Inhalation, dermal , ingestion , etc. various route of toxicant

1. EXPOSURE :- (Toxicant)TRANSPORTATION

2. EXPOSURE ROUTE
Absorption
● Inhalation
● Ingestion
● Dermal contact
● Injection
Excretion
● Urine
● Faeces
● Secretions
● Expired Air

3. INGESTION (Oral) ROUTE
Factors affect absorption
● Type of cells at the specific site.
● Period of time that the substance remains at the site
● pH of stomach or intestinal contents at the site.
● mouth and esophagus,:-Nicotine readily penetrates
the mouth mucosa.
● Nitroglycerin is placed under the tongue (sublingual)
for immediate absorption and treatment of heart
conditions
● The stomach, with its high acidity (pH 1-3), is a
significant site for the absorption of weak organic
acids, which exist in a diffusible, nonionized and
lipid-soluble form. In contrast, weak bases will be
highly ionized and therefore poorly absorbed

4. INGESTION ROUTE
● greatest absorption of chemicals, as with nutrients, takes place in
the intestine, particularly in the small intestine.
● The intestine has a large surface area consisting of outward
projections of the thin (one-cell thick) mucosa into the lumen of
the intestine (the villi)
● . This large surface area facilitates diffusion of substances across
the cell membranes of the intestinal mucosa
● Lipid soluble, small molecules effectively enter the body from the
intestine by passive diffusion.as well by active transport
● biotransformed products may be absorbed and be more toxic than
the ingested substance
● example is the formation of carcinogenic nitrosamines from non-
carcinogenic amines by intestinal flora
Very little absorption takes place in the colon and rectumAnusol
(hydrocortisone preparation) used for the treatment of local
inflammation which is partially absorbed (about 25%)

5. INHALATION ROUTE
● Particles 5 μm or larger usually are deposited in the
nasopharyngeal region and are removed by nose wiping,
blowing, or sneezing. The mucous blanket of the ciliated
nasal surface propels insoluble particles by the movement of
the cilia.
● Next, pharynx or may be absorbed through the nasal
epithelium into blood.
● Particles approximately 2.5 μm are deposited mainly in the
tracheobronchiolar regions of the lungs,
● Particles 1 μm and smaller penetrate to the alveolar sacs of
the lungs. They may be absorbed into blood or cleared
through the lymphatics after being scavenged by alveolar
macrophages.
● lower the solubility, the lower is the removal rate.

6. DERMAL ROUTE
● through the skin, must pass through the epidermis or the
appendages (sweat and sebaceous glands and hair follicles).
● Then pass through seven cell layers before entering the blood
and lymph capillaries in the dermis
● . The rate determining barrier in the dermal absorption of
chemicals is the stratum corneum, the uppermost layer of the
epidermis with densely packed keratinized cells
● next, by diffusion and enter the systemic circulation through
the numerous venous and lymphatic capillaries in the dermis.
Factors increasing absorption
● increased stratum corneum hydration, increased temperature,
which increases dermal blood flow, low solubility of toxicant in
the vehicle, and small size.
● The small size of nanoparticles will potentially increase
penetration and systemic exposures to these small molecules.

7. INJECTION ROUTE
● by special routes, including (1)Intraperitoneal, (2)
subcutaneous, (3) intramuscular, and (4) intravenous.
● The intravenous route introduces the toxicant directly
into the bloodstream elimininating the process of
absorption.
● Intraperitoneal injection results in rapid absorption of
xenobiotics because of the rich blood supply and the
relatively large surface area of the peritoneal cavity.
Intraperitoneally administered compounds are absorbed
primarily through the portal circulation and therefore
must pass through the liver before reaching other organs
by way of systemic circulation.
● Subcutaneously and intramuscular administered
toxicants are usually absorbed at slower rates but enter
directly into the general circulation.

8. STORAGE
● Liver and Kidney as Storage
Depots
● Fat Storage
● Bone as Storage Depot
● Blood–Brain Barrier-CNS
● Passage of Toxicants Across the
Placenta

9. EXCRETION
● compounds are excreted into urine by the same mechanisms
the kidney uses to remove
● end products of intermediary metabolism from the body:
glomerular filtration, tubular excretion by passive diffusion,
and active tubular secretion
● Fecal Excretion
● Biliary excretion
● biotransformation of toxicants, and the metabolites thus
formed may be excreted directly into bile.
● Xenobiotics and/or their metabolites entering the intestine
with bile may be excreted with feces or undergo an
enterohepatic circulation
● Exhalation
● Substances that exist predominantly in the gas phase at body
temperature and volatile liquids are eliminated mainly by the
lungs.
● Cerebrospinal Fluid
● Milk, Sweat and Saliva

10. Ill-Effects of Exposure
● Soma cell-
Carcinogenesis
● Germ cell-Mutagenesis
● Primordial cell-
teratogenesis