a small dose of metals – 04/13/11 an introduction to the health effects of metals a small dose of...
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A Small Dose of Metals – 04/13/11
An Introduction To The Health Effects of Metals
A Small Dose of ™ Metal
ENVIRONMENTAL AND OCCUPATIONAL TOXICOLOGY III
(ENVH 516)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Introduction
Complex relationship to metals –
Nutritionally Important
Toxicologically Important
Medical Important
Chelation
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Lead - usage began 4000 years ago Hippocreates – 370 BC noted abdominal
colic in miner Arsenic – therapeutic and a poison (400 BC) “Lead makes the mind give way”. The Greek
Dioscerides 2nd century BC
Ancient Awareness
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
80 of 105 elements in the periodic table are labeled as metals
“Mad Hatter” – mercury exposure
Historical Awareness
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Thoughts on Metals
Redistribution• Naturally occurring – break down of rock• Human – mining, purify, recombine, use• E.g. lead – rise in Greenland ice
Changed form• E.g. inorganic to organic mercury
Occupational exposure Home exposure
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Susceptibility to Metals
Age – young or old? Nutrition (competion with essential
metals) Allergic response (immune system) Form of metal (organic or inorganic) Lifestyle – smoking or alcohol Occupation Home environment (lead paint?)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Chromium (Cr) Copper (Cu) Iron (Fe) Magnesium (Mg) Manganese (Mn) Selenium (Se) Zinc (Zn)
Nutritionally Important
Some metals have very important physiological functions
Cr
Cu
Fe
Mg
Mn
Se
Zn
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – essential element, associated with insulin, stainless steel, tanning leather
• Source –food supply, inhalation• Recommended daily – 50-200 µg• Absorption – intestine• Toxicity – acute exposure cause kidney
damage, lung cancer• Facts – comes in different oxidized forms
– Cr3+, Cr6+
Chromium (Cr)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – essential element, widely used• Source – readily available in food• Recommended daily – 1.5-3.0 mg• Absorption – intestine• Toxicity – deficiency – anemia
- excess rare, Wilson’s disease• Facts – excess treated with penicillamine
- can be toxic grazing animals
Copper (Cu)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – oxygen carrying hemoglobin• Source – food• Recommended daily – 10-15 mg• Absorption – intestine• Toxicity – excess causes bloody fesses,
bloody vomit, liver damage• Facts - 3-5 grams in the body
• 67% associated with hemoglobin
Iron (Fe)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – essential nutrient, associated with many enzymes, antacids
• Recommended daily – 280-350 mg• Source – food supply, nuts, cereals,
seafood, meats, drinking water• Absorption – small intestine• Toxicity – deficiency – convulsions
- excess – nervous system• Facts – 20 grams in body
Magnesium (Mg)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – trace element, associated with many enzymes
• Source – food supply, grains, nuts• Recommended daily – 2 to 5 mg• Absorption – intestine poor (5%)• Toxicity – inhalation – respiratory
disease, nervous system, Parkinson’s -like syndrome, psychiatric disorders
• Facts – half-live 37 days
Manganese (Mn)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – essential element, present in most tissue, anticancer, reduces toxicity of metal mercury and cadmium
• Source – food supply, shrimp, meat• Recommended daily – 55-70 µg/day,
not to exceed 200 µg/day• Absorption – intestine• Toxicity – deficiency – heart disorders
- excess – “blind staggers”, neurological effects
Selenium (Se)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – essential element, cofactor with several enzymes, and proteins
• Source – food supply, drinking water• Recommended daily – 12-25 mg• Absorption – intestine• Toxicity – deficiency – impaired
growth, neurological disorders, - inhalation can cause metal fume fever
Zinc (Zn)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Aluminum (Al) Arsenic (As) Cadmium (Cd) Cobalt (Co) Lead (Pb) Mercury – Inorganic (Hg) Mercury – Organic (Hg-CH3)
Nickel (Ni) Tin (Sn)
Toxic Metals
Pb
Co
Al
As
Cd
Hg
Hg-CH3
Ni
Sn
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – wide range of consumer products, airplanes to cans
• Source – food, drinking water• Absorption – poor• Toxicity – Dialysis dementia,
possibly neurotoxic• Facts – non-essential, intake 1-10
mg/day
Aluminum (Al)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – pesticide and herbicide• Source – food, drinking water• Absorption – intestine• Toxicity – cancer, heart, liver,
neurological• Facts – exists in different states –
trivalent (most common), pentavalent, arsenic trioxide, organic and inorganic ...etc…
Arsenic (As)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – metal alloy, nuclear power plants• Source – workplace, coal combustion• Absorption – lung, skin• Toxicity – lung, can be delayed and is
progressive, contact dermatitis probable carcinogen
• Facts – discovered in 1828, more that 1250 tons from oil and coal combustion
Beryllium (Be)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – alloy in metal, paint• Source – shellfish, cigarette smoke, workplace
