By TIM FAULKNER/ecoRI
News staff
Eastern equine
encephalitis (EEE) is an insidious virus. It kills about 40 percent of humans
who become infected, according to the Centers for Disease Control and Prevention. A third of those afflicted suffer permanent neurological damage. The rest recover with little or no long-term health effects.
This year one human case
of EEE has been reported in Rhode Island, on Aug. 30. The West Warwick resident
died Sept. 8, the state’s first fatal human EEE case since 2007, according to
the Rhode Island
Department of Health.
Seven people have been
infected in Massachusetts. A resident of Fairhaven, Mass., died from the virus
in mid-August.
The virus is transmitted by mosquitoes and is prevalent along the East
Coast, but the virus is most common in the freshwater swamps of Florida and
southeastern Massachusetts, where mosquitoes breed in large numbers.
Although the virus is
always present, it spreads in late summer and early fall. The threat subsides
after the first frost kills off much of the mosquito population.
The pesticide Anvil 10+10 is the preferred insecticide used to kill
mosquitoes. Spray trucks and aerial misting are the most common methods for
releasing the chemical. Each treatment creates a fog of droplets that attach to
and kill insects.
Anvil poses few short-term health risks to humans, but the poison can last up to two months in soil. It’s highly toxic to freshwater fish, invertebrates, amphibians, and other insects such as honeybees.
Most applications occur
at night and early morning, when bees are inside their hives. But not all
colonies stay in their hives at night. A recent story
by WBUR in Boston noted that some beekeepers put wet sheets over their hives to
reduce pesticide exposure.
Anvil has two primary
ingredients: sumithrin and piperonyl butoxide. Sumithrin, or d-phenothrin, is a general-purpose pesticide used
indoors to kill ants; in shampoos to treat head lice; and on pets to kills
fleas and ticks. Piperonyl butoxide is a petroleum solvent similar to paint
thinner and kerosene.
It’s unclear if Anvil is
an endocrine disruptor. Experimental studies have found that high exposure to
piperonyl butoxide causes liver tumors in rats and mice.
The Environmental
Protection Agency (EPA) doesn’t consider Anvil toxic to plants.
Due to the infrequency
of treatment and the fact that Anvil breaks down quickly in sunlight and water,
human health effects are considered rare, although no studies have been done to
determine if Anvil causes any long-term human health impacts.
Short-term exposure can
impact the nervous system, causing a loss of coordination, tremors or tingling,
and numbness on the skin. Anvil can irritate the eyes, skin, nose, throat, or
lungs. Increased exposure can trigger vomiting and depression.
Children are at greater
risk than adults to health effects. In communities where applications are
occurring, people and pets should stay indoors during treatment. Windows and
doors should be closed and air conditioners turned off.
Organic farmers are
exempt from the aerial spraying. Homegrown fruits and vegetables should be
rinsed in water after an application.
Other than organic
farms, open bodies of water, such as reservoirs, some coastal areas, and
unpopulated natural areas will be excluded from spraying.
In Massachusetts, 36
communities are classified at critical risk, 42 at high risk, and 115 at
moderate risk for the EEE virus.
In all, 110,000 acres in
portions of 21 communities in Rhode Island will be treated. Some of the areas
abut portions of Massachusetts where EEE has been detected.
On Sept. 5, Rhode Island
dispersed larvicide pellets in “swampy areas” near Central Falls and in Westerly
and West Warwick. Granules of Bti, a naturally occurring bacterium, were
dispersed by helicopter. According to the EPA, Bti is not a risk to humans.
Bti produces toxins that
target the larvae of mosquitoes, black flies, and fungus gnats. These toxins
don’t harm other insects such as honeybees. Bti is approved for pest control in
organic farming.
