
- Anvil and Permanone are mixed with the synergist Piperonyl Butoxide (PBO). PBO is classified as a possible carcinogen by EPA.
- TRUMPET (Naled) is toxic to the nervous system. Naled’s breakdown product dichlorvos (another organophosphate insecticide) interferes with prenatal brain development. In laboratory animals, exposure for just 3 days during pregnancy when the brain is growing quickly reduced brain size 15 percent. Dichlorvos also causes cancer, according to the International Agency for Research on Carcinogens. In laboratory tests, it caused leukemia and pancreatic cancer. Two independent studies have shown that children exposed to household “no-pest” strips containing dichlorvos have a higher incidence of brain cancer than unexposed children. Aerial applications of Naled can drift up to one-half mile. According to the U.S. Environmental Protection Agency, Naled is moderately to highly toxic to birds and fish. It also reduced egg production and hatching success in tests with birds and reduced growth in tests with juvenile fish.
Pesticides Used For Mosquitoes Control in Maryland
Inert ingredients are chemicals used in pesticide products to make the pesticide more potent or easier to use. Despite their misleading name, inerts are neither chemically, biologically nor toxicologically inert. Often the greatest percentage of chemicals in a pesticide product is inert ingredients – chemicals claimed as trade secrets by manufacturers. Many inerts are hazardous. Of the almost 2600 chemicals that EPA believes are currently used as inert ingredients, more than 600 have already been classified as hazardous by state, federal and international agencies. Examples of hazardous and commonly used inerts include crystalline silica (causes cancer and genetic damage), naphthalene (causes anemia and liver damage) and xylene (cause headaches, confusion and fetal death).
In light of our support of the public’s right-to-know, we have gathered information on the pesticides used by MDA for mosquito control and their potential adverse health effects from various sources including, US EPA, EXTONET (a pesticide information project of the Cooperative Extension offices of Cornell University, Oregon State University, the University of Idaho, the University of California at Davis and Michigan State University), Consumer Policy Institute Of Consumers Union, Beyond Pesticides/National Coalition Against the Misuse of Pesticides and the National Coalition for Alternatives to Pesticides.