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Safe Drinking Water for Maine: Lead in Your Drinking Water
Bulletin #7088
John M.
Jemison, Jr., Extension water quality and soil specialist
The Dangers of Lead
The water you drink may be contaminated with
lead. Even if your water is treated by the water district or a public water
utility, it may still contain high levels of lead. Drinking water can be the
primary source of lead entering the body. Lead has been demonstrated to have
toxic effects on humans, particularly infants and pregnant women, even at very
low concentrations. Excessive exposure to lead can cause irreversible damage to
a child's physical and mental development. Education is needed to prevent damage
to both children and adults.
Lead in the Environment
Lead serves a number of important purposes in the
construction, manufacturing, and nuclear industries. Lead is found in some
paints, ceramics and glass. Lead was once used as an antiknock agent in
gasoline. However, this use of lead has been virtually eliminated.
Generally, only small amounts of lead are found
naturally in soil and rock formations. Most of the lead in soils, rock
formations, surface water (lakes and streams) and groundwater is tied up in
chemical complexes, and is generally not in a form that is dangerous to humans.
Most of the lead in the environment results from
human activities, primarily industrial emissions. For instance, the burning of
coal releases lead into the atmosphere. Lead released to the atmosphere through
industrial emissions falls back to the earth in precipitation. It may be trapped
by soils or absorbed by plants, or be dissolved in water, possibly causing
increased lead concentrations in water supplies.
Occupational exposure to lead is a problem in
specific industries, such as paint spraying, ship building and automobile
battery manufacturing. If you work around lead, be careful to minimize contact
with these materials by wearing appropriate clothing and protective gear.
As you return home from work, treat these clothes carefully to reduce lead
exposure to infants.
Human Intake of Lead
Many factors influence the amount of lead
consumed by people: age, size, eating habits, water consumption and location.
Under most circumstances, normal lead intake is below harmful levels. However,
if humans, particularly children or pregnant women, are exposed to lead in
drinking water, lead paint, or some other source, detrimental health effects may
ensue.
 d
In humans, lead has been shown to interfere with
essential physiological reactions. The body stores lead in bone material; once
bones are saturated with lead, blood lead levels will begin to increase, causing
damage to nerve tissue. Chronic exposure to lead, even at very low levels
(ingesting 1 mg daily), may cause problems.
Pregnant women and infants are particularly
susceptible to lead contamination because children and fetuses absorb 40 to 50
percent of ingested lead, compared to only five to 10 percent in adults.
Exposure to lead in the water supply has been shown to result in increased
miscarriages and stillbirths. Infant exposure to lead may cause a variety of
health problems, including slowed development, mental retardation, kidney
disease and hearing loss. If you are pregnant and are unsure of lead levels in
your home water supply, it is a good idea to have your water tested.
Lead in Drinking Water
The Latin word for lead is plumbum, which
connects it to the words "plumber," "plumbing" and "plumbism" (a disease
associated with excessive lead intake). For many years, lead pipes were commonly
used to transport water. They can still be found in some older buildings today.
Use of lead piping for service connections that join homes to the local water
supply has only recently been stopped (see Figure 1).
In the United States, approximately 20
percent of the service-connecting pipes are made of lead. In addition, houses
constructed prior to 1988 may have lead solder used to connect copper pipes;
with soft, acidic water, such as that found in
Maine, lead may be leached out of the solder or
lead service connection lines, making lead concentrations exceed the drinking
water standard.
Other solders are available, such as tin-antimony
and tin-silver solders that are equally as effective, and only slightly more
expensive. As buildings age, hard water will deposit a layer of minerals around
the pipes that will effectively coat the lead solder. This may reduce the amount
of lead that is leached from the pipes. A plumber can tell you whether your
pipes are made of lead, or if your house has tin-lead solder, if you are in
doubt. Under most circumstances, this is the most likely source of lead
contamination for humans.
Lead in Home Water
Systems
Your home may have high lead levels if:
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Your home was built before 1930 and was
constructed with lead pipes.
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Your home was built before 1988 and has copper
pipes with lead solder.
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A water softener is used in your home.
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Water sits in your pipes for hours before use,
and the solder or pipes contain appreciable amounts of lead.
What Can Be Done to
Reduce or Prevent Lead Contamination?
If you want to be sure that your drinking water
is safe, you should have your water tested by a certified lab. It is not
possible to taste lead in water. However, if your water has a slight to strong
metallic taste, it indicates that the water is corrosive and that some metals
are being dissolved into it. If that corrosive water is in contact with lead in
the plumbing, lead levels could be high. If you find blue or green
staining in your sinks, copper (and possibly lead) may be leaching out.
