8. mercury toxicity

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MERCURY & ITS TOXICITY

PRESENTED BY DR. G. RADHIKA PG STUDENT DEPARTMENT OF PUBLIC HEALTH DENTISTRY SIBAR INSTITUTE OF DENTAL SCIENCES GUNTUR

CONTENTSIntroduction History Physical

and chemical properties Sources of mercury Usage of mercury Biotransformation Mercuralism- signs and symptoms

and normal levels Mercury exposure from dental office Methods to monitor mercury levels Precautions to avoid mercury toxicity Hygiene recommendations for mercury in dentistry Amalgam waste management Conclusion References Acceptable

INTRODUCTION Liquid

metal Used in dentistry Dental amalgam Acc to ADA > 100 million silver fillings/ year

The Amalgam Controversy-the Evidence Based AnalysisJADA,2001

HISTORY>

2000 years in preparations such as diuretics, anti-bacterial ointments, laxatives and skin ointments. original amalgamation process was demonstrated by a chemist in France

The Amalgam Controversy-the Evidence Based AnalysisJADA,2001

HISTORY In

1833, two English Entrepreneurs, The Crawcour Brothers

Strudevents Art and Science of Operative Dentistry; T.M. Robers

HISTORYdental restorations in China 600 AD First amalgam War 1980 controversy Huggins, a Practicing Dentist in Colorado publicly condemned amalgam Tin-mercury

Strudevents Art and Science of Operative Dentistry; T.M. Roberson

HISTORY Multiple

sclerosis, Alzheimers Disease -

no basis In Japan 1952, mercury was dumped in Minamata Bay by a local chemical plant (Chisso Corporation

The Amalgam Controversy-the Evidence Based AnalysisJADA,2001

PHYSICAL & CHEMICALPROPERTIES

number - 80 Atomic mass - 200.59 g.mol -1 Electronegativity - 1.9 Density - 13.6 g.cm-3 at 20C Melting point - - 38.9 C Boiling point - 356.6 C Atomic

PHYSICAL & CHEMICAL PROPERTIES ADA

Specification No. 6 Mercury exists in 3 chemical formsElemental mercury Half

Inorganic salts of mercury

Organic mercury

life of mercury 55 days Half life of methyl mercury 70 dayshttp:www.mercury.wikipedia.org.com

USES OF MERCURY Elementaly y

mercury:

Sphygmomanometers, thermometers, barometers Liquid at room temp volatilises easily

Inorganicy y y

mercury:

Traditional remedies (ayurvedic, chinese) Used in gold extraction, caustic soda manufacturing Rodenticides

Organicy y

mercury:

Fungicides, seed dressings Methylmercury in fish

SOURCE OF MERCURY 2,700

and 6,000 tons of mercury are released annually from the oceans and the Earths crust The greatest source - mercury vapor released during volcanic eruptions

2,000

to 3,000 tons are released from human activities, primarily burning household and industrial waste Swordfish and tuna - 1000 g/kg of mass

160

mg/kg in cattle and 25 mg/kg in humans mercury compounds are routinely used as fungicides and herbicides to coat seeds used to plant farm fields.

Methyl

http:www.mercury.wikipedia.org.com

Dental

fillings are composed of mercury, silver, tin, copper, and zinc. The approximate percentages are as follows: 50% mercury, 33-37% silver, 12.5-13.5% tin 0-3% copper 0-1% zinc

USES OF MERCURY & ITS EFFECTS Calomel

(mercurous chloride) was used for the treatment of syphilis. Inorganic mercury - electrical applications, chlorine production and dental restorations

Thimerosol

as medicine in Hepatitis B, Diptheria, Pertussis and Tetanus vaccines

Mercury

in vaccines have caused death of infants - diapers and kawasaki disease teething powder

Acrodynia

Gerald T. Charbenue; Principles and Practices of Operative Dentistry

BIOTRANSFORMATION Mercury

from dental amalgam is released in two forms Mercury vapors Mercuric ions

Inhalation

is the major route of entry into the human body. Metallic mercury is poorly absorbed to the skin or via the gastro intestinal tract. normal circumstances, mercury is biochemically processed and excreted

Under

The dental Amalgam Contraversy:A ReviewJCC,1996

ions (Hg0) circulate readily in the blood but pass the membrane barriers of the brain and placenta with difficulty Non-ionized mercury (Hg) is capable of crossing through lipid layers barriers and if subsequently oxidized within these tissues neuromuscular problems Mercury

Strudevents Art and Science of Operative Dentistry; T.M. Robers

MERCURALISM Acute

toxicity Chronic toxicity (Hydrargyrism) Erethism

William. G.Shafer, M.K. Hine; A Text book of Oral Pathology

Neurological

increase plasma creatine level Immunological Reproductive Cardiac Blood Liver Nervous system Oral manifestations Thyroid RenalWilliam. G.Shafer, M.K. Hine; A Text book of Oral Pathology

PINKS

disease, Acrodynia, Swift disease - 6 Ps hands & feet: puffy, pink, painful, peeling, parasthetia, perspiring

