Will the City of Boston spray adult mosquitoes this year?
Last year new guidelines regarding mosquito control efforts were developed by the Commonwealth of Massachusetts, the City of Boston, and surrounding communities. These guidelines recommend that ground spraying with pesticides should only be looked at as an option when there is considerable evidence of a risk of human infection with West Nile Virus (WNV) or Eastern Equine Encephalitis (EEEV). Such a risk may exist when there are numerous and increasing numbers of WNV infected birds, and multiple WNV or EEEV infected mosquito pools and at least one pool of mammal biting WNV or EEEV infected mosquitoes. Even when such conditions exist, ground spraying may not be recommended because its appropriateness is conditional on the weather, time of the mosquito breeding season, and other factors. Furthermore, within the City of Boston ground spraying will only be considered in the event of a locally acquired human case.

If spraying does occur, what agency is responsible for its application?
If spraying does occur in Boston, Suffolk County Mosquito Control will be the agency responsible for applying the pesticide. People with questions about how to exempt their property from spraying should contact that program. However, please be aware that the official deadline for requesting an exemption (March 1st) has passed.

Which pesticides will be used?
If ground spraying does occur, the pesticide that will be used for controlling adult mosquitoes is Resmethrin. It was used in New York to control mosquitoes during the WNV outbreak for several years, and was used in Boston and many other cities and towns in Massachusetts in the summer of 2000. It can be very effective in killing adult mosquitoes when used in targeted areas under the appropriate conditions.

What is Resmethrin?
Resmethrin is a pesticide that is used to control mosquitoes in outdoor residential and recreational areas. It contains 3 active chemicals: resmethrin, piperonyl butoxide and petroleum distillate. Resmethrin is a synthetic pesticide similar to a natural pesticide (pyrethrum) produced by chrysanthemum flowers. Piperonyl butoxide does not directly kill insects on its own but acts to increase the ability of resmethrin to kill insects. Other pesticide products (such as Raid) containing these ingredients are used indoors and on pets to control insects such as fleas, ticks and ants.

Can pets be outside during the spraying?
In order to reduce your pets' exposure, keep them inside during the spraying.

Is Resmethrin harmful to my health?
When used in residential neighborhoods, Resmethrin is applied in very low concentrations. As a result, the likelihood of any negative health effects is very low.

Because pesticides are inherently toxic however, no pesticide is absolutely risk free. The possibility of experiencing adverse health effects as a result of exposure to any pesticide, including Resmethrin, depends primarily on how much of the pesticide a person comes into contact with and the amount of time the person is in contact with that pesticide. In addition, a person's age, sex, and/or general health may affect their likelihood of experiencing adverse health effects as a result of exposure to pesticides. People with asthma or other respiratory illness, or those allergic to chemicals may be particularly sensitive to pesticides.

Accidental, short-term exposures to very high levels of pyrethroid pesticides similar to Resmethrin could affect the nervous system, causing problems with coordination, tremors, or tingling and numbness in areas of skin contact. Short exposures to high levels of petroleum distillates can cause irritation of the eye, skin, nose, throat or lungs. Vomiting or central nervous system depression may occur if very high levels of petroleum distillates are ingested.

There are no studies examining whether the use of Resmethrin to control mosquitoes has caused any long-term health effects in humans. However, since Resmethrin is applied at very low concentrations, it is unlikely that adverse health effects will occur as a result of limited use to control mosquitoes. Nevertheless, some individuals may experience health effects as a result of short-term exposure to the very low levels of Resmethrin. For these reasons, individuals should take steps to minimize their exposure to Resmethrin(see below).

Are certain people more likely to experience symptoms after they have been in contact with Resmethrin?
If residential spraying is done, it is often done late at night or early in the morning before sunrise when most people are inside. While the vast majority of individuals do not experience any symptoms, some may be particularly sensitive to one or more constituents of Resmethrin, and could experience short-term effects such as eye, skin, nose or throat irritation or breathing problems. Children, in particular, may be more likely than adults to experience adverse effects. For this reason, children with asthma, other respiratory conditions or allergies are advised to remain indoors with air conditioners off (or on recirculate) if and when spraying occurs.

If I'm pregnant, can the spraying affect this pregnancy or harm my baby?
Neither Resmethrin nor piperonyl butoxide are likely to affect pregnancy outcomes in people as a result of spraying. Although some effects occurred in laboratory animals that were given large amounts of either Resmethrin or piperonyl butoxide, these amounts far exceeded the amounts that individuals are likely to contact from the spraying with Resmethrin. However, pregnant women should minimize their exposure to pesticides as an added precaution.

Should I be concerned about cancer because of the spraying program?
Available information suggests that Resmethrin is not likely to cause cancer if people are exposed during or following the spraying program.

Resmethrin did not cause cancer in rats or mice given large doses for their entire lifetime, so it is considered unlikely to cause cancer in humans. Experimental studies have reported that piperonyl butoxide causes liver tumors in rats and mice when they are fed high levels of piperonyl butoxide every day for a long period of time. The amount of piperonyl butoxide ingested by animals in these studies, however, far exceeds the amount humans might be exposed to as a result of the use of Resmethrin to control mosquitoes. All available information thus indicates that piperonyl butoxide is unlikely to cause cancer in humans as a result of its use to control mosquitoes.

Should I be concerned about my private swimming pool?
Resmethrin breaks down fairly quickly in water and in sunlight. You could cover your pool before the spraying occurs; however, given the small concentrations of Resmethrin being sprayed, no special precautions or waiting periods are recommended for swimming pools.

What can I do to reduce my exposure to the insecticide?
As with any pesticide, you may want to reduce or eliminate exposures that are not necessary. The following steps will help reduce possible exposures to Resmethrin during spraying:

• Remain inside whenever spraying takes place and for about one hour after.
• Close windows and doors before spraying begins. Turn off fans and air conditioners facing the streets that are being sprayed.
• If you have to remain outside, take every precaution to stay far away from the truck doing the spraying. If in spite of those precautions you are exposed, immediately rinse your eyes with water and wash exposed skin surfaces with soap and water.
• Thoroughly rinse homegrown fruits and vegetables that may have been exposed to pesticide with water before cooking or eating.
• Bring pets inside and cover ornamental fishponds to avoid direct exposure.
• Consult your physician if you think you are experiencing health effects as a result of the spraying.

Are other mosquito control activities being undertaken?
Yes. Larvacide (pesticide designed to prevent mosquito larvae from maturing into adults) will be added to catch basins to kill mosquitoes before they hatch. These pesticide additives are not toxic to humans and do not affect the water supply.

If spraying occurs, does that mean I no longer need to take precautions against mosquitoes?
No. The goal of spraying is to decrease the population of mosquitoes that could potentially carry disease. This will not eliminate mosquitoes. In order to protect yourself and your family from mosquito bites you should:

• Avoid being outside between dusk and dawn, the peak times for mosquito activity.
• If you must be outside during peak mosquito hours, consider wearing long pants, long sleeve shirts and socks to cover exposed skin.
• Use an insect repellent containing DEET or an EPA approved alternative. If you use a product containing DEET, do not use concentrations of more than 35% for adults and 10% for children). Infants should not use repellents containing DEET. Pregnant women should follow the manufacturers' instructions.