BY Abisha

A xenobiotic is a foreign chemical substance found within an organism that is not normally naturally produced by or expected to be present within.

It can also cover substances that are present in much higher concentrations than are usual.

Specifically, drugs such as antibiotics are xenobiotics in humans because the human body does not produce them itself, nor are they part of a normal food.

The term xenobiotic is derived from the Greek words ξένος (xenos) = foreigner, stranger and βίος (bios, vios) = life.

They donot occur in nature thus they are foreign to the biosphere

Drugs

Biotransformation

The excretion of xenobiotics, and happens mostly in the liver. Excretion routes are urine, feces, breath, and sweat

Environmental fate of xenobiotic

The effects of xenobiotics on fish tissues: morphological studies.

Emphasis has been placed on two types of contaminants, petroleum hydrocarbons andchlorobiphenyls, as examples of important xenobiotics found in the marine environment

Impact of these contaminants on the olfactory organ, liver, lens, and intestine from several species of fish.

The morphological aspects of damage to the olfactory organs of fish exposed to petroleum hydrocarbons included hyperplasia and attenuation of the chemosensory cilia.

In the liver of fish exposed to chlorobiphenyls, one of the most evident cellular anomalies was whorls of smooth endoplasmic reticulum.

The rough endoplasmic reticulum appeared proliferated and its cisternae were dilated.

Changes in the amount of lipid stored in the hepatocytes have been observed in fish exposed to both petroleum hydrocarbons and chlorobiphenyls.

Some hydrocarbons affected eye tissues.

Fish exposed to petroleum hydrocarbons alone, chlorobiphenyls alone, and the combined contaminants.

All three groups of contaminant-exposed fish have subcellular inclusions that are distinctly abnormal.

A strategy for assessing the effects of xenobiotics on fish reproduction.

xenobiotics may cause disruption of the reproductive endocrine system, or they may directly affect gamete development and viability as a result either of their cytotoxicity or by altering the hormonal environment during gamete development.