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Creative Writing: Malade Papillion
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Soil Module: Guide to Soil What
Is Soil? Soil is the substrate upon which many organisms live. Plants obtain their nutrients from soil. Eventually, all plants die. Over time, plant matter will decompose and mix with the soil. This increases the organic matter in the soil. Worms and microorganisms break down the organic matter, causing it to release more nutrients into the soil. What
factors influence the ability of contaminants to bind to soil? Another factor is particle size. In general, the smaller the particle size of soil, the more contaminants the soil can hold. This is in part due to the increased surface area per unit volume of small-grained soil. Also, small-grained soils (e.g. clays) have a unique surface chemistry that increases their ability to bind with contaminants. The chemical characteristics of the contaminant itself influence its ability to bind to soil, too. Other factors that influence the ability of contaminants to bind to soil include soil acidity and soil salinity. What
are soil contaminants? Pesticides, gasoline, and jet fuels are examples of organic contaminants. Organic contaminants generally bind well to soils that contain high organic content. Metals such as lead are inorganic contaminants. The ability of a metal to bind to soil is highly dependent upon soil acidity. What
Is Lead? How
does lead interact with the environment? Lead tends to stay where it is deposited (i.e. in the top 1-3" of soil). It does not deteriorate. Lead forms crystalline salt on the surface that prevents it from chemical breaking down. Organic matter and phosphates bind to lead in the soil. Hot water can cause some leaching of lead salts from the soil (or from household plumbing!) to water. Unlike other heavy metals, lead does not accumulate in animals' tissues as you go up the food chain. What
Is the History of Lead? How
was lead used during the Renaissance? How
was lead used during the Industrial Era? How
is lead used today? Even with regulations reducing or banning the use of lead in many U.S. products, it still exists as a contaminant. Lead can be found in old paint, emissions from old cars, industry, old pipes and solder, glazed pottery, tile, and unusual sources such as medicines, crayons, candle wicks, and mini-blinds. In addition to remnants of lead contamination from pre-regulation U.S. sources, lead is often inadvertently brought to the states from developing nations that do not have regulations banning or reducing the use of lead in their country. The
Epidemiology of Lead Poisoning: How Are Humans Exposed to Lead? Normal childhood behavior often results in exposure to lead. Children can come in contact with lead by playing outside, playing with pets, and crawling around. Children are often putting objects in their mouths. Sometimes they eat non-food items such as paint chips or dirt that may contain lead. Children are the population of people who are most vulnerable to chronic lead poisoning. Children ages 1-6 absorb more of the lead they take in. Their critical neurological development that occurs at this time is permanently hampered if lead is present. The impact of lead exposure is long-term. It can cause learning disabilities, attention span problems, hyperactivity, aggressiveness, and impaired memory. Urban and other generally poor populations also run a high risk for lead exposure. Rental housing is often in poor condition. The homes tend to be concentrated in areas near highways and industrial parks. These populations have reduced access to health care because of low income and frequent moving. This results in minimal medical screening or follow-up. In addition, these populations of people tend to be undernourished. Undernourishment is known to increase the absorption of lead in the body. The
Pathophysiology of Lead Poisoning: What Are the Effects of Lead on Human
Health? Lead binds with calcium and iron receptors in the body; this minimizes its absorption. The metal is stored away in bones, except during pregnancy or severe illness when it is re-released into the bloodstream. Lead is eventually excreted from the body via urine, feces, and hair. In adults exposed to life only once, the half-life of the lead in the blood is 25 days, in soft tissue about 40 days, and in non-labile bone more than 25 years. What
are the symptoms of lead poisoning? Measuring,
Monitoring and Treatment: What Can Be Done? Blood tests reflect a person's exposure to lead over the previous 1-3 months. An X-ray can show the amount of lead stored in a person's bones. This provides an exposure history. After a home visit, investigation, and education, an exposed child is re-tested and monitored to ensure blood lead levels drop after intervention. Medical treatment is only given in severe cases of lead poisoning. Medical therapy for lead poisoning is called "chelation" from the Latin word for "key." During chelation treatment, succimer is given orally. It chemically binds with the lead and is excreted in urine by the kidneys. Adults are given a chelation reagent called EDTA intravenously. This reagent "challenges" body; that is to say it draws the lead out of the bones. This treatment re-exposes the brain to the toxin. People given chelation treatments MUST NOT return to lead-contaminated environments. The source of the lead must be found and eliminated. How
Is Lead Contamination of Soil Remedied and Prevented? To remediate lead contamination, soil can be removed and buried; or it can be covered and capped with clean fill, grass, or shrubs. Lead-containing paint in good condition or out of reach of children is usually safe. Peeling paint can be covered by special chemicals. This is called encapsulation. New walls may even be built over walls with peeling lead paint. Hazardous paint can also be removed. All lead remediation must be performed by a trained professional. The area must be wetted down, dust control measures must be taken, and waste must be wrapped up and disposed of properly. The entire site must then be cleaned up with trisodiumphosphate (TSP). It is best to prevent contact with lead from the beginning. To do this, control dust in the house with regular wet mopping, wash hands before eating and after play, wash toys regularly, and wipe down windowsills and other surfaces with TSP and water. Avoid peeling paint, and do not play in areas with bare soil. Supervise children's play and choose a good daycare center in a clean, modern building. Eat a diet rich in calcium, iron, and Vitamin C. Eat frequently and do not skip meals. Do not garden in soil not known to be safe. Limit contact with clothing that may be contaminated with lead from the workplace. Eliminate sources of lead from the home such as old tile flooring, deteriorating mini-blinds, imported ceramic ware, and traditional medicine (e.g. azarcan and greta). What
Is Lead Doing To Residents of Miami? Another risk facto is the weather. Many residents of Miami are exposed to lead in the soil when the dust blows through their windows that they often leave open all year long because the weather is so very hot. What
is the epidemiology of Miami's lead problem? |
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