Heavy metals like aluminum, antimony, arsenic, lead, mercury, and bismuth can cause both acute and chronic toxicity in humans. Acute poisoning from heavy metals may produce symptoms resembling many common diseases, while chronic exposure through occupational or environmental routes is more common. The signs and symptoms of toxicity can differ depending on the heavy metal, dose, and route of exposure. Target organs include the central nervous system, kidneys, lungs, and skin. Chronic heavy metal toxicity may lead to conditions like neuropathy, hyperkeratosis, anemia, and increased cancer risk over time. Proper screening and consideration of exposure history is important for diagnosing heavy metal poisoning.

1. Heavy Metals
• Generally they are potent, tasteless and readily available
• and produce symptoms similar to many common diseases.
• Severe acute poisoning with these agents is rare
• Chronic poisoning, as a result of occupational or environmental
exposure to heavy metals is common.
• The signs and symptoms of acute poisoning may differ from those
associated with chronic toxicity.

2. Aluminium
• Powerful neurotoxin,
• accumulates in bone and lung tissue
• Urinary excretion is the primary route of absorbed aluminum. Unabsorbed
aluminum is eliminated in the feces. ( accumulates in the lung tissue and leach
out very slowly over several months through urine)
• Toxicity:
• bind to transferrin and citrate in the blood
• affect calcium availability
• Bone tissue (osteomalacia or bone softening) and central nervous system (CNS)
are the target organs.
• Patients on long-term dialysis are susceptible to a fatal neurological syndrome
possibly caused by aluminum toxicity (dialysis dementia).

3. Antimony
• The signs and symptoms of acute antimony poisoning include metallic
taste, dysphagia, epigastric pain, violent vomiting, diarrhoea,
abdominal pain and circulatory collapse. These symptoms are almost
indistinguishable from those of acute arsenic poisoning, but larger
doses are required.
• Chronic effects of occupational antimony exposure include ‘antimony
spots’ on the skin and pneumoconiosis

4. Arsenic
• Organic forms and elemental arsenic i-e [As0 or As (0)] are relatively
nontoxic whereas salt forms are most toxic.
• The relative toxicity for these species is as follows:
As0 < As+5 < As+3 < arsine.
• Arsenic trioxide, sankhya (white arsenic or sugar of arsenic) popular as a
homicidal poison.
• The trivalent inorganic salts of arsenic (e.g. sodium arsenite; NaAsO2) are
the most toxic and may cause serious toxicity or death after acute ingestion
of relatively small doses (<200 mg).
• Inhalation of arsine gas (AsH3) may cause massive haemolysis, renal and
other organ failure and rapid death, as in industrial accidents.

5. • Primarily absorbed via the respiratory and gastrointestinal (GI) tracts.
• Urine is the major elimination pathway .
MOA:
Arsenic binds the sulfhydryl group of mitochondrial enzyme i-e pyruvate
oxidase and interferes with mitochondrial respiration.
As arsenic binds the sulfhydryl group it concentrates in hair and nails.
• Arsenic has been used in wood preservatives, insecticides (e.g., calcium
and lead arsenates), herbicides (arsenites), sheep dips, fly paper, arsenical
soaps, germicides, and rat poisons.
Acute Toxicity Symptoms:
• GI symptoms (abdominal pain, diarrohea, vomiting) i-e cholera symptoms
• bloody stools/rice stools
• Complaints of skeletal muscle pain and severe thirst are common.
• Circulatory collapse
• Comma

6. Arsenic
• Chronic Toxicity Symptoms
• Muscle weakness,
• hyperkeratosis
(especially on the palms of the hands and soles of the feet),
• garlic breath
• Mee’s lines,
• Ischaemic gangrene (black foot)
• anemia
• Neuropathy
• CVS collapse
• Increased risk of cancer (skin, liver lung)

7. Hyperkeratosis
Mee`s Lines

8. Postmortem Findings:
• Pink/red velvety stomach
• Congestion of liver, spleen, kidney and brain
• Hyperkeratosis
• Mee,s lines
• Fatty infiltration of liver

9. Lead
• Acute lead poisoning is relatively uncommon, however, and most
symptomatic cases result from chronic ingestion, or inhalation of lead
fumes or dusts during occupational exposure.
• Lead and its compounds are very rarely involved in suspected homicides.
• Very Low absorption from GI tract.
• High absorption when inhaled.
• The best-understood toxic effect of lead is its influence on haemoglobin
synthesis. leading to anaemia. Lead inhibits the enzyme ferrochelatase,
which is involved in iron transport in the bone marrow and catalyses the
introduction of ferrous iron (Fe2+) into the porphyrin ring to form haem.

10. Mercury
• The most toxic forms of inorganic mercury are its divalent (Hg2+) water-soluble salts,
particularly mercuric chloride.
• The fatal (oral) dose of mercuric chloride is less than 5 g in an adult, which led to its
popularity as a homicidal and suicidal poison and gave it its popular name, corrosive
sublimate.
• Significant toxicity associated with both acute and chronic inhalation of (elemental)
mercury vapour, which has a very high vapour pressure at normal room temperature.
• Broken mercury thermometers can constitute a serious risk in children through
inhalation of vapour.
• Organic forms of mercury, such as methylmercury, are strongly neurotoxic and, being
relatively lipid soluble, can accumulate in fatty tissues of the body such as the brain.
• Mercury poisoning may also be seen after the use of traditional medicines and cosmetics

11. • The signs and symptoms of acute and chronic mercury poisoning
mainly involve the central nervous system, kidney or skin
• Characteristic symptoms in children include acrodynia (‘pink disease’),
which include signs such as pink hands and feet.
• Mercury species may be retained in the body for a long time
• Mercury may be excreted in the urine for 6–12 months after
cessation of exposure,

12. Mercury
• Both metallic mercury and organic mercury bind to sulfhydryl groups.
• This disrupts protein structure and thus can interfere with the
function of any tissue or organ system.

13. Bismuth
• Bismuth, a heavy metal, produces toxicity that mimics with lead and
mercury. For this reason, it can be useful
to include bismuth in any heavy-metal screening procedure under-
taken in patients with unexplained neurological symptomatology or
acute renal failure.
• Inorganic salts of bismuth are relatively insoluble in water and are
poorly absorbed from the GI tract, they cause minimal toxicity.
• Lipid-soluble organic compounds, are known to accumulate in the
body after excessive dosing and can cause severe neurotoxicity.
• Water-soluble compounds of bismuth are more likely to cause renal
damage, including oliguria and acute renal failure