Bulk
A subset or increment of a water sample that was taken from a larger sample.
Also called gross, lot, raw or grab sample. Bulk samples usually consist of raw water
taken directly from a source that is untreated in any way (such as acidified to
preserve metals, etc.).
Alkalinity (
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Alkalinity refers to the capacity of water to neutralize acid. In uncontaminated water, alkalinity is
primarily a measure of dissolved bicarbonate and carbonate; concentrations of other acid-
consuming solutes such as hydroxide, silicate, borate, and dissolved organic compounds are
usually small compared to the amount of bicarbonate and carbonate. Alkalinity is reported as the
equivalent amount of calcium carbonate in mg/L.
The primary source of natural alkalinity is carbon dioxide in the atmosphere and in soil gases that
dissolves in rain, surface water, and groundwater. Bicarbonate released through dissolution of
carbonate minerals also contributes to alkalinity. Major contaminant sources of alkalinity include
landfills and other sites where alkaline or basic chemicals have been dumped. High levels of
alkalinity may be accompanied by objectionable taste, or precipitation of scale in pipes and
containers.
Conductivity (
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Conductivity measures the ability of water to transmit an electric current. Pure water is a poor
electrical conductor. However, the ability of water to transmit electricity increases as the amount
of dissolved solutes increases. Water with high conductivity may have objectionable taste, cause
staining, and precipitate scale in pipes and containers. Conductivity is reported in micromhos per
centimeter at 25
o C, or the equivalent microsiemens per centimeter in the International
System of Units.
Hardness (
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Hardness describes the capacity of water to precipitate an insoluble residue when soap is used.
Hard water reduces the ability of soap to clean clothes; leaves a sticky film on skin, clothes, and
hair; and deposits scale in water heaters, boilers, and industrial equipment.
Calcium and magnesium are largely responsible for the behavior of soap in water; therefore
hardness is defined as the concentrations of dissolved calcium and magnesium expressed as an
equivalent amount of calcium carbonate.
A frequently used classification of hardness in water supplies is:
| Hardness Category | Concentration (mg/L) |
|---|
| Soft | 0 to 17 |
| Slightly Hard | 18 to 60 |
| Moderately Hard | 61 to 120 |
| Hard | 121 to 180 |
| Very Hard | more than 180 |
pH (
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The parameter pH (negative base-10 logarithm of hydrogen ion activity) is a fundamental water-
quality parameter. It is readily measured on-site, indicates whether water will be corrosive,
determines the solubility and mobility of many dissolved metals, and provides an indication of
the types of gases and minerals groundwater has reacted with as it flows from recharge region to
sample site.
The neutral pH of pure water at room temperature is 7.0. Rain that has equilibrated with
atmospheric carbon dioxide has a pH value of about 5.6. Streams and lakes in wet climates such
as Kentucky typically have pH values between 6.5 and 8.0. Soil water in contact with decaying
organic material can have pH values as low as 4.0, and the pH of water that has reacted with iron
sulfide minerals in coal or shale can be even lower. In the absence of coal or iron sulfide
minerals, the pH of groundwater typically ranges from about 6.0 to 8.5, depending on the type of
soil and rock contacted. Reactions between groundwater and sandstones result in pH values
between about 6.5 and 7.5, whereas groundwater flowing through limestone strata can have
values as high as 8.5.
There are no health-based drinking-water standards for pH. However, pH values that are not near
neutral can lead to high concentrations of metals for which there are drinking-water standards and
associated health effects. Water with pH higher than 8.5 or lower than 6.5 can produce staining,
etching, or scaling. For this reason, EPA has established a
Secondary Maximum Contaminant Level of 6.5 to 8.5.
Caffeine & Derivatives
Caffeine and its derivatives are usually sampled for in groundwater when researchers are looking for anthropogenic
(human-derived) sources of contamination.
Herbicides
Herbicides are chemical substances designed to kill undesirable plants. They have many uses,
from killing weeds in residential lawns and gardens, to clearing industrial areas or railways of all
plant material. Smaller amounts are used in farming, forestry and managing wildlife habitats.
