ENVIRONMENTAL Disorders Dr zameer pasha

ENVIRONMENT All that which is external to man is the environment broadly speaking. Environmental hazards :- Environmental hazards may be biological, chemical, physical, psychological, sociological, or site and location hazards

Mechanisms of Toxicity Absorption at portals of entry ingestion inhalation skin contact Distribution within the body Metabolism and Excretion Toxic effects

Common Exposures Personal Medications Outdoor Air Pollution Indoor Air Pollution Industrial Exposures Agricultural Hazards Natural Toxins Radiation Injury Physical Injury Note even radiation and physical injuries are regarded as “exposures”, not just chemical substances. There is NO DESIRE to go into detail on all these items, in fact, it’s just not possible. This the pretty much the “ENVIRONMENTAL” half of the chapter.

Tobacco cancer cardiovascular disease respiratory disease cerebrovascular disease Cigarette smoke exacerbates bronchitis, asthma, associated with exposure to silica, coal dust, grain dust, cotton dust, and welding fumes

Contd.. Drugs and chemicals that are used systemically are discussed separately below: 1. Arsenic 2. Bismuth 3. Lead 4. Mercury 5. Silver

Lead Lead is classified as a heavy metal (others include mercury, arsenic, and cadmium) Source of exposure lead paint lead solder in plumbing (older houses) lead-glazed ceramics industrial exposure Route of exposure inhalation with industrial exposure ingestion with household exposure

Lead Distribution and Excretion Lead is cation that is taken up by bone and developing teeth in children (80% to 85%) Half-life of lead in bone is 30 years Blood accumulates 5% to 10% of lead, but lead is rapidly cleared from the blood lead in blood indicates recent exposure blood level does not allow the determination of total body burden Remainder is distributed in the soft tissues Excretion is via the kidneys The body often thinks PB++ is really Ca++, an understandable misunderstanding!

Effects of Lead Inhibition of membrane-associated enzymes inhibition of heme biosynthesis with hypochromic anemia Competition with calcium ions As cation, lead competes with calcium and is stored in bone. It also interferes with nerve transmission and brain development. Inhibition of membrane-associated enzymes Lead inhibits 5'-nucleotidase activity and sodium-potassium ion pumps, leading to decreased survival of red blood cells (hemolysis), renal damage, and hypertension.

Lead Effects: Lead poisoning . Clinical features: Serious gastro-intestinal disturbances (vomiting, nausea, abdominal colic, constipation etc.)

Contd.. Oral manifestations: Lead line . Ulcerative stomatitis. Excessive salivation, metallic taste etc. Treatment and prognosis: Treatment depends upon the systematic conditions of the patient.

Arsenic Uses: both organic and inorganic forms is used therapeutically. Effects: Arsenical keratoses (a diffuse macular pigmentation, palmar and plantar hyperkeratosis, and pre-malignant lesions).

Contd.. Oral manifestations: Oral mucous membranes becomes intensely inflamed and develops severe gingivitis. Painful tissues. Produced ulceration when locally contact with arsenic trioxide. Produces excessive salivation.

Bismuth Uses: Treatment of syphilis. Treatment of certain dermatologic disorders. Oral manifestations: Bismuth pigmentation of oral mucosa, particularly of the gingiva and buccal mucosa.

BISMUTH

Contd.. Bismuth line( a thin blue-black line in the marginal gingiva). burning sensation of the mucosa and a metallic taste. Histologic features: granules are small, irregular black collections of pigments, sometimes perivascular in location.

Contd.. Treatment and prognosis: No specific treatment for the bismuth line. Can be bleached by concentrated hydrogen peroxide. good oral hygiene is recommended.

Mercury poisoning There are 3 different forms of mercury - elemental - inorganic - organic Each has a different toxicological profile

Sources of mercury Elemental mercury: Inorganic mercury: Sphygmomanometers, thermometers, barometers, in amalgam filling as a liquid Liquid at room temp – volatilises easily Inorganic mercury: Traditional remedies (ayurvedic, chinese) Used in gold extraction, caustic soda manufacturing Rodenticides Organic mercury: Fungicides, seed dressings Methylmercury in fish …

Methylmercury Methylmercury (organic) is far more toxic than other forms and is well absorbed when ingested It can be measured in blood and hair It is very slowly eliminated, ½ life of 2 to 3 months Methylmercury Sources of Exposure Elemental mercury is biotransformed by bacteria into methyl mercury and then the bacteria are eaten by fish, prowns etc. Poorly eliminated so it concentrates up the food chain… Biggest and oldest predators at the top of the ecosystem have the highest concentrations Methylmercury is distributed evenly throughout the fish and is not changed by cooking

Organic mercury poisoning: Rare … but severe Exposure: ingestion, topical or inhalation CNS Toxicity: poor concentration, fatigue, ataxia, tremor, constricted visual fields, coma & convulsions

Inorganic mercury poisoning Gastrointestinal phase: Hg2+ is a potent GI irritant gingivitis, stomatitis oesophageal, gastric, small and large bowel erosions haematemesis, bloody diarrhoea, CVS collapse Systemic toxicity: Hg2+ hypotension, lactic acidosis Nephrotoxicity: Hg2+ deposits in the tubules  acute renal failure potentially leads to CRF

MERCURY Effects: Chronic mercurialism after prolonged contact with mercurial compounds. Mercurial compounds: Teething powders Cathartic agents

Contd.. Clinical features: Abdominal pain Vomiting Diarrhoea Thirst Pharyngitis Gastric disturbances Insomnia Nephritis etc.

Contd.. Oral manifestations: Excessive flow of saliva (ptyalism). Metallic taste in the mouth. Hyperemia and swelling of gingiva. Treatment and prognosis: The treatment of poisoning is secondary but the prognosis is usually good.

Silver (argyria, argyrosis) Effects: Appearance of slate-blue line along the gingival margins. Amalgam tattoo (a permanent grayish-black pigmentation). Clinical features: Amalgam tattoo appear as macules. They are located in gingiva (28%), buccal mucosa (23%) and alveolar mucosa (19%).

AMALGAM RESTORATIONS

AMALGAM TATTOO

Contd.. Histologic features: Larger particles evoke granuloma formation (multinucleated giant cells, lymphocytes, severe fibrosis etc.). Fine particles of amalgam can also be found within the cytoplasm of a large number of cells and tissues including muscles, blood vessels.