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
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
•
Effects of Lead
• 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:
• 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.