Herbicides can be selective, intended to kill only certain plants, or non-selective, designed to kill any
plant they come into contact with.
2,4-D (
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2,4-D belongs to the chemical class of phenoxy compounds. Predominant uses are as a systemic
herbicide used to control broadleaf weeds in cultivated agriculture, pasture and range land, forest
management, home and garden settings, and to control aquatic vegetation.
2,4-D has a low persistence in soils with a half-life less than 7 days, and is readily degraded by
microorganisms in aquatic environments. EPA has established a
Maximum Contaminant Level
of 0.07 mg/L for 2,4-D because the nervous system can be damaged from exposure to higher
levels.
Inorganics
Inorganic compounds are traditionally considered to be substances that are mineral in origin as opposed to
biologic or carbon-based. Inorganic compounds in groundwater consist primarily of metals, nutrients and salts,
but these are broken out into separate categories in the Groundwater Data Repository.
Here, inorganics are considered bromide, chloride, fluoride and sulfate.
Chloride (
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Chloride is one of the most common anions in uncontaminated groundwater. Most soils, rocks,
and minerals contain small amounts of chloride, as does saline water from salt licks or discharges
from deep groundwater-flow systems. Other potential sources include agricultural or urban
runoff, wastewater from industry, oil well wastes, effluents from wastewater treatment plants, and
road salt. Chloride is very mobile in groundwater and is not readily removed by inorganic or
biological processes.
Small amounts of chloride are needed for normal cell functioning in plants and animals. Higher
concentrations can corrode metal pipes and valves, increase metals concentrations in water, and
affect the taste of foods. No significant health threats are associated with moderate chloride
concentrations in drinking water. EPA has set the
Secondary Maximum Contaminant Level for
chloride at 250 mg/L because higher concentrations give water an unpleasant taste.
Flouride (
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Fluoride is a minor anion, usually present at less than about 1 mg/L in groundwater. Natural
sources of fluoride include the mineral fluorite, which is common in carbonate rocks. The major
contaminant sources are discharges from fertilizer- and aluminum-production facilities.
Because of the proven value of fluoride in maintaining healthy teeth and bones, it is added to
most public water supplies to maintain a concentration of approximately 1 mg/L in the finished
water. Although fluoride has a beneficial effect at low concentrations, at higher concentrations it
may cause pain and weakness of the bones and staining or mottling of teeth. For these reasons,
EPA has established a
Maximum Contaminant Level of 4 mg/L in public drinking water, and
a
Secondary Maximum Contaminant Level of 2 mg/L.
Sulfate (
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Sulfate is a major anion in most groundwaters. The most common natural sources of sulfate in
Kentucky are oxidation of iron sulfide minerals in coal or shale, and dissolution gypsum or
anhydrite in carbonate strata.
There is no primary drinking-water standard for sulfate. EPA has set a
Secondary Maximum Contaminant Level of
250 mg/L because water containing higher concentrations has an
unpleasant taste that makes it unsuitable for domestic use. Water having sulfate concentrations
greater than about 500 mg/L is a mild laxative.
Field
These are analytes measured on-site at a well or spring.
Conductivity (
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Conductivity measures the ability of water to transmit an electric current. Pure water is a poor
electrical conductor. However, the ability of water to transmit electricity increases as the amount
of dissolved solutes increases. Water with high conductivity may have objectionable taste, cause
staining, and precipitate scale in pipes and containers. Conductivity is reported in micromhos per
centimeter at 25
o C, or the equivalent microsiemens per centimeter in the International
System of Units.
pH (
map image)
The parameter pH (negative base-10 logarithm of hydrogen ion activity) is a fundamental water-
quality parameter. It is readily measured on-site, indicates whether water will be corrosive,
determines the solubility and mobility of many dissolved metals, and provides an indication of
the types of gases and minerals groundwater has reacted with as it flows from recharge region to
sample site.
