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Pesticides can
sometimes first appear in drinking water wells decades after the pesticides
were applied or spilled, depending on the chemical properties of the pesticide
and the geologic conditions
filterwater.com
Pesticides are chemicals used to kill or control pests such as
insects, weeds, fungus, bacteria, rodents, fish or any other type of organism
that poses a problem.
Pesticides are most often applied to farmland, gardens and
lawns.
Pesticides are also applied to water bodies (for example,
rivers, canals or lakes) to control pests such as mosquitoes, weeds or invasive
fish species.
Pesticide contamination of drinking water is very common, especially
in agricultural areas.
Accidental or illegal spilling or dumping of pesticides can lead
to contamination of drinking water, and even proper application of pesticides
can lead to contamination of drinking water through leaching into groundwater
or runoff into surface water bodies.
Concentrations of pesticides tend to be highest in streams
adjacent to agricultural areas.
In a study published in 2006 by the U.S. Geological Survey,
atrazine (a pesticide banned in the European Union but still widely used in the
U.S.) was found 90% of the time in streams in agricultural areas and 70% of the
time in streams in urban areas, and it was also frequently detected in
groundwater.
Because groundwater can move very slowly, pesticides can
sometimes first appear in drinking water wells decades after the pesticides
were applied or spilled, depending on the chemical properties of the pesticide
and the geologic conditions.
Because of this, even pesticides that are no longer in use can
still contaminate water supplies.
When using pesticides that may contaminate water supplies, the
risk of contamination may be minimized by
1) using short-lived pesticides that biodegrade
easily,
2) using pesticides that tend to stick to soil and not
move easily, and
3) avoiding disposal of pesticides where they may
contaminate water resources, such as near a well or spring or down a storm
sewer.
Interesting fact: The pesticide DDT is so persistent
in the environment that it is still found in fish more than 40 years after it
was banned in the U.S. in 1972.
Health Effects Associated with Pesticides in Drinking
Water
There are many different pesticides, each with a different level
of toxicity.
The health risks associated with pesticides in drinking water
are related to how toxic the compound is, how much is in the water, and how
much exposure a human gets to the contaminated water.
In large doses, which could come from direct exposure to
pesticides, they can cause health problems such as cancer, organ damage,
reproductive effects, birth defects, or nervous system damage.
In drinking water, concentrations are usually low, but some
pesticides are toxic even at very low levels.
“High levels of nitrate from chemical fertilizers in
the water supply may indicate possible contamination by pesticides.”
Many pesticides are not regulated as contaminants in drinking
water, but the U.S. Environmental Protection Agency (USEPA) has set maximum
contaminant levels (MCLs) for several pesticides.
A MCL is the maximum concentration of a contaminant that is
legally allowed in public drinking water systems under the Safe Drinking Water
Act.
The long-term health risks associated with concentrations above
the MCL are considered to be unacceptable.
The MCLs for individual pesticides are based on their toxicity,
with more toxic pesticides having lower MCLs. Their values range from 0.00005
to 4 milligrams per liter (mg/L or parts per million).
For example, the MCL for atrazine, which is the most commonly
detected pesticide in drinking water in the U.S., is 0.003 milligrams per
liter.
High levels of nitrate from chemical fertilizers in the water
supply may indicate possible contamination by pesticides.
Because these tests are expensive and only test for specific
compounds, it is best to only test for pesticides that you think may be
contaminating your water.
How to Treat Drinking Water for Pesticides
Pesticides can be removed from drinking water by reverse osmosis
or granulated activated carbon (GAC) filters.
Reverse osmosis works by forcing the water through a membrane
that allows water molecules to pass through but blocks larger ions or
molecules, such as ones associated with iron, lead or pesticides.
In homes, reverse osmosis systems are usually small systems
(called point-of-use systems) located near the kitchen sink.
Reverse osmosis systems are cost-effective, but low end systems can only produce a
few gallons of treated water each day.
Significant recent improvements in membrane elements allow for
more expensive systems to produce 100 or more gallon per day.
The taste of the water may be affected by the removal of the
minerals.
Granulated activated carbon (GAC) filters are relatively
inexpensive and are simple to use. They remove pesticides and other
contaminants that stick to small particles of material such as coal or
charcoal.
These filters can take the form of point-of-use systems or
pitchers manually filled with water. GAC filters must be replaced or
regenerated periodically to maintain their effectiveness.
We have a number of different residential and commercial systems that can remove
pesticides. We highly
recommend you to have one even if your water comes from a municipality.
The Water Superstore
Our company was created with
the goal to provide clean drinking water along with best overall customer
experience, and promote healthy lifestyle and clean water supply. We are happy
to offer our customers best water testing and water purification products on
the market at a guaranteed low price.
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