Biology 464 Aquatic Toxicology Professor Zed Mason 03 May 2011 Picture from scienceblogscom What is Lead Not the stuff on your pencil mind you Lead is defined as a bluishwhite lustrous ID: 929604
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Slide1
Lead Presentation
Raymond Fellerman
Biology 464 Aquatic ToxicologyProfessor Zed Mason03 May, 2011
Picture from scienceblogs.com
Slide2What 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.
I
t
tarnishes upon exposure to
air, but an oxide will form to prevents deeper corrosion to the air.
Slide3Basic Information
Name of the element: leadSymbol: Pb
Atomic Number: 82Atomic mass: 207.2 amuMelting point: 327.5 degrees Celsius, 621.5 degrees FahrenheitBoiling point: 1,740
degrees Celsius,
3,164
degrees Fahrenheit
Number of protons and electrons: 82
Number of Neutrons: 125Natural 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
Slide4History and UsesLead 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.
Slide5Contamination.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.
Slide6Environmental 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.
Slide7BioavailabilityKnowing 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
*H
2
O)
Lead Chloride (PbCl2)Lead Dioxide (PbO2)Lead Oxide (Pb3O4)Lead Nitrate (Pb(NO2) 2)Tertraethyl Lead (Pb(C2
H5) 4)
Tetramethyl Lead (Pb(CH
3
)
4
the latter being the most toxic form.
Lead is most soluble under acidic conditions such as those present in the stomach.
Slide8Lead in GasTetraethyl 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.
Slide9Entry into OrganismsLead
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.
Slide10Effects of LeadLead has the ability to inhibit or mimic the actions of calcium at lower
concentrationsLead 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.
Slide11The 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 hemoglobin
and by lowering its production causes symptoms of anemia.
ALAD
Slide12DetoxificationDetoxification 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.
Slide13ReferencesAnderson, Marti J., Fukunaga, Atsuko.Bioaccumulation of copper, lead, and zinc by the bivalves
Macomona liliana and Austrovenus
stutchburyl. 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