The neutral pH of pure water at room temperature is 7.0. Rain that has equilibrated with
atmospheric carbon dioxide has a pH value of about 5.6. Streams and lakes in wet climates such
as Kentucky typically have pH values between 6.5 and 8.0. Soil water in contact with decaying
organic material can have pH values as low as 4.0, and the pH of water that has reacted with iron
sulfide minerals in coal or shale can be even lower. In the absence of coal or iron sulfide
minerals, the pH of groundwater typically ranges from about 6.0 to 8.5, depending on the type of
soil and rock contacted. Reactions between groundwater and sandstones result in pH values
between about 6.5 and 7.5, whereas groundwater flowing through limestone strata can have
values as high as 8.5.
There are no health-based drinking-water standards for pH. However, pH values that are not near
neutral can lead to high concentrations of metals for which there are drinking-water standards and
associated health effects. Water with pH higher than 8.5 or lower than 6.5 can produce staining,
etching, or scaling. For this reason, EPA has established a
Secondary Maximum Contaminant Level of 6.5 to 8.5.
Metals
Metals are inorganic substances consisting of positive ions and containing no carbon.
Heavy metals, 28 of which may be found in groundwater, have a specific gravity at least five times that of water.
Metals have been separated from the inorganic category in the Kentucky Division of Water database, and are
therefore included as a separate category here, because the Repository framework mirrors that of DOW.
Arsenic (
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Arsenic is a metalloid that occurs naturally at low concentrations in rocks, soils, plants, and
animals. In Kentucky, arsenic is commonly found in sulfide minerals associated with coal and
black shales. It is released when these sulfides oxidize during weathering. Once released, arsenic
is readily sorbed onto iron oxides and oxyhydroxides. This sorption can limit dissolved arsenic
concentrations in groundwater, but can produce high total arsenic concentrations in unfiltered
groundwater samples that contain suspended particulate material. Arsenic can undergo
biochemical processes to form complex ions that are not readily removed from solution by
sorption onto soils or the aquifer matrix.
Arsenic is used as a wood preservative and in paints, dyes, metals, drugs, soaps, semiconductors,
animal feed additives, and pesticides. From 1860 through 1910, arsenic was heavily used in
embalming fluids. It was banned in 1910 because it interfered with investigations into suspected
poisoning deaths, but old graveyards may still contribute arsenic to groundwater. Waste-disposal
sites and landfills may be sources of arsenic contamination because of the materials placed there,
coal burning can release arsenic, and agricultural drainage can carry arsenic from pesticides into
the groundwater. Hydrocarbons from leaking underground storage tanks can dissolve iron oxide
minerals in soils, thus releasing naturally occurring arsenic to the environment.
Long-term exposure to arsenic in drinking water has been linked to cancer of the skin, bladder,
lungs, kidneys, nasal passages, liver, and prostate. Arsenic has also been linked to damage of the
cardiovascular, pulmonary, immunological, neurological, and endocrine systems. Because of
these health effects, EPA set the
Maximum Contaminant Level for arsenic in drinking water at
0.050 mg/L in 1974. In 2001 EPA announced that this would be lowered to 0.010 mg/L, effective
January 2006.
Barium (
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Barium is an alkaline earth element that occurs naturally as the mineral barite (barium sulfate) in
sandstone and limestone. Barite deposits have been mined throughout Kentucky, primarily in the
Inner and Outer Bluegrass Regions. In groundwater, barium concentrations are generally low,
because of the very low solubility of barite and the common presence of dissolved sulfate. Where
dissolved sulfate concentrations are very low, barium concentrations may be as high as several
mg/L. Barium is used in electronic components, metal alloys, bleaches, dyes, fireworks, ceramics,
and glass, and as an additive to drilling fluids used in oil and gas wells. Barium may be released
to soil and water from the discharge of drilling wastes or from leaking landfills in which barium-
containing materials were discarded.
EPA has set the
Maximum Contaminant Level for barium at 2 mg/L. Short-term exposure to
higher concentrations can cause gastrointestinal distress and muscular weakness, whereas long-
term exposure can cause high blood pressure.
Cadmium (
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Cadmium is a metallic element that occurs naturally with zinc ores and in the mineral sphalerite.
It is rare in most Kentucky soils and bedrock. Cadmium is a byproduct of the metal industry,
especially in zinc-, lead-, and copper refining. Industrial uses include metal electroplating and
coating processes, nickel-cadmium and solar batteries, paint pigments, printing inks, stabilizers in
plastics, and electrical batteries. It can be released to groundwater from buried wastes containing
these materials, and by coal combustion.
