1. ENVIRONMENTAL Disorders
Dr zameer pasha

2. 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

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

4. 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.

5. 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

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

7. 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

8. 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!

9. 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.

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

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

12. 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).

13. 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.

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

15. BISMUTH

16. 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.

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

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

19. 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 …

20. 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

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

22. 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

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

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

25. 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.

26. 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%).

27. AMALGAM RESTORATIONS

28. AMALGAM TATTOO

29. 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.