The Health and Environmental Testing Laboratory in Augusta analyzes samples for
lead. To obtain a test kit and current prices for various tests call (207)
287-2727. Once you have obtained a test kit, follow the directions carefully
because the analysis is meaningless if the water is not sampled according to the
directions.
If you suspect a problem with lead in your water:
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Avoid drinking water that has been in contact
with pipes for more than six hours.
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Let the water run from the faucet until the
water is as cold as it can get. Do this for each faucet that you drink from.
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Fill a large container of fresh water and place
in the refrigerator for future use to reduce excess water consumption caused
by running the water.
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Use only cold water for drinking, cooking and
especially for preparing infant formulas.
Under most circumstances, taking these measures
will reduce most of the lead that may be in your water. However, do not forget
other sources of lead in your home that may be accessible to children (cracking
or peeling paint on walls or cribs, for instance).
Under rare circumstances, the water supply
(groundwater) may be contaminated by lead. Methods such as distillation or
reverse osmosis are available to correct these problems.
Legislation Concerning Lead in Drinking
Water
Prior to 1988, the Federal Safe Drinking Water
Act had established a drinking water standard of 50 µg/L, or 50 parts per
billion. However, the act was amended in 1988 with the passage of the Lead
Contamination Control Act. The new legislation provided guidelines for lead
levels in school drinking water, use of specific materials in plumbing fixtures
and types of drinking water fountains.
Specifically, the law banned the following uses
of lead:
All water coolers with lead-lined tanks were to
be replaced within one year following passage of the law, and solder containing
more than 0.2 percent lead was not to be used in water systems. If school water
fountains were found to be above the drinking water standard, they were to be
repaired or replaced.
Lead in Maine Schools
In March 1989, the state of Maine conducted a
survey of drinking water lead concentrations in the Portland school district.
The researchers compared lead levels in two types of water fountains
(refrigerated and non-refrigerated) that were flushed or not flushed with fresh
water. The results are summarized in Table 1. Concentrations were highest when
the water remained in the coolers overnight (in constant contact with any lead
in the fountain), and were lowest when the fountains had been purged with fresh
water. These results were likely caused by corrosive water having sufficient
time to react with the lead in the plumbing, which leached out a significant
amount of lead from the pipes or lead solder.
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Table 1. Average
concentrations and percentages of water fountains that exceeded the
drinking water standard in the Portland School District. |
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Avg. Concentration
(μg/L or parts per billion*) |
Exceeding Standard (percent) |
|
Refrigerated (flushed) |
14 |
11.3 |
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Refrigerated (not flushed) |
44 |
46.3 |
|
Non-Refrigerated (flushed) |
15 |
13 |
|
Non-Refrigerated (not flushed) |
39 |
30 |
Fountains that exceeded the levels were
subjected to additional testing. If they still exceeded the level, but were less
than 100 g/L, it was recommended that they be flushed for 30 seconds each
morning prior to student use. If levels exceeded 100 g/L,
then it was recommended that they be replaced.
These data indicate the importance of water
residence time on lead concentrations. The longer water has contact with
lead in pipes, water fountains, or solder, the more lead can leach into the
water.
Public Water Supplies
If you are on public water, you can be fairly
confident that you will not be exposed to lead through your drinking water.
Legislation passed with the reauthorization of the Clean Water Act in 1988
required public water suppliers to test first-draw water in homes. If
greater than 15% of homes had lead levels that exceeded the 15 ppb "action"
guideline, the water suppliers were required to take steps to make the water
safer. By elevating the pH of water (through addition of soda ash), water
suppliers can be more confident in the safety of the water supply.
Understanding Drinking Water Standards
g = gram (454 g= 1 pound)
mg = milligram = one-thousandth of a gram
ug = microgram = one-millionth of a gram
mg/L = milligram per liter, part per million
g/L = microgram per liter, part per billion
Concentrations of dissolved metals and compounds
are either expressed in parts per million or parts per billion. A compound with
two parts per million means that there are two parts of the compound per million
parts water, or two grams of the substance in a million grams of water.
Remember, if a standard is set for a compound in terms of parts per billion
(such as lead, at 15 ppb), it is a more toxic compound to humans than a standard
for a compound expressed in parts per million (such as nitrate, at 10 mg/L).
©
2002
Extension
books and publications homepage
Published and distributed in furtherance of Acts of Congress of May 8 and June
30, 1914, by the University of Maine Cooperative Extension, the Land Grant
University of the state of Maine and the U.S. Department of Agriculture
cooperating. Cooperative Extension and other agencies of the U.S.D.A. provide
equal opportunities in programs and employment.
Call
800-287-0274 or TDD 800-287-8957 (in Maine), or 207-581-3188, for information on
publications and program offerings from University of Maine Cooperative
Extension, or visit www.extension.umaine.edu.
 Last
Modified:
08/19/09
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