Cadmium can be ingested by eating plants grown in contaminated soil, eating fish or seafood
from contaminated water, or by drinking water that contains cadmium. Cadmium is a probable
carcinogen. Acute exposure can cause nausea, vomiting, diarrhea, muscle cramps, liver injury,
convulsions, and kidney failure. EPA indicates that long-term exposure to cadmium in drinking
water has been linked to health problems such as liver, kidney, bone and blood damage. Because
of these adverse health effects, the
Maximum Contaminant Level for cadmium in drinking
water is 0.005 mg/L.
Calcium (
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Calcium is a naturally abundant alkaline earth element and is common in Kentucky rocks and
soils. It is generally the most abundant cation in uncontaminated groundwater systems,
particularly those in contact with limestone, dolomite, gypsum, or sandstones that contain
calcium carbonate cement. Calcium is found in many urban and industrial wastes, and in sewage
effluents.
Calcium is a necessary nutrient to ensure strong bones and teeth. There are no health effects of
calcium in drinking water; however, it is a primary cause of hardness in water and results in the
formation of scale in plumbing and water containers. Calcium concentrations do not limit
groundwater use for irrigation or stock water.
The EPA has not set limits on calcium in drinking water, but most water suppliers try to maintain
concentrations below about 30 mg/L.
Chromium (
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Chromium is a naturally occurring metal that is generally found at very low concentrations in
soils and rocks. Its greatest uses are in metal alloys such as stainless steel, protective coatings on
metals to impart specific properties, magnetic tapes, and as pigments for paints and other
materials. It also has been used extensively for wood preservatives and for pressure-treated
lumber. Chromium is rare in groundwater that is not affected by point-source contamination.
Chromium compounds are readily sorbed onto soil particles, which limit its mobility.
The largest sources of chromium emissions are the chemical manufacturing industry and
combustion of natural gas, oil, and coal. It may also be released from landfills or other solid-
waste disposal sites.
EPA has set the
Maximum Contaminant Level at 0.1 mg/L in drinking water. Short-term
exposure to chromium concentrations above this can result in skin irritation or ulceration,
whereas long-term exposure can damage the liver and kidneys.
Copper (
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Copper is a metal that occurs naturally in ore deposits, but only at very low concentrations in
most soils and rocks. Copper is an essential element in plant and animal metabolism. Copper is
used extensively in plumbing pipes and fixtures, and may be dissolved from water pipes if the pH
of the water is less than 7. Copper salts are sometimes added to water-supply reservoirs to
suppress algal growth, and copper compounds have been used extensively in agricultural
pesticide sprays.
Short-term exposure to copper in drinking water can lead to gastrointestinal distress; long-term
exposure can lead to liver or kidney damage. Copper contamination of drinking-water supplies
generally occurs from corrosion of household copper pipes; therefore copper cannot be directly
controlled or removed from the water-supply system by treatment facilities. EPA has established
a
Maximum Contaminant Level Goal of 1.3 mg/L. EPA requires water systems to control the
corrosiveness of water provided to homes if copper concentrations exceed 1.3 mg/L in more than
10 percent of samples.
Iron (
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Iron is a naturally occurring metal that is widely present in soils, rocks, and groundwater.
Dissolved iron can exists in either an oxidized (ferric) or reduced (ferrous) state. At normal
groundwater pH values, ferric iron is rapidly precipitated as an iron oxide, iron hydroxide, iron
oxyhydroxide (rust), or poorly crystalline to amorphous material. Under reduced conditions,
ferrous iron is stable and will remain dissolved in groundwater. When pH is low, such as in the
case of acid mine drainage, substantial amounts of iron can occur in water.
Iron is commonly associated with acid mine drainage, and is a secondary cause of hardness in
water. At concentrations of more than 0.3 mg/L, iron can stain plumbing fixtures and clothing.
Iron imparts an objectionable taste to water at concentrations more than 1 mg/L, and is a problem
for many industrial uses, such as food processing, paper manufacturing, and brewing at such
concentrations.
