MERCURY TOXICITY.pptx

MERCURY TOXICITY

1. MERCURY TOXICITY DR ASHWINI M PATIL Reader Navodaya dental college Raichur

2. Introduction Mercury (Hg) is a naturally occurring metal and exists in three forms: elemental (metallic), inorganic, and organic. The form of mercury greatly influences mercury’s distribution within the body and its health effects. Mercury is a heavy, silvery-white liquid metal known as quick silver. And its the only common metal which is liquid at ordinary temperatures. A fair conductor of electricity, and poor conductor of heat if compared with other metals.

3. Mercury is a heavy silvery liquid metal with atomic number 80 a standard atomic weight of 200.59 . The amount of mercury in dental amalgam may be specified as alloy – mercury ratio = 1:1 . The name comes from Greek name, hydrargyrum, which means " hydr- " water and " argyros " silver to reflect its shiny surface , it has a silvery tinge and it, as a liquid, flows quickly . It alloys easily with many metals, such as gold, silver, and tin, these alloys are called amalgams. Introduction

4. Mercury in the environment Mercury is a compound that can be found naturally in the environment as metal form, mercury salts or as organic mercury compounds. Found mainly in cinnabar ore (HgS). Also present as an impurity in many other minerals, in particular the non-ferrous metals, and in fossil fuels, coal. Easily vaporize in room temperature into an odorless, colorless vapor that can easily inhaled.

5. Elemental mercury is a shiny, silver-white liquid (quicksilver) primarily obtained from the refining of mercuric sulfide in cinnabar ore. Elemental mercury is used in dental amalgams. Elemental mercury easily vaporizes at room temperature to an invisible, odorless toxic gas referred to as elemental mercury vapor. Usually used in school science lab.

6. Inorganic mercury Inorganic mercury compounds, or mercury salts, are formed when mercury combines with other elements such as chlorine (e.g., mercuric chloride), sulfur, or oxygen. Its exist in two oxidative states— mercurous (+1) and oxide mercuric (+2). Mercury salts are highly toxic and corrosive. White in color except cinnabar (Red). Enters body through mouth and skin from disinfectant and fungicide. Usually used in school science lab.

7. Organic mercury compounds are formed when inorganic mercury is methylated or combines with organic agents. The most important organic form of mercury in terms of human exposure is methylmercury, is formed by anaerobic methylation of inorganic mercury by microorganisms in sediments. The primary source of human exposure to mercury is through the consumption of fish and shellfish containing methylmercury.

8. Other forms of organic mercury may be found in outdated fungicides, antiseptics, and disinfectants. Most of these uses have been discontinued, however, small amounts of these compounds may still be found in some medicines.

9. Composition of amalgam 50% Mercury 35% Silver 13% Tin 2% Copper and Zinc

10. γ 1 forms first a n d then γ 2 . Alloy is mixed with mercury in the ratio of 1:1. Mercury is insufficient to completely consume the alloy particles. γ 1 - D o minant ph a se – 54 - 56 %. U n reacted γ - 27 - 35 % . γ 2 - 1 1 - 13 %

11. Risks Easily crosses blood brain barrier and can enter breast milk. Potent neurotoxin. Neurological effects - tremors , mood swings, irritability, excessive shyness. Very high exposure can cause kidney effects, respiratory failure and death. Birth defects. Impairment of vision, speech, walking.

12. Mercury exposure in dental clinic.

13. In 1845 , American Society of Dental Surgeons condemned the use of all filling material other than gold as toxic, thereby igniting. The society went further and requested members to sign a pledge refusing to use amalgam. In mid 1920's a German dentist, Professor A. Stock. He claimed to have evidence showing that mercury could be absorbed from dental amalgam, which leads to serious health problems. He also expressed concerns over health of dentists, stating that nearly all dentists had excess mercury in their urine.

