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Lead Presentation

Lead Presentation. Raymond Fellerman Biology 464 Aquatic Toxicology Professor Zed Mason 03 May, 2011. Picture from scienceblogs.com. What is Lead?. Not the stuff on your pencil mind you!

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Lead Presentation

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  1. Lead Presentation Raymond Fellerman Biology 464 Aquatic Toxicology Professor Zed Mason 03 May, 2011 Picture from scienceblogs.com

  2. What is Lead? Not the stuff on your pencil mind you! Lead is defined as a bluish-white lustrous metal that is very soft, highly malleable, ductile, and a poor conductor of electricity. It is fairly resistant to corrosion. It tarnishes upon exposure to air, but an oxide will form to prevents deeper corrosion to the air.

  3. Basic Information • Name of the element: lead • Symbol: Pb • Atomic Number: 82 • Atomic mass: 207.2 amu • Melting point: 327.5 degrees Celsius, 621.5 degrees Fahrenheit • Boiling point: 1,740 degrees Celsius, 3,164 degrees Fahrenheit • Number of protons and electrons: 82 • Number of Neutrons: 125 • Natural isotopes : 204, 206, 207, and 208. • (204Pb, 206Pb, 207Pb, and 208Pb) • Radiogenic isotope: 202Pb (half life of 52,500 years) • Lead isotopes are the end products of each of naturally occurring radioactive elements. www.chemicalelements.com

  4. History and Uses • Lead has been used for thousands of years. • It is fairly common, easy to extract via smelting and is highly malleable and ductile. • Earliest use for lead was in jewelry as beads, but it was later used as pigments in pottery. • Romans used lead in piping, from which the term plumbing comes from. • Lead used to be in paint as it was a primer. • Lead used to be used in gasoline as an additive. • Lead was banned from consumer paint in the U.S. in 1977, but is still used in bridge paint. • Lead is still used in commercial products such as automotive batteries, computers, jewelry, pewter, some ceramic glazes. • Oddly it is also used in dental fillings.

  5. Contamination. • Lead can contaminate water, food, and beverages, but it’s presence can’t be seen, tasted, or smelled. • Imported home remedies and cosmetics can contain lead. • Lead concentrations in soil, air, and water can be high near the sites of current or historic mining.

  6. Environmental Modes of Entry • Lead can enter organisms by being ingested, inhaled, or absorbed through the skin. • Anthropogenic emissions are the leading cause of lead pollution and lead to an alteration of the natural lead cycle. • Deposition from the atmosphere is the major contributor to lead in aquatic systems. • Lead can also be carried in runoff from mines or contaminated soils in dissolved or particulate forms. • Only a few lead compounds can dissolve in water as most lead is precipitated and incorporates into the sediments.

  7. Bioavailability • Knowing the total lead content of a soil is not helpful in assessing the potential risk. • The degree of exposure depends on the form of the lead. • Common compounds: • Lead Azide (PbN6) • Lead Bromate (Pb(Bro3)2*H2O) • Lead Chloride (PbCl2) • Lead Dioxide (PbO2) • Lead Oxide (Pb3O4) • Lead Nitrate (Pb(NO2) 2) • Tertraethyl Lead (Pb(C2H5) 4) • Tetramethyl Lead (Pb(CH3) 4 the latter being the most toxic form. • Lead is most soluble under acidic conditions such as those present in the stomach.

  8. Lead in Gas • Tetraethyl lead (TEL) gets a special mention as it was used in leaded fuels to prevent engine knocking. • Unfortunately it could react with compounds in the gasoline to produce the more toxic organic forms and be inhaled. • The burning of TEL may cause the formation of various free radicals.

  9. Entry into Organisms • Lead enters most organisms via ingestion, typically only 20% is absorbed. Though if it is inhaled nearly all of it is absorbed. • Some organisms (such as molluscs) can absorb solid lead compounds from sediments, but there hasn’t been many studies on it. • Inorganic lead is not metabolized in the liver while all organic lead is metabolized in the liver. • The half-life of lead in adults is 28-36 days. • Lead can be deposited in the blood, bone, and soft tissues.

  10. Effects of Lead • Lead has the ability to inhibit or mimic the actions of calcium at lower concentrations • Lead can act like other metals in enzymatic reactions and binds with the sulfur groups called sulfhydryls on proteins or enzymes and inactivates them. • Lead can also bind to DNA and is a known Carcinogen. • 10 μg/dL was adopted by CDC in 1991 as an action level for children, and is also an advisory level for the environment.

  11. The nervous system is the most sensitive target of lead exposure, while renal effects, and increased susceptibility to disease may also occur. • Lead effects Delta-aminolvulic acid dehydratase (ALAD) which is important in the biosynthesis of heme. • Lead also inhibits the enzyme ferrochelatase which is also involved in heme production. • Heme is a cofactor in hemoglobinand by lowering its production causes symptoms of anemia. ALAD

  12. Detoxification • Detoxification systems for lead include metallothionein, cytochrome P-450, and bile. • One of the primary ways the body gets rid of lead is from the liver into the bile where it is taken to the small intestine and excreted in the feces. • As mentioned earlier lead can also be incorporated into the bones, inactivating it for years.