Iron is an essential element for metabolism in animals and plants, and is vital for transporting
oxygen in the blood. There is no EPA primary drinking water standard for iron in water supplies
because it presents no serious health threats. There is, however, a
Secondary Maximum Contaminant Level of 0.3 mg/L
because higher concentrations produce objectionable odor, taste, color, staining, corrosion, and scaling.
Lead (
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Lead is a metal found widely disseminated at very low concentrations in soils and bedrock and
concentrated in natural ore deposits. In Kentucky, lead has been mined in all regions except the
Jackson Purchase, but particularly from the Western Kentucky Fluorspar District in Crittenden
and Livingston Counties. Lead is used extensively in plumbing equipment, water service lines,
and electrical storage batteries; lesser amounts are used in solder, leaded glass, and radiation
shielding. Until recently, lead was added to paint as a pigment and to speed drying, increase
durability, retain a fresh appearance, and resist moisture. Lead was also used as an additive to
promote efficient gasoline combustion.
Lead can enter the groundwater system from leaking landfills, aerial fallout of exhaust from
combustion engines, and coal burning. Lead is strongly sorbed onto soils, which limits its
mobility in the natural environment. The most significant source of lead in drinking water is from
leaching of lead or lead-based solder in water-supply lines. The capacity of water to leach lead
from plumbing equipment is strongly dependent of factors such as the pH, alkalinity, and
hardness of the water, as well as the amount of dissolved organic matter and calcium.
Lead can cause a variety of adverse health effects when people are exposed to it for relatively
short periods. These effects may include interference with red blood-cell chemistry; delays in
normal physical and mental development in babies and young children; deficits in attention span,
hearing, and learning abilities of children; and increases in the blood pressure of adults. Long-
term exposure to lead has the potential to cause stroke, kidney disease, and cancer.
EPA has set a
Maximum Contaminant Level Goal for lead in drinking water of zero. Because
lead contamination usually occurs from corrosion of household lead pipes, it cannot be removed
by the water-supply treatment system. EPA requires public water systems to control the
corrosiveness of their water if the level of lead at home taps exceeds 0.015 mg/L. EPA believes
this is the lowest level to which water systems can reasonably be required to control lead should it
occur in drinking water at their customers&apst homes.
Magnesium (
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Magnesium is an alkaline earth metal that is generally one of the most abundant cations in
groundwater. It is common in sedimentary rocks, particularly limestones, as well as in soils, and
is essential in plant and animal nutrition. Dietary magnesium is also important to human health.
There are no EPA limits of acceptable levels of magnesium in drinking water for either health or
aesthetic reasons. However, magnesium contributes to water hardness; so high magnesium
concentrations may make groundwater unacceptable for some domestic uses.
Manganese (
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Manganese is a naturally occurring cation that is widely present in rocks, soils, and groundwater.
Small amounts of manganese are typically present in limestone and dolomite, and in the waters
that contact those rocks. Manganese and iron behave similarly geochemically, so high manganese
concentrations can be expected from wells and springs that produce water with high iron
concentrations. In waters derived from acid mine drainage, it is common for both iron and
manganese to be in solution near the mine, but with distance acid is neutralized, iron precipitates,
and high manganese concentrations persist.
Manganese is an essential element in plant metabolism. There is no EPA primary standard for
manganese in water supplies because there are no identified, serious health threats posed by it.
There is, however, a
Secondary Maximum Contaminant Level of 0.05 mg/L for manganese
because higher concentrations produce objectionable odor, taste, color, corrosion, and staining.
Mercury (
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Mercury is a naturally occurring metal. Elemental mercury is a liquid that occurs in some ore
deposits; it may also be concentrated around hot springs.
Currently, about 50 percent of mercury use is for electrical products such as dry-cell batteries,
fluorescent lights, switches, and other control equipment. Mercury is also used in the electrolytic
preparation of chlorine gas and caustic soda, in paint manufacture, and in pesticide production. In
the past, large amounts of mercury were used in thermometers and pressure gauges. Forest fires,
combustion of fossil fuels, sewage discharge, metal-refining operations, cement manufacture,
municipal landfills, and chemical industries are major sources of mercury in the environment.