14. Remarkably, the Food and Drug Administration (FDA) has separately approved the mercury and the alloy powder for dental use; but the amalgam mixture has never been approved as a dental device. In 1980 primarily through the seminars and writings of Dr. Huggins. He was convinced that mercury released from dental amalgam was responsible for human diseases affecting the cardiovascular system and nervous system. Also stated that patients claimed recoveries from multiple sclerosis, Alzheimer’s disease and other diseases as a result of removing their dental amalgam fillings.

15. Due to the health effects of mercury exposure, industrial and commercial uses are regulated in many countries. The World Health Organization (WHO) , Occupational Safety and Health Administration (OSHA) , and National Institute for Occupational Safety and Health (NIOSH) all treat mercury as an occupational hazard, and have established specific occupational exposure limits. Environmental releases and disposal of mercury are regulated in the U.S. primarily by the United States Environmental Protection Agency .

16. Amounts of Mercury released Trituration Placement of restorations Dry Polishing Wet Polishing : 1-2 μg : 6-8 μg : 44μg : 2.4 μg Removal of restorations using water spray and high volume suction : 1.5 - 2μg Additional evacuation for 1 minute to remove amalgam dust : 1.5 – 2 μg

17. Mercury management Spills of triturated materials are collected with vacuum aspirator. Vapor releases must be cleared by airflow system of room. During intra oral placement and condensation procedure rubber dam can be used to isolate patient and high vacuum evacuation is used.

18. Storages location should be near a vent that exhaust air out of the building. Before use : Store in a plastic container with threaded cover Scrap amalgam, from condensation is stored under water , glycine or spent x ray fixer and tightly capped jar. Mercury management

19. ADA Recommendations for dental mercury hygiene. Train all personnel regarding mercury handling and hazards. Make them aware of the potential sources of mercury vapor in the clinic. Work in well ventilated spaces with an exhaust. Replace air conditioning filters periodically. Monitor the dental clinic atmosphere for mercury vapor.

20. Design work area properly. Floor covering should be nonabsorbent, seamless and easy to clean. Use precapsulated alloys. Use amalgamator with completely enclosed arm. Avoid skin contact with mercury or freshly prepared amalgam. Re-cap single use capsules after use if possible. ADA Recommendations for dental mercury hygiene.

21. Use high volume evacuation while finishing or removing amalgam. Salvage and store all scrap amalgam. Dispose amalgam scrap and mercury contaminated items as per applicable regulations. Clean up spilled mercury using trap bottles, tape or freshly mixed amalgam. Do not use household vacuum cleaner. Remove professional clothing before leaving the workplace. ADA Recommendations for dental mercury hygiene.

22. Management of mercury spills In case of an accidental mercury spill (regardless of size), Never use a vacuum cleaner to clean up the mercury. Never use household cleaning products to clean up the spill, particularly those containing ammonia or chlorine. Never allow mercury to go down the drain. Never use a broom or a paintbrush to clean up the mercury. Never allow people whose shoes may be contaminated with mercury to walk around.

23. Mercury spillage kit Spill kits are essential for the management of mercury spills and breakages. Procedure: Put on the Personal Protective Equipment which is provided in the kit. Using the scoop collect the amalgam or mercury waste. If it is mercury droplets use the syringe to pick up as many globules, then place the full syringe in the waste container (provided in the kit). Open the container which contains calcium hydroxide and sulphur. Tip out onto the spillage area, close the center of the spillage. Using the scoop mix the powders with the spilt amalgam or mercury (which you could not pick up). The powder may start to go grey as the mercury is absorbed.

