Classification of Toxic Chemicals

Classification of Toxic Chemicals

Toxic chemicals may be classified according to their function and effects. According to the “international resister of potentially toxic chemical” of the United Nations environment programme, there are four million known chemicals in the world today and another 30000 new compound are added to the list every year. Among these 60000 to 70000 chemicals are commodity used.

According to environment on which it present toxic chemicals are divided into two class:
1. Toxic chemicals in Air
2. Toxic chemicals in water.


1. Toxic chemicals in Air
About 24 extremely hazardous substances in the atmosphere. These are given below:

a) Acrylonitrile
b) As
c) Asbestos
d) Benzene
e) Be
f) Cd
g) Chlorinated solvent
h) CFC
i) Chromates
j) Coke oven emission
k) Diethyl stillbesterol
l) Dibromomonochloropropane
m) Ethylene dibromate
n) Ethylene oxide
o) Pb
p) Hg
q) Nitrosoamine
r) Ozone
s) Polybromominated biphenyl
t) Polychlorinated biphenyl
u) Radiation
v) Sulpher Dioxide
w) Vinyl chloride
x) Toxic waste.



2. Toxic chemicals in water.

A. Arsenic
Sources: mining by-product, pesticides, chem. Waste, etc.
Effects: Toxic, possibly carcinogenic, etc.

B. Cadmium
Sources: Industrial discharge, mining waste, metal plating, water pipes, etc.
Effects: Replaces Zn biochemical, causes high blood pressure, kidney damage, destruction of testicular tissue and red blood cell, toxicology to aquatic bio, etc.


C. Boron
Sources: Coal, Detergent formation, industrial waste, etc.
Effects: toxic to plants, etc.

D. Chromium
Sources: Metal plating, cooling tower, water additives, normally found as chromium polluted water, etc.
Effects: essential trace element, possibly carcinogenic, etc.

E. Copper
Sources: metal plating, industrial and domestic waste, mining, mineral leaching, etc.
Effects: Essential trace element not very toxic to animals, toxic to plant and algae at moderate levels, etc.

F. Fluorine
Sources: Natural geological sources, industrial waste and water additives, etc.
Effects: Prevent tooth decay about 1 mg/l.

G. Lead
Sources: Industry, mining, plumbing, coal, gasoline, etc.
Effects: Toxic, wild-life destroyed, etc.

H. Manganese
Sources: mining, industrial wastes, acid mine drainage, microbial action on manganese minerals at low potential, etc.
Effects: relatively non-toxic to animal, toxic to plant at higher level, stains material, etc.

I. Mercury
Sources: Industrial waste, mining, pesticide, coal, etc.
Effects: highly toxic, etc.

J. Molybdenum
Sources: industrial waste, industrial sources, etc.
Effects: possibly toxic to animal, essential to plant, etc.

K. Selenium
Sources: Natural geological sources, sulphur, coal, etc.
Effects: essential at low level and toxic at high level, etc.

L. Zinc
Sources: Industrial waste, metal plating, plumbing, etc.
Effects: Essential in many metallo-enzyme toxic to plant at higher level, etc.


M. Beryllium
Sources: Coal, nuclear power and space industry, etc.
Effects: Acute and chrome toxicity, possibly carcinogenic, etc.