The health hazards of mercury exposure depend on the form of mercury to which an individual is
exposed. Elemental mercury is relatively inert, although it gives off hazardous fumes at room
temperature that can be adsorbed through the skin. If swallowed, however, it is not readily
absorbed by the stomach, and will usually pass through the body without harm. Inorganic
mercury compounds such as mercuric chloride can be inhaled or adsorbed through the skin, and
can cause severe kidney damage. Inorganic mercury compounds can also be ingested through
consumption of food grown in mercury-contaminated soils.
The greatest health hazards result when anaerobic bacteria mediate the conversion of inorganic
mercury to organic methylmercury, which is highly soluble in water and is concentrated in fish
and shellfish. People are exposed to mercury primarily by eating fish that have been contaminated
as a result of improper disposal of industrial waste and chemicals. Chronic mercury poisoning can
result in mood swings and severe nervous disorders. Both short-term and long-term exposure to
high mercury levels has been found to cause kidney damage. These health effects have caused
EPA to set the
Maximum Contaminant Level for mercury in drinking water at 0.002 mg/L.
Selenium (
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Selenium is a naturally occurring element that is found at trace levels in many soils and rocks,
particularly marine sedimentary rocks. Selenium compounds are commonly used in electronic
components, photocopiers, metal alloys, rubber paint pigments, glass-making, and photographic
emulsions. Selenium is also used in vitamins, dandruff shampoo, and as a dietary supplement for
livestock.
Selenium is an essential trace nutrient which acts as an antioxidant by reducing free radicals that
damage cell membranes. However, too much selenium can be harmful. EPA has set a
Maximum Contaminant Level
of 0.05 mg/L for selenium in drinking water because short-term exposure
above this level may cause damage to hair and fingernails, damage to the peripheral nervous
system, fatigue, and irritability. Long-term exposure to selenium concentrations above the MCL
can result in hair and fingernail loss, and damage to the kidneys, liver, and the nervous and
circulatory systems. Studies in animals have shown that elevated selenium concentrations can
affect reproductive systems, particularly in fish and birds that feed on aquatic animals. For this
reason, the aquatic wildlife standard for selenium in surface water has been set at 0.005 mg/L.
Sodium (
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Sodium is one of the most common inorganic solutes in surface water and groundwater. It is
abundant in soils and rocks, and highly mobile in aqueous systems. Natural sources of sodium in
Kentucky groundwater include saline waters found at depth throughout the state and beneath
stream valleys in the Eastern Kentucky Coal Field, and salty seeps found throughout the state.
The principal contaminant sources are improperly completed oil and gas wells, leaking on-site
sewage disposal systems, and road salt. Evaporation of irrigation water can also produce high
sodium concentrations that may reach the water table.
Sodium is included on the EPA Drinking Water Contaminant Candidate List as a solute that is not
subject to national primary drinking-water regulations but may pose some health concerns
because high levels may be associated with high blood pressure in some people. Sodium is an
essential nutrient for humans, however, and EPA also found that sodium concentrations in most
public water-supply systems are not likely to contribute to adverse health effects.
Pesticides
Pesticides are substances used to control, prevent or destroy any type of pest
(undesirable species of animals). Some definitions include herbicides in the pesticide category,
because certain plants may be considered “pests”, however in the new Repository data framework,
the two categories are separate.
A large number of synthetic organic pesticides have been developed and applied in agricultural
and urban settings. Some, such as the organochlorine insecticide DDT, were banned decades ago
but still persist in soils and sediments and can still be found in groundwater. Most recently
developed pesticides are less persistent in natural environments; however, they may still have
undesirable impacts on human health and groundwater-quality.
According to recent agriculture sales data, atrazine, glyphosate, metolachlor, and simazine
are the top four animal pesticides sold in Kentucky. Alachlor and cyanazine have also been used
extensively in the past. Toxicological information for pesticides was obtained from the Extension
Toxicology Network (
ace.orst.edu/info/extoxnet/pips/)
and the EPA Integrated Risk Information System (
epa.gov/iris).