William. G.Shafer, M.K. Hine; A Text book of Oral Pathology

Women

who are exposed to mercury in pregnancy have given birth to children with serious birth defects due to mercury poisoning. In utero mercury exposure can lead to Minamata disease

Allergy Others

- White cell reaction, reaction to N2O, hyperventilation, reaction to diet pills, gall bladder, painful menstruation, hepatitis, severe complexion problems

William. G.Shafer, M.K. Hine; A Text book of Oral Pathology

TREATMENT Supportive

treatment

DMPS Chelation (2,3-Dimercapto-1propanesulphonate) - Chelation therapy of choice for mercury - For both acute and chronic mercury poisoning. - Urinary excretion of mercury two hours after DMPS administration - (Aposhian et. al, 1992)

Discontinuance

of exposure to mercury . The administration of BAL (British Anti-lewisite) pencillamine

William. G.Shafer, M.K. Hine; A Text book of Oral Pathology

Acute

mercurialism - Sodium ascorbate

Dr.

Olympio Pinto of Rio de Janeiro remove amalgams when the WBC remained over 11,000 for three months without visible medical cause

The dental Amalgam Contraversy:A ReviewJCC,1996

N-Acetyl-Cysteine

(NAC) For Mercury Detoxification

NAC

is produced in living organisms from the amino acid cysteine. Thus NAC is a natural sulfur-containing amino acid derivative found naturally in foods and is a powerful antioxidant

The dental Amalgam Contraversy:A ReviewJCC,1996

NORMAL LEVELSIntake of mercury vapor - 0.4 to 4.4 ug/day depending on number of amalgam fillings. Mercury concentration in urine - 15 ug/lt 4 nanograms in blood 1 micro gram/ m3 in air

Tolerable daily intake (TDI) of .014 g Hg0/kg-day (Richardson, 1996)

Richardson, GM; Allan, M. A Monte Carlo assessment of mercury exposure and risks from dental amalgam. Human and Ecol Risk Assess

(RICHARDSON, 1996)Age groups (yrs) No. of amalgam fillings0 -1 1-3 2-4 2-4

3 - 11 12 - 19 20 - 59 60 +

Tissue Whole blood Urine Tooth alveolar bone Gum mucosa Mouth papilla Tongue Parotid gland

ng Hg/g 9.0 4.7 318.2 323.7 19.7 13.0 7.8

Mercury vapor exposure established by OSHA is 50 micro grams urinary excretion of mercury is 2 to 20 mcg/liter

Mercury

in pure air - 0.002 g/m 3

Urban air - 0.05 g/m 3 near industrial parks - 3 g/m3

Air

Air in mercury mines - 300 g/m3. TLV for exposure to mercury vapor for a 40-hour work week is 50 /g/m3 is 100 g/m3 for clinical mercurism and 50 g/m3 for nephrotoxicity

LOAEL

The Amalgam Controversy: An Evidense-Based Analysis, JADA, 2001

Engle et al found that dry polishing of amalgam restorations resulted in release of 44ug of mercury vapor /restoration. 8 Vimy and Lorscheider (1985) showed that 829ug of mercury vapor was released every 24 hrs for 4-12 amalgams. 9 Berglund (1990) showed that 1.7ug of mercury vapor was released from amalgam in 24hr period.

MERCURY EXPOSURE IN DENTAL OFFICE Incorrect

storage of mercury or waste

amalgam Spillage

of mercury or waste amalgam

Mishandling

at any stage would result in mercury splashing on the bench or floor causing it to be scattered widely as small droplets.

Strudevents Art and Science of Operative Dentistry; T.M. Robers

How

would you clean up the mercury?

1. Spill on a non-porous surface: y lift the mercury with card or paper (remove gold rings and wear gloves) y place in a sealed container & dispose in general waste 2. Spill on a carpet: y Use a sulphur based (calcium polysulfide) powder p mercuric sulphide & then can vacuum upStrudevents Art and Science of Operative Dentistry; T.M. Robers

Mixed

but unhardened dental amalgam during trituration, insertion and intraoral setting. During finishing and polishing of amalgam Removal of amalgam restoration. Amalgam raw materials being stored for use. Amalgam scrap that has insufficient alloy to consume the mercury present completely

Strudevents Art and Science of Operative Dentistry; T.M. Robers

MONITORING MERCURY LEVELS Detection

meter mercury sniffer Paper discs impregnated with palladium chloride

Mercury vapour analyzer

A

badge system - mercury is adsorbed on gold foil Mercury in vapor and dust form absorbing system and then quantifying the absorbed mercury

Mercury monitoring system

PRECAUTIONS Mercury-containing

products should not be stored in the open, but rather in closets or cabinets Reusable capsules and precapsulated designs - vacuum aspirator During trituration Sprinkling sulfur powder Scrap amalgam from condensation procedures

Strudevents Art and Science of Operative Dentistry; T.M. Robers

PRECAUTIONS Mercury

during finishing & polishing procedures Spent capsules and mercurycontaminated cotton rolls or paper napkins

Strudevents Art and Science of Operative Dentistry; T.M. Robers

CANADIAN DENTAL ASSOCIATION, 1996 Recommendations

Avoid using mercury to restore children's teeth. Avoid placing or removing amalgam in the teeth of pregnant women. Avoid using dental amalgams in patients suffering from kidney ailments. Use methods and equipment to reduce the risks of exposure to mercury vapor

"The Safety of Dental Amalgam: Health Canada, Dept. of Supply and Services

Avoid

using amalgams in patients who risk suffering from allergic hypersensitivity. Remove amalgams from a patient who has become sensitive. Avoid placing amalgam in contact with other metal appliances in the mouth Fully inform patients of the risks and benefits involved. Recognize the patient's right to refuse treatment using a specific material.

