Lead History and Health Effects
Lead has been used since ancient times. The earliest artifacts are over 5000 years old. Lead was used to glaze Egyptian pottery, serve as Chinese money, as cosmetics in India and as water pipes in the Roman Empire. The most widespread use in the 20th century was as a paint additive.
Health problems associated with exposure to lead were first described in 370 BC by Hippocrates. In the 1700’s the health effects were known and clearly described by physicians and scientists. In fact, the Massachusetts Bay Colony passed an act forbidding the use of lead in still heads because of complaints from customers in other colonies.
A significant percentage of lead poisoning today comes from lead-based paint. Millions of tons of this paint was applied to housing and structures prior to its ban in the 1970’s. It was considered the highest quality paint because it does not crack or peel and keeps its color.
Airborne lead has come from a variety of sources. One of the largest contributors has been leaded gasoline. Much of this lead is still present in the environment in soil and dust. Lead is also emitted to the air from industrial sources including smelters, refineries, incinerators, power plants, manufacturers and many other sources.
Lead in soil comes from the deterioration of paint, the improper disposal of building materials, lead settled out from burned gasoline and other sources. This increases the overall lead burden and has increased the level of lead in our food supply.
Drinking water may have relatively high levels of lead. The lead normally comes from pipes or service connectors. The most serious problems result when the water is acidic, which causes lead to leech out. Water in Tuscaloosa is not acidic.
It is clearly evident that lead is found in many places in our environment. Lead is constantly taken into our bodies and constantly eliminated. Unusual exposures to lead may upset the balance and push the overall total body load to dangerous levels.
Lead can be measured in a person’s blood. The usual way to report the concentration of lead in blood is micrograms of lead per deciliter of blood. This is written as ug/dl. 50 ug/dl is the upper limit for medical treatment.
Lead can also be indirectly measured. A chemical in the blood, zinc protoporphyrin (ZPP), increases with the amount of lead in the body. Some experts feel this is a better indicator of total lead stored in the body. However; it should be noted, that elevated ZPP blood levels can be indicative of other factors besides increased amounts of lead.
The routes of exposure for inorganic lead are inhalation and ingestion. An acute exposure occurs when a person receives a large dose of lead in a short period of time. Several disorders can result from an acute exposure. Among these are: anemia, ataxia, apathy, colic, vomiting, and lead encephalopathy.
Chronic exposure occurs with the continuous exposure to lead over a long period of time. The concentration may be high or low. The health effects of low exposures are not always noticeable until they are permanent. The following disorders can result from chronic lead exposure: anemia, anorexia, colic, constipation, diarrhea, kidney damage, nausea, nervous system disorders, reproductive effects, vomiting and ashen skin color.
Acute and chronic exposure to lead can impair body functions and damage organs and systems.
Overexposure to lead can lead to anemia. This is a reduction of red blood cells. As a result the hemoglobin level is lowered. Hemoglobin carries oxygen to all the cells in the body. This decrease in oxygen can manifest itself in dizziness or fatigue. Symptoms may develop with blood lead levels as low as 50 ug/dl.
Gastrointestinal problems are the most common form of lead poisoning. The symptoms are colic, anorexia, nausea, vomiting, diarrhea, constipation and ashen skin. Intestinal colic below blood lead levels of 80 ug/dl is unusual.
High level exposures must be experienced to cause kidney damage. The damage is permanent once it occurs.
Lead can have serious effects on both the central nervous system (brain, spinal cord) and the peripheral system (nerves). The ingestion or inhalation of large amounts of lead is required to cause effects to the central nervous system. Symptoms which may occur are: headache, insomnia, personality changes, irritability, delirium, tremors and slow intellectual growth. Symptoms of CNC disorders rarely appear below blood levels of 100 ug/dl.
Overexposure to lead may have serious effects on the reproductive systems of men and women. Men may suffer from a decrease in libido, impotence and sterility. Women may suffer from menstrual irregularities, sterility, premature birth, miscarriages and stillbirth. Pregnant women should avoid exposure to lead. Lead can cross the placental barrier and affect the fetus.
A possible relationship between blood lead levels and hypertension has been noted. Levels above 30 ug/dl may slightly increase systolic pressure, but research is inconclusive.
Chronic exposure to lead can result in the storage of lead in the long bones of the body. This lead may be slowly released over a long period of time, or much more quickly if sudden changes in body chemistry occur.
The human body does not utilize lead for any function. Children are more affected by lead than any other population group. They are much more affected by the routes of entry. While the same health effects occur in children as in adults, the effects occur at lower exposures. Slower intellectual development has been associated with very low levels in the blood. The CDC used to use the level of 10 ug/dl as a “level of concern” in children. CDC is no longer using the term “level of concern”. Instead, they use the reference value of 5 ug/dl to identify children who have been exposed to lead and who require case management.
EHS conducts surveys of building materials on campus, generally in support of renovation or demolition projects. Housing facilities have been evaluated which were constructed within specified years.
EHS has a NITON XRF which is the most up to date portable lead analyzer available. EHS personnel are certified to operate XRF and to conduct evaluations in buildings. For more information about lead on campus contact EHS at 348-5905.
Marty Sumners firstname.lastname@example.org
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