Lead Poisoning
From Chempedia
From the dawn of civilization, lead has found a role attributed to empires’ greatest remnants and monuments. In ancient China, lead was used as water ducts, roofs, utensils and ornaments. The Roman Empire also left behind lead cookware, lead wine storage bottles, and great aqueducts that used lead in their plumbing. Other practical uses of lead the Romans utilized were coins and ceramics; however, some argue that it was due to the great abundance of this toxic element that the fall of the empire occurred. In effect, the production and use of lead mirrored the empire in regards to its decline. In fact, it was not until hundreds of years later that the employment of lead was reintroduced into society, contributing greatly to the era of industry. The Industrial Revolution sparked the production of lead in the world once again. Unfortunately, this reintroduction also brought about an array of illnesses and ailments to mammals in many lead exposed areas and environments. By the 1970’s, American legislation implemented regulations for various leaded products including paints and gasoline to reduce lead emissions. Lead is defined as "a soft heavy toxic malleable metallic element; bluish white when freshly cut but tarnishes readily to dull gray."[1] It is one of the basic elements, which allows it to combine with other elements to form various compounds. On the periodic table the symbol for lead is Pb and the normal process of obtaining lead is to mine it and then allow it to be processed. There are multiple lead-containing products that are within reach of most people, of which they should be aware. Some of the items that cause most cases of exposure include deteriorating lead-base paint, lead contaminated dust and emissions, and lead contaminated residential soil. There is also a possibility of lead-contaminated drinking water in homes that have plumbing with lead or lead solder. Some other items include old furniture and toys, and lead glazed pottery or porcelain, which has the possibility of storing food. Finally, in regards to mammals other than humans, lead is found in most fishing jigs and sinkers, which often poison fish, and in bullets that hunters use to kill game or use recreationally. Although many lead poisoning incidents involve household items, there are various forms of lead, such as lead azide and lead arsenate, which are employed as detonating agents and insecticides, respectively. In addition, auto emissions often contaminate soil around houses and next to freeways; and despite the efforts of the EPA (Environmental Protection Agency) to phase lead out of gasoline, these emissions still contribute 98% of the lead in the air. Clearly, there are many household and recreational items that pose a threat to human beings and all mammals if more proper care is not taken to avoid these hazards.
Figure 1. Global Annual lead emissions
Due to the nature of this element, there are many ways that the poisonous material can make its way into the body; these pathways include absorption, ingestion, and inhalation.
Occupations dealing with lead products are dangerous because lead fragments can stick to clothes and be transported various places, such as the home. In addition, lead paint chips as well as dust and emissions from lead are located in soil, in which child\’s play often occurs, causing lead to be inhaled into the upper respiratory system and lungs. Afterwards, if children then lick their fingers, lead is ingested via the mouth and travels through the body with the possibility of being absorbed into the bloodstream through the intestinal tract. Interestingly enough, the toxic levels of lead in the blood are extremely similar between adults and children, with anything over 70-80 micrograms of lead per deciliter of blood being considered a medical emergency. Finally, a common way of ingesting lead is through drinking water that has traveled through old, contaminated pipes or lead solders. As for other mammals, hunting, recreational shooting, and fishing have caused much infectivity in wildlife due to the use of lead bullets and other equipment. Often times, birds and fish are prey to other mammals and become easily poisoned; and other mammals feed off them, thus, contracting the infection. While animals may not be able to control this, humans should more carefully regulate food that has the possibility of being infected.
Upon the entrance of lead into the body, while most is excreted, some accumulates in small amounts within certain organs, such as soft tissues and the blood. The remaining lead in the body attaches itself to proteins. Its ability to attach to these proteins is superior to the ability of other metals in the body, such as calcium and zinc, which are important dietary supplements. These metals, including calcium, zinc, cobalt, and manganese, are trace minerals that play a helpful role in speeding up chemical reactions in the body by acting as enzymes. Conversely, when lead binds to these proteins, it removes these beneficial metals from the protein to which they were attached to form 3 chemical bonds, as opposed to the 4 bonds that zinc forms. This results in abnormally shaped protein, which impairs the protein\’s ability to interact with DNA. When this interaction is unable to proceed, the result is a disruption of gene function, causing growth retardation, learning and behavioral problems, and short-term memory. This process is similar in the bodies of mammals besides humans. Delta-aminoevulinic acid dehydratase (ALAD) is one such enzyme, which animals use in the production of heme (oxygen-carrying pigment within the blood), part of the hemoglobin molecule used in the bloodstream for oxygen transport. When lead binds to the site on the enzyme where zinc normally binds, the result is a malformed heme molecule, which disrupts hemoglobin production within the body.
Figure 2. This is a photo of Hematopathology, or coarse basophilic stippling. It illustrates the dramatic increase of red blood cells due to abnormalities in hemoglobin synthesis. It is often found in subjects with lead poisoning.
Lead may also interfere with the body’s metabolic rate as well as with the synthesis of the heme in humans, which may lead to anemia. The risks are even more severe in children because they are in a state of rapid growth; therefore, lead poisoning may greatly impair a child’s ability to properly grow and develop the skills needed for everyday life. Other effects of lead in the body include behavioral problems and damage to the nervous, gastrointestinal, and reproductive systems, and may be signaled by poor memory, loss of appetite, or colic.
The best way to prevent lead from entering the system is to be careful when handling lead containing products like old paint and solder and to wash your hands after handling lead, in order to prevent consumption. OSHA (Occupation Safety & Health Administration) standards have been employed in various environments in attempts to lessen lead exposure to workers, and there are many helpful and easy tips available to avoid lead poisoning in the home. For humans, reading literature and having knowledge about lead is one of the best ways to avoid its dangerous effects; however, other mammals outside the humankind do not have that luxury. Thus, in order to protect all species, it is the responsibility of the human race to be cautious with lead handling practices and to have control over humans’ use of lead containing products.
Researched and written by:
Claire Mance
Jason Dally
Dan Majkowski
Bethany Krebs
Aaron Meilicke
Resources
http://www.utoronto.ca/imap/collections/air_quality/global_na_emissions.htm http://www.lead.org.au/fs/fst7.html-http://www.lead.org.au/fs/fst7.html http://www.ldaint.org/technotes5.htm-http://www.ldaint.org/technotes5.htm http://www.unbc.ca/nlui/wildlife_diseases_bc/lead_poisoning.htm-http://www.unbc.ca/nlui/wildlife_diseases_bc/lead_poisoning.htm http://ohioline.osu.edu/cd-fact/0193.html-http://ohioline.osu.edu/cd-fact/0193.html http://www.dartmouth.edu/\~toxmetal/TXQApb.shtml-http://www.dartmouth.edu/~toxmetal/TXQApb.shtml http://www.moea.state.mn.us/reduce/sinkers.cfm http://www.nigms.nih.gov/news/findings/mar05/pdf/godwin_slidekit.pdf http://www.drgreene.com/21_1132.html http://www.merriamwebster.com/cgi-bin/dictionary-http://www.merriamwebster.com/cgi-bin/dictionary http://www.epa.gov/lead/leadinfo.htm\#facts-http://www.epa.gov/lead/leadinfo.htm http://www.osha.gov/-http://www.osha.gov/ http://www.med.und.nodak.edu/depts/path/pathlab/H-Images/ http://www.labtestsonline.org/understanding/conditions/leadpoison.html http://www.drgreene.com/21_1132.html