The Safety of Dental Amalgam: Health Canada, Dept. of Supply and Services

MERCURY HYGIENE Minimize

the contamination Drain, vacuum cuspidor or sink is fitted with a filter, strainer or trap Spilled mercury - dusting with sulfur powder or spraying with a solution of sodium thiosulfate Mercury

spillage kit -->

Strudevents Art and Science of Operative Dentistry; T.M. Robers

Rubber

dam and high volume evacuation

Amalgam

should be polished at slow speed using water spray ventilation

Proper

Mercury

vapor level in office should be periodically monitoredStrudevents Art and Science of Operative Dentistry; T.M. Robers

Office

personnel should also be monitored alloys should be used

Pre-capsulated

Skin

contact with mercury should be avoided masks after removing amalgam restorationsStrudevents Art and Science of Operative Dentistry; T.M. Robers

Change

Mercury

contaminated items should be deposited in sealed bags mercury should be cleaned with trap bottles, taps or fresh mixes of amalgam removal of the defective mercury with air turbine

Spilled

The

Strudevents Art and Science of Operative Dentistry; T.M. Robers

AMALGAM WASTE MANAGEMENT Closed

system Newer systems Spent capsules Alternatives to amalgam

Strudevents Art and Science of Operative Dentistry; T.M. Robers

STUDIESbaseline mouth air of people with amalgams contains more mercury than that of people without amalgams as detected by Jerome Mercury Vapor Detector . Old amalgams contain significantly less mercury than new ones (Gay et al, 1979 ; Vimy and Lorscheider, 1990) The

Conclusion

HOW CAN IT BE SAFE?y

Saying that the mercury in amalgam can cause harm is a little like saying the chloride in table salt can kill you. Putting only chloride on food is a bad idea. The chemical will ruin the food. But combine the chloride with just the right amount of sodium and you create the tasty flavor enhancer called table salt.

y

y

Similarly

The mercury in silver fillings is not harmful because the mercury is transformed in the process of making an alloy. is made by mixing mercury with other metals, such as silver, copper and tin, Trajtenberg says. The mercury binds to the other metals to make a stable alloy, and therefore is safe for dental applications.

Amalgam

Where

there is Smoke there just might be fire there is Amalgam there just might be Mercury poisoning

Where

REFERENCES Strudevents

Art and Science of Operative Dentistry; T.M. Roberson, Herald. O. Heymann, Edward J.Swift; 5th edition pg 162- 172. T. Charbenue; Principles and Practices of Operative Dentistry; Dental Amalgam Restoration Pg: 248-249; 3rd edition; Varghese Publishing House.

Gerald

REFERENCES VIMAL

.K. SIKRI; Textbook of operative dentistry 2nd edition, CBS Publications& distributors; pg 257-260 Lund Bales, Vernetti; Operative Dentistry; Mercury Control, 4th edition; BI Publications.

Gilmore

William.

G.Shafer, M.K. Hine; A Text book of Oral Pathology; 4th edition; Pg: 578-579, W.B.Saunders company.

Gay

et al. Chewing Releases Mercury from Fillings. Lancet, 985, 5 May 1979. MJ; Lorscheider, FL. Dental amalgam mercury daily dose estimated from intro-oral vapor measurements: A predictor of mercury accumulation in human tissues. J Trace Elem Exper Med, 3:111-23, (1990). HV; et al. Urinary mercury after administration of 2,3-dimercaptopropane-lsulfonic acid: Correlation with dental amalgam score. FASEB J, 6:2472-6, 1992

Vimy,

Aposhian,

George

Feuer, H. S. Injeyan; The Dental Amalgam Contraversy- A Review; J.Can. Chiorpr. Assoc.; 40(3); pg: 169-178; 1996.

Richardson,

GM; Allan, M. A Monte Carlo assessment of mercury exposure and risks from dental amalgam. Human and Ecol Risk Assess. 2: 709-761 (1996).

"The

Safety of Dental Amalgam: Health Canada, Dept. of Supply and Services Canada Cat. H49-105/1996E ISBN 0-66281449-5 (1996)

John

E. Dodes; The Amalgam Controversy. An Evidence Based Analysis; J.Am.Dent.Assoc.; vol: 132; Pg: 348-356; 2001. Strudevents Art and Science of Operative Dentistry; T.M. Robers; Herald. O. Heymann, Edward J.Swift; 5th edition pg 162- 172. Dental Amalgam: update on safety concerns. ADA council on Scientific Affairs; JADA, vol 129; April 1998 pg 494-503

DONT METAL WITH YOUR TEETH