Page 229 - Concise Pathology for Exam Preparation ( PDFDrive )

214 SECTION I General Pathology

Cyanide

• Sources: Combustion of wool, silk and plastic upholstery
• Effects: Hypoxic injury to brain, liver and kidney

Mushroom Poisoning

• Sources: Amanita phalloides and Amanita muscaria
• Effects: Vomiting, abdominal cramps, CNS changes, renal and hepatic necrosis

Insecticides

• Sources: Chlorinated hydrocarbons, DDT, chlordane and organophosphates
• Effects: Hyperexcitability, muscle twitching to paralysis, cardiac arrhythmias, delirium,
convulsions and coma

Methanol

• Source: Organic solvents
• Effects: Toxic necrosis of retinal ganglion cells with blindness

Q. Write briefly about lead toxicity.

Ans. Lead exposure occurs through contaminated air, water and food.

Sources
• House paints, gasoline, mines, foundries, batteries, automatic exhaust, urban soil and
spray paints
• Most of the absorbed lead is taken up by bone and teeth.

Effects of Lead Poisoning
1. Bones: Radiodense deposits in epiphyses (excess lead interferes with vitamin D me-
tabolism and calcium homoeostasis thereby interfering with normal remodelling of
calcified cartilage and primary bone trabeculae in the epiphyses of children)
2. Nervous system: Excess lead causes neurological effects in adults and children
(encephalopathies, demyelination, peripheral neuropathies, low intellectual capacity,
hyperactivity, poor organizational skills, headache and memory loss)
3. Gingiva: Lead line (lead stimulates hyperpigmentation of the gums)
4. Blood: Lead has high affinity for sulphydryl groups and interferes with enzymes
involved in haem synthesis; iron incorporation into haem is impaired leading to
microcytic hypochromic anaemia and basophilic stippling. The levels of erythrocyte
protoporphyrin are increased.
5. Kidney: Chronic tubulointerstitial disease (excretion of lead occurs via the kidney)
6. GIT: Abdominal pain or colics

Q. Write briefly about the effects of climate change on human health.
Ans. During the preceding 1000 years, maximum warming of earth has taken place in the
last 50 years. Rising levels of CO 2 , methane and ozone (greenhouse gases) along with
water vapour lead to increased absorption and re-emission of infrared energy which radi-
ates from the surface of the earth and normally lost into space. This event raises the global
temperature (greenhouse effect).
• Increase in global temperature increases the surface heat absorption leading to:
a) Loss of ice and snow
b) Increased content of atmospheric water vapour due to increased evaporation from
water bodies

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