24. Brush the contaminated powder into the scoop and place in the waste container. Close the lid on the waste container or sealable bag. Dispose of the Personal Protective Equipment in the waste container . Label the waste container or bag with ‘hazardous waste sign. Contact the licensed waste carrier company you use to remove the hazardous waste. Cleanup of large mercury spills requires experienced environmental personnel. Mercury spillage kit

25. Alternatives to Dental Amalgam Composite dental restoration. Glass ionomer filling. Ivoclar cention

26. Effects of Mercury toxicity on the body The toxic effects of mercury depend on its chemical form and the route of exposure. Allergy, Contact dermatitis represent the most likely physiologic side effect to dental amalgam, an alternative material (e.g. Composite or ceramic) must be used. Release of mercury induced an acute reaction which resulted in erythematous lesions, severe burning and itchy sensation and difficulty in breathing

27. Inhalation of mercury vapors causes: Chemical pneumonia, Pulmonary oedema, Gingivostomatitis, Increased salivation. CNS symptoms like: Ataxia, Restriction of field of vision, Delerium, Polyneuropathy. Symptomatic patients who have experienced acute high-dose elemental mercury inhalation exposure should receive supportive care and be monitored for development of acute pneumonitis and pulmonary edema in a hospital setting. Mercury can be inhaled and absorbed through the skin and mucousmembranes, so containers of mercury should be securely sealed to avoid spills and evaporation.

28. Ingestion of Mercury The signs and symptoms start immediately after swallowing the mercury: Hot burning pain in mouth, stomach and abdomen. Stools are blood stained , urine is suppressed and scanty,contain blood and albumin is accompanied by necrosis of renal tubules and damage to the glomeruli .

29. Hoarseness of voice. Difficulty in breathing Acrid metallic taste in mouth. Feeling of constriction or choking of throat. Pulse is quick small and irregular. Thrombocytopenia and bone marrow depression. Ingestion of Mercury

30. Chronic Mercury Poisoning/ Hydrargyrism Workers may get poisoned due to vapors or dust. When small doses are taken for prolonged time or used as ointment for long period. The signs and symptoms of chronic mercury start at a blood level 100 mg/ml. Patient is symptomatic at daily urinary excretion more than 300 mg/ml

31. Hydrargyrism/ Signs and symptoms Excessive salivation with swollen and painful salivary glands. Foul smelling breathing, inflamed and ulcerated gums with brownish blue line and loosening of teeth. Mercura lentis: A brownish reflex from the anterior lens capsule of both the eyes is seen when observed in slit lamp in person exposed to mercury vapors for some years. It is bilateral and has no effect on the visual acuity.

32. Oral cavity problems Inflammation of the mouth. Loss of bone around teeth. Ulcerated gums and other areas in the mouth. Darkening of gums. Taste of metal. Bleeding gums.

33. Acrodynia (Pink disease) There is generalized rashes over the body. Results from chronic exposure to mercury in any forms. Erythematous, eczematous (watery and weeping) popular type of skin lesion. Mostly in the hands and feet accompanied with thickening of skin.

34. Hunter-Russell syndrome The term Hunter-Russell syndrome derives from a study of mercury poisoning among workers in a seed packing factory in England in the late 1930s who breathed methyl mercury that was being used as a seed disinfectant and preservative. Syndrome is characterized by paresthesia, visual field constriction, ataxia, impaired hearing, and speech impairment.

35. Erethism (Mad hatter disease, or mad hatter syndrome) In 19th century , inorganic mercury in the form of mercuric nitrate was commonly used in the production of hats. It caused a slow release of volatile free mercury. Erethism commonly characterized by behavioral changes such as irritability, low self-confidence, depression, apathy, shyness and timidity. In some extreme cases delirium personality changes and memory loss occur.

36. Laboratory Tests Urine test: A urinary mercury concentration of less than four micrograms per liter (μg/L) would be considered within the background range.

37. Blood test Blood level greater than 10 mcg/L indicates an unusual level of exposure for someone who does not regularly work with mercury. Amount present will decrease by half about every 3 days as the mercury moves into organs such as the brain and kidneys. Therefore, blood testing must be done within days of suspected exposure

38. Amount of exposure Length of exposure Length of mercury accumulation in body Amount of accumulated mercury Overall health of the patient ( for detoxification) Toxic effect of Mercury depend on: