Target organ toxicityTypes of organ specific toxic effects are:

•Blood/vascular toxicity•Dermal or occular toxicity•Genetic toxicity•Hepato toxicity•Immuno toxicity•Nephrotoxicity•Neurotoxicity•Reproductive toxicity•Respiratory toxicity

Blood or cardiovascular toxicity

Blood and cardiovascular toxicity results from xenobiotics acting directly On cells circulating blood, bone marrow and heart.

Examples of blood and cardiovascular toxicities are:

•Hypoxia due to carbon monoxide binding of hemoglobin preventing transport Of oxygen as The affinity between CO and hemoglobin is 200 times stronger than the affinity between hemoglobin and oxygen. •Decrease in circulating leukocytes due to chloramphenicol damage to bone marrowCells.•Leukemia due to benzene damage to bone marrow suppression

•Methoglobinemia

•Arteriosclerosis due to cholesterol accumulation in the arteries and veins.

Dermal toxicityDermal toxicity may result from direct contact or internal distribution tothe skin. Effects range from mild irritation to severe changes, such asCorrosivity, hypersensitivity, and skin cancer. Examples of dermal toxicityare:

•Dermal irritation due to skin exposure to gasoline•Dermal corrosion due to skin exposure to sodium•Dermal hypersensitivity due to skin exposure to poison ivy.•Skin cancer due to ingestion of arsenic or skin exposure to UV light.

Eye ToxicityEye toxicity results from direct contact or internal distribution to the eye. The cornea and conjunctiva are directly exposed to toxicants.Thus, conju-Nctivities and corneal erosion may be observed following occupationalExposure to chemicals.Many household chemicals can cause conjunctivitis.Chemicals in the circulatory system can distribute to the eye and cause cornealOpacity, retinal and optic nerve damage.e.g.

• acids and strong alkalis may cause severe corneal corrosion.

•Corticosteroids may cause cataracts.•Methanol may damage of optic nerves

HepatotoxicityHepatotoxicity is the toxicity to the liver, bile duct and gall bladder.The liver is particularly susceptible to xenobiotics due to a large bloodSupply and its role in metabolism.Thus it is exposed to high doses of Toxicant or its toxic metabolites. The primary form of hepatotoxicity are:

Steatosis: Lipid accumulation in hepatocytesChemical hepatitis: Inflammation of the liverHepatic necrosis: Death of the hepatocytesIntrahepatic cholestasis: Back of the bile salts into the liver cells.Hepatic cancer: cancer of the liver cellsCirrhosis: Chronic fibrosis, often due to alcoholHypersensitivity: Immune reaction resulting in hepatic necrosis.

ImmunotoxicityImmunotoxicity is the toxicity of the immune system. It can take several forms:Hypersensitivity (allergy and autoimmunity),immunodeficiency and uncontrolledProliferation (leukemia and lymphoma). The normal function of the immune systemIs to recognize and defend against foreign invaders. This accomplished by productioOf cells that engulf and destroy the invaders or by antibodies that inactivate foreignMaterials. e.g

•Contact dermatitis due to exposure to poison ivy

•Systemic erythematous in workers exposed to hydrazine

•Immunosuppresion by cocaine

•Leukemia induced by benzene

Nephrotoxicity

The kidney is highly susceptible to toxicants for two major reasons.A high volume of blood flows through it and it filtrates large amountsOf toxins which can concentrate in the kidneys. It can result in systemicToxicity causing:

•Decrease ability to excrete body wastes

•Inability to maintain body fluid and electrolyte balance

•Decreased synthesis of essential hormones ( e.g. erythropoetin)

•Inability to maintain PH balance

NeurotoxicityNeurotoxicity represents toxic damage to cells of the central nervousSystem( brain and spinal chord) and the peripheral nervous system(nerves outside the CNS).

Respiratory toxicityRespiratory toxicity relates to effects on the upper respiratory system(nose,pharynx, larynx, and trachea) and the lower respiratory system(bronchi, brochioles and lung alveoli). The primary types of respiratoryToxicity are: Pulmonary irritationAsthma/ bronchitisReactive airway diseaseEmphysema Allergic alveolitisFibrotic lung diseasePneumoconisisLung cancer

The primary types of neurotoxicities are:

NeuronopathiesAxonopathies Demyelination Interference with neurotransmission

Reproductive toxicity

Reproductive toxicity involves toxic damage to either male or female reproductive system. Toxic effects may cause

Decrease libido and impotence

Infertility

Interrupted pregnancy ( abortion, fatal death, or premature delivery)

Infant death or childhood morbidity

Altered sex ratio and multiple birth

Chromosome abnormalities and birth defects

Childhood cancer.