  13. References • Anderson, Marti J., Fukunaga, Atsuko.Bioaccumulation of copper, lead, and zinc by the bivalves MacomonalilianaandAustrovenusstutchburyl.Journal of Experimental Marine Biology and Ecology. Volume 396, Issue 2, 1 January 2011, Pages 244-252. • http://www.sciencedirect.com.mcc1.library.csulb.edu/science?_ob=ArticleURL&_udi=B6T8F-51H5SD4-2&_user=521382&_coverDate=01%2F01%2F2011&_alid=1739281599&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5085&_sort=r&_st=4&_docanchor=&_ct=1&_acct=C000059561&_version=1&_urlVersion=0&_userid=521382&md5=e3a16d438545450daa248cbaed66d4ed&searchtype=a • Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological profile for Lead. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service. http://www.atsdr.cdc.gov/csem/lead/docs/lead.pdf • Bentor, Yinon. Chemical Element.com - Lead. http://www.lenntech.com/periodic/elements/pb.htm • Kenneth Barbalace. Periodic Table of Elements - Lead - Pb. • EnvironmentalChemistry.com. 1995 - 2011. http://EnvironmentalChemistry.com/yogi/periodic/Pb.html • LEAD: the facts. International Lead Association. http://www.ila-lead.org/lead-information/lead-the-facts • Lead Compounds. Technology Transfer Netweork Air Toxics Website. Hazard Summary-Created in April 1992; Revised in January 2000. U.S. Environmental Protection Agency. http://www.epa.gov/ttn/atw/hlthef/lead.html • Korashy, Hesham M. and El-Kadi, Ayman O.S. Modulation of TCDD-mediated induction of cytochrome P450 1A1 by mercury, lead, and copper in human HepG2 cell line. Toxicology in Vitro. 22, February1, 2008. 154-158. • http://www.sciencedirect.com.mcc1.library.csulb.edu/science?_ob=ArticleURL&_udi=B6TCP-4PFDDM9-4&_user=521382&_coverDate=02%2F29%2F2008&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_acct=C000059561&_version=1&_urlVersion=0&_userid=521382&md5=57a3af7f13583625e2bad3311a4c162d&searchtype=a • Bai, Xuetao. Effect of lead on energy metabolism, protein and mRNA expressions of GluR2 in postnatal rat hippocampal neurons in culture. Journal of hygiene research. 33, 1. January 1, 2004. • Tokar, Erik J., Diwan, Bhalchandra A., and Waalkes, Micheal P. Early life inorganic lead exposure induces testicular teratoma and renal and urinary bladder preneoplasia in adult metallothionein-kockout mice but not in wild type mice. Toxicology. 276, 1. September 30, 2010. 5-10. • http://www.sciencedirect.com.mcc1.library.csulb.edu/science?_ob=ArticleURL&_udi=B6TCN-50CDSSD-1&_user=521382&_coverDate=09%2F30%2F2010&_rdoc=1&_fmt=high&_orig=gateway&_origin=gateway&_sort=d&_docanchor=&view=c&_acct=C000059561&_version=1&_urlVersion=0&_userid=521382&md5=ac23111b2537315db11b346197b07e6c&searchtype=a • Li, Xiaomin M. et al. Lead inhibited N-methyl-d-aspartate receptor-independent long-term potentiation involved ryanodine-sensitive calcium stores in rat hippocampal area CA1. Neuroscience.139, 2. 2006. 463-47. http://www.sciencedirect.com.mcc1.library.csulb.edu/science?_ob=ArticleURL&_udi=B6T0F-4J5T8BJ-2&_user=521382&_coverDate=12%2F31%2F2006&_alid=1741050357&_rdoc=4&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=4861&_sort=r&_st=4&_docanchor=&_ct=305326&_acct=C000059561&_version=1&_urlVersion=0&_userid=521382&md5=613cf04ad30a5927a06029cc1c74a0b2&searchtype=a • Li, Sun, Zhao, Zhengyan, Zhou, Xielai, and Liu, Suhang . The effect of lead on intracellular Ca2+ in mouse lymphocytes. Toxicology in Vitro. 22, 8. December 2008. 1815-1819.http://www.sciencedirect.com.mcc1.library.csulb.edu/science?_ob=ArticleURL&_udi=B6TCP-4T8SM0J-1&_user=521382&_coverDate=12%2F31%2F2008&_alid=1741060841&_rdoc=2&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5176&_sort=r&_st=4&_docanchor=&_ct=137303&_acct=C000059561&_version=1&_urlVersion=0&_userid=521382&md5=86f89a5c4b39cceda765ba11dc38fb54&searchtype=a

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