May 26, 2001
Health Hazards of Lead
By Maureen Alvarez, CIH, CSP
Different about Lead and Lead Poisoning?
is one of the few natural substances that has no known use
in the human body.† At even very low levels, lead has been
shown to cause health problems.† The difficulty with lead
is that once it is mined from the earth, there is no known
way to destroy or make it harmless.† This makes it extremely
important that we reduce our use of lead and dispose of it
good news about lead poisoning is that unlike many other diseases,
it is a totally preventable disease.
Does Lead get into the Body?
of the lead used today is inorganic lead and it enters the
body through breathing (inhalation) and swallowing (ingestion),
which are called "routes of exposure".† Lead dust
or particles cannot go through the skin if the skin is unbroken.†
The type of lead used in gasoline is organic lead and it can
get through the skin.†
small children, ingestion is the main route of exposure.†
For bridge workers and those working with leaded paint the
main route of exposure is inhalation.† However, lead dust
can be ingested if it is on your hands and you smoke a cigarette
or eat before washing your hands.†
Happens to Lead in the Body?
lead gets into the body it is not used in any way to benefit
the body.† It is absorbed and distributed throughout the body.†
The amount the body absorbs depends on the route of exposure.†
In general, an adult will absorb 10-15% of the lead in the
digestive system, while children and pregnant women can absorb
up to 50%.† People will absorb more lead if they are fasting
or if their diet is lacking in iron or calcium.
lead is inhaled, about 30%-50% of the particles will reach
the lungs, depending on the size of the particle.† Large particles
land in the upper respiratory tract where they get trapped
by the mucous lining and are moved out by the cilia.† Unfortunately,
the mucous is often swallowed, allowing these large particles
to then go into the digestive system.
particles can reach deeper in the lungs and from there be
absorbed into the bloodstream. This means that when there
is burning or welding on lead-painted surfaces, the lead fumes
can be especially dangerous.† The small particles created
as a fume will reach the blood if they are inhaled.† Once
lead is in the blood, some of it moves into soft tissues (organs
such as the brain and kidneys).
total amount of lead that is stored in the body is called
the "body burden".† In adults, bones and teeth contain
about 95% of the body burden.† Lead that is stored in the
bones can leave them and enter the blood and then the soft
tissue.† This can damage the organs or the blood's ability
to make red blood cells.† This trend may increase during pregnancy,
breast-feeding and osteoporosis. †It can also happen when
lead is removed from the blood through medical treatment called
Long Does Lead Stay in the Body?
stays in the body for different periods of time, depending
on where it is.† Half of the lead in the blood will be excreted
in 25 days (this is called the "half-life").† In
soft tissues, it takes 40 days for half of the lead to be
excreted.† In bones and teeth it takes much longer, up to
10 years or longer.
lead is stored in the body, a person can get poisoned from
exposure to just small amounts of lead over a long period
of time (chronic exposure).† You do not need to get exposed
to just large doses of lead to be poisoned (acute exposure).†
It can take months or years for the body to get rid of lead.†
A person will continue to be exposed to lead internally even
after the actual exposure to lead stops.
is Lead Measured in the Body?
tests to measure the amount of lead circulating in the body
were developed over 60 years ago. The results are measured
in micrograms of lead per deciliter of blood (the symbols
used are ug/dl or mcg/dl).† Because there is so much lead
contamination of the environment, people who live in cities
usually have blood lead levels as high as 15 ug/dl.
blood lead test is important for you.† It gives an immediate
estimate of the level of your recent exposure to lead.† This
test will tell you how much lead is in your bloodstream, but
not what is stored in your soft tissues or bones.† The test
will not tell you your body burden of lead or the damage,
if any, that has occurred.
test is called the ZPP Test or zinc protoporphyrin.† This
test is different from the blood test in that it reflects
your lead exposure over a 2-3 month period.† The EP (erythrocyte
protoporphyrin) test is a similar test.
OSHA permissible exposure limit (PEL) for lead, set by the
standard is 50 micrograms of lead per cubic meter of air (50
ug/m3), averaged over an 8-hour workday.† The interim final
standard establishes an action level of 30 micrograms of lead
per cubic meter of air (30 ug/m3), averaged over an 8-hour
workday. †The action level triggers several requirements of
the standard such as exposure monitoring, medical surveillance,
The health protection goals of
the standard state that prevention of adverse health effects
for most workers from exposure to lead throughout a working
lifetime requires that a worker's blood lead level (BLL, also
expressed as PbB) be maintained at or below forty micrograms
per deciliter of whole blood (40 ug/dl). †The blood lead levels
of workers (both male and female workers) who intend to have
children should be maintained below 30 ug/dl to minimize adverse
reproductive health effects to the parents and to the developing
fetus. †The measurement of your blood lead level (BLL) is
the most useful indicator of the amount of lead being absorbed
by your body.
Lead Cause Reproductive Problems in Both Women and Men?
†In men, lead can damage sperm and affect the sperm's ability
to move. †It can affect the number of sperm that is produced
in the testes. †These effects on sperm can harm a man's ability
to father children and have been linked to miscarriages and
birth defects in their partners. †These health effects can
occur at 40-50 ug/dl. †Some studies have also indicated that
lead can affect a man's sex drive and ability to have an erection.
exposure to high levels of lead may cause miscarriages, premature
births, stillbirths and decreased fertility. †More recently,
some studies found that pregnant women with levels of lead
in the umbilical cord blood of 10-15 ug/dl had children who
suffer from learning and behavioral problems later in life.
†This is because lead in the pregnant mother's blood passes
into the blood of the fetus and may affect brain development.
policies have not generally addressed the reproductive health
of workers.† In the OSHA lead standards for general industry
and for construction, workers must be informed of the reproductive
hazards of lead, and a doctor is allowed to medically remove
a worker who is pregnant or who is planning to conceive a
Jobs Have a Lead Hazard?
are many jobs that expose workers to lead. Some examples are:
†deleaders, firing range employees, printers, radiator repair workers, shipbuilders, workers in lead smelters,
ironworkers, lead miners, plumbers, steel welders or cutters,
pipefitters, industrial and construction painters.†
the Lead in Paint Been Replaced by Safer Alternatives?
early years of this century, the paint manufactures had found
other pigment substitutes for lead in paint.† In the 1930ís,
white lead began to be replaced by titanium dioxide and zinc
oxide.† While in 1955 the paint industry had set a voluntary
standard for itself of 1% lead in interior paints, this was
not always followed.† As late as 1971, more that 10% of the
paints tested in New York City had between 2% -11% lead content.†
In 1973, the federal government finally limited the amount
of lead in interior pant to .5% and, in 1978, this limit was
lowered to .06%.
story for industrial paint is different.† Lead is still allowed
in paint for bridge construction and machinery.† It is used
for its ability to expand and contract with the metal surface
of a structure without cracking. †It is also able to resist
corrosion.† Unfortunately, this paint is a significant source
of lead exposure. †Even if its use were banned today, there
would still be exposure to workers and surrounding communities
for years to come due to the number of metal structures, such
as bridges, that are coated with it.
to practice good hygiene when working around lead.† Always
wash your hands prior to eating, drinking or smoking to help
prevent the ingestion of lead.† Proper ventilation and respiratory
protection can prevent inhalation exposures to lead.† Lead
poisoning is preventable if everyone follows safe work practices.
2001 by WorkCare™ All Rights Reserved
you next month, email@example.com