Alachlor (
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Alachlor is used to kill crabgrass and broadleaf plants that occur among various agricultural
crops, including peanuts, sorghum, beans, and tobacco. The three primary breakdown products of
alachlor (ethanesulfonic acid, alachlor oxanlic acid, and 2,6-diethylanaline) may be found in
groundwater and surface water at higher levels than the alachlor itself; however, their health
effects are not well established.
Alachlor has not been shown to cause cancer in humans, but can cause cancer in laboratory
animals. EPA has set the
Maximum Contaminant Level for alachlor at 0.002 mg/L.
Atrazine (
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Atrazine is used as both an agricultural and domestic herbicide for broadleaf and grassy weeds.
Atrazine was used extensively in the 1980&apsts for corn and soybean crops. It is a widely used
pesticide throughout Kentucky.
Short-term health effects for exposure to atrazine include congestion of heart, lungs, and kidneys;
low blood pressure; muscle spasms; weight loss, and damage to the adrenal glands. Long-term
exposure can result in cancer, weight loss, cardiovascular damage, retinal and some muscle
degeneration. Because of these health effects, EPA has set the
Maximum Contaminant Level
for atrazine at 0.003 mg/L.
Cyanazine (
map image)
Cyanazine belongs to the chemical class of triazines. It is used mainly to control annual grasses
and broadleaf weeds in corn. It has low to moderate persistence in soils and is rapidly degraded
by microbial activity. Cyanazine has a half-life of 2 to 14 weeks, depending on soil type, and is
stable in water. There is no
Maximum Contaminant Level for cyanazine; however the Kentucky
Division of Water has set a health advisory limit of 0.001 mg/L.
Metolachlor (
map image)
Metolachlor belongs to the chemical class of amides. It is mainly used to control broadleaf and
grassy weeds in field corn, soybeans, peanuts, grain sorghum, potatoes, pod crops, cotton,
safflower, stone fruits, and nut trees, highway rights-of-way, and woody ornamentals. It is
moderately persistent in soils with a half-life of 15 to 70 days, and is highly persistent in water.
There is no
Maximum Contaminant Level for metolachlor; the Kentucky Division of Water has
set a health advisory limit of 0.1 mg/L.
Simazine (
map image)
Simazine belongs to the chemical class of triazines. It is predominantly used to control broadleaf
weeds and annual grasses in fields where berry fruits, nuts, vegetables, and ornamental crops are
grown, and on turfgrass. It is moderately persistent in soils, with a half-life of about 60 days, and
is moderately persistent in water, with a half-life that depends on the amount of algae present.
The
Maximum Contaminant Level for simazine is 0.004 mg/L. At higher levels, long-term
exposure can cause tremors; damage to testes, kidneys, liver, and thyroid; and gene mutations.
There is some evidence that simazine may have the potential to cause cancer from a lifetime
exposure at levels above the MCL.
Volatile Organic Compounds (VOC's)
Volatile organic compounds are carbon-based substances having boiling points lower than those of
semivolatile organic compounds, and therefore readily produce gases or vapors at room temperature.
They include gasoline and solvents used in many industrial applications
The volatile organic compounds benzene, ethylbenzene, toluene, and xylene are characterized by
a pale to colorless appearance, sweet odor, and high volatilization. They are used as solvents and
in the production of plastics, rubber, and resins. They are also components of gasoline and are
most commonly introduced to the environment through spills from leaking gasoline-storage
tanks, fumes and exhaust from gas-power engines, and runoff from gasoline- or oil-contaminated
surfaces such as highways and parking lots. Local groundwater contamination from these
compounds can also result from improper disposal of used oil. MTBE (methyl tertiary-butyl
ether) is an oxygenate additive used to promote fuel combustion and reduce carbon monoxide and
ozone emissions from vehicles. Releases to the environment are most commonly the result of
leaking underground storage tanks and pipelines, other spills, and, to a lesser extent, from air
deposition around refineries or urban areas.
The following summaries of potential sources and health effects of the selected volatile organic
compounds were taken from the EPA Web pages “Current Drinking Water Standards”
(
epa.gov/safewater/mcl/html)
and "Integrated Risk Information System" (epa.gov/iris).