– welding, paints• Absorption – intestine, lungs• Toxicity – lung, emphysema, kidney, calcium
metabolism, possible lung carcinogen• Facts – “Itai-Itai” is Japanese for “ouch-ouch”
– refers to bone pain related to calcium loss
Cadmium (Cd)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – component of vitamin B12, • Source – alloy in metals, magnets• Recommended daily – none• Absorption – intestine• Toxicity – excessive heart failure,
inhalation – “hard metal” lung disease• Facts – once used a foaming agent in
beer
Cobalt (Co)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – not essential, batteries, old paint and previously gasoline, hobbies
• Source – home, paint, dust, kids-hands to mouth, workplace
• Absorption – intestine (50% kids, 10% adults)• Toxicity – developmental and nervous system• Facts – developing nervous system very
sensitive to low levels of exposure
Lead (Pb)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – consumer products, industry, dental amalgams, switches, thermometers
• Source – mining, environment• Absorption – inhalation, intestine poor• Toxicity – nervous system toxicant, “Mad
Hatters” disease• Facts – liquid silver evaporates at room
temperature, bacteria convert to organic methyl mercury (see next slide)
Inorganic Mercury (Hg)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – limited laboratory use - most common is methyl mercury (Hg-CH3)
• Source – contaminates some fish (e.g. tuna, shark, pike)
• Absorption – intestine very good (90%)• Toxicity – nervous system toxicant, and
developmental toxicant• Facts – bacteria convert inorganic
mercury to methyl mercury then in to food supply (bioaccumulation)
Organic Mercury (Hg-CH3)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – not essential, metal alloy, stainless steel
• Source – food supply, jewelry, workplace• Absorption – intestine, skin• Toxicity – carcinogen (lung), contact
dermatitis• Facts – discovered in 1751, 200,000
metric tons used yearly
Nickel (Ni)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – inorganic – consumer products- organic – fungicide, bactericides
• Source – food packaging• Absorption – intestine (low inorganic, high
organic)• Toxicity – inorganic - little
- organic – central nervous system• Facts – triethyltin and trimethyltin most toxic
Tin (Sn)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Bismuth (Bi) Fluoride (F) Gallium (Ga) Gold (Au) Lithium (Li) Platinum (Pt)
Medically Important
A small group of metals are used to treat disease
F
Li
Pt
Ga
Au
Bi
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – antacids, diarrhea• Source – mining, consumer products• Absorption – intestine• Toxicity – kidney, chronic use results
in range of effects• Facts – discovered in 1753, used to
treat syphilis and malaria
Bismuth (Bi)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – tooth protection• Source – drinking water, food supply• Absorption – intestine• Toxicity – excess causes mottled
teeth enamel (fluorosis)• Facts – common water level 0.5 to 1.5
ppm, 3 ppm effects teeth
Fluoride (F)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – visualization tool for soft tissues in x-rays
• Source – mining, medical injection• Absorption – very poor• Toxicity – kidney• Facts – liquid at room temperature,
half-life 4 to 5 days
Gallium (Ga)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – treat rheumatoid arthritis, range of industrial uses
• Source – mining, medical injection• Absorption – poor• Toxicity – kidney, skin and mouth
lesions• Facts – long half-life
Gold (Au)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – treat psychiatric disorders• Source – food supply, plants & meat• Absorption – intestine• Toxicity – wide range, e.g. tremor,
seizures, slurred speech, cardiovascular, nausea, vomiting
• Facts – daily intake about 2 mg
Lithium (Li)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
• Use – anti-cancer agent (cisplatin), catalytic converters, metal alloy
• Source – mining, road dust• Absorption – poor, as a drug
intravenous administration• Toxicity – neuromuscular, kidney• Facts – inhibits cell division, treat
ovarian & testicular cancer
Platinum (Pt)
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Properties• Metal chelators accelerate the excretion
of metal from the body• Non-specific – can remove essential
metals and elements• Chelate is from the Geek word for claw
Examples• BAL – one of the first, broad action but
potentially toxic• Calcium EDTA – lead• Penicillamine – copper• Desferrioxamine – iron• DMPS – lead, mercury• Number of others
Chelation
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
We can not live without metals but some require
our utmost respect.
Summary
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Additional Information
Web Sites• Health Canada - Nutrition.
http://www.hc-sc.gc.ca/english/lifestyles/food_nutr.html
• U.S. Agency for Toxic Substance Disease Registry (ATSDR). http://www.atsdr.cdc.gov/
• Dartmouth Toxic Metals Research Program. http://www.dartmouth.edu/~toxmetal/HM.shtml The site has general information on toxic metals.
A Small Dose of Metals – 04/13/11 A Small Dose of Toxicology
Authorship Information
For Additional Information ContactSteven G. Gilbert, PhD, DABT
E-mail: [email protected]: www.asmalldoseof.org
This presentation is supplement to “A Small Dose of Toxicology”