Benzene (
map image)
Benzene is a clear, colorless, aromatic organic compound that is highly flammable. It is used in
the manufacture of gasoline, plastics, rubber, resins, and synthetic fabrics. It is also used as a
solvent in printing, paints, and dry cleaning.
The most common sources of benzene in groundwater are leaks from underground gasoline-
storage tanks and landfills. Benzene is released to the air by fumes and vehicle exhaust. Industrial
discharges and losses during fuel spills can release benzene to soils and water supplies. Runoff
from roads or parking lots, and improper disposal of gasoline and oil products around the home,
can also contribute benzene to the groundwater system. Benzene does not degrade by reaction
with water, but can be degraded by microbes in soil and water.
Short-term health effects of benzene exposure include anemia, immune-system depression, and
temporary nervous-system disorders. Long-term effects include chromosome abnormalities and
increased risk of cancer. For these reasons, EPA has set the
Maximum Contaminant Level for
benzene at 0.005 mg/L.
Ethylbenzene (
map image)
Ethylbenzene is a clear, colorless, organic liquid that smells like gasoline. It is used primarily in
the manufacture of styrene (a constituent of plastics), and is a component of gasoline.
Ethylbenzene is also used in making plastic wrap and rubber, and is a solvent for coatings.
Common sources of ethylbenzene are discharges from petroleum refineries and leaking
underground gasoline-storage tanks. Runoff from roads or parking lots, and improper disposal of
gasoline and oil products around the home, can also contribute ethylbenzene to the groundwater
system.
Short-term exposure to ethylbenzene can result in fatigue, drowsiness, headaches, eye irritation,
and respiratory-system irritation. Long-term exposure over a lifetime can induce liver and kidney
damage, as well as damage to the central nervous system and eyes. For these reasons, EPA has set
the
Maximum Contaminant Level for ethylbenzene at 0.7 mg/L.
Methyl-tert-butyl ether (MTBE) (
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MTBE (methyl-tertiary-butyl ether) is a gasoline additive used to promote combustion and reduce
emissions. The primary sources of MTBE in groundwater are leaks from gasoline-storage tanks
or gasoline spills; atmospheric fallout of exhaust gases is also a potential source. Runoff from
roads or parking lots, and improper disposal of gasoline and oil products around the home, can
also contribute MTBE to the groundwater system.
Potential health effects of MTBE in water have not been established; however, the Kentucky
Division of Water has set a risk-based water-quality standard of 0.050 mg/L.
Toluene (
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Toluene is a clear, colorless, organic liquid that smells like gasoline. It is used primarily in
making benzene, a component of gasoline. Toluene is also used in making urethane, a solvent
and coating. Toluene evaporates quickly when released to soils, and within a few hours when
released to water. It is not as easily broken down by microbes as are other volatile organic
compounds. The largest releases of toluene occur at petroleum-refining operations.
Common sources of toluene in groundwater are discharge from petroleum refineries and leaking
underground gasoline-storage tanks. Runoff from roads or parking lots, and improper disposal of
gasoline and oil products around the home, can also contribute toluene to the groundwater
system.
Short-term exposure to ethylbenzene can result in nervous system disorders such as fatigue,
nausea, and confusion. Long-term exposure over a lifetime can result in serious medical problems
such as spasms, hearing impairments, memory loss, and kidney and liver damage. Therefore, the
EPA has set the
Maximum Contaminant Level for ethylbenzene at 1.0 mg/L.
Total Xylenes (
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Xylenes are a group of compounds that are clear liquids with a sweet odor. They are used as
solvents and in the manufacture of plastics, and are a component of gasoline.
Xylenes in groundwater are usually the result of discharge from petroleum refineries or chemical
factories, or leaking underground gasoline-storage tanks. Runoff from roads or parking lots, and
improper disposal of gasoline and oil products around the home, can also contribute xylenes to
the groundwater system.
The primary health effect of xylenes in drinking water is damage to the nervous system. The
Maximum Contaminant Level is 10 mg/L for the sum of O-Xylene, P-Xylene, and M-Xylene.